Comets, Meteors & Celestial Wonders : A Cosmic Special | Space Nuts: Astronomy Insights & Cosmic...

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Kind: captions
Language: en

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Hello again. Thank you for joining us on


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another episode of Space Nuts. My name


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is Andrew Dunley, your host. It's great


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to have your company. As I mentioned


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last episode, Fred is away for a few


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weeks or a couple of years. No, it's a


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few weeks. And uh in hisstead, we'll be


00:00:16.720 --> 00:00:19.670
joined by Professor Jonty, who you know


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and love because he's been with us


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before and uh he's a part of the team.


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So, uh, we will be doing over the next,


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uh, several episodes, um, taking a


00:00:30.080 --> 00:00:31.750
different approach. Uh, we we're going


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to focus on specific topics within each


00:00:35.920 --> 00:00:38.630
of the episodes. Uh, we could call them


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specials if you like. And today, our


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focus will be on comets and meteors.


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Stick around. We're doing all of that on


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this episode of Space Nuts.


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>> 15 seconds. Guidance is internal. 10 9


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Ignition sequence start.


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>> Space Nuts.


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>> 5 4 3 2


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>> 1 2 3 4 5 5 4 3 2 1


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>> Space Nuts.


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>> Astronauts report. It feels good.


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>> And it's great to have him back.


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Professor Jonty her, professor of


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astrophysics at the University of


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Southern Queensland. Jonty, hello.


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>> Ah, hey. How are you going?


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>> Good. Great to see you again.


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>> Well, it's good to be back. It's


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something nice to keep me entertained


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while I'm having a little bit of a a


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restful couple of weeks. I'm, you know,


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I've got a bit of leave so I'm um


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recovering from a minor surgery and


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therefore I can give my entire forecast


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to talking about fun things rather than


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doing Adam in effectively. But means I


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get to see a little bit of the life Fred


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gets to live.


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>> Yeah, maybe. Yes. Although he he doesn't


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seem to slow down much. Um, in fact, I


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think the worst thing you can do when


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you retire is slow down because um that


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the brain matter decides to give up the


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ghost and that's when it's all over Red


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Rover. But, uh, no, he he's going going


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great guns and um, you didn't mention


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that you're having a little bit of a


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recuperation. Um, are you in a position


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to talk about that or is it too


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embarrassing? Oh, well, it's one of


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those things that when I when I first


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had this pointed out, I a bit


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embarrassed about it, but I don't think


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as blossing


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past a little bit of embarrassment. So,


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I'm in my late 40s and I went to the


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doctor about a year ago cuz I had a


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little bit of bleeding when I was


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sitting down and stuff like this. And


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nothing dramatic. Um, but I found out


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two things. Firstly, in Australia, and I


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don't know about the rest of the world,


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you should look this up, but when you're


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in your 40s, the Medicare system here


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affords the opportunity for you to get


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health checks.


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>> Yep.


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>> Which is brilliant. So, you basically


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get what in the UK they'd call an MOT


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for a car. You get everything run over


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and you get your blood pressure done and


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your heart rate done and everything


00:02:43.519 --> 00:02:45.350
else. And then you go back every 3


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months and do it again and again and


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again. And it's basically, you're at an


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age where things start to break. Let's


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get on top of it early so that you can


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enjoy the rest of your life in peace.


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effectively. I think it's a really good


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idea and I suspect from a government


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point of view makes a lot of sense cuz


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if you find things easy earlier they're


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easier and quicker and cheaper to solve.


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Um, what it turned out from that was I


00:03:06.159 --> 00:03:07.430
spent about two months going back and


00:03:07.440 --> 00:03:09.030
forth with a doctor who thought I had


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one thing wrong, which is not what it


00:03:10.640 --> 00:03:12.869
was. And then I got got sent to this


00:03:12.879 --> 00:03:14.149
specialist who said, "You've got


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something called a fistula down near


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your backside."


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>> Which not life-threatening, not the end


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of the world, not doomed, but it's


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uncomfortable. Um, and you know, it's


00:03:23.519 --> 00:03:24.869
been slightly embarrassing in that I've


00:03:24.879 --> 00:03:27.270
had to learn more about sanitary pads


00:03:27.280 --> 00:03:29.110
than, you know, um, you would have


00:03:29.120 --> 00:03:31.589
expected, you know, which the women in


00:03:31.599 --> 00:03:32.710
the audience are going about bloody


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time. a man learned about this. Um, but


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it's a weird one because it's not


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life-threatening. It's nothing of a


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problem. Something 10 or 20% of guys


00:03:40.879 --> 00:03:42.789
apparently get them, but they can take


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multiple surgeries to fix. And when I


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went in for the first surgery in


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January, the there was another guy there


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who was on surgery number seven.


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>> Wow.


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>> Um, which Yeah. deep and joyous. Um,


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it's kind of day surgery, but you get a


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full general and you go under and doctor


00:03:56.799 --> 00:03:58.309
does snippy snippy things and you get a


00:03:58.319 --> 00:03:59.670
couple of weeks off work, which is where


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I am now. So, I've just had surgery


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number two and the doctor is hopeful,


00:04:04.480 --> 00:04:05.910
confident, whatever that surgery number


00:04:05.920 --> 00:04:08.229
three will be the final fix. And it's


00:04:08.239 --> 00:04:09.509
one of these weird things cuz people


00:04:09.519 --> 00:04:10.550
say, "What's wrong with you?" And if


00:04:10.560 --> 00:04:12.149
it's a sore arm, you just say, "I've


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hurt my arm or you've broken your arm or


00:04:13.840 --> 00:04:15.509
something like that." Or in Australia, a


00:04:15.519 --> 00:04:17.430
really common one, a melanoma. People


00:04:17.440 --> 00:04:19.030
have been in the sun too much. Going


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into hospital, what do you get? Oh, I've


00:04:20.239 --> 00:04:22.150
got a melanoma taken off. But as soon as


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it's anywhere between about your belly


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button and your knee, people are bashful


00:04:25.040 --> 00:04:27.270
about talking about it. And I


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>> first few months I was mortified and


00:04:28.880 --> 00:04:30.629
like wouldn't talk about it. And I


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realization is that if you don't talk


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about it, people don't get checked and


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we as men are terrible for that. And so,


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yeah, worth talking about. I'm a bit


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embarrassed about it, but I shouldn't


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be. And it's good to tune up. And it


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means that in 40 years time, I'll still


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be up and kicking and having a lot of


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fun rather than in discomfort and


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grumbling about a problem I could have


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got fixed.


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>> Yeah. Yeah. And um I think you're right.


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I think men do tend to keep things to


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themselves. uh a lot of them go into


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denial uh or they just think well no


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that won't happen to me so no problem


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but uh when I was diagnosed with


00:05:05.919 --> 00:05:08.150
prostate cancer it was like a bolt from


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the blue and I didn't I I I never


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expected to get it because there was


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next to no history of it in my family so


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um that was that was a bit of a shock


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and this is what how long is it now 3


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years 3 years and I'm still working my


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way through it. So, um, but the latest


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scans are all good. So, fingers crossed


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that we've, you know, reached a a good


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position. But, um, it it's just an


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ongoing thing in your life. You just got


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to get used to it. But, you my my advice


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to men is go and get checked. If you're


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over 50, go and get a prostate exam. Go


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and get your PSA tests done because if


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you don't


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and then they find it, it might be too


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far along. Um and then then the then the


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treatment becomes more dramatic.


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>> So anyway um it's a good thing to bring


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up.


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>> It is and it goes for the mental health


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stuff as well. I have a former partner


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of mine kind of 20 years ago who was


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very severely bipolar. Had a lot of


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challenges and she was continually


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frustrated by people's responses to that


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in public in that it's a hidden illness.


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It's there. She's getting treatment. But


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what she always said is, "It's real


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frustrating. If I if I had a broken leg


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or I had an injury to my arm and people


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could see it, they'd be supportive." But


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with mental health, she got a hell of a


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lot of, "Oh, just get over it or toughen


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up or


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>> Yep."


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>> And


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>> and you know, she was female, so she's


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more likely to go to the doctor and talk


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about it statistically. Men with mental


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health challenges tend to avoid that


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even more than they'll go to the doctor


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with physical health challenges. And


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it's something I'd like to see change. I


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come from a workingass background in


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Yorkshire where men don't talk about


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anything. You know, you're meant to be


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stoic and the only the only expression


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of emotion you're allowed is rage or a


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single manly tear. You know, it's


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>> really crazy the way we're conditioned.


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And even though I'm, you know, I went to


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uni, I've had a life, I've grown up, all


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this stuff still there at the back of


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your head and you've got to fight


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against it because the instinct is, ah,


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there's nothing wrong. I won't bother.


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>> Yeah.


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>> Yeah. And uh yeah, you see it way too


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often. Um, I I know it's a departure


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from what this podcast is all about, but


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I I


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when given the opportunity will, um,


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openly say to men, um, you know, don't


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don't hesitate to go to the doctor, not


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not when you think something's wrong,


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just preemptively go and get once a


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year, go and get checked and make sure


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everything's where it's supposed to be


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or whatever. Um,


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>> we do it do it for our cars, we do it


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for our pets.


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>> Yeah. Yeah, do it for yourself as well.


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>> Yeah, exactly.


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>> And yeah, I think it's probably a record


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for the quickest we've ever got off


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topic and possibly we should have a


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trigger warning at the front of it and


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all the rest of it, but no, good way to


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start even though it is off topic.


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>> It's okay. We'll get on to topic right


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now because uh what uh as I mentioned


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these these uh next uh several uh


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episodes are going to be dedicated to


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singular topics each and today it's uh


00:08:06.400 --> 00:08:09.029
well related topics, comets and meteors.


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Uh, this is a this is a pet topic of


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yours. I imagine


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>> it is. I I've always been a bit more


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into the nearby stuff than the more


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distant stuff. So, it always tickles me


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a little bit that when questions come in


00:08:20.720 --> 00:08:22.390
when I'm on the show, we get all the big


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bang and cosmology ones. And I'm sure if


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you got someone like the wonderful


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Tamara Davis on to talk cosmology, she'd


00:08:27.759 --> 00:08:29.029
get all the planets questions. It's


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always the way it goes. Yeah.


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>> But comets and meteors a big part of


00:08:32.640 --> 00:08:34.790
what hooked me into astronomy as a kid.


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And my thinking behind this is that


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we're recording in advance. You know, um


00:08:39.839 --> 00:08:42.630
obviously Fred is away, but you've got


00:08:42.640 --> 00:08:44.949
recordings with Fred already. And so the


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news that we would normally talk about


00:08:46.399 --> 00:08:49.430
hasn't happened yet. So I I have many


00:08:49.440 --> 00:08:50.790
talents, but seeing Into the Future


00:08:50.800 --> 00:08:52.310
isn't one of them to that degree. And so


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I thought it better to have a discussion


00:08:54.160 --> 00:08:55.750
about the general stuff in a bit more


00:08:55.760 --> 00:08:57.350
depth


00:08:57.360 --> 00:08:59.670
than go into particular news topics. And


00:08:59.680 --> 00:09:01.350
it's it could almost be a bit of an


00:09:01.360 --> 00:09:03.269
explainer, a bit of the background, and


00:09:03.279 --> 00:09:05.509
hopefully at least gives my insight into


00:09:05.519 --> 00:09:07.030
why a given topic's interesting, but


00:09:07.040 --> 00:09:09.190
also what people can look out for in the


00:09:09.200 --> 00:09:12.070
future and how they can get more into


00:09:12.080 --> 00:09:14.710
more out of that particular topic, if


00:09:14.720 --> 00:09:15.750
that makes sense.


00:09:15.760 --> 00:09:16.550
>> Yeah.


00:09:16.560 --> 00:09:18.310
>> Um, a little bit different. I understand


00:09:18.320 --> 00:09:20.310
for some listeners it might be a bit bit


00:09:20.320 --> 00:09:22.310
of an abrupt departure and a change. So,


00:09:22.320 --> 00:09:23.269
it'll be interesting to see what


00:09:23.279 --> 00:09:25.509
feedback you get. But hopefully people


00:09:25.519 --> 00:09:27.030
like it as a little bit of a change in a


00:09:27.040 --> 00:09:28.790
breath of fresh air. And if they don't,


00:09:28.800 --> 00:09:30.070
well, there's only a couple of episodes


00:09:30.080 --> 00:09:31.990
and Fred's back anyway, so you'll have


00:09:32.000 --> 00:09:33.590
to deal with it and we'll see.


00:09:33.600 --> 00:09:35.350
>> I'm sure it'll be fine. Comets and


00:09:35.360 --> 00:09:39.030
meteors are a very uh popular topic. So,


00:09:39.040 --> 00:09:41.110
um, where do we start? Maybe maybe look


00:09:41.120 --> 00:09:43.190
at a bit of the history of this.


00:09:43.200 --> 00:09:45.670
>> Yeah, I think that is a always a good


00:09:45.680 --> 00:09:46.790
place to start because it sets the


00:09:46.800 --> 00:09:49.269
context of where we are now. And for


00:09:49.279 --> 00:09:51.829
both comets and meteors, there's a kind


00:09:51.839 --> 00:09:54.389
of global connection society that really


00:09:54.399 --> 00:09:57.829
predates by a long long way our


00:09:57.839 --> 00:09:59.670
scientific knowledge essentially the


00:09:59.680 --> 00:10:01.030
modern scientific viewpoint and the


00:10:01.040 --> 00:10:03.509
scientific method. All cultures across


00:10:03.519 --> 00:10:05.030
the world from our wonderful traditional


00:10:05.040 --> 00:10:07.269
owners here in Australia to the peoples


00:10:07.279 --> 00:10:09.590
of every continent and every land both


00:10:09.600 --> 00:10:12.550
current and past historically had a


00:10:12.560 --> 00:10:14.150
really firm connection to the night sky.


00:10:14.160 --> 00:10:15.590
They knew the night sky better than most


00:10:15.600 --> 00:10:17.110
people these days do because it wasn't


00:10:17.120 --> 00:10:19.030
light pollution. There weren't TVs and


00:10:19.040 --> 00:10:21.590
Xboxes. So the sky was something people


00:10:21.600 --> 00:10:24.069
were much more exposed to.


00:10:24.079 --> 00:10:25.910
A lot of cultures had this kind of idea


00:10:25.920 --> 00:10:28.949
of as above so below, as below so above.


00:10:28.959 --> 00:10:30.949
So they were very firmly of the idea


00:10:30.959 --> 00:10:32.949
that major events on the earth were


00:10:32.959 --> 00:10:35.430
reflected in the sky and major events in


00:10:35.440 --> 00:10:37.430
the sky would have their counterparts on


00:10:37.440 --> 00:10:40.230
the earth. And that's where astrology


00:10:40.240 --> 00:10:42.310
was born. And for a long time astrology


00:10:42.320 --> 00:10:44.069
and astronomy were one and the same. You


00:10:44.079 --> 00:10:46.550
know, people doing astronomy studies


00:10:46.560 --> 00:10:47.990
were doing it because they wanted to


00:10:48.000 --> 00:10:49.350
understand the events that would


00:10:49.360 --> 00:10:51.590
influence what's on the earth. And there


00:10:51.600 --> 00:10:53.750
are good examples of this in terms of


00:10:53.760 --> 00:10:55.670
the nominally fixed stars. Things like


00:10:55.680 --> 00:10:58.230
the ancient Egyptians using the rising


00:10:58.240 --> 00:11:00.630
of Sirius in the dawn sky after it


00:11:00.640 --> 00:11:02.710
disappeared in the evenings as a


00:11:02.720 --> 00:11:04.150
predictor of the flooding of the Nile,


00:11:04.160 --> 00:11:05.590
for example, the use of the night sky as


00:11:05.600 --> 00:11:08.710
a calendar. Lots of stuff like that. But


00:11:08.720 --> 00:11:10.389
because people were so aware of the


00:11:10.399 --> 00:11:13.509
night sky, anything that was ephemeral,


00:11:13.519 --> 00:11:15.110
anything that was transitory that


00:11:15.120 --> 00:11:16.550
appeared and then disappeared that was


00:11:16.560 --> 00:11:19.190
unexpected was often seen as kind of a


00:11:19.200 --> 00:11:22.790
potent or an omen. Something that was an


00:11:22.800 --> 00:11:24.310
indication either of major change and


00:11:24.320 --> 00:11:26.150
upheaval currently happening or one soon


00:11:26.160 --> 00:11:28.949
to come. And really bright comets and


00:11:28.959 --> 00:11:30.949
spectacular meteor showers kind of often


00:11:30.959 --> 00:11:33.110
filled this role. And you can go back


00:11:33.120 --> 00:11:35.269
through ancient history where we have


00:11:35.279 --> 00:11:37.509
the records and see good examples of


00:11:37.519 --> 00:11:40.389
this. I've got in one of my talks talks


00:11:40.399 --> 00:11:45.509
about a guy called Mithridatis um up 6 I


00:11:45.519 --> 00:11:46.710
think his name was. He was one of the


00:11:46.720 --> 00:11:48.949
great enemies of the Roman Empire. And


00:11:48.959 --> 00:11:51.509
there are quotes ascribed to him saying


00:11:51.519 --> 00:11:53.910
things like um even the heavens


00:11:53.920 --> 00:11:55.670
predicted the greatness of this man. For


00:11:55.680 --> 00:11:57.190
in the year in which he was born and the


00:11:57.200 --> 00:11:59.190
year in which he came to reign, a comet


00:11:59.200 --> 00:12:02.630
shone through both periods for 70 days


00:12:02.640 --> 00:12:04.870
as bright as the sun. Each rising and


00:12:04.880 --> 00:12:06.949
setting took four hours each. And that's


00:12:06.959 --> 00:12:08.870
kind of hyperbolic, but it gives this


00:12:08.880 --> 00:12:11.350
idea that people saw something in the


00:12:11.360 --> 00:12:14.069
sky that was unusual and tied it to


00:12:14.079 --> 00:12:16.470
events on Earth. Another good example


00:12:16.480 --> 00:12:18.550
would be the alleged comet called


00:12:18.560 --> 00:12:23.269
Caesar's comet in 44 BC 43US 43


00:12:23.279 --> 00:12:26.389
which is recorded in Roman writings from


00:12:26.399 --> 00:12:29.990
a century or two later talking about


00:12:30.000 --> 00:12:31.990
after the death of Caesar a comet blazed


00:12:32.000 --> 00:12:34.710
in the sky for seven days that was


00:12:34.720 --> 00:12:36.310
spectacularly bright. then disappeared


00:12:36.320 --> 00:12:38.310
and was never seen again. Now, that


00:12:38.320 --> 00:12:39.990
comet is a really good example of the


00:12:40.000 --> 00:12:42.310
challenge people have with historical


00:12:42.320 --> 00:12:43.990
records


00:12:44.000 --> 00:12:45.269
>> because on the one hand, you've got


00:12:45.279 --> 00:12:46.629
these clear reports from the Roman


00:12:46.639 --> 00:12:49.190
Empire. None of them at the time though,


00:12:49.200 --> 00:12:51.829
all of them a bit later on. But that


00:12:51.839 --> 00:12:53.430
comet is not recorded from anywhere else


00:12:53.440 --> 00:12:54.790
on the planet and there were cultures


00:12:54.800 --> 00:12:56.790
around the globe leaving records like


00:12:56.800 --> 00:12:58.710
ancient China and ancient Korea who


00:12:58.720 --> 00:13:01.430
would have seen it. So, was that comet


00:13:01.440 --> 00:13:03.590
real? Or was it a case of after the


00:13:03.600 --> 00:13:05.829
event people inventing a night sky


00:13:05.839 --> 00:13:08.629
phenomena to tie with the soul of the


00:13:08.639 --> 00:13:10.710
emperor rising to heaven? It's one of


00:13:10.720 --> 00:13:12.069
the challenges people in the kind of


00:13:12.079 --> 00:13:13.829
cultural astronomy space face, I think,


00:13:13.839 --> 00:13:15.910
in terms of disentangling


00:13:15.920 --> 00:13:17.750
the narrative from the events that


00:13:17.760 --> 00:13:19.110
prompted it, if that kind of makes


00:13:19.120 --> 00:13:19.670
sense.


00:13:19.680 --> 00:13:22.629
>> Yeah. But what's certainly true is that


00:13:22.639 --> 00:13:24.230
for as long as we've looked at the sky,


00:13:24.240 --> 00:13:26.870
really bright comets and unusually


00:13:26.880 --> 00:13:29.350
powerful meteor showers were things that


00:13:29.360 --> 00:13:31.590
people took note of. And recently there


00:13:31.600 --> 00:13:33.509
was a lot of meteor media coverage of


00:13:33.519 --> 00:13:36.230
the April Lyid meteor shower, which is


00:13:36.240 --> 00:13:37.750
not one of the strongest of the year,


00:13:37.760 --> 00:13:40.389
but one of the reasonable moderate ones.


00:13:40.399 --> 00:13:41.910
It's a kind of one that if you're a


00:13:41.920 --> 00:13:43.509
meteor enthusiast, you'll go out and


00:13:43.519 --> 00:13:44.870
watch, but isn't worth going out if


00:13:44.880 --> 00:13:46.150
you're not that interested cuz there's


00:13:46.160 --> 00:13:48.069
too few. M


00:13:48.079 --> 00:13:49.430
>> I had to grumble about some of the


00:13:49.440 --> 00:13:50.790
coverage here in Australia cuz it's not


00:13:50.800 --> 00:13:53.110
a great shower for us. But that meteor


00:13:53.120 --> 00:13:55.590
shower was recognized by the traditional


00:13:55.600 --> 00:13:57.030
owners in Australia and there are


00:13:57.040 --> 00:13:59.590
stories from Victoria from I think the


00:13:59.600 --> 00:14:01.110
Bong people although I stand to be


00:14:01.120 --> 00:14:03.189
corrected on that that associate this


00:14:03.199 --> 00:14:04.949
meteor shower with the Malifile one of


00:14:04.959 --> 00:14:07.189
the big grand nesting birds in Australia


00:14:07.199 --> 00:14:09.509
which nests around that time of year.


00:14:09.519 --> 00:14:11.269
The meteors seen shrieking from low in


00:14:11.279 --> 00:14:12.949
the northern sky were viewed as being


00:14:12.959 --> 00:14:15.030
the dust being kicked up by the nesting


00:14:15.040 --> 00:14:17.350
bird celestially. So they recorded this


00:14:17.360 --> 00:14:18.790
meteor shower, even though it isn't a


00:14:18.800 --> 00:14:22.389
particularly strong one. But our oldest


00:14:22.399 --> 00:14:24.550
written record of any meteor shower is


00:14:24.560 --> 00:14:26.389
the Aprils and it's dated back to


00:14:26.399 --> 00:14:29.670
something like 687 B.CE when stars fell


00:14:29.680 --> 00:14:31.350
like rain when there was a major storm


00:14:31.360 --> 00:14:33.509
from the Lyids and it was significant


00:14:33.519 --> 00:14:36.310
enough for people to record. So comets


00:14:36.320 --> 00:14:39.189
and meteors way before the modern


00:14:39.199 --> 00:14:41.670
scientific understanding of them really


00:14:41.680 --> 00:14:45.110
had this important cultural role. Um,


00:14:45.120 --> 00:14:46.710
even in the Battle of Hastings, if you


00:14:46.720 --> 00:14:48.949
ever go to see the bio tapestry, this


00:14:48.959 --> 00:14:51.030
wonderful woven record of the Battle of


00:14:51.040 --> 00:14:52.629
Hastings and the invasion of William the


00:14:52.639 --> 00:14:55.030
Conqueror, Comet Hi features prominently


00:14:55.040 --> 00:14:58.069
on that because in 1066,


00:14:58.079 --> 00:14:59.829
>> you had the second best apparition of


00:14:59.839 --> 00:15:01.750
Comet Halley in the last 2,000 years.


00:15:01.760 --> 00:15:03.750
Arguably, it was very spectacular in the


00:15:03.760 --> 00:15:05.430
sky at the time the conquest was going


00:15:05.440 --> 00:15:07.430
on. And that was considered important


00:15:07.440 --> 00:15:10.310
enough to be recorded in the tapestry


00:15:10.320 --> 00:15:12.150
that was woven at the time. You know,


00:15:12.160 --> 00:15:14.949
it's amazing that you've got this panel


00:15:14.959 --> 00:15:16.389
where there's all the peasants pointing


00:15:16.399 --> 00:15:18.389
up at this thing in the sky and somebody


00:15:18.399 --> 00:15:20.069
whispering King Harold's ear about the


00:15:20.079 --> 00:15:22.310
comet that's visible. So yeah, don't


00:15:22.320 --> 00:15:24.710
know whether the invading forces took it


00:15:24.720 --> 00:15:26.230
as a good sign or a bad sign, but they


00:15:26.240 --> 00:15:27.670
thought it was important enough to


00:15:27.680 --> 00:15:29.030
include.


00:15:29.040 --> 00:15:31.189
>> So that in itself's fairly breathtaking.


00:15:31.199 --> 00:15:32.949
And so when we see these objects, it's a


00:15:32.959 --> 00:15:35.350
lovely connection to thousands of years


00:15:35.360 --> 00:15:37.750
of our heritage of people looking at the


00:15:37.760 --> 00:15:41.350
night sky in wonder. I think the first


00:15:41.360 --> 00:15:45.590
step we had really in moving from


00:15:45.600 --> 00:15:48.230
cultural commentary astronomy to modern


00:15:48.240 --> 00:15:50.629
scientific astronomy in a way came with


00:15:50.639 --> 00:15:53.670
the great comet of 1577


00:15:53.680 --> 00:15:56.230
which was another of the really amazing


00:15:56.240 --> 00:15:58.949
spectacular bright comets that was


00:15:58.959 --> 00:16:01.670
widely observed hence why it's a great


00:16:01.680 --> 00:16:03.910
comet but it was observed by the great


00:16:03.920 --> 00:16:06.550
astronomer Tiko Brahhe and I'm sure


00:16:06.560 --> 00:16:08.710
Brahe is featured on the podcast many


00:16:08.720 --> 00:16:10.470
times before, but the quirky individual


00:16:10.480 --> 00:16:12.550
he was. It's well worth looking up his


00:16:12.560 --> 00:16:15.350
Wikipedia record. Is this wealthy


00:16:15.360 --> 00:16:18.069
nobleman with a silver replacement nose


00:16:18.079 --> 00:16:20.310
after he lost half his nose in a duel?


00:16:20.320 --> 00:16:21.910
He's that guy.


00:16:21.920 --> 00:16:22.230
>> Yes.


00:16:22.240 --> 00:16:24.389
>> Yes. Um he had a pet moose that died


00:16:24.399 --> 00:16:25.749
when it fell down the steps because it


00:16:25.759 --> 00:16:27.670
got drunk at a banquet. He


00:16:27.680 --> 00:16:31.189
>> really odd odd man. Um but probably


00:16:31.199 --> 00:16:33.910
viewed as being the last great pre-


00:16:33.920 --> 00:16:36.150
telescope astron astronomical observer


00:16:36.160 --> 00:16:38.310
if that makes sense. Naked eye observer.


00:16:38.320 --> 00:16:40.710
Now, at this time, comets were kind of


00:16:40.720 --> 00:16:42.310
thought to be probably atmospheric


00:16:42.320 --> 00:16:44.710
phenomenon. They were nearby, high in


00:16:44.720 --> 00:16:46.550
the atmosphere,


00:16:46.560 --> 00:16:48.949
and so that was what was going on.


00:16:48.959 --> 00:16:50.710
People had that kind of idea. He


00:16:50.720 --> 00:16:53.269
realized that if that were true, these


00:16:53.279 --> 00:16:55.189
things would display a noticeable


00:16:55.199 --> 00:16:57.430
parallax if people observed them from


00:16:57.440 --> 00:16:58.629
different locations.


00:16:58.639 --> 00:16:59.110
>> Uhhuh.


00:16:59.120 --> 00:17:01.189
>> So, in other words, people looking from


00:17:01.199 --> 00:17:03.509
different locations would see the comet


00:17:03.519 --> 00:17:05.590
in a different place in the sky because


00:17:05.600 --> 00:17:07.510
it was in the foreground. It's the same


00:17:07.520 --> 00:17:09.029
technique we use to measure the distance


00:17:09.039 --> 00:17:11.189
to the nearest stars. If you put your


00:17:11.199 --> 00:17:12.870
finger in front of your face and look at


00:17:12.880 --> 00:17:14.230
it through one eye and then look through


00:17:14.240 --> 00:17:15.829
the other, you'll see your finger


00:17:15.839 --> 00:17:17.990
blinking side to side. And the further


00:17:18.000 --> 00:17:20.390
away your finger is, the less it moves.


00:17:20.400 --> 00:17:21.909
>> We use that to measure the distance to


00:17:21.919 --> 00:17:23.590
stars by observing from one side of the


00:17:23.600 --> 00:17:25.429
Earth's orbit than the other. But what


00:17:25.439 --> 00:17:27.510
Brah did was collect observations from


00:17:27.520 --> 00:17:29.909
around Europe of where the comet was in


00:17:29.919 --> 00:17:33.350
the sky. With those observations, he


00:17:33.360 --> 00:17:34.549
would have been able to detect a


00:17:34.559 --> 00:17:37.110
parallax for the comet if it were closer


00:17:37.120 --> 00:17:39.190
than the orbit of the moon. So if it was


00:17:39.200 --> 00:17:40.950
atmospheric, absolutely definitely would


00:17:40.960 --> 00:17:43.350
do. But no measurable parallax was


00:17:43.360 --> 00:17:45.350
found, which showed the comet had to be


00:17:45.360 --> 00:17:47.190
at least a couple of million km away.


00:17:47.200 --> 00:17:48.950
And in fact, it was probably several


00:17:48.960 --> 00:17:51.750
tens of millions of kilome distant. He


00:17:51.760 --> 00:17:53.830
got this beautiful figure and I've I use


00:17:53.840 --> 00:17:56.470
this in my talks occasionally that is


00:17:56.480 --> 00:17:58.150
his drawing of the motion of the comet


00:17:58.160 --> 00:18:00.070
and it's fascinating from cultural point


00:18:00.080 --> 00:18:02.230
of view because it's clearly at the time


00:18:02.240 --> 00:18:03.990
when you still have the geocentric model


00:18:04.000 --> 00:18:05.190
the earth was the center of the


00:18:05.200 --> 00:18:07.029
universe. So you've got the Earth in the


00:18:07.039 --> 00:18:09.029
middle, the Sun going around the Earth,


00:18:09.039 --> 00:18:10.630
but then Mercury, Venus, and the Moon


00:18:10.640 --> 00:18:12.150
going around the Sun,


00:18:12.160 --> 00:18:14.150
>> this kind of weird hybrid thing, but


00:18:14.160 --> 00:18:15.669
you've got the path of the comet moving


00:18:15.679 --> 00:18:17.750
through there that he's determined. And


00:18:17.760 --> 00:18:19.990
what's really interesting to me, what's


00:18:20.000 --> 00:18:22.310
really fascinating is he's got the tails


00:18:22.320 --> 00:18:24.390
pointing away from the sun all the time.


00:18:24.400 --> 00:18:26.150
So he's got the phenomenology of where


00:18:26.160 --> 00:18:28.230
the comet is in the solar system,


00:18:28.240 --> 00:18:31.110
modular, the the sun's going around the


00:18:31.120 --> 00:18:33.270
Earth, and the tails pointing the right


00:18:33.280 --> 00:18:36.070
way as it moves. tales of comets always


00:18:36.080 --> 00:18:38.549
pointing away from the sun. And to me


00:18:38.559 --> 00:18:41.270
that kind of marks the dawn of the


00:18:41.280 --> 00:18:44.390
modern scientific view of comets from


00:18:44.400 --> 00:18:46.789
the cultural we don't know what they are


00:18:46.799 --> 00:18:49.350
but they are important.


00:18:49.360 --> 00:18:51.590
>> I think that's a real kind of boundary


00:18:51.600 --> 00:18:52.549
point for me.


00:18:52.559 --> 00:18:54.390
>> Yeah. Yeah. Fascinating. I was actually


00:18:54.400 --> 00:18:56.070
going to ask you about the uh you know


00:18:56.080 --> 00:18:58.310
the point in time where we went from the


00:18:58.320 --> 00:19:01.909
mythology to the understanding that this


00:19:01.919 --> 00:19:04.310
this was something else and yeah you


00:19:04.320 --> 00:19:06.390
covered that beautifully. Going to just


00:19:06.400 --> 00:19:08.950
take a breath on Space Nuts. Uh you're


00:19:08.960 --> 00:19:10.950
with Andrew Dunley and Professor Jonty


00:19:10.960 --> 00:19:13.029
Horner.


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00:21:01.200 --> 00:21:02.710
>> G. And I feel


00:21:02.720 --> 00:21:03.669
>> Space Nuts.


00:21:03.679 --> 00:21:05.750
>> I did say a breath. That was quick. Um,


00:21:05.760 --> 00:21:07.830
let's continue talking about comets and


00:21:07.840 --> 00:21:10.310
meteors. There have been a lot of them


00:21:10.320 --> 00:21:14.310
in the news of late uh comet pan stars


00:21:14.320 --> 00:21:17.190
is um you know it was very very uh


00:21:17.200 --> 00:21:22.630
popular late April. uh and uh we we've


00:21:22.640 --> 00:21:25.750
seen in recent times u a new kind of


00:21:25.760 --> 00:21:27.270
comet and those are the ones that are


00:21:27.280 --> 00:21:31.270
coming from other systems uh not not the


00:21:31.280 --> 00:21:34.149
ones that are con continually rotating


00:21:34.159 --> 00:21:35.830
through our own solar system. We've had


00:21:35.840 --> 00:21:39.350
these exo comets that have been quite


00:21:39.360 --> 00:21:42.310
intriguing and and uh opening up all


00:21:42.320 --> 00:21:44.549
sorts of new ideas and questions about


00:21:44.559 --> 00:21:47.270
uh comets and other other parts of the


00:21:47.280 --> 00:21:49.110
the universe and what we could learn


00:21:49.120 --> 00:21:53.029
from them. Um and and new comets are


00:21:53.039 --> 00:21:54.870
being discovered all the time. That


00:21:54.880 --> 00:21:56.070
doesn't mean they haven't been here


00:21:56.080 --> 00:21:58.470
before, but it does mean that they've


00:21:58.480 --> 00:22:02.630
got very longitudinal travel times. So,


00:22:02.640 --> 00:22:04.710
um, you know, some we won't ever see


00:22:04.720 --> 00:22:06.630
because we'll have been and gone before


00:22:06.640 --> 00:22:10.149
they get here, and others we'll maybe


00:22:10.159 --> 00:22:12.950
see several times during our lifetimes.


00:22:12.960 --> 00:22:15.270
>> Absolutely. Now, historically, people


00:22:15.280 --> 00:22:17.669
broke the comets we found down into two


00:22:17.679 --> 00:22:20.230
categories. We had short period comets,


00:22:20.240 --> 00:22:22.630
which are comets. The definition when I


00:22:22.640 --> 00:22:24.390
was a kid was comets whose orbital


00:22:24.400 --> 00:22:26.549
periods were less than 200 years.


00:22:26.559 --> 00:22:27.830
Shorter than that and you were a short


00:22:27.840 --> 00:22:29.270
period comet. Longer than that, and you


00:22:29.280 --> 00:22:31.029
were a long period comet. Now there are


00:22:31.039 --> 00:22:33.029
subtleties within that. Within the short


00:22:33.039 --> 00:22:34.710
period comets we have comets like comet


00:22:34.720 --> 00:22:36.149
Halley which are called the Halley type


00:22:36.159 --> 00:22:38.789
comets which come around with a period


00:22:38.799 --> 00:22:40.470
comparable to a human lifetime or a bit


00:22:40.480 --> 00:22:42.149
longer. And the two brightest and most


00:22:42.159 --> 00:22:43.430
famous of those are comet Halley and


00:22:43.440 --> 00:22:44.950
comet Swift Tuttle.


00:22:44.960 --> 00:22:46.789
>> You then have the Jupiter family comets


00:22:46.799 --> 00:22:48.789
which are comets whose orbits are just a


00:22:48.799 --> 00:22:50.549
few years and are typically under


00:22:50.559 --> 00:22:52.950
Jupiter's control. And when I was a kid,


00:22:52.960 --> 00:22:54.789
anything longer than 200 years was


00:22:54.799 --> 00:22:57.110
considered long period. Now that kind of


00:22:57.120 --> 00:22:58.710
got smashed into the ground a bit in the


00:22:58.720 --> 00:23:01.110
early 2000s when comet Eaya Jang was


00:23:01.120 --> 00:23:04.950
cited because comet Eaya Jang was very


00:23:04.960 --> 00:23:06.470
well observed. Its orbit was well


00:23:06.480 --> 00:23:07.750
calculated. It was found to have a


00:23:07.760 --> 00:23:10.950
period of 366 years I think it is and


00:23:10.960 --> 00:23:13.029
that allowed people to identify the


00:23:13.039 --> 00:23:14.870
previous observations of that comet from


00:23:14.880 --> 00:23:17.430
the last time it was around. So that's


00:23:17.440 --> 00:23:19.909
currently the record holder where we're


00:23:19.919 --> 00:23:22.390
absolutely certain that it's been seen


00:23:22.400 --> 00:23:25.350
on multiple occasions and it has a a


00:23:25.360 --> 00:23:27.750
periodic comet designation. Now now a


00:23:27.760 --> 00:23:29.990
subtlety to that is we do have the crot


00:23:30.000 --> 00:23:31.510
sungrazing comets and I can talk more


00:23:31.520 --> 00:23:33.909
about them a little later where we have


00:23:33.919 --> 00:23:36.470
a strong identification between an


00:23:36.480 --> 00:23:38.549
observation of the comet say with comedy


00:23:38.559 --> 00:23:40.789
Keki in 1965


00:23:40.799 --> 00:23:44.070
and a previous apparition in the 1100s


00:23:44.080 --> 00:23:46.789
which is about an 800year return. Yeah,


00:23:46.799 --> 00:23:48.950
>> that's a bit woolly because the comets


00:23:48.960 --> 00:23:50.950
we observe now are fragments of one


00:23:50.960 --> 00:23:53.669
comet back then and so therefore several


00:23:53.679 --> 00:23:55.350
comets tied to that initial apparition.


00:23:55.360 --> 00:23:57.909
So there's all that complexity there. We


00:23:57.919 --> 00:24:00.470
then have the long period comets which


00:24:00.480 --> 00:24:03.750
like I say were 200 years or more. It


00:24:03.760 --> 00:24:05.990
still kind of is but with those objects


00:24:06.000 --> 00:24:07.270
that are both long period and short


00:24:07.280 --> 00:24:08.870
period thanks to a jang. You've got


00:24:08.880 --> 00:24:10.549
these objects whose orbital periods are


00:24:10.559 --> 00:24:12.950
so long that they are marketkedly longer


00:24:12.960 --> 00:24:15.350
than a human lifetime. even if they're


00:24:15.360 --> 00:24:16.710
comets that have been through before. So


00:24:16.720 --> 00:24:18.950
a good example of a really bright comet


00:24:18.960 --> 00:24:21.350
that is considered long period but has


00:24:21.360 --> 00:24:23.350
been through many times before is comet


00:24:23.360 --> 00:24:25.909
Hailbop. Comet Hailbop was spectacular


00:24:25.919 --> 00:24:28.549
in 9697. It was visible with a naked eye


00:24:28.559 --> 00:24:30.149
for 18 months shattering all the


00:24:30.159 --> 00:24:32.390
records. It will be back in about the


00:24:32.400 --> 00:24:34.310
year 4400. It was the last round when


00:24:34.320 --> 00:24:36.549
the Egyptians were building pyramids.


00:24:36.559 --> 00:24:39.190
And that is perversely a long period


00:24:39.200 --> 00:24:40.870
comet with a relatively short period


00:24:40.880 --> 00:24:43.909
orbit for a long period of comet. And so


00:24:43.919 --> 00:24:45.269
scientifically we'd call that


00:24:45.279 --> 00:24:48.390
dynamically old or not a new comet


00:24:48.400 --> 00:24:49.669
because it's been around a number of


00:24:49.679 --> 00:24:52.789
times. At the very long period end of


00:24:52.799 --> 00:24:54.149
the long period comets you get things


00:24:54.159 --> 00:24:56.390
that are coming in from halfway to the


00:24:56.400 --> 00:24:58.230
nearest star from a region we describe


00:24:58.240 --> 00:25:01.590
as the or cloud or the opic cloud. And


00:25:01.600 --> 00:25:03.990
those things on their way in have


00:25:04.000 --> 00:25:06.470
calculated orbital periods of hundreds


00:25:06.480 --> 00:25:09.190
of thousands or even millions of years.


00:25:09.200 --> 00:25:10.710
And many of those actually only come


00:25:10.720 --> 00:25:12.630
through once and then they get nudged


00:25:12.640 --> 00:25:14.549
and ejected from the solar system never


00:25:14.559 --> 00:25:15.750
to return


00:25:15.760 --> 00:25:17.990
>> going out to wander among the stars. And


00:25:18.000 --> 00:25:19.590
it's objects like that that will become


00:25:19.600 --> 00:25:22.710
the interstellar comets for other stars


00:25:22.720 --> 00:25:24.549
in the same way that this third group of


00:25:24.559 --> 00:25:26.070
comets that you alluded to that we found


00:25:26.080 --> 00:25:28.710
recently are interstellar comets in our


00:25:28.720 --> 00:25:30.310
system. So these are the objects coming


00:25:30.320 --> 00:25:32.549
through so quickly that they are not


00:25:32.559 --> 00:25:34.870
gravitationally bound to the sun, but


00:25:34.880 --> 00:25:36.470
also so quickly that there is no


00:25:36.480 --> 00:25:38.630
possibility that they ever were. They've


00:25:38.640 --> 00:25:40.870
been flung in so quickly that they must


00:25:40.880 --> 00:25:44.070
come from another place. The most recent


00:25:44.080 --> 00:25:46.390
one was ThreeI Atlas, which got talked


00:25:46.400 --> 00:25:49.029
about a huge amount. Yes. Was definitely


00:25:49.039 --> 00:25:51.909
not an alien spaceship. And to avoid


00:25:51.919 --> 00:25:53.750
getting too political, just a very brief


00:25:53.760 --> 00:25:55.190
comment on that because it needs to be


00:25:55.200 --> 00:25:57.909
stated and restated, which is that the


00:25:57.919 --> 00:25:59.510
arguments of that being an alien


00:25:59.520 --> 00:26:02.310
spaceship were the work of one person. M


00:26:02.320 --> 00:26:04.310
>> one person who is not a solar system


00:26:04.320 --> 00:26:06.149
astronomer historically but has reached


00:26:06.159 --> 00:26:08.549
that age and level of senility that they


00:26:08.559 --> 00:26:10.310
believe they can be an expert in things


00:26:10.320 --> 00:26:12.390
that they are not and has a certain


00:26:12.400 --> 00:26:14.789
financial interest in keeping people


00:26:14.799 --> 00:26:16.630
interested in aliens because they buy


00:26:16.640 --> 00:26:20.789
his book. And the community of


00:26:20.799 --> 00:26:22.470
astronomers has been very upset and very


00:26:22.480 --> 00:26:24.390
stressed about that cuz it diverts


00:26:24.400 --> 00:26:25.750
attention from what is a really


00:26:25.760 --> 00:26:28.070
fascinating object on the fact that it's


00:26:28.080 --> 00:26:30.390
really fascinating but also breeds a


00:26:30.400 --> 00:26:31.830
certain amount of fear. And I genuinely


00:26:31.840 --> 00:26:34.070
had people reaching out to me when he


00:26:34.080 --> 00:26:36.310
was pushing this narrative of it being


00:26:36.320 --> 00:26:37.669
aliens that were going to invade because


00:26:37.679 --> 00:26:39.669
they were frightened. They were


00:26:39.679 --> 00:26:41.350
genuinely worried because a Harvard


00:26:41.360 --> 00:26:43.029
astronomer was saying aliens were going


00:26:43.039 --> 00:26:45.350
to come and beat us all up.


00:26:45.360 --> 00:26:47.269
>> Yeah. And it's problematic because it


00:26:47.279 --> 00:26:49.590
hides the science, but it's also more


00:26:49.600 --> 00:26:51.590
widely problematic at a time when we


00:26:51.600 --> 00:26:53.990
have lowering levels of engagement with


00:26:54.000 --> 00:26:56.950
science and very much lowering levels of


00:26:56.960 --> 00:26:59.750
trust in science and scientists. It's


00:26:59.760 --> 00:27:01.269
very bad to have someone acting


00:27:01.279 --> 00:27:02.950
disingenuously,


00:27:02.960 --> 00:27:05.990
telling lies or muddying the water and


00:27:06.000 --> 00:27:07.830
then arguing that everybody else is


00:27:07.840 --> 00:27:09.269
wrong and mean to me and I'm the only


00:27:09.279 --> 00:27:11.669
one telling the truth. And it's part of


00:27:11.679 --> 00:27:13.350
that whole fake news thing that I think


00:27:13.360 --> 00:27:16.230
is dangerous and damaging. You know, we


00:27:16.240 --> 00:27:18.070
need people to


00:27:18.080 --> 00:27:19.669
>> have trust and faith in science because


00:27:19.679 --> 00:27:21.190
it's so integral to our lives. And it's


00:27:21.200 --> 00:27:23.510
good to question, but it's bad when


00:27:23.520 --> 00:27:25.190
people say things that they


00:27:25.200 --> 00:27:26.950
fundamentally know are not true just to


00:27:26.960 --> 00:27:28.950
get hits or clicks or money.


00:27:28.960 --> 00:27:32.789
>> Yeah. I and it's important to debunk


00:27:32.799 --> 00:27:36.230
that kind of uh approach because I I've


00:27:36.240 --> 00:27:38.390
had people come up to me very recently


00:27:38.400 --> 00:27:40.950
who know I do this podcast


00:27:40.960 --> 00:27:42.310
uh who've said to me, "Oh, what do you


00:27:42.320 --> 00:27:44.230
think of that alien spaceship?" And I


00:27:44.240 --> 00:27:47.750
go, "It's it's bullshit." That's what I


00:27:47.760 --> 00:27:50.230
think because it's it's somebody trying


00:27:50.240 --> 00:27:51.669
to get media attention. It's got


00:27:51.679 --> 00:27:53.669
nothing. It's a rock. It it's actually


00:27:53.679 --> 00:27:56.149
it's it's an it's an ice conglomerate.


00:27:56.159 --> 00:27:58.230
It's it's not a it's not a spaceship at


00:27:58.240 --> 00:28:00.789
all. It's not behaving like a spaceship


00:28:00.799 --> 00:28:02.389
would. It's behaving like something


00:28:02.399 --> 00:28:04.470
passing through our solar system


00:28:04.480 --> 00:28:06.389
>> and


00:28:06.399 --> 00:28:08.230
and people people the thing is Johnny


00:28:08.240 --> 00:28:10.470
people are buying this rubbish.


00:28:10.480 --> 00:28:12.470
>> But there's a old saying that you know a


00:28:12.480 --> 00:28:14.710
lie can run around a lie can run around


00:28:14.720 --> 00:28:16.149
the world before the truth has got its


00:28:16.159 --> 00:28:17.350
boots on.


00:28:17.360 --> 00:28:19.190
>> Especially when it's an attractive lie.


00:28:19.200 --> 00:28:21.909
It's I mean again digging into my


00:28:21.919 --> 00:28:23.350
memories of Terry Pratchett stuff which


00:28:23.360 --> 00:28:25.669
happens a lot. It's the old quote when


00:28:25.679 --> 00:28:27.590
they're talking about newspapers and


00:28:27.600 --> 00:28:29.350
nobody really ever wants to hear a story


00:28:29.360 --> 00:28:31.029
about dog bites man because it happens


00:28:31.039 --> 00:28:32.230
all the time. But if you got a story


00:28:32.240 --> 00:28:34.070
that says man bites dog, everybody's


00:28:34.080 --> 00:28:34.950
fascinated.


00:28:34.960 --> 00:28:35.350
>> Yeah.


00:28:35.360 --> 00:28:37.269
>> And this story has all the elements.


00:28:37.279 --> 00:28:39.750
It's so salacious that it gets coverage


00:28:39.760 --> 00:28:42.070
and people who don't normally read or


00:28:42.080 --> 00:28:44.230
digest science are not interested will


00:28:44.240 --> 00:28:46.389
see this and hook into it. And when the


00:28:46.399 --> 00:28:48.870
by line is Harvard astronomer that gives


00:28:48.880 --> 00:28:50.870
it a huge amount of credence. It does


00:28:50.880 --> 00:28:53.909
>> and nobody hears the rebuttals. It's


00:28:53.919 --> 00:28:55.269
A bit like, you know, when there are


00:28:55.279 --> 00:28:56.630
claims of life on a planet around


00:28:56.640 --> 00:28:59.909
another star, nobody remembers the t the


00:28:59.919 --> 00:29:01.909
follow-ups that say actually it wasn't.


00:29:01.919 --> 00:29:03.669
They just remember, oh, we found aliens


00:29:03.679 --> 00:29:05.110
and we haven't.


00:29:05.120 --> 00:29:08.549
>> I mean, I think that the story that uh


00:29:08.559 --> 00:29:11.269
the most recent story that I recall


00:29:11.279 --> 00:29:14.389
where that that claim was made was um


00:29:14.399 --> 00:29:17.269
the one about the something they what


00:29:17.279 --> 00:29:18.630
was it they found in the in the


00:29:18.640 --> 00:29:20.789
atmosphere of Venus? It was


00:29:20.799 --> 00:29:22.789
>> phosphine. Yes. Now I I can go on a


00:29:22.799 --> 00:29:24.310
little bit of a side rant about that. My


00:29:24.320 --> 00:29:27.350
heart broke. Um the lead author on that


00:29:27.360 --> 00:29:29.590
study was Jane Greavves in the UK who's


00:29:29.600 --> 00:29:31.110
someone I knew very well when I was in


00:29:31.120 --> 00:29:32.870
the UK and she's a fabulous science and


00:29:32.880 --> 00:29:35.590
just all around wonderful individual and


00:29:35.600 --> 00:29:39.510
the story was led by a UK team who if


00:29:39.520 --> 00:29:41.669
you actually read the paper don't say


00:29:41.679 --> 00:29:44.230
anything that is this is life. What they


00:29:44.240 --> 00:29:46.870
say is we found a very weak signal


00:29:46.880 --> 00:29:49.110
>> of this gas in Venus's atmosphere. It's


00:29:49.120 --> 00:29:50.870
right down in the noise. So there is a


00:29:50.880 --> 00:29:53.110
chance it's a false positive anyway. So


00:29:53.120 --> 00:29:54.549
there needs to be a bit bit of extra


00:29:54.559 --> 00:29:56.789
work done. It's a little bit interesting


00:29:56.799 --> 00:29:59.350
because on the earth the only processes


00:29:59.360 --> 00:30:03.190
that produce this peculiar gas are


00:30:03.200 --> 00:30:05.750
technology and industry or life.


00:30:05.760 --> 00:30:06.070
>> Yeah.


00:30:06.080 --> 00:30:07.350
>> We don't know of any other way that it's


00:30:07.360 --> 00:30:08.789
made. But that doesn't mean that there


00:30:08.799 --> 00:30:10.310
aren't other ways that it's made.


00:30:10.320 --> 00:30:11.990
>> Isn't that a tasty morsel for the


00:30:12.000 --> 00:30:12.950
popular press?


00:30:12.960 --> 00:30:14.630
>> Absolutely. But what happened then was


00:30:14.640 --> 00:30:17.510
that there is an American


00:30:17.520 --> 00:30:19.350
outreach journal um science


00:30:19.360 --> 00:30:21.909
communication journal that broke embargo


00:30:21.919 --> 00:30:24.230
on this story. Didn't talk to Jane and


00:30:24.240 --> 00:30:26.389
her colleagues, but instead ran a story


00:30:26.399 --> 00:30:28.230
saying British scientists find life on


00:30:28.240 --> 00:30:29.830
Venus, which is not what they'd said at


00:30:29.840 --> 00:30:30.710
all. No,


00:30:30.720 --> 00:30:32.549
>> that's what started the absolute bum


00:30:32.559 --> 00:30:35.190
fight. And the vitrial and the hate and


00:30:35.200 --> 00:30:36.870
the death threats, believe it or not,


00:30:36.880 --> 00:30:39.350
that Jen Greavves got because of this


00:30:39.360 --> 00:30:41.669
>> were astonishing. It was absolutely


00:30:41.679 --> 00:30:43.909
terrible. And instead of being able to


00:30:43.919 --> 00:30:45.669
manage the deployment of this wonderful


00:30:45.679 --> 00:30:47.830
story about this fascinating new result


00:30:47.840 --> 00:30:49.590
they got, they spent all their time in


00:30:49.600 --> 00:30:53.990
damage control because this publication


00:30:54.000 --> 00:30:56.310
chose to break the embargo early and run


00:30:56.320 --> 00:30:58.070
a story that was not factually true but


00:30:58.080 --> 00:30:59.669
again would get them clicks.


00:30:59.679 --> 00:31:02.230
>> Yep. Yeah. And and that's unfortunately


00:31:02.240 --> 00:31:05.029
the modern media and um the the


00:31:05.039 --> 00:31:07.430
internet's to blame. Well, it's not the


00:31:07.440 --> 00:31:08.710
internet that's to blame. It's the


00:31:08.720 --> 00:31:11.029
people who use it that are to blame. And


00:31:11.039 --> 00:31:13.669
it's one of the um one of the things you


00:31:13.679 --> 00:31:16.630
really got to be careful of when you are


00:31:16.640 --> 00:31:18.710
following a story, whether it's an exoc


00:31:18.720 --> 00:31:22.310
comet that's not a spaceship or uh life


00:31:22.320 --> 00:31:25.909
that's not in Venus's atmosphere. Um and


00:31:25.919 --> 00:31:28.870
and even to a lesser degree, and you and


00:31:28.880 --> 00:31:30.630
I mentioned this before we started, the


00:31:30.640 --> 00:31:33.269
way the media gets its information


00:31:33.279 --> 00:31:37.190
confused, such as uh reporting on uh you


00:31:37.200 --> 00:31:40.549
upcoming spectacular meteor showers that


00:31:40.559 --> 00:31:42.230
uh everyone gets excited about and then


00:31:42.240 --> 00:31:43.430
they realize they're on the wrong side


00:31:43.440 --> 00:31:44.549
of the planet.


00:31:44.559 --> 00:31:46.710
>> Absolutely. And this is a caution I give


00:31:46.720 --> 00:31:48.710
to everybody both for comets and for


00:31:48.720 --> 00:31:49.990
meteors actually, but particularly for


00:31:50.000 --> 00:31:51.830
those of us in the southern hemisphere.


00:31:51.840 --> 00:31:55.430
Um, meteor showers and comets are things


00:31:55.440 --> 00:31:57.590
that are best seen from some latitudes


00:31:57.600 --> 00:31:59.430
and not from others. And for each comet


00:31:59.440 --> 00:32:00.789
or for each meteor shower, that's


00:32:00.799 --> 00:32:02.950
different. Now, I'll talk later on about


00:32:02.960 --> 00:32:04.870
a newly discovered comet that might be


00:32:04.880 --> 00:32:07.830
very spectacular in late 2028.


00:32:07.840 --> 00:32:09.190
That comet is primarily going to be a


00:32:09.200 --> 00:32:11.830
southern hemisphere object. So, it will


00:32:11.840 --> 00:32:13.269
probably be better for us in Australia


00:32:13.279 --> 00:32:14.710
and New Zealand than it will be for


00:32:14.720 --> 00:32:16.549
people in the UK or the US, just as an


00:32:16.559 --> 00:32:18.070
example.


00:32:18.080 --> 00:32:19.990
when events are happening that are


00:32:20.000 --> 00:32:21.430
primarily good for the northern


00:32:21.440 --> 00:32:22.950
hemisphere. The northern hemisphere has


00:32:22.960 --> 00:32:24.870
more people and more media. And what


00:32:24.880 --> 00:32:26.789
I've seen happen more and more is that


00:32:26.799 --> 00:32:30.230
the media in Australia and I know the


00:32:30.240 --> 00:32:31.830
Australian stuff because that's local to


00:32:31.840 --> 00:32:33.430
us. It's probably just the same in New


00:32:33.440 --> 00:32:35.110
Zealand, South Africa, South America,


00:32:35.120 --> 00:32:37.029
all these other places. But the media


00:32:37.039 --> 00:32:38.549
there will pick up these stories and


00:32:38.559 --> 00:32:41.990
just run them without running the sanity


00:32:42.000 --> 00:32:44.710
featur filter. So the April lyids are a


00:32:44.720 --> 00:32:46.070
really good example of this, but a


00:32:46.080 --> 00:32:47.750
better one is probably the Percid meteor


00:32:47.760 --> 00:32:50.310
shower in August. Now, as a little bit


00:32:50.320 --> 00:32:52.149
of background here, when we've got a


00:32:52.159 --> 00:32:54.149
meteor shower, we're getting bits of


00:32:54.159 --> 00:32:55.669
dust and debris hitting the Earth's


00:32:55.679 --> 00:32:58.549
atmosphere and ablating at an altitude


00:32:58.559 --> 00:33:01.990
of about 80 km. Now, ablation is a


00:33:02.000 --> 00:33:03.350
slightly weird thing. People often


00:33:03.360 --> 00:33:05.029
describe this as burning up, but it's


00:33:05.039 --> 00:33:06.870
not burning up in the sense of a flame


00:33:06.880 --> 00:33:09.029
being lit and a fire burning. It's


00:33:09.039 --> 00:33:10.310
rather that these things push into the


00:33:10.320 --> 00:33:12.470
atmosphere at really high speed, pile


00:33:12.480 --> 00:33:13.990
the air up in front of them, getting the


00:33:14.000 --> 00:33:16.310
air superheated, creating a load of


00:33:16.320 --> 00:33:18.070
plasma, and the heat from that bakes and


00:33:18.080 --> 00:33:20.630
vaporizes the bit of debris. So, it's


00:33:20.640 --> 00:33:22.710
not burning up in the traditional sense.


00:33:22.720 --> 00:33:24.389
And anytime you see a meteor, you see a


00:33:24.399 --> 00:33:25.509
shooting star, that's what you're


00:33:25.519 --> 00:33:27.110
seeing. And the bigger the bit of dust,


00:33:27.120 --> 00:33:29.350
the brighter it will be. The faster it's


00:33:29.360 --> 00:33:31.110
moving at a given size, the more energy


00:33:31.120 --> 00:33:32.549
it's got. So, again, the brighter it'll


00:33:32.559 --> 00:33:33.190
be.


00:33:33.200 --> 00:33:33.669
>> Yeah.


00:33:33.679 --> 00:33:36.389
>> And you see shooting stars on any night


00:33:36.399 --> 00:33:39.029
of the year. typically three or four an


00:33:39.039 --> 00:33:41.669
hour in the evenings, five or six an


00:33:41.679 --> 00:33:43.029
hour in the mornings potentially. And


00:33:43.039 --> 00:33:44.389
that difference is just because in the


00:33:44.399 --> 00:33:45.830
mornings you're facing the direction the


00:33:45.840 --> 00:33:47.430
earth's moving. So you getting


00:33:47.440 --> 00:33:49.190
collisions that are headon. So the


00:33:49.200 --> 00:33:51.590
average collision speed is higher. So a


00:33:51.600 --> 00:33:53.509
grain of dust that's the same size will


00:33:53.519 --> 00:33:55.669
be a bit brighter. Therefore, the things


00:33:55.679 --> 00:33:56.950
that in the evening that will be too


00:33:56.960 --> 00:33:58.630
faint to see become visible. So you get


00:33:58.640 --> 00:34:00.310
a slight increase in the rate towards


00:34:00.320 --> 00:34:03.110
morning than in the evening. Um, it's


00:34:03.120 --> 00:34:04.789
also you're probably getting a slightly


00:34:04.799 --> 00:34:05.990
increased amount of stuff entering the


00:34:06.000 --> 00:34:07.669
atmosphere cuz you always see more flies


00:34:07.679 --> 00:34:08.869
hit your windscreen than your air


00:34:08.879 --> 00:34:11.669
windscreen. Same kind of idea.


00:34:11.679 --> 00:34:13.589
>> When we get a meteor shower, what's


00:34:13.599 --> 00:34:16.230
happening is we're passing through the


00:34:16.240 --> 00:34:18.790
area of space where the Earth passes


00:34:18.800 --> 00:34:20.470
near the orbit of either a comet or an


00:34:20.480 --> 00:34:22.629
asteroid. And typically, it's a comet.


00:34:22.639 --> 00:34:24.389
>> Now, every time a comet goes around the


00:34:24.399 --> 00:34:27.190
sun, that dirty snowball or snowy dirt


00:34:27.200 --> 00:34:29.990
ball gets hot. The volatile material on


00:34:30.000 --> 00:34:32.790
the surface is too hot to stay solid. So


00:34:32.800 --> 00:34:34.629
becomes a gas in a process called


00:34:34.639 --> 00:34:36.950
sublimation. And you get jets erupting


00:34:36.960 --> 00:34:40.230
from the comet, shrouding in gas, which


00:34:40.240 --> 00:34:41.669
is then blown away from the sun to give


00:34:41.679 --> 00:34:44.470
you the tails. Those jets erupting into


00:34:44.480 --> 00:34:47.109
space carry with them dust.


00:34:47.119 --> 00:34:49.349
Now biggest bits of dust are pushed away


00:34:49.359 --> 00:34:50.950
so gently they'll fall back to the comet


00:34:50.960 --> 00:34:52.389
and clog it up. And some comets


00:34:52.399 --> 00:34:54.389
eventually turn off because of this.


00:34:54.399 --> 00:34:56.149
also is the reason most comets are only


00:34:56.159 --> 00:34:58.230
active from a few few locations on the


00:34:58.240 --> 00:35:00.470
surface, not uniformly because most of


00:35:00.480 --> 00:35:02.310
the surface is clogged up and you've


00:35:02.320 --> 00:35:03.829
just got a few active areas where


00:35:03.839 --> 00:35:05.750
volatile material is exposed.


00:35:05.760 --> 00:35:06.150
>> Yeah.


00:35:06.160 --> 00:35:07.750
>> But that dust that's ejected from the


00:35:07.760 --> 00:35:10.069
comet is ejected with speeds measured in


00:35:10.079 --> 00:35:12.790
meters/s or centimeters/s


00:35:12.800 --> 00:35:14.230
from an object that's traveling at a


00:35:14.240 --> 00:35:15.910
speed measured in tens of kilometers/ a


00:35:15.920 --> 00:35:18.470
second. So, what that means is that that


00:35:18.480 --> 00:35:21.670
dust is moving away from the comet at a


00:35:21.680 --> 00:35:23.589
speed almost identical to the speed the


00:35:23.599 --> 00:35:25.910
comet's traveling itself. I guess it's


00:35:25.920 --> 00:35:28.069
like if you you're driving along the


00:35:28.079 --> 00:35:29.670
road and you drop a tennis ball out of


00:35:29.680 --> 00:35:31.990
the window until the wind resistance


00:35:32.000 --> 00:35:33.910
pushes it back. If there wasn't a wind


00:35:33.920 --> 00:35:35.270
resistance there, it would move along


00:35:35.280 --> 00:35:37.510
with the car just drifting away very


00:35:37.520 --> 00:35:39.030
slightly based on the speed you pushed


00:35:39.040 --> 00:35:41.030
it out of the window. Same idea.


00:35:41.040 --> 00:35:43.109
>> Yeah. I actually saw a a really great


00:35:43.119 --> 00:35:47.990
experiment once where they were um how


00:35:48.000 --> 00:35:49.750
did they do it? They had a guy on the


00:35:49.760 --> 00:35:53.750
back of a truck and they were driving at


00:35:53.760 --> 00:35:57.430
like 100 kilometers an hour and they


00:35:57.440 --> 00:35:59.829
shot him off the truck in the opposite


00:35:59.839 --> 00:36:03.030
direction at the same speed and he just


00:36:03.040 --> 00:36:04.390
stopped where he landed.


00:36:04.400 --> 00:36:06.150
>> Oh, it's brilliant. I think Mythbusters


00:36:06.160 --> 00:36:07.430
did something similar.


00:36:07.440 --> 00:36:08.390
>> It's amazing.


00:36:08.400 --> 00:36:11.589
>> Our common sense is physics really.


00:36:11.599 --> 00:36:13.910
>> Yeah, simple physics is great, but our


00:36:13.920 --> 00:36:15.349
common sense breaks down in some


00:36:15.359 --> 00:36:17.829
situations because our common sense is a


00:36:17.839 --> 00:36:19.430
naturally inherited thing about the


00:36:19.440 --> 00:36:22.069
world at the speeds we experience it.


00:36:22.079 --> 00:36:23.670
>> And so we tend to think if you're


00:36:23.680 --> 00:36:25.349
running forwards at 10 km an hour and


00:36:25.359 --> 00:36:27.670
you throw something forwards, it will


00:36:27.680 --> 00:36:29.589
travel a bit faster. That breaks down


00:36:29.599 --> 00:36:30.950
when you get to relativity. There's all


00:36:30.960 --> 00:36:33.510
these weird things around it. where our


00:36:33.520 --> 00:36:35.430
common sense gets it wrong for comets


00:36:35.440 --> 00:36:37.510
and for the dust. And it took me a long


00:36:37.520 --> 00:36:38.790
while to get my head around this because


00:36:38.800 --> 00:36:40.710
it's a bit counterintuitive.


00:36:40.720 --> 00:36:43.190
If you eject dust from a comet, you can


00:36:43.200 --> 00:36:44.630
eject the dust forward or backwards. So


00:36:44.640 --> 00:36:46.230
you can imagine this jet from the comet


00:36:46.240 --> 00:36:48.870
working a bit like a geyser turning off


00:36:48.880 --> 00:36:50.710
when it gets dark and it gets cold and


00:36:50.720 --> 00:36:51.910
then turning off again in the morning


00:36:51.920 --> 00:36:53.589
when it gets hot again.


00:36:53.599 --> 00:36:55.829
>> That can throw dust forwards, sidewards,


00:36:55.839 --> 00:36:58.310
and backwards or any combination of the


00:36:58.320 --> 00:37:00.230
above. So that means this comet is


00:37:00.240 --> 00:37:01.670
throwing out dust at a speed of


00:37:01.680 --> 00:37:04.710
meters/s, a bit like a sprinkler into


00:37:04.720 --> 00:37:07.750
space. The dust that has a forward


00:37:07.760 --> 00:37:09.829
component to its speed. So it could be


00:37:09.839 --> 00:37:11.430
going sidewards but a little forward or


00:37:11.440 --> 00:37:12.710
it could be going head-on in front of


00:37:12.720 --> 00:37:14.870
the comet. That is now traveling around


00:37:14.880 --> 00:37:17.750
the sun faster than the comet is, which


00:37:17.760 --> 00:37:19.510
means it will move onto an orbit with a


00:37:19.520 --> 00:37:21.750
longer period than the comet. So the


00:37:21.760 --> 00:37:23.109
next time the comet comes around, that


00:37:23.119 --> 00:37:24.630
grain of dust will arrive after the


00:37:24.640 --> 00:37:27.349
comet. So dust thrown forward ends up


00:37:27.359 --> 00:37:29.510
behind. And similarly does thrown


00:37:29.520 --> 00:37:30.950
backwards is moving slower than the


00:37:30.960 --> 00:37:32.390
comet which puts it on a slightly


00:37:32.400 --> 00:37:34.630
shorter period orbit and therefore it


00:37:34.640 --> 00:37:36.150
will arrive ahead of the comet next


00:37:36.160 --> 00:37:37.910
time. And that little bit of sidewards


00:37:37.920 --> 00:37:39.430
motion also means it will spread out a


00:37:39.440 --> 00:37:42.069
little bit in space. What this means


00:37:42.079 --> 00:37:44.390
over time periods is that comets every


00:37:44.400 --> 00:37:46.870
time they come round essentially shed


00:37:46.880 --> 00:37:48.710
what becomes like a javelin shape, a


00:37:48.720 --> 00:37:51.589
spear of dust into space with a comet at


00:37:51.599 --> 00:37:53.430
the center


00:37:53.440 --> 00:37:55.349
like a spike. And that spike gradually


00:37:55.359 --> 00:37:57.349
diffuses over time, spreads out further


00:37:57.359 --> 00:37:59.349
and further ahead and behind the comet.


00:37:59.359 --> 00:38:01.430
And so over a long time scale, you


00:38:01.440 --> 00:38:03.030
eventually end up with the comet's orbit


00:38:03.040 --> 00:38:05.190
shrouded in dust. And the dust can be


00:38:05.200 --> 00:38:06.790
quite spread out over millions of


00:38:06.800 --> 00:38:07.829
kilometers.


00:38:07.839 --> 00:38:08.150
>> Yeah,


00:38:08.160 --> 00:38:10.150
>> these orbits are oriented randomly in


00:38:10.160 --> 00:38:12.550
space. So many of them don't intersect


00:38:12.560 --> 00:38:14.710
the Earth. Even if the comet gets closer


00:38:14.720 --> 00:38:16.870
to the sun than we are at its closest,


00:38:16.880 --> 00:38:18.790
passes above or below the Earth's orbit,


00:38:18.800 --> 00:38:21.589
nothing happens. But for a subset of


00:38:21.599 --> 00:38:25.270
them, the comet will in its orbit have


00:38:25.280 --> 00:38:26.870
the potential to get very close to the


00:38:26.880 --> 00:38:28.390
Earth. So its orbit and the Earth get


00:38:28.400 --> 00:38:30.870
very close together. And in those cases,


00:38:30.880 --> 00:38:32.870
every time we go around the sun, if that


00:38:32.880 --> 00:38:34.390
comet's been laying dust down for a


00:38:34.400 --> 00:38:36.550
while, we'll run into the dust every


00:38:36.560 --> 00:38:38.470
time we go around. And that dust will


00:38:38.480 --> 00:38:39.990
hit the Earth's atmosphere, which means


00:38:40.000 --> 00:38:41.589
we're going through a dirtier bit of the


00:38:41.599 --> 00:38:43.829
solar system, and we get more meteors.


00:38:43.839 --> 00:38:45.829
That's when we get a meteor shower. But


00:38:45.839 --> 00:38:47.349
the other telltale thing for the meteor


00:38:47.359 --> 00:38:49.750
shower is all the dust grains that hit


00:38:49.760 --> 00:38:52.150
the earth in a meteor shower are moving


00:38:52.160 --> 00:38:53.510
essentially parallel to each other.


00:38:53.520 --> 00:38:54.790
They're all following the same orbit


00:38:54.800 --> 00:38:56.230
around the sun hitting the earth from


00:38:56.240 --> 00:38:59.510
the same direction at the same speed.


00:38:59.520 --> 00:39:01.430
So all this dust is coming towards you


00:39:01.440 --> 00:39:03.349
from a single point in space. So from


00:39:03.359 --> 00:39:05.349
your point of view looking at the sky


00:39:05.359 --> 00:39:06.950
when you see those meteors part of a


00:39:06.960 --> 00:39:09.829
meteor shower they appear to appear


00:39:09.839 --> 00:39:12.069
anywhere in the sky. But if you trace


00:39:12.079 --> 00:39:13.670
them back they'll all point to a single


00:39:13.680 --> 00:39:15.750
point in the sky. something we call the


00:39:15.760 --> 00:39:18.069
radiant and that's effectively the point


00:39:18.079 --> 00:39:19.670
in space they're traveling towards us


00:39:19.680 --> 00:39:21.750
from and they diverge because of


00:39:21.760 --> 00:39:23.829
perspective they're coming closer to you


00:39:23.839 --> 00:39:26.470
so every meteor shower has a radiant in


00:39:26.480 --> 00:39:28.710
the sky the April lids have their


00:39:28.720 --> 00:39:31.190
radiant in Lyra although for a fair part


00:39:31.200 --> 00:39:32.710
of their time it's actually in Hercules


00:39:32.720 --> 00:39:35.109
it drifts a bit the perids have their


00:39:35.119 --> 00:39:37.430
radiant in Perseus the Geminids in


00:39:37.440 --> 00:39:40.069
Gemini and so on


00:39:40.079 --> 00:39:42.790
>> so that's all well and good if the


00:39:42.800 --> 00:39:45.109
radiant is below the horizon horizon.


00:39:45.119 --> 00:39:46.630
That means the meteors are hitting the


00:39:46.640 --> 00:39:47.910
other side of the Earth and you can't


00:39:47.920 --> 00:39:50.390
see them because the Earth's in the way.


00:39:50.400 --> 00:39:52.870
So, first point with a meteor shower is


00:39:52.880 --> 00:39:55.030
unlike some of the media reports, you


00:39:55.040 --> 00:39:56.790
can't see meteors for that meteor shower


00:39:56.800 --> 00:39:58.790
at any time of night. You can only see


00:39:58.800 --> 00:39:59.910
them when the radiant's above the


00:39:59.920 --> 00:40:03.349
horizon. Point number one. Point the


00:40:03.359 --> 00:40:05.030
second is the higher in the sky that


00:40:05.040 --> 00:40:07.670
radiant is, the more head on into the


00:40:07.680 --> 00:40:09.670
stream you're going. So, the more


00:40:09.680 --> 00:40:11.910
meteors you'll see. Now, the analogy I


00:40:11.920 --> 00:40:13.750
I'd use here is if you imagine getting


00:40:13.760 --> 00:40:15.990
your hose pipe and having it on that


00:40:16.000 --> 00:40:17.270
shower mode, you know, where water's


00:40:17.280 --> 00:40:20.230
coming out from many holes all at once.


00:40:20.240 --> 00:40:21.990
If you hold that hose pipe vertically


00:40:22.000 --> 00:40:23.990
and turn the tap on, all the water from


00:40:24.000 --> 00:40:25.430
that hose pipe will hit a relatively


00:40:25.440 --> 00:40:27.349
small area of the ground.


00:40:27.359 --> 00:40:30.550
>> If you turn that hose pipe to 45°, that


00:40:30.560 --> 00:40:32.390
water will spread out over a larger


00:40:32.400 --> 00:40:33.670
surface area.


00:40:33.680 --> 00:40:35.430
>> Yep. Now, if you imagine the meteors,


00:40:35.440 --> 00:40:37.109
the dust in a meteor shower coming in


00:40:37.119 --> 00:40:40.150
towards the Earth, the more directly


00:40:40.160 --> 00:40:42.630
overhead your point that they're coming


00:40:42.640 --> 00:40:45.349
from is, the more meteors you'll get in


00:40:45.359 --> 00:40:47.510
a certain volume of the atmosphere. And


00:40:47.520 --> 00:40:49.190
the lower to the horizon that point is,


00:40:49.200 --> 00:40:50.710
the more you'll spread those same number


00:40:50.720 --> 00:40:53.670
of grains of dust out. So, the higher in


00:40:53.680 --> 00:40:56.470
the sky the radiant is, the more dust is


00:40:56.480 --> 00:40:58.150
hitting the part of the atmosphere you


00:40:58.160 --> 00:40:59.910
can see from your location. So, the more


00:40:59.920 --> 00:41:02.390
meteors you get. And what this means is


00:41:02.400 --> 00:41:03.990
the lower in the sky the radiant is the


00:41:04.000 --> 00:41:06.390
fewer meteors you see. And so you see


00:41:06.400 --> 00:41:08.069
the most meteors for a given meteor


00:41:08.079 --> 00:41:10.230
shower when the radiant is near what we


00:41:10.240 --> 00:41:11.670
call culmination where it's nearly


00:41:11.680 --> 00:41:13.030
highest in the sky.


00:41:13.040 --> 00:41:14.550
>> For the southern hemisphere when it's


00:41:14.560 --> 00:41:16.790
nearly due north for the northern


00:41:16.800 --> 00:41:19.829
hemisphere the radiant nearly due south.


00:41:19.839 --> 00:41:22.309
So all well and good. But what that


00:41:22.319 --> 00:41:24.069
means is that from different locations


00:41:24.079 --> 00:41:26.470
on the earth a given meteor shower will


00:41:26.480 --> 00:41:27.750
give you a different strength of


00:41:27.760 --> 00:41:32.150
display. The April lyids, their radiant


00:41:32.160 --> 00:41:34.950
is 34 degrees north of the equator. So


00:41:34.960 --> 00:41:37.109
that means if you lived 34 degrees north


00:41:37.119 --> 00:41:39.349
of the equator, at about 2:00 a.m. in


00:41:39.359 --> 00:41:40.550
the morning, the radiant would be


00:41:40.560 --> 00:41:42.230
overhead and you're in the best place on


00:41:42.240 --> 00:41:44.470
the planet to see the meteors. If you


00:41:44.480 --> 00:41:47.829
had perfect vision, perfectly dark sky,


00:41:47.839 --> 00:41:50.309
you'd see a number of meteors 15 to 20


00:41:50.319 --> 00:41:52.069
per hour for the Aprils. And that's


00:41:52.079 --> 00:41:54.550
called the zenithl hourly rate. That's


00:41:54.560 --> 00:41:55.990
the number of meters you'd see in


00:41:56.000 --> 00:41:58.309
perfect conditions with perfect eyesight


00:41:58.319 --> 00:42:00.069
with no light pollution if the radiant


00:42:00.079 --> 00:42:02.470
was overhead. The lower the radiant is


00:42:02.480 --> 00:42:03.750
in the sky, the more that number


00:42:03.760 --> 00:42:07.030
shrinks. So the ZHR is the theoretical


00:42:07.040 --> 00:42:10.790
maximum number you'd see. So good meteor


00:42:10.800 --> 00:42:12.150
shower, not a great one from the


00:42:12.160 --> 00:42:13.829
northern hemisphere, but for us in


00:42:13.839 --> 00:42:17.589
Brisbane, let's say 26° south, the


00:42:17.599 --> 00:42:19.430
radiant of the April Lyids at its


00:42:19.440 --> 00:42:21.510
highest in the sky is only 30° above the


00:42:21.520 --> 00:42:24.710
horizon. That means that the volume of


00:42:24.720 --> 00:42:26.710
space where the dust is arriving is


00:42:26.720 --> 00:42:28.790
doubled. So you'd only see half the


00:42:28.800 --> 00:42:30.550
number of meteors.


00:42:30.560 --> 00:42:32.550
>> So instead of 20 per hour, you're down


00:42:32.560 --> 00:42:35.270
to 10 an hour immediately before


00:42:35.280 --> 00:42:37.510
anything else kicks in. And the further


00:42:37.520 --> 00:42:39.829
south you go, the lower the rates are.


00:42:39.839 --> 00:42:41.510
But the problem is the journalist


00:42:41.520 --> 00:42:42.950
covering this will pick up on a northern


00:42:42.960 --> 00:42:45.190
hemisphere article and just repeat it.


00:42:45.200 --> 00:42:46.790
There's this meteor shower happening.


00:42:46.800 --> 00:42:48.309
You can see them all night every night.


00:42:48.319 --> 00:42:49.990
Well, that's not right. If the radiant's


00:42:50.000 --> 00:42:51.910
below the horizon, you can't see them.


00:42:51.920 --> 00:42:53.910
and you'll see 100 per hour and that's


00:42:53.920 --> 00:42:55.670
because they've seen the zenithal rate


00:42:55.680 --> 00:42:57.990
quoted as 100 per hour and they just use


00:42:58.000 --> 00:42:59.270
it as a number.


00:42:59.280 --> 00:42:59.750
>> Yeah.


00:42:59.760 --> 00:43:01.910
>> Unless you are incredibly incredibly


00:43:01.920 --> 00:43:04.309
fortunate, you will never see the same


00:43:04.319 --> 00:43:07.750
number of meteors as the ZHR predicts


00:43:07.760 --> 00:43:09.829
because the radiant won't be directly


00:43:09.839 --> 00:43:11.990
overhead. So the rate gets lower. Your


00:43:12.000 --> 00:43:13.910
eyes are not perfect unless you're one


00:43:13.920 --> 00:43:15.910
of the very rare observers. The rates


00:43:15.920 --> 00:43:17.109
will get lower.


00:43:17.119 --> 00:43:18.710
>> There might be light pollution. The


00:43:18.720 --> 00:43:21.190
phentto meteors are not seen. the rates


00:43:21.200 --> 00:43:23.030
get lower. The moon might be in the sky.


00:43:23.040 --> 00:43:24.630
The faint meters are not seen. The rates


00:43:24.640 --> 00:43:28.309
are lower. So you will never see a


00:43:28.319 --> 00:43:29.910
number of meters in the sky equal to the


00:43:29.920 --> 00:43:32.790
ZHR unless the meteor shower is more


00:43:32.800 --> 00:43:34.950
active than predicted in which case the


00:43:34.960 --> 00:43:37.589
ZHR will be higher and you'd see more.


00:43:37.599 --> 00:43:39.670
Where this really comes in is for meteor


00:43:39.680 --> 00:43:41.510
showers like the perids. The perids are


00:43:41.520 --> 00:43:43.670
one of the big three. There are three


00:43:43.680 --> 00:43:45.349
awesome meteor showers a year that are


00:43:45.359 --> 00:43:48.870
by far the best in a given year. They're


00:43:48.880 --> 00:43:51.190
the highest rate. So most dust coming in


00:43:51.200 --> 00:43:53.510
or the highest speed. The quadrantids in


00:43:53.520 --> 00:43:55.270
early January


00:43:55.280 --> 00:43:57.109
are very very shortlived. They're a wage


00:43:57.119 --> 00:43:58.550
shower. You've got a very low rate of


00:43:58.560 --> 00:43:59.829
meteors for most of the time they're


00:43:59.839 --> 00:44:01.589
active and then a very narrow spike that


00:44:01.599 --> 00:44:04.470
can be very big. But if you manage to


00:44:04.480 --> 00:44:05.670
see that spike, there's a lot of


00:44:05.680 --> 00:44:07.589
meteors. They're only really visible


00:44:07.599 --> 00:44:09.990
from the northern hemisphere. The perids


00:44:10.000 --> 00:44:12.470
in August are probably the most storied


00:44:12.480 --> 00:44:16.069
meteor shower with long history of


00:44:16.079 --> 00:44:17.589
observations


00:44:17.599 --> 00:44:19.349
linked to comet Swift Tuttle which goes


00:44:19.359 --> 00:44:22.390
around every 120 130 years incidentally


00:44:22.400 --> 00:44:24.069
will be incredibly spectacular in the


00:44:24.079 --> 00:44:26.390
year 2126 if people hang around to see


00:44:26.400 --> 00:44:26.870
it.


00:44:26.880 --> 00:44:28.710
>> Yeah. Okay. I'll I'll write that in my


00:44:28.720 --> 00:44:29.829
diary.


00:44:29.839 --> 00:44:31.910
>> Um Percids are brilliant but their


00:44:31.920 --> 00:44:34.470
radiant is at about 55° north in the


00:44:34.480 --> 00:44:36.069
sky.


00:44:36.079 --> 00:44:37.910
Fabulous from Northern Europe, fabulous


00:44:37.920 --> 00:44:39.670
from North America, places north of the


00:44:39.680 --> 00:44:41.510
equator to get a really good show. But


00:44:41.520 --> 00:44:44.150
we get articles every year on commercial


00:44:44.160 --> 00:44:45.910
media here in Australia saying the


00:44:45.920 --> 00:44:47.270
persons are happening. Go out tonight


00:44:47.280 --> 00:44:49.510
and you'll see 100 meters an hour. And


00:44:49.520 --> 00:44:51.510
for most of Australia, the radiant never


00:44:51.520 --> 00:44:54.069
even rises. Never. You know, south of


00:44:54.079 --> 00:44:56.230
about 35° south, the radiant will never


00:44:56.240 --> 00:44:57.990
rise. I think that's about the latitude


00:44:58.000 --> 00:44:59.829
of Sydney.


00:44:59.839 --> 00:45:01.430
>> North of that, it will rise, but it'll


00:45:01.440 --> 00:45:02.870
be very low to the horizon. And so


00:45:02.880 --> 00:45:04.470
you'll see a much lower rate unless


00:45:04.480 --> 00:45:05.990
you're in the top top end. If you're in


00:45:06.000 --> 00:45:07.349
the top end of Australia, it's a bit


00:45:07.359 --> 00:45:10.309
different. And so when you see articles


00:45:10.319 --> 00:45:12.950
like this, you need to engage your


00:45:12.960 --> 00:45:14.550
science brain and say the journal is


00:45:14.560 --> 00:45:15.270
wrong.


00:45:15.280 --> 00:45:15.589
>> Yeah.


00:45:15.599 --> 00:45:19.430
>> Where's my location? What's the radiance


00:45:19.440 --> 00:45:21.510
declination, which is latitude in the


00:45:21.520 --> 00:45:23.750
sky effectively? Figure out how high in


00:45:23.760 --> 00:45:24.870
the sky it'll get, and that will give


00:45:24.880 --> 00:45:26.470
you a feel for what you might actually


00:45:26.480 --> 00:45:29.510
see. Now, if you want to um look at the


00:45:29.520 --> 00:45:31.030
meteor shower calendar and figure out


00:45:31.040 --> 00:45:32.790
when there are good ones happening, the


00:45:32.800 --> 00:45:35.030
International Meteor organization is my


00:45:35.040 --> 00:45:37.030
go-to on this. They're a fabulous


00:45:37.040 --> 00:45:38.550
organization that put together every


00:45:38.560 --> 00:45:41.030
year a calendar. And that calendar lists


00:45:41.040 --> 00:45:42.230
all the meteor showers from the


00:45:42.240 --> 00:45:43.750
incredibly minor ones that give one


00:45:43.760 --> 00:45:45.990
meteor every two hours, you know, to the


00:45:46.000 --> 00:45:48.790
major ones. And every year it writes


00:45:48.800 --> 00:45:50.550
about the conditions in terms of


00:45:50.560 --> 00:45:52.950
moonlight as well. Because if the moon


00:45:52.960 --> 00:45:55.349
is bright, you will see far fewer


00:45:55.359 --> 00:45:57.750
meteors. And coming up in a couple of


00:45:57.760 --> 00:45:59.589
weeks from when we're having this


00:45:59.599 --> 00:46:01.670
discussion, but in the past as we


00:46:01.680 --> 00:46:03.589
actually go live to air, you've got the


00:46:03.599 --> 00:46:05.829
peak of the Aquarids. Now the Aquarids


00:46:05.839 --> 00:46:07.190
are one of the few showers that's better


00:46:07.200 --> 00:46:08.630
for southern hemisphere than northern


00:46:08.640 --> 00:46:10.790
hemisphere. Fragments of comet Hali and


00:46:10.800 --> 00:46:13.109
they're at their peak around the 3rd to


00:46:13.119 --> 00:46:16.150
the 7th of May. Have quite a broad peak.


00:46:16.160 --> 00:46:18.950
But this year the moon is a waning


00:46:18.960 --> 00:46:21.349
gibbus. So at the time of night when you


00:46:21.359 --> 00:46:22.870
could see these meteors, the sky will be


00:46:22.880 --> 00:46:25.349
really bright and so far fewer will be


00:46:25.359 --> 00:46:27.589
visible than normal and you can get that


00:46:27.599 --> 00:46:29.349
from these calendars. But the highlight


00:46:29.359 --> 00:46:30.790
of every year for me showers is the


00:46:30.800 --> 00:46:34.150
Geminids in December and they are pretty


00:46:34.160 --> 00:46:36.790
much global as a phenomenon and they're


00:46:36.800 --> 00:46:38.390
brilliant everywhere. Obviously better


00:46:38.400 --> 00:46:39.670
for the northern hemisphere than the


00:46:39.680 --> 00:46:42.150
south. That's like a recurring theme,


00:46:42.160 --> 00:46:45.270
but they are great every year and this


00:46:45.280 --> 00:46:47.990
year moon will be effectively new. So,


00:46:48.000 --> 00:46:49.349
if you want to go see the Geminids


00:46:49.359 --> 00:46:51.750
peaking on the 14th or 15th of December,


00:46:51.760 --> 00:46:53.510
they're the highlight this year and


00:46:53.520 --> 00:46:54.870
pretty much every year.


00:46:54.880 --> 00:46:56.870
>> Okay. Uh, we're going to take another


00:46:56.880 --> 00:46:58.710
breath and then we'll come back and wrap


00:46:58.720 --> 00:47:00.710
it all up in this episode of Space Nuts


00:47:00.720 --> 00:47:05.589
with Andrew Dunley and Jonty Horner.


00:47:05.599 --> 00:47:07.589
>> Swift


00:47:07.599 --> 00:47:09.670
base here. The angle has landed.


00:47:09.680 --> 00:47:13.430
>> Space Nuts. One of my big frustrations


00:47:13.440 --> 00:47:16.069
uh when I want to observe comets is I


00:47:16.079 --> 00:47:19.190
live on a very flat area of the planet.


00:47:19.200 --> 00:47:22.150
Uh we don't have mountains nearby. We


00:47:22.160 --> 00:47:24.790
barely have hills and a lot of the


00:47:24.800 --> 00:47:29.430
comets are visible in the low horizon


00:47:29.440 --> 00:47:33.430
just after sunset or thereabouts. And


00:47:33.440 --> 00:47:35.750
they're short-lived and they're they're


00:47:35.760 --> 00:47:38.790
below the horizon way too quick. uh


00:47:38.800 --> 00:47:40.950
which makes astrophotography a real pain


00:47:40.960 --> 00:47:44.550
in the butt for me. But it is just a a


00:47:44.560 --> 00:47:49.510
quirk of where I live. Um I believe the


00:47:49.520 --> 00:47:51.589
that we do have some pretty spectacular


00:47:51.599 --> 00:47:54.550
ones coming up. I I the one that I've


00:47:54.560 --> 00:47:56.470
seen in my life that was the most


00:47:56.480 --> 00:48:00.150
spectacular for me was in 2007, January


00:48:00.160 --> 00:48:01.829
2007.


00:48:01.839 --> 00:48:05.109
Uh the it was Comet McNort. It was


00:48:05.119 --> 00:48:08.790
amazing. like naked eye comet wise it


00:48:08.800 --> 00:48:12.069
was unmissable. Uh it dominated the sky


00:48:12.079 --> 00:48:14.710
for quite some time. Uh we don't see


00:48:14.720 --> 00:48:17.270
many like that though do we? We don't.


00:48:17.280 --> 00:48:18.950
Now comet McNaugh was probably the


00:48:18.960 --> 00:48:21.349
brightest comet since the 1960s and it


00:48:21.359 --> 00:48:24.309
was truly a great comet. Now when we


00:48:24.319 --> 00:48:26.790
talk about the brightest comets and the


00:48:26.800 --> 00:48:29.190
ones people want to see great comet is


00:48:29.200 --> 00:48:30.790
the Appalachian people attached to


00:48:30.800 --> 00:48:32.309
comets and it's got a woollyish


00:48:32.319 --> 00:48:33.990
definition. It's basically the comet was


00:48:34.000 --> 00:48:35.990
bright enough and spectacular enough


00:48:36.000 --> 00:48:37.510
that even people who weren't that


00:48:37.520 --> 00:48:39.030
interested could just step outside and


00:48:39.040 --> 00:48:40.870
see it. Comet McNot's definitely like


00:48:40.880 --> 00:48:43.430
that. Arguably Comet Chuchchin Chan


00:48:43.440 --> 00:48:46.309
Atlas in 2024 and Comet Atlas in early


00:48:46.319 --> 00:48:50.069
2025 just made that threshold. So if you


00:48:50.079 --> 00:48:51.829
saw those comets, you'd probably say


00:48:51.839 --> 00:48:53.990
they are right at the lower end of what


00:48:54.000 --> 00:48:56.150
we consider a great comet. M


00:48:56.160 --> 00:48:58.230
>> on average if you go back through


00:48:58.240 --> 00:49:00.230
historical comic records you'd probably


00:49:00.240 --> 00:49:02.790
get about 10 great comics per century


00:49:02.800 --> 00:49:05.829
with very wide variance and that's not


00:49:05.839 --> 00:49:07.670
one every 10 years though like buses you


00:49:07.680 --> 00:49:09.430
wait 30 years and two come along at once


00:49:09.440 --> 00:49:12.150
and you saw that back in 1996 with comet


00:49:12.160 --> 00:49:14.470
Hailbop and comet H high kitaki which


00:49:14.480 --> 00:49:16.230
were visible in the sky at the same time


00:49:16.240 --> 00:49:18.230
as great comets.


00:49:18.240 --> 00:49:19.829
>> It's really hard to predict when they're


00:49:19.839 --> 00:49:21.190
going to come in but we've seen some


00:49:21.200 --> 00:49:23.270
really fascinating advances in the last


00:49:23.280 --> 00:49:26.309
few years on two fronts. Firstly, our


00:49:26.319 --> 00:49:28.549
ability to find things early has


00:49:28.559 --> 00:49:31.030
improved. We've got better telescopes,


00:49:31.040 --> 00:49:34.069
more automated surveys, and comet maps


00:49:34.079 --> 00:49:35.270
earlier this year, which turned out to


00:49:35.280 --> 00:49:36.630
be a bit of a disappointment for many


00:49:36.640 --> 00:49:37.990
people, is a really good example of


00:49:38.000 --> 00:49:39.750
that. That's a member of the CO


00:49:39.760 --> 00:49:42.630
sungrazing family. And the CO sungrazers


00:49:42.640 --> 00:49:44.870
have numbered many of the brightest


00:49:44.880 --> 00:49:46.390
great comets of the last couple of


00:49:46.400 --> 00:49:49.349
thousand years. Comet maps was the


00:49:49.359 --> 00:49:50.950
earliest we've ever found a crot


00:49:50.960 --> 00:49:53.750
sungrazer on the way in earlier even


00:49:53.760 --> 00:49:56.150
than comedy kayeki which was probably


00:49:56.160 --> 00:49:58.150
the brightest comet in the 20th century


00:49:58.160 --> 00:50:00.790
back in the late 1960s and so people's


00:50:00.800 --> 00:50:02.710
hopes were high but in reality it was


00:50:02.720 --> 00:50:04.950
quite a small fragment of the crot's


00:50:04.960 --> 00:50:07.349
parents sunraer these crots comets are


00:50:07.359 --> 00:50:08.950
all fragments of a bigger comet in the


00:50:08.960 --> 00:50:10.790
past and it just fell apart on its way


00:50:10.800 --> 00:50:13.990
in nothing to see here but our ability


00:50:14.000 --> 00:50:17.030
to find things earlier means that we get


00:50:17.040 --> 00:50:18.150
more warning


00:50:18.160 --> 00:50:19.510
when a bright comet's coming. Now,


00:50:19.520 --> 00:50:21.510
that's not absolutely guaranteed. We had


00:50:21.520 --> 00:50:23.589
a comet and the name of it slipped my


00:50:23.599 --> 00:50:27.670
mind um comet 12 18 months ago. Um no, I


00:50:27.680 --> 00:50:31.109
think it was like last September that


00:50:31.119 --> 00:50:33.109
was discovered when it was almost naked


00:50:33.119 --> 00:50:35.589
eye visibility. It just about became


00:50:35.599 --> 00:50:37.270
naked eye visible. Wasn't great by any


00:50:37.280 --> 00:50:37.990
means.


00:50:38.000 --> 00:50:38.309
>> Swan,


00:50:38.319 --> 00:50:39.990
>> but we got no warning. That's it. Comet


00:50:40.000 --> 00:50:42.390
swan. And the reason that that was found


00:50:42.400 --> 00:50:44.150
so late was it came at us from behind


00:50:44.160 --> 00:50:46.710
the sun and suddenly popped into view.


00:50:46.720 --> 00:50:49.030
So that does still happen. But with


00:50:49.040 --> 00:50:50.790
facilities like Vera Rubin coming


00:50:50.800 --> 00:50:52.230
online, we're going to find comets


00:50:52.240 --> 00:50:54.470
earlier and earlier, which means we get


00:50:54.480 --> 00:50:56.549
more prior warning, but it also means


00:50:56.559 --> 00:50:58.309
that the uncertainty about how bright


00:50:58.319 --> 00:50:59.670
they're going to get is possibly even


00:50:59.680 --> 00:51:02.309
higher cuz we're almost finding them now


00:51:02.319 --> 00:51:03.829
before they've really started to become


00:51:03.839 --> 00:51:05.349
active while they're far enough from the


00:51:05.359 --> 00:51:06.630
sun that we're almost seeing a bare


00:51:06.640 --> 00:51:09.750
nucleus or we're seeing a much smaller


00:51:09.760 --> 00:51:10.870
comet that's have a little bit of an


00:51:10.880 --> 00:51:12.870
outburst at that distance. And whether


00:51:12.880 --> 00:51:14.870
that far away, we effectively can't tell


00:51:14.880 --> 00:51:16.309
the difference. they're still like a


00:51:16.319 --> 00:51:18.309
single pixel. There's a really good


00:51:18.319 --> 00:51:20.309
example of this in the form of comet


00:51:20.319 --> 00:51:22.870
Chuch Chin Chan. Um, not comet Chuchchan


00:51:22.880 --> 00:51:24.069
Atlas from a couple of years ago, but


00:51:24.079 --> 00:51:25.750
comet Chuch Chin Chan that has just been


00:51:25.760 --> 00:51:27.349
discovered in the last couple of months.


00:51:27.359 --> 00:51:30.549
Comet C/2026C1.


00:51:30.559 --> 00:51:32.790
As we record this, that comet is still


00:51:32.800 --> 00:51:34.950
more distant from the sun than the orbit


00:51:34.960 --> 00:51:36.390
of Saturn.


00:51:36.400 --> 00:51:38.069
>> It was found a couple of months ago. It


00:51:38.079 --> 00:51:39.349
will not be at its closest to some


00:51:39.359 --> 00:51:42.549
perihelion until November 2028. So,


00:51:42.559 --> 00:51:45.190
we've got two and a half years to wait.


00:51:45.200 --> 00:51:47.589
Now, what factors into a comet's


00:51:47.599 --> 00:51:49.670
brightness is very complicated. Um, but


00:51:49.680 --> 00:51:51.030
it can boil down to a few different


00:51:51.040 --> 00:51:53.829
things. Firstly, if everything else is


00:51:53.839 --> 00:51:55.829
equal. So, imagine we only change one


00:51:55.839 --> 00:51:58.309
thing. Typically, the bigger the nucleus


00:51:58.319 --> 00:51:59.990
of the comet, the bigger its surface


00:52:00.000 --> 00:52:03.030
area is, so the more dust and gas it can


00:52:03.040 --> 00:52:05.430
produce. And we see the comet from the


00:52:05.440 --> 00:52:06.870
light that is reflected from the dust


00:52:06.880 --> 00:52:08.470
and gas. That's what makes the tails in


00:52:08.480 --> 00:52:10.549
the coma. The snowballs at the head are


00:52:10.559 --> 00:52:12.230
actually pretty small. Comet McNaugh was


00:52:12.240 --> 00:52:14.950
only about 5 km across for the nucleus,


00:52:14.960 --> 00:52:17.670
but it grew tails more than 300 million


00:52:17.680 --> 00:52:18.710
km long.


00:52:18.720 --> 00:52:21.190
>> Yeah, that's different. Incredible.


00:52:21.200 --> 00:52:23.270
>> So, if you have two comet nuclei that


00:52:23.280 --> 00:52:25.670
are in all senses identical other than


00:52:25.680 --> 00:52:27.510
their size, the bigger one will


00:52:27.520 --> 00:52:29.030
typically be more active and produce


00:52:29.040 --> 00:52:32.710
more gas and dust. However, some comets


00:52:32.720 --> 00:52:34.470
have a larger fraction of their surface


00:52:34.480 --> 00:52:36.790
active than others. Some comets are


00:52:36.800 --> 00:52:38.470
almost dormant because they're clogged


00:52:38.480 --> 00:52:39.910
up and there's very little activity even


00:52:39.920 --> 00:52:42.069
from a larger nucleus. So already a bit


00:52:42.079 --> 00:52:44.549
complex, but first rule of thumb, the


00:52:44.559 --> 00:52:46.230
bigger the nucleus, the more likelihood


00:52:46.240 --> 00:52:47.589
there is that it will be able to produce


00:52:47.599 --> 00:52:48.870
a lot of gas and dust and be more


00:52:48.880 --> 00:52:51.750
spectacular. With comet Chuch Chen Shan,


00:52:51.760 --> 00:52:53.430
that's interesting. We found it so far


00:52:53.440 --> 00:52:55.349
away, which suggests it is either a


00:52:55.359 --> 00:52:57.510
comet with quite a large nucleus because


00:52:57.520 --> 00:52:59.510
it's probably not that active at that


00:52:59.520 --> 00:53:01.750
distance, but it may have just had a bit


00:53:01.760 --> 00:53:04.230
of an outburst of activity driven by


00:53:04.240 --> 00:53:06.390
something like carbon monoxide, which


00:53:06.400 --> 00:53:08.150
can turn from solid to gas at a very low


00:53:08.160 --> 00:53:09.750
temperature. So, it might be


00:53:09.760 --> 00:53:11.510
masquerading as a bigger comet than it


00:53:11.520 --> 00:53:13.109
is, and we don't know.


00:53:13.119 --> 00:53:13.670
>> Okay.


00:53:13.680 --> 00:53:15.190
>> The next thing that factors into how


00:53:15.200 --> 00:53:16.790
bright a comet gets is how close it gets


00:53:16.800 --> 00:53:18.470
to the sun. So the closer it gets to the


00:53:18.480 --> 00:53:19.349
sun,


00:53:19.359 --> 00:53:21.510
>> the hotter its surface gets and the more


00:53:21.520 --> 00:53:23.349
strongly it will be active. So with


00:53:23.359 --> 00:53:26.069
comet McNaut, you had a 5 km nucleus


00:53:26.079 --> 00:53:28.470
which is fairly respectable but not as


00:53:28.480 --> 00:53:31.190
big as Hailbot which was 50 km. Hailbot


00:53:31.200 --> 00:53:33.670
was ridiculous. But comet McNaut got


00:53:33.680 --> 00:53:35.750
very close into the sun. So it got


00:53:35.760 --> 00:53:38.150
really incredibly intensely active was


00:53:38.160 --> 00:53:39.670
throwing off huge amounts of gas and


00:53:39.680 --> 00:53:42.390
dust. So that contributed again to more


00:53:42.400 --> 00:53:44.870
stuff to reflect sunlight and also being


00:53:44.880 --> 00:53:46.390
nearer to the sun, the intensity of


00:53:46.400 --> 00:53:47.829
light reflecting off it's higher as


00:53:47.839 --> 00:53:49.430
well. So kind of get a double whammy


00:53:49.440 --> 00:53:51.589
there. The other factor is how close


00:53:51.599 --> 00:53:53.430
they get to the earth. So if you have


00:53:53.440 --> 00:53:55.190
two comets that are the same size and


00:53:55.200 --> 00:53:57.109
the same distance from the sun and one


00:53:57.119 --> 00:53:59.109
is closer to the earth than the other,


00:53:59.119 --> 00:54:00.549
the one closer to the earth will be


00:54:00.559 --> 00:54:01.910
brighter, but will also potentially be


00:54:01.920 --> 00:54:03.510
more spread out and more diffuse in the


00:54:03.520 --> 00:54:05.430
sky. So that brightness might be spread


00:54:05.440 --> 00:54:07.349
over a different area.


00:54:07.359 --> 00:54:09.670
You've then got subtleties of how dusty


00:54:09.680 --> 00:54:12.230
or gassy they are. Some comets like


00:54:12.240 --> 00:54:15.030
comet Pan Stars seem to be more gassy.


00:54:15.040 --> 00:54:16.630
Some comets like Chuch Chin Chan Atlas


00:54:16.640 --> 00:54:17.990
was more dusty and that can have an


00:54:18.000 --> 00:54:20.230
impact on how they brighten. Bringing


00:54:20.240 --> 00:54:21.589
all this back together though for comet


00:54:21.599 --> 00:54:24.549
Chuch Chin Chan. At its closest to the


00:54:24.559 --> 00:54:26.150
Sun, it will be a little bit further


00:54:26.160 --> 00:54:28.150
from the Sun than the Earth is. So, it's


00:54:28.160 --> 00:54:29.670
not like comet McNaugh that's going to


00:54:29.680 --> 00:54:32.309
get really close in. But 1 AU from the


00:54:32.319 --> 00:54:33.829
Sun's fairly respectable. it can still


00:54:33.839 --> 00:54:35.349
maintain a fairly decent level of


00:54:35.359 --> 00:54:37.349
activity at that distance. Comet hellbop


00:54:37.359 --> 00:54:38.950
didn't get much closer than that and was


00:54:38.960 --> 00:54:40.470
fantastic.


00:54:40.480 --> 00:54:41.829
So that's in its favor. It's going to


00:54:41.839 --> 00:54:43.670
get close enough in that you could get a


00:54:43.680 --> 00:54:46.309
decent level of activity.


00:54:46.319 --> 00:54:48.870
Also, because it's only going to get


00:54:48.880 --> 00:54:50.230
that close to the sun, it'll take a bit


00:54:50.240 --> 00:54:51.510
longer to pass through the inner solar


00:54:51.520 --> 00:54:53.030
system. Comets that get really close to


00:54:53.040 --> 00:54:55.589
the sun get traveling incredibly quickly


00:54:55.599 --> 00:54:57.030
at that point. So they tend to whip in


00:54:57.040 --> 00:54:58.390
and whip out fairly quickly. Whereas


00:54:58.400 --> 00:55:00.150
with cometry chinchan, it's going to


00:55:00.160 --> 00:55:03.190
hang around for a fair while. It is


00:55:03.200 --> 00:55:05.190
potentially quite a large cometry


00:55:05.200 --> 00:55:07.670
nucleus, but we don't know yet. This is


00:55:07.680 --> 00:55:10.150
the the caution I give. If it turns out


00:55:10.160 --> 00:55:11.750
that we've caught it during an outburst,


00:55:11.760 --> 00:55:13.349
it may be a bit of a disappointment. If


00:55:13.359 --> 00:55:14.630
we've actually seen it as a bare


00:55:14.640 --> 00:55:18.470
nucleus, that orers very very very well.


00:55:18.480 --> 00:55:20.150
What this all suggests is that comet


00:55:20.160 --> 00:55:23.270
chaan has the potential to be bright in


00:55:23.280 --> 00:55:26.950
late 2028. Depending on which fit to its


00:55:26.960 --> 00:55:28.950
current brightness you use, it could


00:55:28.960 --> 00:55:30.950
become barely naked eye visible, which


00:55:30.960 --> 00:55:33.109
is still pretty good. You know, we see


00:55:33.119 --> 00:55:35.990
20 or 30 comets a year and very only


00:55:36.000 --> 00:55:37.190
maybe one will get to naked eye


00:55:37.200 --> 00:55:39.349
visibility. Or it could get as bright as


00:55:39.359 --> 00:55:40.950
the brightest stars. And if it gets as


00:55:40.960 --> 00:55:43.190
bright as the brightest stars, then it


00:55:43.200 --> 00:55:45.910
gets into great comet type territory.


00:55:45.920 --> 00:55:47.670
That's a factor of a 100 difference in


00:55:47.680 --> 00:55:49.990
brightness between those two extremes.


00:55:50.000 --> 00:55:51.430
And it could get brighter than the


00:55:51.440 --> 00:55:52.950
brightest extreme there or fainter than


00:55:52.960 --> 00:55:55.109
the faintest extreme. We just don't know


00:55:55.119 --> 00:55:57.510
yet. But having found it so early or as


00:55:57.520 --> 00:56:00.150
well, but typically predicting the next


00:56:00.160 --> 00:56:01.990
great comet is a fool's bargain until


00:56:02.000 --> 00:56:04.630
it's discovered. What we can say is that


00:56:04.640 --> 00:56:07.589
there are a few periodic comets that


00:56:07.599 --> 00:56:09.750
will be great in the future. Comet


00:56:09.760 --> 00:56:11.990
Halley will be a lot better in 2061 than


00:56:12.000 --> 00:56:15.030
it was in 1986. In 1986, we had the


00:56:15.040 --> 00:56:16.950
worst operation of comet Hali for 2,000


00:56:16.960 --> 00:56:17.589
years.


00:56:17.599 --> 00:56:18.630
>> Tell me about it.


00:56:18.640 --> 00:56:21.910
>> Yeah. Bit disappointing. 2061 will be


00:56:21.920 --> 00:56:22.630
better.


00:56:22.640 --> 00:56:24.470
>> Oh, good. Well, I don't know if I'll be


00:56:24.480 --> 00:56:27.030
around by then, but um probably not.


00:56:27.040 --> 00:56:29.270
I'll be 99.


00:56:29.280 --> 00:56:31.109
>> Make everybody feel really cheerful.


00:56:31.119 --> 00:56:32.950
It's now closer to Comet Hall's next


00:56:32.960 --> 00:56:34.549
apparition than the last one. It turned


00:56:34.559 --> 00:56:35.910
around, I think, last year. So, it's on


00:56:35.920 --> 00:56:36.950
its way back. Yeah.


00:56:36.960 --> 00:56:38.549
>> Comet Halley will be even better in


00:56:38.559 --> 00:56:40.470
2135.


00:56:40.480 --> 00:56:42.069
Will be really good that year. And that


00:56:42.079 --> 00:56:43.670
will be the best apparition for a couple


00:56:43.680 --> 00:56:45.829
of hundred years. Comet Swift Tuttle


00:56:45.839 --> 00:56:48.069
will be incredible in 2126. We know that


00:56:48.079 --> 00:56:49.430
cuz we know pretty much exactly when


00:56:49.440 --> 00:56:50.789
it'll come back. We know where it will


00:56:50.799 --> 00:56:52.789
be compared to the Earth and the Sun.


00:56:52.799 --> 00:56:55.430
There is a suggestion that in 2097 we


00:56:55.440 --> 00:56:57.030
may have the comet of the century or


00:56:57.040 --> 00:56:58.789
close to it. This is research that came


00:56:58.799 --> 00:57:01.270
out last year. One of the greatest


00:57:01.280 --> 00:57:03.510
comets of the last thousand years was


00:57:03.520 --> 00:57:07.750
comet dishes in 1744. Also called comet


00:57:07.760 --> 00:57:09.670
Clinkenberg. Comet that is famous for


00:57:09.680 --> 00:57:12.390
having had six tails. Incredibly bright


00:57:12.400 --> 00:57:15.109
almost visible in broad daylight. A


00:57:15.119 --> 00:57:16.870
couple of astronomers, I think the lead


00:57:16.880 --> 00:57:19.030
researcher on this was Mike Meyer,


00:57:19.040 --> 00:57:20.950
published a paper last year that went


00:57:20.960 --> 00:57:23.430
back through historical observations and


00:57:23.440 --> 00:57:25.430
found a number of previous comets over


00:57:25.440 --> 00:57:27.349
the last 2,000 years that were all


00:57:27.359 --> 00:57:29.910
incredibly bright, really spectacular,


00:57:29.920 --> 00:57:31.510
but seem to have been moving the same as


00:57:31.520 --> 00:57:33.750
that comet, linked them together, and


00:57:33.760 --> 00:57:35.510
it's a very compelling tale that if


00:57:35.520 --> 00:57:38.150
their research is correct, that comet


00:57:38.160 --> 00:57:40.150
actually has an orbital period of just a


00:57:40.160 --> 00:57:43.109
little bit less, just around 450 years,


00:57:43.119 --> 00:57:45.829
I think 400 years. No, 350 years,


00:57:45.839 --> 00:57:47.910
wouldn't it? Do the mental arithmetic.


00:57:47.920 --> 00:57:50.950
Yeah, about 350 years, which means it


00:57:50.960 --> 00:57:53.109
should return in 2097.


00:57:53.119 --> 00:57:56.390
And if it does, it will be awesome. Um,


00:57:56.400 --> 00:57:57.990
sadly, I don't think you or I will be


00:57:58.000 --> 00:57:59.109
around for that.


00:57:59.119 --> 00:58:00.150
>> Probably not.


00:58:00.160 --> 00:58:01.589
>> Probably not. But things like that we


00:58:01.599 --> 00:58:02.950
can predict. But most


00:58:02.960 --> 00:58:04.309
>> Fred will be, but


00:58:04.319 --> 00:58:06.069
>> absolutely. Fred is indestructible, and


00:58:06.079 --> 00:58:09.270
I'll stand by that. But most of the big


00:58:09.280 --> 00:58:11.510
cometry nuclei coming through are on


00:58:11.520 --> 00:58:13.030
such long period orbits with the


00:58:13.040 --> 00:58:15.349
exception of Halley and Swift Tuttle


00:58:15.359 --> 00:58:17.109
that their apparitions are so infrequent


00:58:17.119 --> 00:58:18.549
that we've not identified them as


00:58:18.559 --> 00:58:20.390
periodic visitors and many of them have


00:58:20.400 --> 00:58:22.309
periods of thousands or tens of


00:58:22.319 --> 00:58:24.549
thousands of years. So we typically only


00:58:24.559 --> 00:58:27.190
find them on their way in a few weeks or


00:58:27.200 --> 00:58:30.150
a few months before apparition in case


00:58:30.160 --> 00:58:32.870
of comet hellopet was 2 years which was


00:58:32.880 --> 00:58:34.710
exceptional at the time. KZ of comet


00:58:34.720 --> 00:58:36.309
Chuchin Shan it's more than two and a


00:58:36.319 --> 00:58:39.030
half years away but our technology has


00:58:39.040 --> 00:58:41.510
improved hugely so I don't think it's


00:58:41.520 --> 00:58:43.030
fair necessarily to say that Chuchin


00:58:43.040 --> 00:58:45.270
Shan will be another hail bop


00:58:45.280 --> 00:58:47.349
>> but if you look at the brighter end of


00:58:47.359 --> 00:58:48.870
the predictions it could be naked eye


00:58:48.880 --> 00:58:50.950
visible for 3 four 5 months


00:58:50.960 --> 00:58:51.349
>> wow


00:58:51.359 --> 00:58:52.789
>> which would be awesome and it would


00:58:52.799 --> 00:58:54.470
potentially be circumpolar for us in the


00:58:54.480 --> 00:58:56.309
southern hemisphere because at its


00:58:56.319 --> 00:58:57.670
closest to the sun of the earth it's


00:58:57.680 --> 00:58:59.670
going to be way south not going to be


00:58:59.680 --> 00:59:01.829
good for the northern hemisphere but we


00:59:01.839 --> 00:59:03.190
can't really predict that it's the same


00:59:03.200 --> 00:59:05.109
with meteor showers, we can predict the


00:59:05.119 --> 00:59:06.950
annual ones roughly how good they're


00:59:06.960 --> 00:59:07.750
going to be.


00:59:07.760 --> 00:59:08.470
>> Y


00:59:08.480 --> 00:59:10.390
>> and if you go back to when I was a kid,


00:59:10.400 --> 00:59:11.990
we couldn't really predict meteor


00:59:12.000 --> 00:59:13.670
storms, meteor outbursts, and that's one


00:59:13.680 --> 00:59:15.190
of the things people really love to see.


00:59:15.200 --> 00:59:17.030
So Geminids are great. Northern


00:59:17.040 --> 00:59:19.349
hemisphere, you'll see maybe even 80 or


00:59:19.359 --> 00:59:20.870
100 an hour at their peak in the early


00:59:20.880 --> 00:59:22.710
hours of the morning. I've seen 50 an


00:59:22.720 --> 00:59:25.109
hour from our latitude near Brisbane.


00:59:25.119 --> 00:59:27.030
They're really good. But what people


00:59:27.040 --> 00:59:28.950
really want to see are meteor storms,


00:59:28.960 --> 00:59:31.270
and they're much rarer. There's a few


00:59:31.280 --> 00:59:33.109
amazing ones historically. There was the


00:59:33.119 --> 00:59:36.230
one in 1833 that was linked to the


00:59:36.240 --> 00:59:39.750
Leonid meteor shower that had a rate in


00:59:39.760 --> 00:59:43.109
excess of 100,000 an hour was best seen


00:59:43.119 --> 00:59:47.670
from the contiguous US and it was bright


00:59:47.680 --> 00:59:49.349
enough there were sufficient meteors in


00:59:49.359 --> 00:59:52.870
the sky that miners in the US were woken


00:59:52.880 --> 00:59:54.630
from their campsites by the light


00:59:54.640 --> 00:59:56.549
shining through their tents and people


00:59:56.559 --> 00:59:57.990
were convinced that the end times had


00:59:58.000 --> 01:00:00.549
come the apocalypse was here because he


01:00:00.559 --> 01:00:02.789
were getting as many as 20 meteors per


01:00:02.799 --> 01:00:03.910
second.


01:00:03.920 --> 01:00:04.470
>> Incredible.


01:00:04.480 --> 01:00:06.710
>> Um, now that in the way that kind of


01:00:06.720 --> 01:00:09.190
Taiko's observations in 1577 were


01:00:09.200 --> 01:00:11.190
probably the birth of modern cometry


01:00:11.200 --> 01:00:14.230
astronomy, 1833, I think, was possibly


01:00:14.240 --> 01:00:16.069
the birth of modern meteor astronomy


01:00:16.079 --> 01:00:17.670
because there had been a storm from the


01:00:17.680 --> 01:00:20.870
lineage in 1799. People predicted that


01:00:20.880 --> 01:00:23.030
there might be another one in 1866


01:00:23.040 --> 01:00:24.470
because maybe this was happening every


01:00:24.480 --> 01:00:26.710
33 years when the comet came back and


01:00:26.720 --> 01:00:29.750
indeed that happened in 1866.


01:00:29.760 --> 01:00:32.470
And so that was a bit like the birth of


01:00:32.480 --> 01:00:34.390
modern meteor science. And after that,


01:00:34.400 --> 01:00:35.589
people said, "Well, there'll be one in


01:00:35.599 --> 01:00:38.549
1899." And there wasn't. So that then


01:00:38.559 --> 01:00:41.270
tricked people up. So thanks to that,


01:00:41.280 --> 01:00:42.710
we've gradually developed a better


01:00:42.720 --> 01:00:44.150
understanding of the physics of how


01:00:44.160 --> 01:00:46.549
meteor showers work. And I'm aware time


01:00:46.559 --> 01:00:48.549
is running away from us. But it for


01:00:48.559 --> 01:00:50.549
people interested in this, in the run-up


01:00:50.559 --> 01:00:53.589
to the Leonid heavy leanid activity in


01:00:53.599 --> 01:00:56.789
1999 through to 2002, there was some


01:00:56.799 --> 01:01:00.390
amazing research done by um David Asher


01:01:00.400 --> 01:01:02.789
from Amar Observatory and I think fondly


01:01:02.799 --> 01:01:04.309
on David because he was a lovely mentor


01:01:04.319 --> 01:01:07.430
to me when I visited Amar in 1999. very


01:01:07.440 --> 01:01:09.270
quiet guy but incredibly talented


01:01:09.280 --> 01:01:12.230
scientist and he did this remarkable


01:01:12.240 --> 01:01:15.109
work making predictions of when we would


01:01:15.119 --> 01:01:17.910
and wouldn't get Leonid storms by


01:01:17.920 --> 01:01:19.990
modeling the ejection of dust from the


01:01:20.000 --> 01:01:22.069
cometry nucleus and evolving the dust


01:01:22.079 --> 01:01:24.150
forward in time and go back way earlier


01:01:24.160 --> 01:01:27.589
on I mentioned these javelin sh spikes


01:01:27.599 --> 01:01:29.670
he event he effectively modeled those


01:01:29.680 --> 01:01:31.109
and figured out where the spikes will be


01:01:31.119 --> 01:01:32.789
and a slight nudge up or down means that


01:01:32.799 --> 01:01:34.470
the earth will run through the spike or


01:01:34.480 --> 01:01:36.870
not and the great lean zones are


01:01:36.880 --> 01:01:38.789
produced by dust left behind just one or


01:01:38.799 --> 01:01:41.910
two revolutions ago. So the activity


01:01:41.920 --> 01:01:45.589
between 1999 and 2002 resulted from a


01:01:45.599 --> 01:01:47.829
few different streams. The older they


01:01:47.839 --> 01:01:49.670
are, the more diffuse they get. But now


01:01:49.680 --> 01:01:51.910
we have the ability for comets we know


01:01:51.920 --> 01:01:54.150
well and meteor showers we know well to


01:01:54.160 --> 01:01:55.430
figure out where those spikes are


01:01:55.440 --> 01:01:57.510
roughly going to be, how long they are,


01:01:57.520 --> 01:02:00.390
and make predictions going forward. Now,


01:02:00.400 --> 01:02:01.990
there aren't any great meteor storms


01:02:02.000 --> 01:02:03.589
predicted in the relatively near future.


01:02:03.599 --> 01:02:05.829
The Leonids are not likely to give major


01:02:05.839 --> 01:02:09.109
storms in 2033 or 2066, but will give


01:02:09.119 --> 01:02:11.430
increased activity. The reason for that


01:02:11.440 --> 01:02:13.670
is Jupiter and Saturn are pulling those


01:02:13.680 --> 01:02:16.230
javelins around and making them miss the


01:02:16.240 --> 01:02:18.789
Earth. The leanings will probably return


01:02:18.799 --> 01:02:21.430
in force in I think 2097 with a


01:02:21.440 --> 01:02:23.589
possibility of a storm of like 20,000 an


01:02:23.599 --> 01:02:26.069
hour. But we're getting to understand


01:02:26.079 --> 01:02:28.390
that. So with meteor showers, we can


01:02:28.400 --> 01:02:30.630
predict the annual showers. They're very


01:02:30.640 --> 01:02:32.549
reliable. They gradually get better and


01:02:32.559 --> 01:02:34.230
worse with time as the streams move


01:02:34.240 --> 01:02:35.829
around and we insect more of the


01:02:35.839 --> 01:02:38.069
material or less, but they're pretty


01:02:38.079 --> 01:02:39.829
reliable.


01:02:39.839 --> 01:02:41.589
Outbursts are harder to predict, but


01:02:41.599 --> 01:02:44.950
we're getting better at doing it. But


01:02:44.960 --> 01:02:46.470
predicting an outburst from a shower


01:02:46.480 --> 01:02:48.710
we've never seen before or a shower


01:02:48.720 --> 01:02:50.950
that's incredibly rare, we typically


01:02:50.960 --> 01:02:53.430
can't do until it happens because we


01:02:53.440 --> 01:02:55.109
need to have a feel for what it's done


01:02:55.119 --> 01:02:57.270
in the past. So, we occasionally will


01:02:57.280 --> 01:02:58.950
get an outburst of a meteor shower we've


01:02:58.960 --> 01:03:01.349
never seen before. and you can't predict


01:03:01.359 --> 01:03:02.630
that. And that's when it's really


01:03:02.640 --> 01:03:04.390
exciting because then you can start to


01:03:04.400 --> 01:03:06.470
learn about a new meteor shower being


01:03:06.480 --> 01:03:08.230
born. You can learn about the comet that


01:03:08.240 --> 01:03:10.710
birthed it. Put all that together. And


01:03:10.720 --> 01:03:11.990
that's one of the things where I'll go


01:03:12.000 --> 01:03:13.589
out and I love my meteor showers. I'll


01:03:13.599 --> 01:03:15.270
sit out under the sky and watch them.


01:03:15.280 --> 01:03:16.789
But I would love to just be outside when


01:03:16.799 --> 01:03:18.470
there's an unexpected outburst when we


01:03:18.480 --> 01:03:20.309
see something new like a meteor shower


01:03:20.319 --> 01:03:22.309
being born for the first time. Just


01:03:22.319 --> 01:03:24.549
>> and and and that's what we recommend to


01:03:24.559 --> 01:03:26.870
all our space listeners. uh get up at


01:03:26.880 --> 01:03:30.470
2:00 every morning every day and go out


01:03:30.480 --> 01:03:32.150
and just wait. And you know, one day


01:03:32.160 --> 01:03:34.069
you'll get lucky. Might take 20 years,


01:03:34.079 --> 01:03:34.950
but


01:03:34.960 --> 01:03:36.549
>> doesn't have to be 2 a.m. I mean, there


01:03:36.559 --> 01:03:38.710
is a little bit of a preference for


01:03:38.720 --> 01:03:41.670
meteor showers to be more active in the


01:03:41.680 --> 01:03:43.270
morning hours and the evening hours, but


01:03:43.280 --> 01:03:45.190
that's purely a geometry thing. Yeah,


01:03:45.200 --> 01:03:46.309
>> it's linked a little bit to the


01:03:46.319 --> 01:03:47.589
direction of the Earth's motion and the


01:03:47.599 --> 01:03:48.789
direction things are crossing the


01:03:48.799 --> 01:03:51.270
Earth's orbit in that if you think about


01:03:51.280 --> 01:03:52.870
something crossing the Earth's orbit at


01:03:52.880 --> 01:03:55.029
right angles to the Earth because the


01:03:55.039 --> 01:03:57.029
Earth's moving forward at 30 km a


01:03:57.039 --> 01:03:59.029
second, the direction you would see that


01:03:59.039 --> 01:04:00.710
coming from is actually a bit ahead of


01:04:00.720 --> 01:04:01.910
you because you've got the addition of


01:04:01.920 --> 01:04:03.750
the speed the debris is going and the


01:04:03.760 --> 01:04:06.230
speed the Earth's moving. M so meteor


01:04:06.240 --> 01:04:07.990
showers


01:04:08.000 --> 01:04:10.950
that are visible with radiance that will


01:04:10.960 --> 01:04:12.789
be in the morning sky. You've got a


01:04:12.799 --> 01:04:14.150
little bit of an additive effect between


01:04:14.160 --> 01:04:15.589
the speed the debris is going and the


01:04:15.599 --> 01:04:17.670
speed the earth's moving which means the


01:04:17.680 --> 01:04:19.190
average impact speed of the debris is


01:04:19.200 --> 01:04:21.029
higher and you get more meteors. But


01:04:21.039 --> 01:04:23.430
also you get this effect of the earth's


01:04:23.440 --> 01:04:24.710
motion being a bit like you're driving


01:04:24.720 --> 01:04:26.870
into a snowstorm. You know if you're


01:04:26.880 --> 01:04:28.549
driving into a snowstorm where there's


01:04:28.559 --> 01:04:29.990
no wind and the snowflakes are falling


01:04:30.000 --> 01:04:32.150
down vertically you will perceive them


01:04:32.160 --> 01:04:33.910
as coming from in front of your car not


01:04:33.920 --> 01:04:36.069
overhead. And so there's a preference


01:04:36.079 --> 01:04:37.910
for meteor showers to be slightly more


01:04:37.920 --> 01:04:39.430
likely to have activity that peaks in


01:04:39.440 --> 01:04:41.109
the morning hours and the evening, but


01:04:41.119 --> 01:04:43.109
that's not a guarantee. There are some


01:04:43.119 --> 01:04:45.029
meteor showers that are at the highest


01:04:45.039 --> 01:04:46.470
where the radiant culminates in the


01:04:46.480 --> 01:04:49.990
evening sky. It just depends. Some like


01:04:50.000 --> 01:04:51.910
the Aquarids are only visible for a


01:04:51.920 --> 01:04:53.190
couple of hours before dawn. There's


01:04:53.200 --> 01:04:54.870
even a few meteor showers that are


01:04:54.880 --> 01:04:56.390
daylight showers where the radiance's


01:04:56.400 --> 01:04:57.990
only really above the horizon during the


01:04:58.000 --> 01:04:59.910
hours of daylight. And we know about


01:04:59.920 --> 01:05:01.750
them primarily from radio observations.


01:05:01.760 --> 01:05:04.230
Radar pe well not radar people listening


01:05:04.240 --> 01:05:06.870
to radio reflecting off the ionized


01:05:06.880 --> 01:05:09.109
streaks that the meteors leave in the


01:05:09.119 --> 01:05:11.270
ionosphere that allows you to see over


01:05:11.280 --> 01:05:13.670
the horizon to radio stations that are


01:05:13.680 --> 01:05:14.789
broadcasting that you don't normally


01:05:14.799 --> 01:05:16.950
get. So you can hear meteor showers.


01:05:16.960 --> 01:05:17.349
>> Yeah.


01:05:17.359 --> 01:05:18.870
>> So we know there are daytime showers


01:05:18.880 --> 01:05:20.630
that we cannot see at night and some of


01:05:20.640 --> 01:05:22.549
them are possibly as active as the


01:05:22.559 --> 01:05:24.710
Geminis of the Percids. If you know if


01:05:24.720 --> 01:05:26.870
we could turn the sun off I mean that


01:05:26.880 --> 01:05:28.150
would be a bad thing. Please don't do


01:05:28.160 --> 01:05:29.750
it. If you're a super villain listening,


01:05:29.760 --> 01:05:32.630
do not take this as an idea. But if we


01:05:32.640 --> 01:05:34.230
could turn the sun off and see, there


01:05:34.240 --> 01:05:35.510
are a couple of meteor showers in the


01:05:35.520 --> 01:05:36.870
daytime that could be pretty


01:05:36.880 --> 01:05:38.789
spectacular.


01:05:38.799 --> 01:05:41.109
It is all very fascinating. And I


01:05:41.119 --> 01:05:43.430
suppose the best advice would be to uh


01:05:43.440 --> 01:05:45.990
go and look for the the better sources


01:05:46.000 --> 01:05:47.990
of forecasting rather than trying to


01:05:48.000 --> 01:05:50.230
figure it out for yourself. And uh and


01:05:50.240 --> 01:05:51.510
you've mentioned a couple of them


01:05:51.520 --> 01:05:54.710
already, uh comet maps and what was the


01:05:54.720 --> 01:05:56.950
other one about meteors? For meteors, I


01:05:56.960 --> 01:05:58.230
really strongly recommend the


01:05:58.240 --> 01:05:59.990
International Meteor Organization. If


01:06:00.000 --> 01:06:02.630
you go to their website, hover over the


01:06:02.640 --> 01:06:04.549
resources link, click on it to get the


01:06:04.559 --> 01:06:05.990
drop down. Click on meteor shower


01:06:06.000 --> 01:06:07.910
calendar. They have on the right hand


01:06:07.920 --> 01:06:10.870
side the best showers of the year with


01:06:10.880 --> 01:06:12.150
information and what the moon will be


01:06:12.160 --> 01:06:13.589
like. But there's also on the left side


01:06:13.599 --> 01:06:15.990
a PDF that you can download that goes


01:06:16.000 --> 01:06:17.750
into much more minute detail and talks


01:06:17.760 --> 01:06:19.990
about even the more minor showers. And


01:06:20.000 --> 01:06:21.670
that's a very good point of truth for


01:06:21.680 --> 01:06:24.150
meteor showers. Well, I I kind of


01:06:24.160 --> 01:06:25.910
describe them being like three tiers of


01:06:25.920 --> 01:06:28.069
meteor showers, ignoring the outbursts.


01:06:28.079 --> 01:06:29.589
There are the big three, which are the


01:06:29.599 --> 01:06:31.430
quadrantids, the perids, and the


01:06:31.440 --> 01:06:33.670
geminids, which are even if you're not


01:06:33.680 --> 01:06:35.990
that interested at all in space. And if


01:06:36.000 --> 01:06:37.589
you are, thanks for listening to the


01:06:37.599 --> 01:06:39.750
podcast anyway, but it's not really our


01:06:39.760 --> 01:06:41.430
target audience. But even people who are


01:06:41.440 --> 01:06:43.029
not that interested, that's a spectacle


01:06:43.039 --> 01:06:44.390
you can go out and see with them and


01:06:44.400 --> 01:06:46.630
share with them. Just make sure that you


01:06:46.640 --> 01:06:48.309
figure out when the radiant rises from


01:06:48.319 --> 01:06:49.670
your location because you don't want to


01:06:49.680 --> 01:06:51.910
turn people off by looking at a time


01:06:51.920 --> 01:06:53.910
when you can't see meteors. So for the


01:06:53.920 --> 01:06:55.750
Geminids, the best time is around 2:00


01:06:55.760 --> 01:06:57.910
a.m. But depending on where you are in


01:06:57.920 --> 01:07:00.950
the world, from our latitude, you're


01:07:00.960 --> 01:07:02.390
looking at you can't see any before


01:07:02.400 --> 01:07:04.470
9:30, 10:00 at night. Obviously, if


01:07:04.480 --> 01:07:05.750
you're somewhere with daylight savings


01:07:05.760 --> 01:07:07.270
in the Southern Hemisphere, add an hour


01:07:07.280 --> 01:07:09.589
to that. So for you down in New South


01:07:09.599 --> 01:07:11.029
Wales where the clocks change, you're


01:07:11.039 --> 01:07:13.109
talking after 11:00 p.m. for you. But if


01:07:13.119 --> 01:07:15.109
you're in Northern Europe, the Geminid


01:07:15.119 --> 01:07:17.190
radiant never sets. So where I grew up


01:07:17.200 --> 01:07:18.789
in the UK, as soon as it got dark, I


01:07:18.799 --> 01:07:20.390
could see them. The rates still got


01:07:20.400 --> 01:07:21.750
better through the night. Similarly for


01:07:21.760 --> 01:07:24.069
the Percids in particular, Percids are a


01:07:24.079 --> 01:07:26.549
northern hemisphere only thing. It's


01:07:26.559 --> 01:07:27.990
light until quite late. Certainly for


01:07:28.000 --> 01:07:29.750
the high northern latitudes like the UK,


01:07:29.760 --> 01:07:31.270
but as soon as it gets dark, you can see


01:07:31.280 --> 01:07:33.589
them. So they're the showers that are


01:07:33.599 --> 01:07:35.430
well worth going out to look at as a


01:07:35.440 --> 01:07:37.990
beginner. And you just sit out there. I


01:07:38.000 --> 01:07:39.510
would figure out where the radiant is


01:07:39.520 --> 01:07:41.670
and look 30 or 40 degrees to the left or


01:07:41.680 --> 01:07:43.349
right of it to get the best balance


01:07:43.359 --> 01:07:45.510
between a lot of meteors but decent ones


01:07:45.520 --> 01:07:48.950
to see and just get a comfy chair, lie


01:07:48.960 --> 01:07:51.029
back, wrap up warm with the people you


01:07:51.039 --> 01:07:53.190
love and tell stories and relax and


01:07:53.200 --> 01:07:54.470
occasionally you'll see something good


01:07:54.480 --> 01:07:55.910
and it's quite addictive. You think, you


01:07:55.920 --> 01:07:57.430
know, I'll go to bed but I just want to


01:07:57.440 --> 01:07:59.109
see one more and then well that was


01:07:59.119 --> 01:08:00.710
rubbish so I want to see another one


01:08:00.720 --> 01:08:02.870
that's actually good. You've then got


01:08:02.880 --> 01:08:05.510
like the mid-tier showers which can be


01:08:05.520 --> 01:08:06.870
decent but you need to be a bit more


01:08:06.880 --> 01:08:08.230
dedicated for. These are the ones where


01:08:08.240 --> 01:08:10.390
you might see 10 or 15 an hour instead


01:08:10.400 --> 01:08:13.430
of 50 an hour. And I wouldn't recommend


01:08:13.440 --> 01:08:14.789
people who are beginners go out and see


01:08:14.799 --> 01:08:16.630
them because it's there's not enough


01:08:16.640 --> 01:08:18.789
happening. And that's why I worry about


01:08:18.799 --> 01:08:21.430
coverage for the April liids even in the


01:08:21.440 --> 01:08:23.430
northern hemisphere because they're just


01:08:23.440 --> 01:08:25.349
not that good. If you're someone who's


01:08:25.359 --> 01:08:27.910
really keen, you'll enjoy them, but for


01:08:27.920 --> 01:08:29.349
most people they'll be a let down and


01:08:29.359 --> 01:08:30.630
you don't want to turn people off the


01:08:30.640 --> 01:08:32.950
subject. Then there are the minor


01:08:32.960 --> 01:08:34.870
showers that you frankly need to be very


01:08:34.880 --> 01:08:36.390
obsessive to follow. And I've seen


01:08:36.400 --> 01:08:38.550
stories of a lot of the science of this


01:08:38.560 --> 01:08:41.349
has been done by amateur astronomers and


01:08:41.359 --> 01:08:42.709
quite often by people who are quite


01:08:42.719 --> 01:08:46.630
obsessive about the topic. And I saw one


01:08:46.640 --> 01:08:48.630
guy who was in North America where it


01:08:48.640 --> 01:08:51.749
gets brutal, brutal cold in the winter,


01:08:51.759 --> 01:08:54.550
who built himself a an insulated coffin


01:08:54.560 --> 01:08:56.789
with an incredibly transparent glass lid


01:08:56.799 --> 01:08:58.950
that he would carry out with him that


01:08:58.960 --> 01:08:59.990
was big enough for him to have a


01:09:00.000 --> 01:09:01.510
notebook and write down the details of


01:09:01.520 --> 01:09:03.669
every meteor he saw. So he could lie out


01:09:03.679 --> 01:09:05.749
in minus40°


01:09:05.759 --> 01:09:08.070
and I think that's um units ambivalent.


01:09:08.080 --> 01:09:09.590
I think Fahrenheit and centigrade are


01:09:09.600 --> 01:09:11.590
very similar at that point. But he's in


01:09:11.600 --> 01:09:13.829
an insulated box that keeps him warm and


01:09:13.839 --> 01:09:15.430
he'd lie out all night recording 2


01:09:15.440 --> 01:09:17.349
meters 3 meters an hour.


01:09:17.359 --> 01:09:20.470
>> That isn't for me, but it is for people.


01:09:20.480 --> 01:09:22.070
But when you see a meteor shower with a


01:09:22.080 --> 01:09:25.030
ZHR of less than about 20, I'd probably


01:09:25.040 --> 01:09:27.349
leave that unless you're really keen. If


01:09:27.359 --> 01:09:30.309
it's got a ZHR of 50 plus, well worth


01:09:30.319 --> 01:09:31.590
looking out for. But look for when the


01:09:31.600 --> 01:09:33.430
time of maximum is. For most meteor


01:09:33.440 --> 01:09:35.829
showers, they've got what we call a full


01:09:35.839 --> 01:09:38.470
width half maximum of about 24 hours.


01:09:38.480 --> 01:09:41.110
What that means is that the rate only


01:09:41.120 --> 01:09:42.870
stays above half of the peak rate for


01:09:42.880 --> 01:09:45.349
about 24 hours. For 48 hours, then it


01:09:45.359 --> 01:09:46.950
would stay above a quarter of the rate


01:09:46.960 --> 01:09:48.950
and so on. For the quadrantids, it's


01:09:48.960 --> 01:09:50.789
full width at quarter maximum of about


01:09:50.799 --> 01:09:53.430
12 hours. So that means if you're 6


01:09:53.440 --> 01:09:55.590
hours away from the peak, the rate is


01:09:55.600 --> 01:09:57.270
already down to a quarter of that peak.


01:09:57.280 --> 01:09:59.189
It's a very sharp peak. And if you're


01:09:59.199 --> 01:10:00.950
looking at the wrong time, the show


01:10:00.960 --> 01:10:02.630
won't be as good as you'd like it to be,


01:10:02.640 --> 01:10:05.030
and you'll be disappointed.


01:10:05.040 --> 01:10:06.870
So much to consider, Jonty, but uh


01:10:06.880 --> 01:10:10.070
fascinating cockpits and meteors. Um


01:10:10.080 --> 01:10:11.510
there's so much to talk about and we


01:10:11.520 --> 01:10:13.590
probably didn't really cover absolutely


01:10:13.600 --> 01:10:15.350
everything, although we did uh we did


01:10:15.360 --> 01:10:18.310
hit on quite a fair bit of info. And of


01:10:18.320 --> 01:10:19.990
course, we do welcome questions and


01:10:20.000 --> 01:10:22.550
comments. So, please u go to our website


01:10:22.560 --> 01:10:26.310
and um click that little AMA button at


01:10:26.320 --> 01:10:27.910
the top and you can send us questions


01:10:27.920 --> 01:10:30.630
and comments uh in text and audio form.


01:10:30.640 --> 01:10:32.470
Don't forget to tell us who you are and


01:10:32.480 --> 01:10:33.750
where you're from. But we're going to


01:10:33.760 --> 01:10:35.270
wrap it up there. Jonty, thank you so


01:10:35.280 --> 01:10:37.030
much. We'll catch you on the next show.


01:10:37.040 --> 01:10:38.630
>> Thank you very much.


01:10:38.640 --> 01:10:40.870
>> Professor Jonty her, professor of


01:10:40.880 --> 01:10:43.350
astrophysics at the University of


01:10:43.360 --> 01:10:46.390
Southern Queensland, our special guest


01:10:46.400 --> 01:10:48.790
commentator, while Fred's uh on the


01:10:48.800 --> 01:10:49.910
other side of the planet looking at


01:10:49.920 --> 01:10:53.270
meteors. And uh just a special word for


01:10:53.280 --> 01:10:55.830
uh for Hugh in the studio. He's been a


01:10:55.840 --> 01:10:58.070
little unwell lately. Hugh, get well


01:10:58.080 --> 01:11:00.149
soon, mate. We're all thinking of you.


01:11:00.159 --> 01:11:01.750
And from me, Andrew Dunley, thanks for


01:11:01.760 --> 01:11:03.110
your company. We'll catch you on the


01:11:03.120 --> 01:11:05.350
next episode of Space Nuts.


01:11:05.360 --> 01:11:06.310
>> Space Nuts.


01:11:06.320 --> 01:11:08.390
>> You'll be listening to the Space Nuts


01:11:08.400 --> 01:11:10.709
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01:11:10.719 --> 01:11:13.669
>> available at Apple Podcasts, Spotify,


01:11:13.679 --> 01:11:16.310
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01:11:16.320 --> 01:11:18.709
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01:11:18.719 --> 01:11:21.590
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