Feb. 20, 2025

Earth's Core, Hypervelocity Stars & Cosmic Dandruff: #497 - Unraveling the Mysteries Below and Beyond

Earth's Core, Hypervelocity Stars & Cosmic Dandruff: #497 - Unraveling the Mysteries Below and Beyond

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Space Nuts Episode 497: Earth's Core Dynamics, Hypervelocity Stars, and Cosmic Dust
Join Andrew...

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Space Nuts Episode 497: Earth's Core Dynamics, Hypervelocity Stars, and Cosmic Dust
Join Andrew Dunkley and Professor Jonti Horner in this captivating episode of Space Nuts as they delve into the intriguing dynamics of our planet's core, the discovery of a hyperactive star with a planet, and the fascinating phenomenon of cosmic dust. From the slowing of Earth's inner core to the implications of interstellar objects entering our solar system, this episode is filled with insights that will ignite your curiosity about the universe.
Episode Highlights:
- Earth's Core Dynamics: Andrew and Jonti discuss the recent findings regarding the Earth's inner core, revealing that it has been slowing down. They explore how researchers used data from repeating earthquakes to uncover the complexities of the core's rotation and its implications for our understanding of Earth's geology.
- Hypervelocity Stars: The duo introduces the concept of hypervelocity stars and highlights a newly discovered star that is moving at an astonishing speed of nearly 2 million kilometers per hour. They discuss the significance of this find and its connection to the planet orbiting this remarkable star.
- Cosmic Dust from Neighboring Systems: Andrew and Jonti explore the idea of "space dandruff," where neighboring solar systems contribute to the influx of cosmic dust in our own. They discuss simulations that suggest a million objects from the Alpha Centauri system are currently passing through our solar system, and the potential for detecting these interstellar visitors.
- Debate on Planetary Classification: The episode wraps up with a discussion on a newly discovered object that challenges the boundaries between planets and brown dwarfs. Jonti explains the ongoing debate regarding the definitions of these celestial bodies and how new discoveries are prompting scientists to reconsider traditional classifications.
For more Space Nuts, including our continually updating newsfeed and to listen to all our episodes, visit our website. Follow us on social media at SpaceNutsPod on Facebook, X, YouTube Music Music, Tumblr, Instagram, and TikTok. We love engaging with our community, so be sure to drop us a message or comment on your favorite platform.
If you'd like to help support Space Nuts and join our growing family of insiders for commercial-free episodes and more, visit spacenutspodcast.com/about
Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
00:00 - Introduction to the episode and topics
02:15 - Discussion on Earth's core dynamics and slowing rotation
10:30 - Exploration of hypervelocity stars and their implications
18:00 - The phenomenon of cosmic dust from neighboring systems
26:45 - Debate on planetary classification and the discovery of Gaia 4B
30:00 - Closing thoughts and listener engagement
✍️ Episode References
Earth's Inner Core Research
https://www.nature.com/articles
Hypervelocity Stars and Planet Discovery
https://www.space.com/hypervelocity-stars
Cosmic Dust Studies

 

 

WEBVTT

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Hi there, thanks for joining us. This is Space Nuts.

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My name is Andrew Dunkley, your hosts. Great to have

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your company. Coming up on this episode, we are going

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to look at Earth's core and it's sort of hit

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the news lately, but this is not a news story,

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but we thought we'd better talk about it just in

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case you're wondering Earth's core is slowing down or not

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doing what you'd think it would normally do.

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So we'll talk about that.

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There's a hyperactive star out there and it's got a planet.

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What does that mean? It means it's pretty darn quick.

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We're going to talk space dandruff. Yes, it's true, and

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a new planet that's sparking a bit of debate on

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its status.

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If we've got time.

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If we've got time, we'll do that one. That's all

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coming up on this episode of Space Nuts Channel ten

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nine Ignition Space Nuts or three two Space Nussen actually

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bought it real good.

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Respect for more.

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Professor John D.

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Horner, Professor of vestrophysics at the University of Selling Queensland.

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Hi, Johnny, Hey, how are you going? I am well,

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how are you?

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I'm getting them I'm not a morning person, as I

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was saying I got woken up earlier than I was

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planning this morning by phone call that said, can you

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go on live on the radio for five minutes? So

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I got to be a zombie on live radio, which

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all was good fun.

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There's PESTI journalists, yeah, grade ever since.

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Yeah, I have great sympathy for anybody who works the

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morning show. And we I think we're talking about this

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last week, but it must be had. But I'm not

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at my best at twenty to seven in the morning.

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This is a more reasonable time, but this is still morning.

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It's twenty to twelve.

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At the minute. I used to work Rapy the Deeping Conscience.

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I used to work with the journalists who used to

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have to do the police rounds first thing in the

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morning to get any news from around the various police

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districts in car crashes, all that horrible stuff.

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Fires, et cetera.

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And after a council meeting, they used to have to

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ring the mayor at sparrows in the morning. We had

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one particular mayor who was always nearly asleep when they called,

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and they could never get a good quote from him

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because he was just non compassmentus, not of the day.

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It was a frustration to the journalist.

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I can tell you I'm going to do something at

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five am. I'd rather have said.

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Up all night to do it than sat my a

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larm oler.

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Yes, yes, well I never had a choice for thirty

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odd years, but anyway, that was that was my choice,

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even though I didn't.

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Have a choice.

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I know you have your freedom, so I do. Now,

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let's get down to business.

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Earth's core, the rotation thereof This is a story that's

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been around a little while, but it keeps popping up.

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It popped up again on the weekend and I thought, well,

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let's talk about it. We may have talked about it

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with Fred. I've got an inkling that when it first

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came up we went there. But yes, it's something that

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the press is certainly honing in on.

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Yeah.

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Well, there's a few little fact words about this that

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really caught my arch. So when you sent me the

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link through, I've managed to miss this one. These are

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researchers at the University of Southern California so USC, and

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they've been looking at earthquake data. So if we want

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to study the interior of the Earth with the best

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wall in the world, we can't drill down there. You know.

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The deepest hole ever drilled was less than ten kilometers

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I believe, and the earth is frustrating the opaque. We

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can't see the interiors grounds in the way. So we've

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learned everything that we know about.

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The interior structure of the Earth.

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The call the mantle, how they all behave through earthquakes.

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So you get an earthquake and seismic wave travel outwards

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in all directions. There are two different types of seismic

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waves in a very rough sense, and when they go

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from one medium to another, their speed changes and they're

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refract in just the same way, likeness when it enters

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a swimming pool, same kind of idea. So if you're

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measuring these earthquakes using seismic grass from all around the world,

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you can back out what the interior of the Earth

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looks like and its properties by the time it takes

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the different tax seismic waves to reach you, essentially, and

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by doing that over an incredible long time, we've got

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a very detailed picture of the Earth's interior even now

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to you know the temperatures, the pressures, the compositions, and

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people are monitoring this all the time. But the finer

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the detail you want, the more challenging it is to

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disentangle the information about the earthquake itself from the information

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you're learning about the interior. And this is something we

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see a lot with finding X up on. It says

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a perverse analogy here that we're looking at the light

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from stars, and to get a really good idea of

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what the planet's like, you've got to understand the star first,

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because that is overlaid on the data and you've got

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to disentangle them so to get a real handle on

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the fine details of what's going in in terms of

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the Earth. Your ideal situation will be to have every

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earthquake be identical to the last, so that all the

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earthquakes were the same, and you could take that out

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of your analysis. You could essentially account for that. And

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that was the first thing I say this that I

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thought was really interesting. I mean, obviously the results are cool,

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but it's the way they got them. They looked at

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this sample of what are described as repeating earthquakes. They

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got data from these earthquakes near the South Sandwich Islands,

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one hundred and twenty one of these that occurred between

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nineteen ninety one and twenty twenty three, and it says,

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repeating earthquakes as seismic events that occur at the same

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location and produce identical seismogrants. So rather than using all

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the earthquakes from all around the world, they use this

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one subset that gave them very controlled data and that

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lets you get very fine resolution on the things you're

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looking at because you're not adding extra noise essentially, and

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by doing all this they'll learned a couple of new

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things about the Earth in a core. So we've known

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for a while that while the Earth has a call,

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the core actually has two layers. It's got a molten

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outer core, which the iron and the nickel are essentially liquid.

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They're moving while they're molten, so they're a fluid. They

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move around, and that movement is tied to the formation

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of the earth magnet field. You get the induced magnetism

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that gives us a magnetic field interior to that why

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the pressures hing. Even though the temperature is so high,

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the pressure is such that the inner core has been

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thought to be solid, and so you've got a solid

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with a liquid layer outside, and then the multen layer

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of the mantle, then the solid layer of the crust.

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As a rough kind of structure.

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What these new results have shown is the headline act

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is that that inner core doesn't spin perfectly constantly. It

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had apparently from a long period of time which I

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wasn't aware of, people were are that the spin speed

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of that inner care was gradually increasing. It was speeding

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up a little bit, almost imperceptibly. But what this research

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has shown is that more recently it has now started

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to slow down again. So that's a headline act. The

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inner core has slowed down a little bit. And they're

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talking about here on a scale of about one thousandth

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of a second for the rotation period, so it's a

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tiny effect, but they can measure it thanks to these

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repeating earthquakes that have the same signature. That allows them

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to get and much better resolution on the data.

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The other thing.

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Which I think is very interesting that isn't in the

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main pressure is but is in a couple of the

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other articles, is that the same data suggests that the

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inner core is not totally solid but actually has molten

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areas within it. So this is a bit of a

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change to the paradigm we had of this very simple

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model of a solid inner core than a molten outer

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core that there's actually a bit of moltenness to the

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inner core as well, which probably makes a bit of

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sense in the context of this thing's rotation changing over time.

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If you've got bits that are melting, bits that are

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moving around a little bit, you're moveing angular momentum around.

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So therefore you'll change the rotation period in just the

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same way that the rotation period of the Earth as

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a whole will change if the ice caps melt, will

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change in a measurable way because you're moving mass from.

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The poles to the equator.

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Redistributing that mass will mean that the spin will slow

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a little bit to conserve angular momenta. So it's a

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fascinating story, and I think, yes, the head line side

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of it, the inner core has slowed down. That's interesting.

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That's the headline story. But to me, the really interesting

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stuff was how of how they figured that out, and

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those subtleties of the choice of earthquakes to use and

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the additional things they can figure out. It really shows

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the benefit of continuing to get longer data sets in

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reanalyzing what you thought you knew when you've got better

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data and better instruments. So it's a very cool story

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and do encourage people to have a look around. There's

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a few different versions of the story out there on

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the web. Even CNN covered.

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It at one point, so it's a good one. Interesting.

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By reading a variety of stories, you can get some

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of the different cool facts that maybe the main pressure

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release didn't pick up on.

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Yeah, they figured this out by studying what is one

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hundred and twenty one earthquakes between nineteen ninety one and

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twenty twenty four.

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Yes, help accurate. Do you perceive their data to be well?

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I trust at the end of the day, it's peer

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reviewed and published, so there's a and confidence of fidelity there.

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That's good.

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And I find their data selection really interesting. There the

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fact that you've got thousands of earthquakes happening all the time.

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You know, we see what's happening in Santaurini at the

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minute with what is probably a very large motion of

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magma underneath that ancient volcano that suggests it may well

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erupt again at some point, seeing similarly under aples. So

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earthquakes are happening all the time all around the world.

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And what I loved about this was finding this subset

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of earthquakes that are happening recurrently at the same place

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that are giving them the same signal, which makes a

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data analysis much much much better. I just really like that,

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and it's why, in exactly the same way that we

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can find planets using our radial.

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Velocity of the wobble method much.

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More easily around quiet stars and active starts because active

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stars are roiling and bubbling and boiling, so the lines

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of the spectrum of the star are moving around because

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of the properties of the star. That introduces a lot

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of noise. When you've got a quiet SAA South that

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isn't very active a bit like the Sun, is that

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noise is much less, which means that you can resolve

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much smaller motions thanks to the planets, and so you

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can detect smaller planets around stars that are less active.

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And it's a.

218
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Direct parallel here.

219
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By getting a much simpler set of earthquakes that all

220
00:10:20.519 --> 00:10:23.320
behave the same way, you reduce the noise and therefore

221
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you can get a much more accurate pressure of what's

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going on in the interior. So I guess if you

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want to look at timescale changes in the mantle and

224
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stuff like that, you can use all the data set

225
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and map it that way. But for something like this way,

226
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you need that really fine tooth comb. It's a beautiful

227
00:10:37.960 --> 00:10:38.639
way of doing it.

228
00:10:39.039 --> 00:10:40.879
Yeah. Yeah, it's fascinating story.

229
00:10:40.919 --> 00:10:43.000
It's you know, we're so close to it compared to

230
00:10:43.039 --> 00:10:47.679
everything else we study, but it's it's.

231
00:10:47.519 --> 00:10:51.039
Invisible to us to Yeah, we have to dig deep

232
00:10:52.120 --> 00:10:56.399
instead of getting developed from this then applying astronomy and

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00:10:56.480 --> 00:10:57.519
in planet for science.

234
00:10:57.519 --> 00:10:59.919
You know, we talked previously about Insight, which sat on

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Mars and recorded Mars quakes and that much just single station.

236
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I would love at some point in the future, perhaps

237
00:11:06.039 --> 00:11:09.559
when Syrielon decides that he's finally going to move to Mars,

238
00:11:09.919 --> 00:11:12.480
if he could text some seismometers with him and drop

239
00:11:12.519 --> 00:11:15.240
them in a variety of positions, that'll give us a

240
00:11:15.240 --> 00:11:18.399
lot more information on Mars's interior. Similar with these kind

241
00:11:18.440 --> 00:11:20.480
of techniques are very similar to what my colleagues at

242
00:11:20.519 --> 00:11:24.240
the University of Southern Queensland and elsewhere around the sphere

243
00:11:24.279 --> 00:11:27.480
of academia used to study the interiors of starsks. You've

244
00:11:27.480 --> 00:11:29.919
got the same problem. You look at the Sun and

245
00:11:29.960 --> 00:11:32.360
it's our near as star, but always see it's a surface.

246
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You can't see inside it because the surfaces in the

247
00:11:34.600 --> 00:11:36.879
way now, how do we know about the structure of

248
00:11:36.919 --> 00:11:39.080
the interior. It's exactly the same kind of thing they're

249
00:11:39.080 --> 00:11:42.679
doing here, but using star quakes and star wobbles rather

250
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than earthquakes.

251
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Yeah, really interesting stuff.

252
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And if you'd like to read more about the core

253
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of our own planet slowing down, just do a.

254
00:11:52.200 --> 00:11:54.120
Search for that. It's everywhere.

255
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You can find it on Discover magazine and a few

256
00:11:57.440 --> 00:12:01.720
other sites. Let's take a little break from the show

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00:12:01.759 --> 00:12:05.919
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Now back to the show three Space Nuts. Now, let's

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00:13:48.559 --> 00:13:52.000
go to this story that is talking about a star

287
00:13:52.120 --> 00:13:54.799
that's been described as hyperactives.

288
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This is a star that's moving well. It's probably one

289
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of the.

290
00:13:58.279 --> 00:14:02.799
Fastest, if not the fastest, ever discovered. This story is

291
00:14:02.879 --> 00:14:03.559
quite amazing.

292
00:14:04.679 --> 00:14:07.639
So this is what's called a hypervelost is Sara, and

293
00:14:07.679 --> 00:14:09.559
we do know a few of these in the Milky Way.

294
00:14:10.399 --> 00:14:12.840
These are stars that are traveling at such a high

295
00:14:12.840 --> 00:14:16.519
speed that they're traveling faster than the local escape velosity

296
00:14:16.519 --> 00:14:19.120
for the galaxy at their location. So we're on the

297
00:14:19.120 --> 00:14:20.799
surface of the Earth, and if I throw a tennis

298
00:14:20.799 --> 00:14:22.720
ball up in the air, it will fall back down.

299
00:14:23.360 --> 00:14:24.919
I'll catch it, or I'll fail to catch it.

300
00:14:24.960 --> 00:14:27.519
Bex and English and the English cricket team is doing

301
00:14:27.600 --> 00:14:29.360
terribly at them, and it's I'll probably fail to catch

302
00:14:29.360 --> 00:14:32.879
it because that's where I'm from. Originally, if I threw

303
00:14:32.919 --> 00:14:35.919
it hard enough, the Earth's gravity wouldn't be able to

304
00:14:35.919 --> 00:14:38.399
hold on twit and it would escape. And for the Earth,

305
00:14:38.480 --> 00:14:42.600
that's about eleven kilometers a second. The more massive you are,

306
00:14:43.120 --> 00:14:45.240
the higher that veloci is, but the further you are

307
00:14:45.240 --> 00:14:45.600
from the.

308
00:14:45.559 --> 00:14:47.039
Mass, the lower that veloci is.

309
00:14:47.399 --> 00:14:48.799
I mean, it's the kind of thing we teach in

310
00:14:48.840 --> 00:14:52.000
first year astrophysics as an equation for the escape velocity

311
00:14:52.879 --> 00:14:54.360
where you can work it out, and I think it's

312
00:14:54.399 --> 00:14:59.519
a square of two gm over r now sounds about

313
00:14:59.559 --> 00:15:02.480
right though. That's basically it's related to the mass of

314
00:15:02.480 --> 00:15:05.879
the thing you're going around that and it's investly proportional

315
00:15:05.919 --> 00:15:08.159
to the distance that you are away from that thing

316
00:15:08.720 --> 00:15:12.600
with a square rout there. What that means is that

317
00:15:12.679 --> 00:15:16.720
anything that has mass has an escape velocity. So technically

318
00:15:16.840 --> 00:15:18.559
I have an escape velosity. If you put me in

319
00:15:18.600 --> 00:15:22.039
the vacuum of space far away from any star and

320
00:15:22.080 --> 00:15:24.919
give me that tennis ball, I could, in theory nudge

321
00:15:24.919 --> 00:15:27.000
it gently and make it orbit me. But if I

322
00:15:27.080 --> 00:15:29.879
knowdge too hard, it would escape. But even though I'm

323
00:15:30.000 --> 00:15:33.840
far too heavy, my gravitational pull is incredibly weak because

324
00:15:33.840 --> 00:15:36.399
I'm only one hundred and thirty kilos, not the mass

325
00:15:36.399 --> 00:15:39.519
of the Earth. What that means from the point of

326
00:15:39.600 --> 00:15:42.000
view of our galaxy is that our galaxy has an

327
00:15:42.080 --> 00:15:44.440
escape velosity that varies depending on where you are in

328
00:15:44.440 --> 00:15:47.960
the galaxy mayor you are to the middle. The higher

329
00:15:47.960 --> 00:15:50.360
the speed you need to be traveling is to escape.

330
00:15:50.440 --> 00:15:53.159
Just as in the Solar System, it's harder to escape

331
00:15:53.320 --> 00:15:55.840
from the Sun when your name Mercury is orbit than

332
00:15:55.879 --> 00:15:56.480
it is when you're.

333
00:15:56.399 --> 00:15:57.279
Know Neptron's orbit.

334
00:15:58.480 --> 00:16:01.679
So that's how stars move, and a small fraction of

335
00:16:01.679 --> 00:16:04.600
the stars in our galaxy, because they're constantly moving around

336
00:16:04.600 --> 00:16:07.480
all the other stars because of things going on, a

337
00:16:07.519 --> 00:16:10.080
small number of those stars will eventually get ejected from

338
00:16:10.080 --> 00:16:11.519
the galaxy entirely.

339
00:16:12.120 --> 00:16:12.279
Now.

340
00:16:12.360 --> 00:16:14.679
Quite a few of these actually that are previously known

341
00:16:15.000 --> 00:16:18.039
are linked to stars that were in a binary star

342
00:16:18.120 --> 00:16:20.600
system that was quite close and then one of the

343
00:16:20.639 --> 00:16:24.440
components went super and over and suddenly like the lead

344
00:16:24.559 --> 00:16:27.559
was cut, so suddenly they're rejected at very high speed. Right,

345
00:16:27.720 --> 00:16:29.399
But that's not the only way you can form that

346
00:16:30.639 --> 00:16:33.559
hypervelocity stars. And are these stars whose speed is so

347
00:16:33.759 --> 00:16:36.480
high that they will probably escape and never return, that

348
00:16:36.559 --> 00:16:38.840
will wonder the void between the galaxies in a very

349
00:16:38.919 --> 00:16:44.000
lonely life forevermore. The other side of this story is

350
00:16:44.080 --> 00:16:47.799
planet detection. We've talked before about how the two most

351
00:16:47.799 --> 00:16:50.799
successful methods for finding planets are the transit method and

352
00:16:50.840 --> 00:16:54.039
the radio lossy method, essentially seeing stars warbble and wink.

353
00:16:54.879 --> 00:16:58.320
There is a method of technique called gravitational microlensing that

354
00:16:58.879 --> 00:17:00.919
if you went back to the Latin nineties, people were

355
00:17:00.960 --> 00:17:04.160
really hoping it would find gazillions of planets, that it

356
00:17:04.160 --> 00:17:07.319
would be really successful, and it's never quite found as

357
00:17:07.400 --> 00:17:10.720
many as people expected because it's fundamentally hard to do.

358
00:17:11.160 --> 00:17:13.200
It's not that these events aren't happening, it's just that

359
00:17:13.240 --> 00:17:16.559
they're very hard to observe. But going back to twenty eleven,

360
00:17:16.799 --> 00:17:19.720
a team of scientists that were looking towards the galactic core,

361
00:17:20.160 --> 00:17:22.079
where you've got the most stars on the sky in

362
00:17:22.119 --> 00:17:26.200
the smallest area, observed a gravitational micro lensing event. They

363
00:17:26.240 --> 00:17:29.319
saw a background star brightened and then faded away again,

364
00:17:30.240 --> 00:17:32.480
but it had a double peak in the brightness, so

365
00:17:32.519 --> 00:17:34.960
there were two peaks as it went up, and then

366
00:17:35.000 --> 00:17:36.799
it went up further and then it fell away again,

367
00:17:37.279 --> 00:17:40.000
and that was indicating that in the foreground between us

368
00:17:40.000 --> 00:17:43.359
and that star, something had passed in front that had mass.

369
00:17:44.039 --> 00:17:47.599
That mass curving space time acted as a lens bent

370
00:17:47.680 --> 00:17:49.519
a little bit more of the light from the background

371
00:17:49.559 --> 00:17:52.000
star towards us, and that's why we saw the star brighton.

372
00:17:52.440 --> 00:17:54.599
And then as the thing in the foreground moved away again,

373
00:17:54.720 --> 00:17:57.599
the lens went away and it faded away again. And

374
00:17:57.680 --> 00:18:01.799
when these events happened quite a lot from studying the

375
00:18:01.839 --> 00:18:04.880
degree to which the thing brightened and faded and also

376
00:18:04.920 --> 00:18:08.319
the timescale over which it happened, and the team at

377
00:18:08.319 --> 00:18:11.599
the time announce the results. This is really exciting, but

378
00:18:11.680 --> 00:18:13.720
there's a little bit of what we call a degeneracy.

379
00:18:13.799 --> 00:18:17.759
There are two different models that can equally well explain

380
00:18:17.799 --> 00:18:20.720
what we've observed. The first is that you've got a

381
00:18:20.720 --> 00:18:22.559
star that's about a fifth of the mass of the

382
00:18:22.599 --> 00:18:25.839
Sun with a planet that is about twenty nine times

383
00:18:25.839 --> 00:18:29.559
the mass of the Earth. That's scenario one, so you've

384
00:18:29.559 --> 00:18:32.839
got a star with a planet. The other scenario is

385
00:18:32.880 --> 00:18:35.720
that you had a planet the mass of Jupiter with

386
00:18:35.759 --> 00:18:38.640
a tiny little moon, and in either case, the ratio

387
00:18:38.640 --> 00:18:40.200
of the mass between the big thing and the little

388
00:18:40.240 --> 00:18:44.400
things about twenty three hundred times. Either of these scenarios

389
00:18:44.880 --> 00:18:48.240
could explain perfectly well what was seen. So how do

390
00:18:48.279 --> 00:18:51.000
we differentiate between them. Well, one thing we can do

391
00:18:51.079 --> 00:18:54.559
now that we've got better telescopes and better technology, is

392
00:18:54.599 --> 00:18:57.799
to use the Keck telescopes, which are among the biggest

393
00:18:57.839 --> 00:19:00.480
in the world. There are incredible instruments in South America,

394
00:19:01.039 --> 00:19:04.039
and also the Geyer spacecraft, which has been should finish

395
00:19:04.079 --> 00:19:07.480
its mission, but it spent twelve years in orbit mapping

396
00:19:07.519 --> 00:19:10.599
the positions of the motions of up to two billion

397
00:19:10.720 --> 00:19:15.519
stars with unprecedented mind boggling accuracy. So the team that

398
00:19:15.599 --> 00:19:18.400
found this object in twenty eleven saw this signal in

399
00:19:18.400 --> 00:19:21.599
the gravitational micro lensing said, one way that we could

400
00:19:21.640 --> 00:19:26.039
distinguish between those two different models. Is to look for

401
00:19:26.119 --> 00:19:30.000
the thing that caused the lensing. If it's a star,

402
00:19:30.400 --> 00:19:32.240
in theory, there'll be a point of light there that's

403
00:19:32.279 --> 00:19:34.160
moving that we can see that we can track back

404
00:19:34.200 --> 00:19:35.759
and say it was in the right place at the

405
00:19:35.839 --> 00:19:38.319
right time. We'll be able to see it, and that

406
00:19:38.400 --> 00:19:40.359
shows that the thing that did the lensing was a star.

407
00:19:40.400 --> 00:19:43.039
So it's a star and a planet. If we see nothing,

408
00:19:44.039 --> 00:19:45.920
then the star doesn't work because if there was a

409
00:19:45.920 --> 00:19:47.440
star there, we'd see it, so it must be the

410
00:19:47.480 --> 00:19:50.839
other scenario. So they went away and dug through that data,

411
00:19:50.920 --> 00:19:53.240
and it took them a bit longer than expected, but

412
00:19:53.319 --> 00:19:56.920
they finally found a star that is moving ridiculously quickly

413
00:19:56.960 --> 00:19:59.440
but was in exactly the right place at the right

414
00:19:59.440 --> 00:20:02.480
time caused a micro lensing event. And that star is

415
00:20:02.519 --> 00:20:04.480
also quite near the middle of the galaxy, so it's

416
00:20:04.559 --> 00:20:07.319
quite it was quite far from us, quite near the

417
00:20:07.319 --> 00:20:09.400
thing it was lensing at the time. They've tracked it

418
00:20:09.480 --> 00:20:12.279
back and it turns out that the movement of this

419
00:20:12.400 --> 00:20:14.920
star just at right angle to all ainosites, so the

420
00:20:14.960 --> 00:20:18.240
movement across the sky gives it a speed that is

421
00:20:18.279 --> 00:20:24.599
almost two million kilometers per hour five hundred and forty kilometers.

422
00:20:24.119 --> 00:20:27.240
Per second glimy. That is ridiculous.

423
00:20:27.400 --> 00:20:31.319
You know, stars nearby near the some moving around. We

424
00:20:31.359 --> 00:20:33.759
typically talk of speeds of tens of kilometers a second,

425
00:20:33.799 --> 00:20:36.119
maybe a bit more than one hundred, So five hundred

426
00:20:36.160 --> 00:20:39.559
and forty is ridiculously extreme and is already almost the

427
00:20:39.680 --> 00:20:42.759
escape lossary of the galaxy at that point. Now, the

428
00:20:42.839 --> 00:20:45.279
unknown here is that there could be some movement towards

429
00:20:45.279 --> 00:20:47.160
are away from us as well, So we only see

430
00:20:47.599 --> 00:20:52.039
the movement on the sky, and essentially any movement that

431
00:20:52.160 --> 00:20:55.559
is radial towards are away from us would be enough

432
00:20:55.599 --> 00:20:57.920
to mean that this thing is unbound by the galaxy,

433
00:20:57.960 --> 00:21:01.279
that it will eventually escape. It is therefore a hyper

434
00:21:01.319 --> 00:21:04.079
velocity star, and this is the very first time a

435
00:21:04.119 --> 00:21:08.160
planet has been confirmed around the hypervelosity stat. Now, planets

436
00:21:08.160 --> 00:21:10.319
will form around the stats, that's fine. But to get

437
00:21:10.359 --> 00:21:13.079
the very first one, that's kind of cool, and that's

438
00:21:13.079 --> 00:21:16.599
the planet that is signific cooking massive than the Earth.

439
00:21:17.160 --> 00:21:19.960
That's our probably has other planets. Where you find one planet,

440
00:21:20.160 --> 00:21:23.160
there will be more. So this is a planetary system

441
00:21:23.359 --> 00:21:25.759
that is on a one way ticket out of our galaxy,

442
00:21:25.799 --> 00:21:26.519
never to return.

443
00:21:27.519 --> 00:21:28.000
Wow.

444
00:21:28.559 --> 00:21:31.079
Yeah, that's quite a fine isn't it, And such an

445
00:21:31.119 --> 00:21:35.160
incredible speed. Have they worked out how long it will

446
00:21:35.200 --> 00:21:37.920
take to exit the galaxy? Probably a long time even

447
00:21:37.960 --> 00:21:38.960
at that speed.

448
00:21:39.000 --> 00:21:41.519
Very very long time, even at that speed. So we

449
00:21:41.559 --> 00:21:44.880
can probably try and back of the envelope mental arithmetically.

450
00:21:44.960 --> 00:21:48.119
So I'll get everybody on line to forgive me. But

451
00:21:48.480 --> 00:21:51.160
speed of light is three hundred thousand kilometers a second.

452
00:21:52.160 --> 00:21:54.279
I'm going to say that this is six hundred klometers

453
00:21:54.279 --> 00:21:56.240
a second because that just keeps the mouths easier, right,

454
00:21:57.279 --> 00:22:00.799
six hundred over three hundred thousand is six hundred, which

455
00:22:00.880 --> 00:22:04.519
is two percent thereabouts. So this thing's traveling at two

456
00:22:04.519 --> 00:22:08.599
percent of the speed of light. That's fairly significant. Now

457
00:22:08.640 --> 00:22:10.319
the galaxy is going to be pointing back as long

458
00:22:10.519 --> 00:22:13.079
down as it goes. But if you think about the

459
00:22:13.119 --> 00:22:15.960
diameter of the milky ways, about one hundred thousand light years,

460
00:22:16.680 --> 00:22:18.680
so that means the radius of the milky way's about

461
00:22:18.720 --> 00:22:22.079
fifty thousand light years. If you're traveling at two percent

462
00:22:22.119 --> 00:22:24.119
of the speed of light, that means it will take

463
00:22:24.200 --> 00:22:28.200
you fifty years to travel one light year, right, right,

464
00:22:28.519 --> 00:22:31.839
So fifty years per light year for fifty thousand light

465
00:22:31.920 --> 00:22:36.319
years is two point five million years. Now, that is

466
00:22:37.160 --> 00:22:39.920
a long time for us. But where compuere it to

467
00:22:40.000 --> 00:22:42.119
the fact that it takes to some two hundred and

468
00:22:42.200 --> 00:22:44.240
fifty million years or so to go around the middle

469
00:22:44.240 --> 00:22:46.480
of the galaxy. That gives you a sense of how

470
00:22:46.559 --> 00:22:47.799
quickness is actually moving.

471
00:22:49.400 --> 00:22:53.839
Fascinating. All right, Yeah, so far the fastest found, but

472
00:22:54.200 --> 00:22:57.400
maybe others will probably find another one that's faster at

473
00:22:57.440 --> 00:23:00.240
some stage. Yes, you can read about that. It's based

474
00:23:00.279 --> 00:23:02.440
dot com. If you want to read the actual paper.

475
00:23:03.119 --> 00:23:06.960
It was published this month in the Astronomical Journal. There's

476
00:23:07.000 --> 00:23:09.799
a space nuts with Andrew Dunkley and Professor John T.

477
00:23:09.960 --> 00:23:10.279
Horner.

478
00:23:12.920 --> 00:23:17.599
Okay, we take a space nuts now.

479
00:23:17.519 --> 00:23:20.240
Johnny, let's move on to this problem with.

480
00:23:21.720 --> 00:23:24.880
Dandriff in space that's what it's described as. It's not

481
00:23:24.920 --> 00:23:30.319
really Dandriff. It's just neighboring solar systems dumping their stuff

482
00:23:30.319 --> 00:23:31.279
on us.

483
00:23:31.279 --> 00:23:33.039
So I didn't know. I didn't know that.

484
00:23:33.079 --> 00:23:35.720
Was a thing Amber's doing exactly the same back at

485
00:23:35.720 --> 00:23:35.920
the BIT.

486
00:23:35.920 --> 00:23:37.160
Should have said no, only.

487
00:23:37.039 --> 00:23:40.119
Ask one of those things that I talk about a lot.

488
00:23:40.119 --> 00:23:42.400
In the context of our solar system, we have comets

489
00:23:42.440 --> 00:23:46.079
and asteroids, and the main where that comets get removed

490
00:23:46.079 --> 00:23:48.200
from the Solar System to no longer pose a threat

491
00:23:48.240 --> 00:23:50.680
to the Earth. Is that many of the mess get

492
00:23:50.720 --> 00:23:53.400
the Solar System never to return, usually flung out by

493
00:23:53.400 --> 00:23:56.920
one of the giant planets or by subtle gravitational perturbations

494
00:23:57.000 --> 00:23:59.559
like that. So you can look back over the edge

495
00:23:59.559 --> 00:24:01.839
of the Cellar System and it has continually been shedding

496
00:24:01.880 --> 00:24:05.720
comets and asteroids into the void of space, creating these

497
00:24:05.839 --> 00:24:09.839
interstellar wonderers essentially, And that will have been particularly strongly

498
00:24:09.920 --> 00:24:13.000
the case, incidentally, when the Solar System was still forming,

499
00:24:13.039 --> 00:24:15.119
because big part of the formation of the planets and

500
00:24:15.160 --> 00:24:17.759
the cleanup afterwards was getting rid of most of the

501
00:24:17.759 --> 00:24:20.559
stuff that was left over. So the Solar System over

502
00:24:20.640 --> 00:24:24.119
it some will have shed uncountered objects into space, and

503
00:24:24.240 --> 00:24:27.480
it continues to do so today. And I've often said,

504
00:24:27.720 --> 00:24:30.640
in those socks, it's almost certain that every other star

505
00:24:30.680 --> 00:24:32.599
will be doing the same thing. Any star that has

506
00:24:32.640 --> 00:24:35.799
a planetary system, those planets will be staring things up

507
00:24:35.799 --> 00:24:38.759
and throwing things out. So it's one of those things

508
00:24:38.759 --> 00:24:41.200
that I've just taken for granted. But it's only recently

509
00:24:41.240 --> 00:24:44.960
that we've actually been able to detect the products of

510
00:24:45.000 --> 00:24:48.240
this from other stars. Like I said, for decades people

511
00:24:48.240 --> 00:24:51.319
have talked about the possibility of us finding interstellar objects

512
00:24:51.359 --> 00:24:54.440
in the Solar System. So seeing comets or asteroids coming

513
00:24:54.480 --> 00:24:59.279
through that could be absolutely indefinitively shown not to have

514
00:24:59.319 --> 00:25:01.720
an origin in it our source system, how do we

515
00:25:01.759 --> 00:25:03.440
do that while we look at how quick they're moving.

516
00:25:03.480 --> 00:25:05.119
It's just like what we were talking about a minute

517
00:25:05.119 --> 00:25:08.559
ago with the escape velocity. Objects moving around the Sun

518
00:25:09.440 --> 00:25:12.440
are gravitationally bound. If they get a nudge and they're

519
00:25:12.440 --> 00:25:14.440
going to escape, they will be traveling a bit too

520
00:25:14.559 --> 00:25:18.079
quick to be gravitationally bound, but only just by a

521
00:25:18.160 --> 00:25:21.599
tiny amount. So when we find an object that comes in,

522
00:25:22.039 --> 00:25:24.920
we can work out what speed it would travel at

523
00:25:25.079 --> 00:25:26.920
if it was infinitely far from the Sun.

524
00:25:27.720 --> 00:25:29.559
Top call this the velocity of infinity.

525
00:25:29.640 --> 00:25:31.200
So and once the Sun has slowed it down as

526
00:25:31.279 --> 00:25:34.759
much as it can, how much speed has it got left?

527
00:25:34.960 --> 00:25:38.160
And two objects that were found in the last decade

528
00:25:38.720 --> 00:25:41.680
met this criteria have been interstellar. There were Umau Mau

529
00:25:42.079 --> 00:25:44.559
which came through in twenty seventeen. And despite what a

530
00:25:44.559 --> 00:25:48.200
certain eminent person at Harvard, and I'm trying to choose

531
00:25:48.200 --> 00:25:50.240
my words carefully here because I have a certain opinion,

532
00:25:50.839 --> 00:25:53.400
despite what he keeps trying to tell you to sell

533
00:25:53.400 --> 00:25:55.000
his books and make a lot of money. That was

534
00:25:55.039 --> 00:25:57.920
not an alien spaceship. It never would be an alien spaceship.

535
00:25:58.000 --> 00:26:01.400
It absolutely was not aliens. That was just a lump

536
00:26:01.480 --> 00:26:05.119
of rock and debris. We then had commit Borisov back

537
00:26:05.160 --> 00:26:08.599
in twenty nineteen, which was our second interstellar object. Yeah,

538
00:26:08.839 --> 00:26:10.559
we found two of them. Now the odds are that

539
00:26:10.680 --> 00:26:13.319
in the coming decade we will find hundreds because the

540
00:26:13.440 --> 00:26:17.599
Vera Ruben Observatory is going to come online. Vera Ruben Observatory,

541
00:26:17.599 --> 00:26:19.599
of course, named for one of the grade astronomers of

542
00:26:19.640 --> 00:26:23.839
twentieth century who was a woman in astronomy, And that's

543
00:26:24.279 --> 00:26:26.400
a challenging thing to discuss at the moment with what's

544
00:26:26.400 --> 00:26:28.200
going on in the US. I will just mention in

545
00:26:28.240 --> 00:26:32.039
passing that that is itself a controversy this week because

546
00:26:32.079 --> 00:26:35.079
with the new government in the US, they've been forced

547
00:26:35.079 --> 00:26:39.160
to change the biography of Vera Rubin on the website

548
00:26:39.400 --> 00:26:41.240
because one of the things that she was very active

549
00:26:41.279 --> 00:26:43.960
on was advocating for women in science and you know,

550
00:26:44.000 --> 00:26:45.880
setting up schemes to try and help women get more

551
00:26:45.920 --> 00:26:49.079
involved in astronomy. Now you can't talk about that anyway,

552
00:26:49.160 --> 00:26:51.680
that's an aside, but it's a bit of a frustration

553
00:26:51.720 --> 00:26:55.200
of the human element of this. Yeah, vera Rubin Observatory

554
00:26:55.279 --> 00:26:58.079
named after this incredible astronomer. It's going to come online

555
00:26:58.079 --> 00:27:00.200
in the next year or two, and it's for has

556
00:27:00.200 --> 00:27:02.839
to find tens or hundreds of these objects, because we'll

557
00:27:02.880 --> 00:27:06.200
just be much better at spotting them. What the new

558
00:27:06.279 --> 00:27:09.440
research is is some computer modeling. A group has had

559
00:27:09.519 --> 00:27:11.400
the same idea that we're just talking about and said,

560
00:27:11.480 --> 00:27:14.119
let's model this. Let's try and get a handle on

561
00:27:14.240 --> 00:27:18.160
just how much stuff nearby star systems are throwing our

562
00:27:18.279 --> 00:27:21.839
way to fill the space around us. And they're looked

563
00:27:21.839 --> 00:27:25.400
at our nearest companions. The Alpha Centauri system, which is

564
00:27:25.400 --> 00:27:28.279
the binary star of Alpha Centauri AMB, and then the

565
00:27:28.279 --> 00:27:31.000
red dwarf Proximma, which is currently a bit closer to us,

566
00:27:31.039 --> 00:27:32.119
are the two biggest starts.

567
00:27:33.519 --> 00:27:35.880
They ransom simulations very much of the ILK.

568
00:27:35.720 --> 00:27:37.440
That I do in my day job running on the

569
00:27:38.079 --> 00:27:43.319
supercomputing cluster here saying if this star system has the

570
00:27:43.400 --> 00:27:45.359
kind of objects in it we'd expect for system of

571
00:27:45.359 --> 00:27:49.000
that age, how many getting ejected in our general direction?

572
00:27:49.079 --> 00:27:52.559
And what they have found is that their simulation suggests

573
00:27:52.559 --> 00:27:55.599
there could be as many as a million objects bigger

574
00:27:55.599 --> 00:27:59.279
than one hundred meters across passing through our Solar system

575
00:27:59.319 --> 00:28:03.039
out of the current time that departed from the Alpha

576
00:28:03.039 --> 00:28:06.400
Centaurus system. Now the circulty here is a lot of

577
00:28:06.440 --> 00:28:09.079
the time when we talk about passing through the Solar system,

578
00:28:09.119 --> 00:28:11.119
we think of our local part of the Solar system,

579
00:28:11.160 --> 00:28:13.920
the orbits of the planets, But in reality, the volume

580
00:28:13.960 --> 00:28:16.160
of space we're considering to be the Solar system here

581
00:28:16.680 --> 00:28:18.640
is the entirety of the Oat cloud. So this is

582
00:28:18.680 --> 00:28:22.319
a volume of space something like two light years in

583
00:28:22.359 --> 00:28:26.400
every direction from us. It's an unimaginably vast sphere of

584
00:28:26.480 --> 00:28:30.160
space that has these objects passing through it. So the

585
00:28:30.279 --> 00:28:32.640
likelihood of one getting closer for us to detective the

586
00:28:32.640 --> 00:28:35.720
near future is pretty low, but it's not being the

587
00:28:35.759 --> 00:28:39.200
bounds of possibility. And again, when Vera Rubin comes online,

588
00:28:40.079 --> 00:28:43.799
if any of these are in the domain of the planets,

589
00:28:43.799 --> 00:28:47.359
they're coming close enough to the sum that they are detectable,

590
00:28:47.519 --> 00:28:52.319
Vera Rubin will find them. Now a million objects spread

591
00:28:52.319 --> 00:28:54.359
over the Oat Cloud, to be honest, means that it's

592
00:28:54.480 --> 00:28:56.519
very unlikely one of them will be close enough to see.

593
00:28:57.039 --> 00:28:59.000
But these things are going to be traveling faster than

594
00:28:59.119 --> 00:29:02.759
the escape loss the Sun, so they'll come through fairly quickly,

595
00:29:03.480 --> 00:29:05.440
and that means if they're moving through, just because we

596
00:29:05.440 --> 00:29:07.200
don't see them now doesn't mean if we look again

597
00:29:07.200 --> 00:29:09.319
in five years time, there wouldn't be one that's appeared.

598
00:29:09.880 --> 00:29:10.680
The other thing that.

599
00:29:10.599 --> 00:29:12.720
Came out of this is that they talked about the

600
00:29:12.759 --> 00:29:16.079
smaller particles more common, and it's quite likely that there

601
00:29:16.079 --> 00:29:19.240
may be as many as ten meteas per year on

602
00:29:19.319 --> 00:29:21.200
the Earth that are bits of dust from the off

603
00:29:21.279 --> 00:29:25.000
Centaurus system hitting our planet. Now ten per year across

604
00:29:25.000 --> 00:29:27.119
the entire surface of the Earth means that you're very

605
00:29:27.200 --> 00:29:30.200
unlikely to find them, but it reminded me of stories

606
00:29:30.200 --> 00:29:32.680
that go back much further, because we have these wonderful

607
00:29:32.680 --> 00:29:35.720
networks of cameras across the Earth that look up at

608
00:29:35.720 --> 00:29:39.920
shooting stav and try and get multi session observations so

609
00:29:39.960 --> 00:29:42.480
you can do trigonometry and figure out what their orbit was,

610
00:29:42.519 --> 00:29:45.359
how they were moving, and they've detected over the years

611
00:29:45.400 --> 00:29:49.799
a very small number of definitively interstellar meteors, so Metea's

612
00:29:49.839 --> 00:29:52.680
coming into the Earth's atmosphere with a speed significantly higher

613
00:29:52.720 --> 00:29:55.720
than seventy two kilometers a second, which means that they

614
00:29:55.759 --> 00:29:59.200
can't have been bound to the Solar system. One of

615
00:29:59.200 --> 00:30:01.559
the things that those papers discussed for a long time

616
00:30:01.640 --> 00:30:04.559
is that there is one dominant source of dust through

617
00:30:04.559 --> 00:30:07.039
our Solar system that gives us more than all of

618
00:30:07.119 --> 00:30:12.400
the sources combined. A famous star called Beta Pictoris, which

619
00:30:12.480 --> 00:30:14.920
back in nineteen eighty three was one of three stars

620
00:30:14.720 --> 00:30:18.720
the Infrared Astronomical Satellite was confused about because it found

621
00:30:18.759 --> 00:30:22.079
an infrared excess around that star. It is three light

622
00:30:22.160 --> 00:30:24.119
years away, It's more massive than the Sun and hotter,

623
00:30:24.160 --> 00:30:26.440
but it's very young, and it's still got a disc

624
00:30:26.480 --> 00:30:29.319
of debris around it forming planets. It's got planets in

625
00:30:29.400 --> 00:30:32.880
that disk that we've discovered. But then incredibly active stellar

626
00:30:32.920 --> 00:30:35.240
wind that that massive star has is blowing lots of

627
00:30:35.279 --> 00:30:39.359
the dust into space, streaming off in all directions, and

628
00:30:39.400 --> 00:30:42.839
the enough of that dust is traveling to reach us

629
00:30:42.880 --> 00:30:46.759
sixty three light years away that we can detect that

630
00:30:46.839 --> 00:30:51.160
as a distinct source of debris crashing into the s atmosphere.

631
00:30:51.759 --> 00:30:54.119
That really boggles my mind that a star that far

632
00:30:54.200 --> 00:30:57.440
away can be putting dust into our atmosphere at a

633
00:30:57.440 --> 00:31:01.319
subfigent level that people have detected that dustry.

634
00:31:02.039 --> 00:31:05.039
It is it's amazing, and this must be happening just

635
00:31:05.039 --> 00:31:10.720
about everywhere. We've probably got systems exchanging junk constantly.

636
00:31:11.000 --> 00:31:11.599
Yeah.

637
00:31:11.640 --> 00:31:15.119
Absolutely, And it ties into the panspermia idea that we've

638
00:31:15.160 --> 00:31:18.599
talked about before as well. If you are constantly ejecting

639
00:31:18.720 --> 00:31:22.000
dust and debris from every planetary system, if you have

640
00:31:22.119 --> 00:31:26.240
somewhere with life in that system, eventually that life has

641
00:31:26.240 --> 00:31:30.400
the potential to travel. And you know, yeah, most of

642
00:31:30.440 --> 00:31:32.640
it will. Most of the debris ejected from the Earth

643
00:31:32.680 --> 00:31:34.799
will never land on any other world. It will just

644
00:31:34.799 --> 00:31:37.559
float in space for forever more. But enough has been

645
00:31:37.599 --> 00:31:42.039
ejected that eventually something ejected from the Earth will land

646
00:31:42.039 --> 00:31:45.319
on a planet around another SAR, or will be incorporated

647
00:31:45.359 --> 00:31:47.640
in a planet forming region around a SATH that's just

648
00:31:47.680 --> 00:31:51.200
been borught. You put enough material out there, with enough

649
00:31:51.240 --> 00:31:54.799
bacteria buried in it, it's very reasonable to imagine that

650
00:31:54.880 --> 00:31:57.400
you could get a situation where, at some point in

651
00:31:57.440 --> 00:31:59.720
the distant future, there is a planet that has life

652
00:31:59.720 --> 00:32:02.200
on it, and that life is having a discussion of

653
00:32:02.200 --> 00:32:05.039
how did life get started, and someone suggests, well, Medley,

654
00:32:05.079 --> 00:32:07.119
life came from the stars, and everybody says, well, that's

655
00:32:07.160 --> 00:32:09.920
a lot of rubbis. Stop watching star trek and after

656
00:32:09.960 --> 00:32:11.640
it was the case because it's earthlife.

657
00:32:12.039 --> 00:32:15.480
Yes, indeed, And this story also proves that you shouldn't

658
00:32:15.480 --> 00:32:18.359
get upset with your neighbors for throwing the grass clippings

659
00:32:18.400 --> 00:32:21.759
over your fence because it happens right through the.

660
00:32:21.720 --> 00:32:25.279
Cosmos absolutely, I mean times into the other space sand

661
00:32:25.359 --> 00:32:25.680
rough thing.

662
00:32:25.720 --> 00:32:26.079
Actually.

663
00:32:26.119 --> 00:32:29.119
So the whole Nambrup connection here, of course, is the

664
00:32:29.200 --> 00:32:32.000
stars shaking their head and comets flying through space, essentially

665
00:32:32.039 --> 00:32:35.200
the beautiful analogy there. But every time you're walking around

666
00:32:35.200 --> 00:32:38.039
outside or anytime you're doing the dust thing in your house,

667
00:32:38.119 --> 00:32:40.039
a certain amount of the dust that is falling on

668
00:32:40.079 --> 00:32:42.720
your shoulders or that is a crewing in your house

669
00:32:43.440 --> 00:32:46.400
is dust from outer space. We have these tiny little

670
00:32:46.400 --> 00:32:50.160
particles of dust, which are sometimes called brownly particles. They

671
00:32:50.240 --> 00:32:52.400
are small enough that they are slowed down by the

672
00:32:52.519 --> 00:32:55.519
very tenuous sout atmosphere before they get into a thick

673
00:32:55.599 --> 00:32:58.279
enough flare of atmosphere that they get ablated that before

674
00:32:58.319 --> 00:33:01.720
they burn up. So there's this steady little sleeked of

675
00:33:01.839 --> 00:33:05.480
micro micro microscopic particles from space running down on the

676
00:33:05.519 --> 00:33:08.000
Earth all the time. So when you do the best thing,

677
00:33:08.079 --> 00:33:10.920
or when you go outside on a day and you're

678
00:33:10.960 --> 00:33:13.319
getting dusts on you. A total fraction of one is

679
00:33:13.319 --> 00:33:16.000
space that you've got spast under running down on you

680
00:33:16.039 --> 00:33:16.920
at old times.

681
00:33:17.640 --> 00:33:20.200
Yeah, it is fascinating to think about. I think we

682
00:33:20.279 --> 00:33:23.359
have touched on that story once before a while ago,

683
00:33:23.559 --> 00:33:28.039
but yeah, fascinating. I think if we're quick, we can

684
00:33:28.079 --> 00:33:30.519
squeeze in one more little story, or if you want

685
00:33:30.519 --> 00:33:33.720
to chase up the space Dandriff story, Life science dot

686
00:33:33.759 --> 00:33:39.039
Com carries that one one last yarn and this one

687
00:33:39.440 --> 00:33:42.119
is something we I think we touched on in the

688
00:33:42.200 --> 00:33:43.960
last couple of weeks about you know, where does a

689
00:33:44.000 --> 00:33:46.359
planet store start and a brown dwarf begin?

690
00:33:47.079 --> 00:33:50.680
And we talked about thirteen jupiter masses.

691
00:33:51.440 --> 00:33:55.079
Well, now our new planet has popped up in a

692
00:33:55.119 --> 00:33:58.559
study that has sparked debate on that very issue.

693
00:33:59.079 --> 00:34:01.279
Yes, so what we to do as humans in all

694
00:34:01.319 --> 00:34:04.680
walks of life is trying to understand the universe. That's

695
00:34:04.799 --> 00:34:07.759
just very fundamentally human thing to do. And to do that,

696
00:34:07.799 --> 00:34:11.960
we break things that are continue up into discrete packets,

697
00:34:12.000 --> 00:34:15.079
into discrete fractions. And we do this with a human lifetime.

698
00:34:15.119 --> 00:34:17.599
You know, you grow up and then suddenly one magical

699
00:34:17.639 --> 00:34:19.800
morning you wake up and you're legally able to drive.

700
00:34:20.199 --> 00:34:22.840
Are you'llegally able to drink so long as you're not driving.

701
00:34:23.159 --> 00:34:25.599
You know, you have these magical thresholds where we've said

702
00:34:25.920 --> 00:34:28.320
one day you're an adult, the day before you were

703
00:34:28.320 --> 00:34:31.639
a child. You're not fundamentally any different across that barrier,

704
00:34:31.679 --> 00:34:35.079
but we're grouping like with like and keeping different things separated.

705
00:34:36.360 --> 00:34:38.679
That's what's happened with definitions of planets. You know, this

706
00:34:38.880 --> 00:34:42.159
was all the age, all the controversy two decades ago

707
00:34:42.239 --> 00:34:44.280
with the emotion of Pluto. It was the same thing.

708
00:34:44.320 --> 00:34:46.760
It was trying to group objects that are similar with

709
00:34:46.840 --> 00:34:49.679
each other in groups so that you can study that.

710
00:34:50.559 --> 00:34:52.840
And one of the great areas where this has happened

711
00:34:52.920 --> 00:34:56.679
is you've got planets, you've got stars, and in between them,

712
00:34:56.719 --> 00:34:59.519
you've got these curious objects that people call brown dwarfs,

713
00:35:00.199 --> 00:35:02.199
which are things that they viewed as been too big

714
00:35:02.199 --> 00:35:05.000
and too massive to be considered a typical planet, but

715
00:35:05.079 --> 00:35:07.719
they're not massive enough to have hydrogen fusion and to

716
00:35:07.800 --> 00:35:10.280
shine and become a star. So the boundary to be

717
00:35:10.320 --> 00:35:12.599
a star is fairly clear. Cup If you get hydrogen

718
00:35:12.639 --> 00:35:16.000
fusion going, you're a star, which leads to the slightly

719
00:35:16.079 --> 00:35:20.239
quirky thing that white dwarfs and neutron stars are not stars.

720
00:35:20.719 --> 00:35:23.960
They's cellar remnant, so they're dead stars, which is a

721
00:35:24.000 --> 00:35:27.920
turtle a site. But between a planet and a star,

722
00:35:28.039 --> 00:35:30.039
there's this domain where you are not massive enough to

723
00:35:30.039 --> 00:35:33.119
burn hydrogen, but the temperature in your core will get

724
00:35:33.159 --> 00:35:35.280
high enough that you will temporarily be able to burn

725
00:35:35.320 --> 00:35:36.360
the uterium, which.

726
00:35:36.199 --> 00:35:37.119
Is heavy hydrogen.

727
00:35:38.000 --> 00:35:39.719
There's not much of that, so you'll get a very

728
00:35:39.760 --> 00:35:42.119
short period of uterium burning and then you'll just fizzle

729
00:35:42.159 --> 00:35:46.800
out and be a little glowing ember. Now where that

730
00:35:47.039 --> 00:35:49.239
boundaries with a star is very clear cup it's a

731
00:35:49.480 --> 00:35:52.440
hydrogen fusion and it's a very observable thing. But the

732
00:35:52.440 --> 00:35:55.039
boundary at the lower end, where you no longer have

733
00:35:55.159 --> 00:35:58.559
enough mass to burn the uterium, is much woolier. And

734
00:35:58.639 --> 00:36:01.719
if people do modeling, it depends on the composition of

735
00:36:01.719 --> 00:36:04.159
the object and how much solid material it's got and

736
00:36:04.199 --> 00:36:06.760
how much deuterium it's got, and all sorts of things

737
00:36:06.800 --> 00:36:10.559
going on. So what's happened historically, because we didn't really

738
00:36:10.639 --> 00:36:12.800
have the capacity to find low mass objects is people

739
00:36:12.840 --> 00:36:15.960
just put this arbitrary boundary of thirteen jupiter masses there

740
00:36:16.719 --> 00:36:19.400
to say anything more massive than that is a brown dwarf.

741
00:36:19.880 --> 00:36:23.079
Anything less massive as a planet. So that is setting

742
00:36:23.119 --> 00:36:26.920
this boundary purely on the physical mass is taking no

743
00:36:26.960 --> 00:36:29.480
account of the composition of the object or how it formed,

744
00:36:30.079 --> 00:36:32.199
And as we finally got the ability to find objects

745
00:36:32.199 --> 00:36:35.320
of this mass, people have started to question that because

746
00:36:35.760 --> 00:36:38.719
the formation mechanism of the composition matters. A planet like

747
00:36:38.800 --> 00:36:41.760
Jupiter has about thirty Earth masters of solid material as

748
00:36:41.800 --> 00:36:45.519
a core because of the way it formed. A star

749
00:36:45.920 --> 00:36:49.440
doesn't have that same kind of structure. So there's a

750
00:36:49.440 --> 00:36:53.800
growing argument that maybe we should divide it by formation mechanism,

751
00:36:54.199 --> 00:36:56.440
and something that formed like a planet is a planet,

752
00:36:56.440 --> 00:36:58.719
even if it's more massive than this limit, and it

753
00:36:58.719 --> 00:37:01.039
probably wouldn't undergo due TOI infusion because a lot of

754
00:37:01.079 --> 00:37:05.840
the masses solid material, so it's got less utarium. Alternatively,

755
00:37:05.840 --> 00:37:08.360
if it formed like a star, even if it's less

756
00:37:08.360 --> 00:37:11.280
massive than thirteen juke to masses, maybe it should be

757
00:37:11.360 --> 00:37:13.679
considered a brand war rather than a planet because of

758
00:37:13.679 --> 00:37:14.800
the formation mechanism.

759
00:37:15.199 --> 00:37:16.159
And it's a debate that.

760
00:37:16.239 --> 00:37:18.000
So we're just starting to kick off because we're only

761
00:37:18.079 --> 00:37:21.039
really able to find these objects now. It's been fired

762
00:37:21.119 --> 00:37:23.519
up here by the discovery of what's known as GAYA

763
00:37:23.599 --> 00:37:26.239
four B. So the guy in spacecraft we talked about

764
00:37:26.239 --> 00:37:29.199
earlier is this incredible mission that was measuring the positions

765
00:37:29.199 --> 00:37:33.320
of the motions of a billion stars with incredible precision.

766
00:37:33.360 --> 00:37:37.760
Two billion stars, absolutely ridiculous. And what Gaya has promised

767
00:37:37.760 --> 00:37:39.880
for a long time is that it would find one

768
00:37:39.960 --> 00:37:43.079
hundred thousand to one million planets around other stars. That

769
00:37:43.239 --> 00:37:45.880
was part of the marketing. So far it has found

770
00:37:46.079 --> 00:37:46.800
four or five.

771
00:37:48.000 --> 00:37:48.960
More will come.

772
00:37:48.760 --> 00:37:50.599
Because they're still doing their big data really says, so

773
00:37:50.639 --> 00:37:53.280
it will give us a deluge of planets at some point.

774
00:37:53.639 --> 00:37:55.679
But the reason it can do this is that it

775
00:37:55.800 --> 00:37:58.079
measures the positions of the stars in the sky so

776
00:37:58.159 --> 00:38:01.320
accurately that it can see than wabbling as they move

777
00:38:02.119 --> 00:38:05.360
as a result of the planets pulling them around. So

778
00:38:05.480 --> 00:38:07.880
this is a counterpart to our radial loss in effort.

779
00:38:08.119 --> 00:38:10.519
The radio lossy sees a movement back and forth on

780
00:38:10.519 --> 00:38:13.239
a line of sight, guyas sees a movement at right

781
00:38:13.280 --> 00:38:17.000
angles to that. So it's been looking at this star.

782
00:38:17.199 --> 00:38:19.760
This star is less massive than the Sun, about two

783
00:38:19.760 --> 00:38:21.880
thirds of the mass of the Sun, and this starts

784
00:38:21.960 --> 00:38:24.119
moving across the night sky. Because it's moving through the

785
00:38:24.159 --> 00:38:27.199
galaxy separately towards it's not what we call proper mation,

786
00:38:27.800 --> 00:38:29.880
and Guy has identified that instead of that proper motion

787
00:38:30.000 --> 00:38:34.280
ministrat line, it's following a corks grow path across the sky, zigzagging,

788
00:38:34.639 --> 00:38:36.800
and that's a telltale sign it's got a planet going

789
00:38:36.800 --> 00:38:40.079
around it. Now, because this sounds a bit like the Sun,

790
00:38:40.119 --> 00:38:43.519
it's a bit cooler. You can do radio lossity observations,

791
00:38:43.599 --> 00:38:45.760
which means you can measure the line of sight wobble

792
00:38:45.800 --> 00:38:49.039
as well, which means you can perfectly constrain what's going

793
00:38:49.079 --> 00:38:51.840
around it. And the evidence here is that this is

794
00:38:51.880 --> 00:38:54.960
an object eleven point eight times a mass of Jupiter,

795
00:38:55.639 --> 00:38:58.119
so it's just underneath that threshold to be a brown dwarf.

796
00:38:58.159 --> 00:39:01.400
We would traditionally call it a planet. And job done.

797
00:39:01.880 --> 00:39:04.599
The complexity comes out that this star is less massive

798
00:39:04.639 --> 00:39:07.960
than the Sun and it's got a roughly similar composition

799
00:39:08.039 --> 00:39:11.760
to the Sun. What that means is a material the

800
00:39:11.800 --> 00:39:14.800
planets around it would have formed from would have been

801
00:39:14.840 --> 00:39:18.280
similar to that around the Sun. It's not particularly metal rich,

802
00:39:18.320 --> 00:39:20.719
so it wouldn't have had far more solid material around

803
00:39:20.760 --> 00:39:23.360
it than the Sun did, which means is a really

804
00:39:23.440 --> 00:39:25.679
difficult question to answer which is, how can a star

805
00:39:25.760 --> 00:39:28.840
less massive than the Sun, which presumably formed from a

806
00:39:28.920 --> 00:39:31.920
less massive cloud of material than the Sun, how can

807
00:39:31.960 --> 00:39:34.079
it form a planet twelve times more massive than the

808
00:39:34.079 --> 00:39:37.760
biggest planet we have in our system. That just doesn't

809
00:39:37.800 --> 00:39:41.400
make much sense. It's really counter to our planet formation models,

810
00:39:41.400 --> 00:39:44.920
which is more massive stars formed more massive planets. So

811
00:39:45.000 --> 00:39:47.159
that then brings up the suggestion that maybe this thing

812
00:39:47.199 --> 00:39:50.119
didn't form as a planet at all. Maybe instead what

813
00:39:50.159 --> 00:39:52.920
we're seeing as a failed binary star system. And this

814
00:39:53.119 --> 00:39:56.719
eleven point eight dupe to mass object formed in the

815
00:39:56.760 --> 00:40:00.440
same way that binary stars would form, and it.

816
00:40:00.400 --> 00:40:01.480
Wasn't core recretion.

817
00:40:01.559 --> 00:40:03.519
You didn't get a load of solid material grow to

818
00:40:03.599 --> 00:40:05.519
thirty times a mass of the Earth or ten times

819
00:40:05.519 --> 00:40:08.199
a mass of the Earth and then sat gathering gas

820
00:40:08.239 --> 00:40:11.079
because of the gravitational pull that instead it formed through

821
00:40:11.119 --> 00:40:14.159
gravitational and instability in the cloud like another star would fall.

822
00:40:14.920 --> 00:40:18.559
And therefore this could be considered a failed star, in

823
00:40:18.599 --> 00:40:19.559
which case.

824
00:40:19.920 --> 00:40:21.199
It should be called a brown dwarf.

825
00:40:21.239 --> 00:40:24.000
Even though it's not massive enough because it didn't fall

826
00:40:24.079 --> 00:40:26.679
as a planet. It may even be because it's so

827
00:40:26.800 --> 00:40:29.000
class of the threshold that it could have almost got

828
00:40:29.000 --> 00:40:31.440
to the deuterium Beurn, England. It could have had that happen.

829
00:40:32.119 --> 00:40:35.440
Now we don't really know if we could go there,

830
00:40:35.480 --> 00:40:39.039
If we could borrow Captain Kirk's spaceship and engage what

831
00:40:39.119 --> 00:40:40.960
Brave and go there, we'd be able to answer this

832
00:40:41.000 --> 00:40:42.920
after a little while. We'd put a mission up like

833
00:40:43.039 --> 00:40:45.960
Juno that's going around Jupiter, that would allow you to

834
00:40:45.960 --> 00:40:48.400
map the interior of the objective bit like the earthquakes

835
00:40:48.400 --> 00:40:51.039
we were talking about the first topic, and figure out

836
00:40:51.039 --> 00:40:52.679
if it had a core or not, and that would

837
00:40:52.679 --> 00:40:53.719
tell you about its formation.

838
00:40:53.840 --> 00:40:54.800
But we can't do that.

839
00:40:55.280 --> 00:40:57.079
We just can't get there. So we at the minute

840
00:40:57.519 --> 00:41:00.760
it's purely in the domain of speculation, but it's efficiently

841
00:41:00.920 --> 00:41:05.159
odd discovery that it is just restarting that old discussion

842
00:41:05.199 --> 00:41:07.280
about at what point do we need.

843
00:41:07.159 --> 00:41:09.000
To look at this again? I guess at.

844
00:41:08.840 --> 00:41:12.159
What point do we need to discuss whether we get

845
00:41:12.159 --> 00:41:16.000
a more physically motivated difference between brand walls and planets,

846
00:41:16.559 --> 00:41:19.039
or whether we're happy to sticking with this arbitrary mass limit.

847
00:41:19.639 --> 00:41:21.679
And as the years go on, Geyer is going to

848
00:41:21.679 --> 00:41:26.039
discover far more objects. We continue to find planets using

849
00:41:26.039 --> 00:41:28.599
all the other methods, there will be more objects that

850
00:41:28.639 --> 00:41:31.360
straddle that boundary. Because nature forms things of all sizes,

851
00:41:31.400 --> 00:41:33.960
it doesn't say I'm going to leave a gap here

852
00:41:34.039 --> 00:41:36.599
to make it massive. There'll be things of all masses,

853
00:41:37.280 --> 00:41:39.639
and there will be things of identical masses that formed

854
00:41:39.679 --> 00:41:42.320
in different ways, and so it's going to be an

855
00:41:42.320 --> 00:41:44.119
ongoing question. I'm sure we could have a chat in

856
00:41:44.119 --> 00:41:45.760
a couple of years time and they'd still be having

857
00:41:45.760 --> 00:41:48.760
the same debates. But it's great when you get to

858
00:41:48.800 --> 00:41:52.400
the point where our ability to find things is such

859
00:41:52.480 --> 00:41:54.679
that it pushes the boundaries of how we define things

860
00:41:54.679 --> 00:41:55.920
and we have to revisit them.

861
00:41:56.199 --> 00:41:57.440
That's how signs works, and I.

862
00:41:57.400 --> 00:41:59.719
Really love it, even if it means you get cranky

863
00:41:59.760 --> 00:42:01.920
people all waving plugs and go Blueto should still be

864
00:42:01.920 --> 00:42:02.880
a planet.

865
00:42:02.679 --> 00:42:07.400
Yes, yes, and that's still happening two years indeed. Yeah,

866
00:42:07.480 --> 00:42:11.559
all right, if you would like to look into Guaya

867
00:42:11.880 --> 00:42:16.239
four B and five B. They've posted a report in

868
00:42:16.320 --> 00:42:20.440
the Astronomical Journal. Yes, a fascinating discovery. And I imagine

869
00:42:20.440 --> 00:42:22.880
the more we look, the more unusual things we'll find.

870
00:42:22.920 --> 00:42:26.519
And yes, we probably will have to redefine where a

871
00:42:26.559 --> 00:42:29.559
Brown law starts and a planet finishes. In the future,

872
00:42:29.599 --> 00:42:32.400
it might come down to that. At the moment, we

873
00:42:32.519 --> 00:42:36.159
just go with what we know until proof sends us

874
00:42:36.159 --> 00:42:40.039
in a different direction. We are just about done. Johnny,

875
00:42:40.079 --> 00:42:40.880
thank you so much.

876
00:42:41.400 --> 00:42:42.239
That's absolute pleasure.

877
00:42:42.239 --> 00:42:45.039
If I keep having me, always a pleasure. And we'll

878
00:42:45.039 --> 00:42:48.239
see you real soon. Professor John T. Horner from the

879
00:42:48.360 --> 00:42:52.239
University of Southern Queensland. And thanks to Hugh in the studio,

880
00:42:52.320 --> 00:42:53.639
who couldn't be with us today.

881
00:42:53.960 --> 00:42:54.880
It's very embarrassed.

882
00:42:54.920 --> 00:42:57.280
He's got a severe case of space Dandriff.

883
00:42:57.920 --> 00:42:59.079
Don't forget to visit.

884
00:42:58.920 --> 00:43:01.760
Us online as well Space Nuts podcast dot com or

885
00:43:01.760 --> 00:43:04.719
space Nuts dot io. And from me Andrew Uncley, thanks

886
00:43:04.719 --> 00:43:07.119
for joining us. We'll see on the very next episode

887
00:43:07.159 --> 00:43:10.519
of Space space Nuts come exert.

888
00:43:11.000 --> 00:43:16.599
Until then, Bye bye to the Space Nuts podcast.

889
00:43:18.280 --> 00:43:23.360
Available at Apple Podcasts, Spotify, iHeart Radio, or your favorite

890
00:43:23.400 --> 00:43:24.280
podcast player.

891
00:43:24.480 --> 00:43:27.639
You can also stream on demand at guides dot com.

892
00:43:27.800 --> 00:43:33.480
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