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

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Language: en

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hi there thanks for joining us this is


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Space Nuts my name is Andrew Dunley your


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host great to have your company coming


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up on this episode we are going to look


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at Earth's core and uh it's sort of hit


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the news lately but this is not a new


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story but we thought we better talk


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about it just in case you're wondering


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uh Earth's core uh is uh is slowing down


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or or not doing what you'd think it


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would normally do so we'll talk about


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that there's a hyperactive star out


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there and it's got a Planet what does


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that mean uh it means it's pretty darn


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quick uh we're going to talk space


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dandruff yes it's true and a new planet


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that's sparking a bit of debate on its


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status if we got time if we've got time


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we'll do that one that's all coming up


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on this episode of Space Nuts 15 seconds


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guidance is internal 10 9 ignition


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sequence Space Nuts 5 4 3 2 1 2 3 4 5 5


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4 3


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Space Nuts asut report it feels good he


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back for more Professor johy Horner


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professor of astrophysics at the


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University of Sal Queensland hi Johnny


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hey how are you going I am well how are


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you I'm getting there I'm not a morning


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person was I was saying I got working up


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earlier than I was planning this morning


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by phone call that said can you go on


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live on the radio in five minutes Sor


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got be a zombie on live radio which all


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was good fun those pisty journalists


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here groy ever since I have great


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sympathy for anybody who works a Morning


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Show and we I think we're talking about


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this last week but must be hard but I


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I'm not at my best at 20 to 7 in the


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morning this is a more reasonable time


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but this is still morning it's 20 to 12


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at the


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minute conscious I used to work with a


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journalist who um used to have to do the


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police rounds first thing in the morning


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to get any news from around the the


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various police districts you know car


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crashes all that horrible stuff um fires


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Etc


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uh and after a council meeting they used


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to have to ring the mayor at sparrows in


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the morning we had one particular mayor


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who um was always nearly asleep when


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they called and they could never get a


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good quote from him because he was just


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non-comp


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menst not of the day it was a


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frustration for the journalist I can


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tell you I'm gonna do something at 5


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a.m. I'd rather have stayed up all night


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to do it then set my alarm early yes yes


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well I never had a choice for the odd


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years but anyway that that was my that


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was my choice even though I didn't have


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a choice and now you have your freedom


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so that's I


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do now um let's get down to business uh


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Earth's core the rotation thereof this


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is a story that's been around a little


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while but it keeps popping up it popped


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up again on the weekend and I thought


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well let's talk about it um we may have


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talked about it with Fred I I got an


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inkling that when it first came up we


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went there but um yes it's something


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that the the press is certainly honing


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in on yeah Well's a few little fact toes


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about this that really caught my


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actually when you sent me the link


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through I've managed to miss this one


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these are researchers at the University


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of Southern California so USC and


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they've been looking at earthquake data


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so if we want to study the interior of


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the Earth with the best will in the


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world we can't drill down there you know


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the deepest Hull ever drilled was less


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than 10 kilm I believe and the Earth is


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frustratingly opaque we can't see the


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interior the 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 the


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cor the mantle how they all behave


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through earthquakes so you get an


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earthquake and seismic waves travel


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outwards in all directions there are two


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different types of seismic waves in a


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very rough sense and when they go from


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one medium to another their speed


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changes and they refract in just the


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same way like does when it enters a


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swimming pool same kind of IA so if


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you're measuring these earthquakes using


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seismal grass from all around the world


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you can back out what the interior of


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the earth looks like in its properties


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by the time it takes a different types


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of seismic waves to reach you


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essentially and by doing that over an


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incredible long time we've got a very


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detailed picture of the Earth's interior


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even down to you know the temperatures


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the pressures the compositions and


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people are monitoring this all the time


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but the finer the detail you want the


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more challenging it is to disentangle


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the information about the earthquake


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itself from the information you're


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learning about the interior and this is


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something we see a lot with fing exop


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planets there a perverse analogy here


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that we're looking at light from stars


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and to get a really good idea of what


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the planet's like you've got to


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understand the star first because that


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is overlaid on the DAT and you've got to


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disentangle them so to get a real handle


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on the fine details of what's going in


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in terms of the earth your ideal


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situation would be to have every


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earthquake be identical to the last so


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that all the earthquakes were the same


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and you could take that out of your


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analysis you could essentially account


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for that and that was the first thing I


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this article that I thought was really


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interesting I mean obviously the results


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are cool but it's the where they got


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them they looked at this sample of what


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a described as um repeating earthquakes


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they got data from these earthquakes


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near the South Sandwich Islands 121 of


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these that occurred between 1991 and


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2023 and it says repeating earthquakes


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are seismic events that occur at the


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same location and produce identical


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seismograms so rather than using all the


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earthquakes from all around the world


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they used this one subset that gave them


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very controlled data and that lets you


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get very fine resolution on the things


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you're looking at because you're not


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adding extra noise essentially and by


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doing all this they learned a couple of


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new things about the Earth's inner core


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so we've known for a while that while


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the Earth has a core the core actually


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has two layers it's got a molten outer


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core which the iron and the nickel are


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essentially liquid they're moving well


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they're molten so they're a fluid they


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move around and that movement is tied to


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the formation of the magnetic field you


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get the induced magnetism that gives us


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the magnetic field interior to that


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where the pressure is high even though


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the temperature is so high the pressure


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is such that the inner core has been


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thought to be


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solid and so you've got a solid with a


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liquid layer outside and then the molten


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layer of the mantle then the solid layer


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of the crust as a rough kind of


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structure what these new results have


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shown is the headline Act is that that


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inner core doesn't spin perfectly


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constantly it had apparently for a long


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period of time which I wasn't aware of


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people were aware that the spin speed of


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that inner cor was gradually increasing


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it was speeding up a little bit almost


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in perceptibly but what this research


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has shown is that more recently it has


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now started to slow down again so that's


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a headline act the inner cor has slowed


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down a little bit and they're talking


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about here at a scale of about a


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thousandth of a second for the rotation


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period so it's a tiny effect but they


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can measure it thanks to these repeating


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earthquakes that have the same signature


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that allows them to get a much better


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resolution on the data the other thing


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which I think is very interesting that


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isn't in the main press release but is


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in a couple of the other articles is


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that these same data suggests that the


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inner core is not totally solid but


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actually has molten areas within it so


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this is a bit of a change to the


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Paradigm we had of this very simple


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model of a solid inner core then a


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molten outer core that there's actually


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a bit of molten to the inner core as


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well which probably makes a bit of sense


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in the context of this thing's rotation


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changing over time if you've got bits


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that are melting bits that are moving


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around a little bit you're moving


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angular momentum around so therefore


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you'll change the rotation period in


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just the same way that the rotation


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period of the Earth as a whole will


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change if the ice caps melt will change


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in a measurable way because you're


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moving Mass from the poles to the


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equator redistributing that mass will


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mean that the earth spin will slow a


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little bit to conserve angular momenta


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so it's a fascinating story and I think


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yes the headline side of it the inner


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core has slow down that's interesting


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that's a headline story but to me the


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really interesting stuff was to how of


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how they figure that out and the


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subtleties of the choice of earthquakes


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to use and the additional things they


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can figure out is really shows the


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benefit of continuing to get longer data


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sets and reanalyzing what you thought


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you knew when you've got better data and


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better instruments so it's a very cool


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story and do encourage people to have a


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look around there's a few different


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versions of the story out there on the


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web um even CNN covered it at one point


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so it's got interest and by reading a


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variety of stories you can get some of


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the different cool facts that maybe the


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M press release didn't pick up on yeah


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they figured this out by studying what


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is21 earthquakes between 1991 and 2024


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yes uh how accurate do you perceive


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their data to be well I I trust at the


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end of the day it's peer reviewed and


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published so there's a certain


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confidence of fidelity there that's good


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and I find their data selection really


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interesting there the fact that you've


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got thousands of earthquakes happening


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all the time you know we see what's


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happening in Santeria at the minute with


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what is probably a very large motion of


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magma underneath that ancient volcano


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that suggests it may well erupt again at


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some point similarly under Naples so


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earthquakes are happening all the time


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all around the world and what I loved


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about this was finding this subset of


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earthquakes that happening recurrently


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at the same place that are giving them


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the same signal which makes a data


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analysis much much much better I just


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really like that and it's why in exactly


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the same way that we can find planets


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using our radial velocity the wobble


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method much more easily around quiet


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Stars than active STS because active


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stars are roiling and bubbling and


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boiling so the lines of the spectrum of


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the star are moving around because of


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the properties of the star that


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introduces a lot of nights when you've


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got a quiet sour of s that isn't very


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active a bit like the sun is that noise


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is much less which means that you can


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resolve much smaller motions facts to


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the planets and so you can detect


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smaller planets around stars that are


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less active and and it's a direct


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parallel here by getting a much simpler


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set of earthquakes that all behave the


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same way you reduce the nois and


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therefore you can get a much more


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accurate impression of what's going on


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in the interior so I guess if you want


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to look at time scale changes in the


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mantle and stuff like that you can use


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all the data set and map it that way but


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for something like this way you need


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that really fine tooth comb it's a


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beautiful way of doing it yeah yeah it's


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fascinating story it's uh yeah we're so


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close to it compared to everything else


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we study oh yeah in Moss but it's um


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yeah it's invisible to us we have to


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yeah we have to dig deep boom boom


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techniques that are getting developed


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from this then apply in astronomy and in


00:10:56.720 --> 00:10:58.190
planetary science you know we talked


00:10:58.200 --> 00:11:00.269
previously about in it which sat on Mars


00:11:00.279 --> 00:11:02.590
and recorded Mars Quakes and that was


00:11:02.600 --> 00:11:04.310
just single station I would love at some


00:11:04.320 --> 00:11:06.870
point in the future perhaps when um


00:11:06.880 --> 00:11:08.790
seron decides that he's finally going to


00:11:08.800 --> 00:11:10.710
move to Mars if he could take some


00:11:10.720 --> 00:11:12.870
seismometers with him and drop them in a


00:11:12.880 --> 00:11:15.190
variety of positions that'll give us a


00:11:15.200 --> 00:11:17.470
lot more information on Mar's interior


00:11:17.480 --> 00:11:19.110
similarly these kind of techniques are


00:11:19.120 --> 00:11:20.430
very similar to what my colleagues at


00:11:20.440 --> 00:11:21.750
the University of Southern Queensland


00:11:21.760 --> 00:11:24.389
and elsewhere around the sphere of


00:11:24.399 --> 00:11:26.750
Academia used to study the Interiors of


00:11:26.760 --> 00:11:28.310
starss you've got the same problem you


00:11:28.320 --> 00:11:29.790
look at the Sun


00:11:29.800 --> 00:11:31.710
and it's our nearest star but all we see


00:11:31.720 --> 00:11:33.590
is the surface you can't see inside it


00:11:33.600 --> 00:11:35.710
because the surface is in the way yeah


00:11:35.720 --> 00:11:36.870
how do we know about the structure in


00:11:36.880 --> 00:11:38.590
the interior it's exactly the same kind


00:11:38.600 --> 00:11:40.310
of thing they're doing here but using


00:11:40.320 --> 00:11:43.949
star Quakes and star wobbles rather than


00:11:43.959 --> 00:11:45.829
earthquakes yeah really interesting


00:11:45.839 --> 00:11:47.949
stuff and if you'd like to read more


00:11:47.959 --> 00:11:50.870
about the inner core of our own Planet


00:11:50.880 --> 00:11:53.030
slowing down just do a search for that


00:11:53.040 --> 00:11:55.310
there it's everywhere you can find it on


00:11:55.320 --> 00:12:00.069
Discover magazine and a few other sites


00:12:00.079 --> 00:12:01.629
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today now back to the show 3 2 1 Space


00:13:46.600 --> 00:13:49.829
Nuts uh now let's go to this uh story


00:13:49.839 --> 00:13:52.590
that is talking about a star that's been


00:13:52.600 --> 00:13:55.389
described as hyperactive this this is a


00:13:55.399 --> 00:13:57.509
star that's moving well it's probably


00:13:57.519 --> 00:14:00.670
one of the fastest if not the fastest


00:14:00.680 --> 00:14:03.110
ever discovered this this story is quite


00:14:03.120 --> 00:14:06.430
amazing yeah so this is what's called a


00:14:06.440 --> 00:14:08.350
hyper velocity star and we do know a few


00:14:08.360 --> 00:14:10.749
of these in the Milky Way these are


00:14:10.759 --> 00:14:12.910
stars that are traveling at such a high


00:14:12.920 --> 00:14:15.310
speed that they're traveling faster than


00:14:15.320 --> 00:14:17.110
the local escape velocity for the Galaxy


00:14:17.120 --> 00:14:19.069
at their location so we're on the


00:14:19.079 --> 00:14:20.430
surface of the Earth and if I throw a


00:14:20.440 --> 00:14:22.269
tennis ball up in the air it will fall


00:14:22.279 --> 00:14:24.590
back down I'll catch it or I'll fail to


00:14:24.600 --> 00:14:26.470
catch it because I'm English and the


00:14:26.480 --> 00:14:27.949
English Cricket team's doing terribly at


00:14:27.959 --> 00:14:29.310
the minutes I'll probably fail to catch


00:14:29.320 --> 00:14:31.389
it because that's where I'm from


00:14:31.399 --> 00:14:34.430
originally if I threw it hard enough the


00:14:34.440 --> 00:14:36.069
Earth's gravity wouldn't be able to hold


00:14:36.079 --> 00:14:38.150
on to it and it would escape and for the


00:14:38.160 --> 00:14:41.670
Earth that's about 11 kilm a second the


00:14:41.680 --> 00:14:43.749
more massive you are the higher that


00:14:43.759 --> 00:14:45.350
velocity is but the further you are from


00:14:45.360 --> 00:14:47.590
the mass the lower that velocity is I


00:14:47.600 --> 00:14:49.069
it's the kind of thing we teach in first


00:14:49.079 --> 00:14:51.110
year astrophysics as an equation for the


00:14:51.120 --> 00:14:53.749
escape Velocity um where you can work it


00:14:53.759 --> 00:14:55.269
out and I think it's a square root of 2


00:14:55.279 --> 00:14:58.030
GM over R um


00:14:58.040 --> 00:15:00.749
now sounds about right so that's


00:15:00.759 --> 00:15:02.470
basically it's related to the mass of


00:15:02.480 --> 00:15:04.590
the thing you're going around and the


00:15:04.600 --> 00:15:06.230
and it's inversely proportional to the


00:15:06.240 --> 00:15:08.710
distance you are away from that thing


00:15:08.720 --> 00:15:10.590
with a square root


00:15:10.600 --> 00:15:13.110
there what that means is that anything


00:15:13.120 --> 00:15:16.150
that has mass has an escape velocity so


00:15:16.160 --> 00:15:17.990
technically I have an escape velocity if


00:15:18.000 --> 00:15:20.590
you put me in the vacuum of space far


00:15:20.600 --> 00:15:22.509
away from any Star and give me that


00:15:22.519 --> 00:15:25.030
tennis ball I could in theory nudge it


00:15:25.040 --> 00:15:26.949
gently and make it orbit me but if I


00:15:26.959 --> 00:15:29.470
nudge too hard it would Escape but even


00:15:29.480 --> 00:15:31.309
though I'm far too heavy my


00:15:31.319 --> 00:15:33.509
gravitational pull is incredibly weak


00:15:33.519 --> 00:15:36.269
because I'm only 130 kilos not the mass


00:15:36.279 --> 00:15:37.470
of the


00:15:37.480 --> 00:15:39.509
Earth what that means from the point of


00:15:39.519 --> 00:15:41.670
view of our galaxy is that our galaxy


00:15:41.680 --> 00:15:43.350
has an escape velocity that varies


00:15:43.360 --> 00:15:45.110
depending on where you are in the


00:15:45.120 --> 00:15:47.590
galaxy nearer you are to the middle the


00:15:47.600 --> 00:15:48.829
higher the speed you need to be


00:15:48.839 --> 00:15:50.829
traveling is to escap just as in the


00:15:50.839 --> 00:15:53.550
solar system it's harder to escap from


00:15:53.560 --> 00:15:55.710
the sun when you know Mercury's orbit


00:15:55.720 --> 00:15:58.670
than it is when you know ne's orbit so


00:15:58.680 --> 00:15:59.790
that


00:15:59.800 --> 00:16:01.590
how stars move and a small fraction of


00:16:01.600 --> 00:16:03.389
the stars in our galaxy because they're


00:16:03.399 --> 00:16:05.069
constantly moving around all the other


00:16:05.079 --> 00:16:07.470
stars because there things going on a


00:16:07.480 --> 00:16:08.749
small number of those Stars will


00:16:08.759 --> 00:16:11.069
eventually get ejected from the Galaxy


00:16:11.079 --> 00:16:13.189
entirely now quite a few of these


00:16:13.199 --> 00:16:15.150
actually that are previously known are


00:16:15.160 --> 00:16:17.710
linked to stars that were in a binary


00:16:17.720 --> 00:16:20.069
star system that was quite close and


00:16:20.079 --> 00:16:21.670
then one of the components went


00:16:21.680 --> 00:16:24.069
supernova and suddenly there it's like


00:16:24.079 --> 00:16:25.509
the lead was cut so suddenly they're


00:16:25.519 --> 00:16:27.910
rejected at very high speed right but


00:16:27.920 --> 00:16:28.910
that's not the only way you can


00:16:28.920 --> 00:16:31.949
conformed that hypervelocity stars and


00:16:31.959 --> 00:16:34.470
are these Stars whose speed is so high


00:16:34.480 --> 00:16:36.110
that they will probably escape and never


00:16:36.120 --> 00:16:37.749
return that will wonder the void between


00:16:37.759 --> 00:16:39.910
the galaxies in a very lonely life


00:16:39.920 --> 00:16:41.230
forever


00:16:41.240 --> 00:16:44.069
more the other side of this story is


00:16:44.079 --> 00:16:46.550
planet detection we've talked before


00:16:46.560 --> 00:16:48.389
about how the two most successful


00:16:48.399 --> 00:16:50.069
methods for finding planets are the


00:16:50.079 --> 00:16:51.629
transit method and the radio velocity


00:16:51.639 --> 00:16:53.430
method essentially seeing Stars wobble


00:16:53.440 --> 00:16:56.110
and wink there is a method a technique


00:16:56.120 --> 00:16:58.910
called gravitational micr lensing that


00:16:58.920 --> 00:17:00.629
if you went back to the late '90s people


00:17:00.639 --> 00:17:02.829
were really hoping it would find


00:17:02.839 --> 00:17:04.470
gazillions of planets that it would be


00:17:04.480 --> 00:17:06.870
really successful and it's never quite


00:17:06.880 --> 00:17:09.230
found as many as people expected because


00:17:09.240 --> 00:17:11.510
it's fundamentally hard to do it's not


00:17:11.520 --> 00:17:12.909
that these events aren't happening it's


00:17:12.919 --> 00:17:15.069
just that they're very hard to observe


00:17:15.079 --> 00:17:17.230
but going back to 2011 a team of


00:17:17.240 --> 00:17:18.870
scientists that were looking towards the


00:17:18.880 --> 00:17:21.069
galactic core where you've got the most


00:17:21.079 --> 00:17:23.870
stars on the sky in the smallest area


00:17:23.880 --> 00:17:25.750
observed a gravitational microlensing


00:17:25.760 --> 00:17:27.390
event they saw a background star


00:17:27.400 --> 00:17:30.590
brightened and then fed away again but


00:17:30.600 --> 00:17:32.310
it had a double peak in the brightness


00:17:32.320 --> 00:17:34.750
so there were two peaks as it went up


00:17:34.760 --> 00:17:35.990
and then it went up further and then it


00:17:36.000 --> 00:17:38.390
fell away again and that was indicating


00:17:38.400 --> 00:17:40.110
that in the foreground between us and


00:17:40.120 --> 00:17:42.590
that star something had passed in front


00:17:42.600 --> 00:17:45.350
that had mass that mass curving


00:17:45.360 --> 00:17:47.990
SpaceTime acted as a lens bent a little


00:17:48.000 --> 00:17:49.070
bit more of the light from the


00:17:49.080 --> 00:17:50.590
background star towards us and that's


00:17:50.600 --> 00:17:52.870
why we saw the star brighten and then as


00:17:52.880 --> 00:17:54.310
the thing in the foreground moved away


00:17:54.320 --> 00:17:56.149
again the lens went away and it faded


00:17:56.159 --> 00:17:59.470
away again and when these events happen


00:17:59.480 --> 00:18:01.070
you could infer quite a lot from


00:18:01.080 --> 00:18:02.950
studying the degree to which the thing


00:18:02.960 --> 00:18:05.190
brightened and faded and also the time


00:18:05.200 --> 00:18:06.669
scale over which it


00:18:06.679 --> 00:18:08.870
happened and the team at the time


00:18:08.880 --> 00:18:10.510
announce their results this is really


00:18:10.520 --> 00:18:12.510
exciting but there's a little bit of


00:18:12.520 --> 00:18:14.630
what we call a degeneracy there are two


00:18:14.640 --> 00:18:17.350
different models that can equally well


00:18:17.360 --> 00:18:20.110
explain what we've observed the first is


00:18:20.120 --> 00:18:21.630
that you've got a star that's about a


00:18:21.640 --> 00:18:23.789
fifth of the mass of the sun with a


00:18:23.799 --> 00:18:26.110
planet that is about 29 times the mass


00:18:26.120 --> 00:18:29.510
of the Earth that's scenario 1 so you've


00:18:29.520 --> 00:18:31.750
got a star with a planet the other


00:18:31.760 --> 00:18:34.789
scenario is that you had a planet the


00:18:34.799 --> 00:18:37.149
mass of Jupiter with a tiny little Moon


00:18:37.159 --> 00:18:39.029
and in either case the ratio of the mass


00:18:39.039 --> 00:18:40.110
between the big thing and the little


00:18:40.120 --> 00:18:43.270
thing is about 2300 times either of


00:18:43.280 --> 00:18:46.149
these scenarios could explain perfectly


00:18:46.159 --> 00:18:48.390
well what was seen so how do we


00:18:48.400 --> 00:18:50.270
differentiate between them well one


00:18:50.280 --> 00:18:51.830
thing we can do now that we've got


00:18:51.840 --> 00:18:54.310
better telescope some better technology


00:18:54.320 --> 00:18:56.950
is to use theek telescopes which are


00:18:56.960 --> 00:18:58.310
among the biggest in the world they're


00:18:58.320 --> 00:19:01.230
incred instruments in South America and


00:19:01.240 --> 00:19:03.390
also the Gia spacecraft which has been


00:19:03.400 --> 00:19:04.750
it's just finished its Mission but it


00:19:04.760 --> 00:19:07.669
spent 12 years in orbit mapping the


00:19:07.679 --> 00:19:10.110
positions of em motions of up to two


00:19:10.120 --> 00:19:12.909
billion stars with unprecedented


00:19:12.919 --> 00:19:15.470
mindboggling accuracy so the team that


00:19:15.480 --> 00:19:17.950
found this object in 2011 saw this


00:19:17.960 --> 00:19:19.710
signal in the gravitational micr lensing


00:19:19.720 --> 00:19:22.190
said one way that we could distinguish


00:19:22.200 --> 00:19:25.549
between those two different models is to


00:19:25.559 --> 00:19:27.630
look for the thing that caused the


00:19:27.640 --> 00:19:29.190
lensing


00:19:29.200 --> 00:19:31.149
if it's a star in theory there'll be a


00:19:31.159 --> 00:19:32.710
point of light there that's moving that


00:19:32.720 --> 00:19:34.230
we can see that we can track back and


00:19:34.240 --> 00:19:35.830
say it was in the right place at the


00:19:35.840 --> 00:19:38.230
right time we'll be able to see it and


00:19:38.240 --> 00:19:39.470
that shows that the thing that did the


00:19:39.480 --> 00:19:41.190
lensing was a star so it's a star and a


00:19:41.200 --> 00:19:44.510
planet if we see nothing then the star


00:19:44.520 --> 00:19:46.149
doesn't work because if there was a star


00:19:46.159 --> 00:19:47.430
there we'd see it so it must be the


00:19:47.440 --> 00:19:49.990
other scenario so they went away and dug


00:19:50.000 --> 00:19:51.590
through that data and it took them a bit


00:19:51.600 --> 00:19:53.830
longer than expected but they finally


00:19:53.840 --> 00:19:56.510
found a star that is moving ridiculously


00:19:56.520 --> 00:19:58.270
quickly but was in exactly the right


00:19:58.280 --> 00:20:00.310
place at the right time to cause the


00:20:00.320 --> 00:20:02.510
micro lensing event and that star is


00:20:02.520 --> 00:20:04.149
also quite near the middle of the Galaxy


00:20:04.159 --> 00:20:06.750
so it's quite it was quite far from us


00:20:06.760 --> 00:20:08.230
quite near the thing it was lensing at


00:20:08.240 --> 00:20:10.630
the time they've tracked it back and it


00:20:10.640 --> 00:20:12.750
turns out that the movement of this star


00:20:12.760 --> 00:20:14.350
just at right angle through our line of


00:20:14.360 --> 00:20:17.149
sight so the movement across the sky


00:20:17.159 --> 00:20:19.390
gives it a speed that is almost two


00:20:19.400 --> 00:20:23.549
million kilometers per hour 540


00:20:23.559 --> 00:20:26.549
kilometers per second glimy that is


00:20:26.559 --> 00:20:28.990
ridiculous you know


00:20:29.000 --> 00:20:30.950
Stars nearby near the Sun that moving


00:20:30.960 --> 00:20:32.470
around we typically talk of speeds of


00:20:32.480 --> 00:20:34.149
tens of kilometers a second maybe a bit


00:20:34.159 --> 00:20:37.630
more than 100 so 540 is ridiculously


00:20:37.640 --> 00:20:39.950
extreme and is already almost the escape


00:20:39.960 --> 00:20:42.630
velocity of the Galaxy at that point now


00:20:42.640 --> 00:20:44.190
the unknown here is that there could be


00:20:44.200 --> 00:20:45.950
some movement towards our away fromers


00:20:45.960 --> 00:20:48.630
as well so we only see the movement on


00:20:48.640 --> 00:20:51.909
the sky and essentially any movement


00:20:51.919 --> 00:20:54.350
that is radial toward us or away from us


00:20:54.360 --> 00:20:56.310
will be enough to mean that this thing


00:20:56.320 --> 00:20:58.230
is Unbound by the Galaxy that it will


00:20:58.240 --> 00:20:59.110
eventually


00:20:59.120 --> 00:21:01.909
escar it is therefore a hypervelocity


00:21:01.919 --> 00:21:04.070
star and this is the very first time a


00:21:04.080 --> 00:21:05.590
planet has been confirmed around the


00:21:05.600 --> 00:21:08.510
hypervelocity star now planets will form


00:21:08.520 --> 00:21:10.110
around these stats that's fine but to


00:21:10.120 --> 00:21:11.909
get the very first one that's kind of


00:21:11.919 --> 00:21:14.909
cool and that's a planet that is


00:21:14.919 --> 00:21:16.310
significantly more massive than the


00:21:16.320 --> 00:21:18.470
earth that star probably has other


00:21:18.480 --> 00:21:20.230
planets where you find one planet there


00:21:20.240 --> 00:21:22.750
will be more so this is a planetary


00:21:22.760 --> 00:21:25.029
system that is on a oneway ticket out of


00:21:25.039 --> 00:21:28.789
our galaxy never to return wow yeah


00:21:28.799 --> 00:21:31.070
that's quite a find isn't it and such an


00:21:31.080 --> 00:21:34.390
incredible speed have they worked out


00:21:34.400 --> 00:21:36.750
how long it will take to exit the Galaxy


00:21:36.760 --> 00:21:38.909
probably a long time even at that speed


00:21:38.919 --> 00:21:40.750
very very long time even at that speed


00:21:40.760 --> 00:21:43.149
so we can probably try and back of the


00:21:43.159 --> 00:21:45.390
envelope mental arithmetic list so I


00:21:45.400 --> 00:21:47.390
I'll for get everybody on line to


00:21:47.400 --> 00:21:50.190
forgive me but speed of light is 300,000


00:21:50.200 --> 00:21:52.909
kmers a second y I'm going to say that


00:21:52.919 --> 00:21:55.149
this is 600 km a second that just keeps


00:21:55.159 --> 00:21:58.029
the maths easier right yeah um 600 over


00:21:58.039 --> 00:22:02.230
300 th000 is 6 over 300 which is 2%


00:22:02.240 --> 00:22:04.310
thereabouts so this thing's traveling at


00:22:04.320 --> 00:22:06.029
2% of the speed of


00:22:06.039 --> 00:22:08.750
light that's fairly significant now the


00:22:08.760 --> 00:22:10.029
Galax is going to be pulling it back and


00:22:10.039 --> 00:22:12.630
SL it down as it goes but if you think


00:22:12.640 --> 00:22:14.230
about the diameter of the Milky Way is


00:22:14.240 --> 00:22:16.950
about a 100,000 light years so that


00:22:16.960 --> 00:22:18.390
means the radius of the Milky Way is


00:22:18.400 --> 00:22:20.990
about 50,000 light years if you're


00:22:21.000 --> 00:22:23.230
traveling at 2% of the speed of light


00:22:23.240 --> 00:22:25.190
that means it will take you 50 years to


00:22:25.200 --> 00:22:29.029
travel one light year right right so 50


00:22:29.039 --> 00:22:31.990
years per Lightyear for 50,000 light


00:22:32.000 --> 00:22:36.110
years is 2.5 million years okay now that


00:22:36.120 --> 00:22:39.750
is a long time for us but we compare it


00:22:39.760 --> 00:22:42.470
to the fact that it takes us some 250


00:22:42.480 --> 00:22:43.950
million years also to go around the


00:22:43.960 --> 00:22:45.909
middle of the Galaxy that gives you a


00:22:45.919 --> 00:22:48.390
sense of how quickness is actually


00:22:48.400 --> 00:22:51.830
moving fascinating all right uh yeah so


00:22:51.840 --> 00:22:54.470
far the fastest found but there may be


00:22:54.480 --> 00:22:56.630
others will probably find another one


00:22:56.640 --> 00:22:59.110
that's faster at some stage yes uh you


00:22:59.120 --> 00:23:00.789
can read about that at space.com or if


00:23:00.799 --> 00:23:03.190
you want to read the actual paper uh it


00:23:03.200 --> 00:23:04.789
was published this month in the


00:23:04.799 --> 00:23:07.789
astronomical Journal this is Space Nuts


00:23:07.799 --> 00:23:12.149
with Andrew Dunley and Professor jonty


00:23:12.159 --> 00:23:14.870
Horner okay we checked all four


00:23:14.880 --> 00:23:18.549
systems Space Nuts now johy let's move


00:23:18.559 --> 00:23:22.390
on to this problem with um dandruff in


00:23:22.400 --> 00:23:24.710
space that's what it's described as it's


00:23:24.720 --> 00:23:26.990
not really dandruff it's just uh


00:23:27.000 --> 00:23:29.990
neighboring uh systems dumping their


00:23:30.000 --> 00:23:32.870
stuff on us absolutely I I didn't know


00:23:32.880 --> 00:23:35.190
that was a thing Amber doing exactly the


00:23:35.200 --> 00:23:37.830
same back of Li should have said no ask


00:23:37.840 --> 00:23:39.870
one of those things that I talk about a


00:23:39.880 --> 00:23:41.669
lot in the context of our solar system


00:23:41.679 --> 00:23:44.269
we have comets and asteroids and the


00:23:44.279 --> 00:23:46.190
main way that comets get removed from


00:23:46.200 --> 00:23:47.909
the solar system to no longer pose a


00:23:47.919 --> 00:23:50.230
threat to the Earth is that many of them


00:23:50.240 --> 00:23:52.510
escate the solar system never to return


00:23:52.520 --> 00:23:53.990
usually flung out by one of the giant


00:23:54.000 --> 00:23:56.190
planets or by subtle gravitational


00:23:56.200 --> 00:23:58.830
perturbations like that so you can look


00:23:58.840 --> 00:24:00.269
back over the edge of the solar system


00:24:00.279 --> 00:24:01.870
and it has continually been shedding


00:24:01.880 --> 00:24:03.909
comets and asteroids into the void of


00:24:03.919 --> 00:24:06.430
space creating these Interstellar


00:24:06.440 --> 00:24:08.830
wonders essentially and that would have


00:24:08.840 --> 00:24:10.390
been particularly strongly the case


00:24:10.400 --> 00:24:12.390
incidentally when the solar system was


00:24:12.400 --> 00:24:13.909
still forming because big part of the


00:24:13.919 --> 00:24:15.669
formation of the planets in the cleanup


00:24:15.679 --> 00:24:17.669
afterwards was getting rid of most of


00:24:17.679 --> 00:24:19.830
the stuff that was left over so the


00:24:19.840 --> 00:24:21.590
solar system over it time will have shed


00:24:21.600 --> 00:24:24.350
uncounted objects into space and it


00:24:24.360 --> 00:24:27.149
continues to do so today and I've often


00:24:27.159 --> 00:24:29.230
said in those thoughts it's almost


00:24:29.240 --> 00:24:30.870
certain that every other star will be


00:24:30.880 --> 00:24:32.389
doing the same thing but any star that


00:24:32.399 --> 00:24:34.950
has a planet syst those planets will be


00:24:34.960 --> 00:24:36.470
stirring things up and throwing things


00:24:36.480 --> 00:24:38.950
out so it's one of those things I've


00:24:38.960 --> 00:24:40.669
just taken for granted but it's only


00:24:40.679 --> 00:24:43.029
recently that we've actually been able


00:24:43.039 --> 00:24:45.269
to detect the products of this from


00:24:45.279 --> 00:24:47.950
other stars like I said for decades


00:24:47.960 --> 00:24:49.430
people have talked about the possibility


00:24:49.440 --> 00:24:51.310
of us finding Interstellar objects in


00:24:51.320 --> 00:24:53.549
the solar system so I've seen comets or


00:24:53.559 --> 00:24:56.630
astroids coming through that could be


00:24:56.640 --> 00:24:59.230
absolutely and definitively not to have


00:24:59.240 --> 00:25:01.750
an origin in our solar system how do we


00:25:01.760 --> 00:25:02.950
do that well we look at how quick


00:25:02.960 --> 00:25:04.149
they're moving it's just like what we


00:25:04.159 --> 00:25:05.549
were talking about a minute ago with the


00:25:05.559 --> 00:25:08.110
escape Velocity objects moving around


00:25:08.120 --> 00:25:11.430
the Sun are gravitationally bound if


00:25:11.440 --> 00:25:12.669
they get a nudge and they're going to


00:25:12.679 --> 00:25:14.510
escape they will be traveling a bit too


00:25:14.520 --> 00:25:16.110
quick to be gravitationally bound but


00:25:16.120 --> 00:25:20.230
only just by a tiny amount so when we


00:25:20.240 --> 00:25:22.669
find an object that comes in we can work


00:25:22.679 --> 00:25:25.310
out what speed it would travel at if it


00:25:25.320 --> 00:25:28.190
was infinitely far from the Sun call


00:25:28.200 --> 00:25:29.950
this the velocity of infinity so once


00:25:29.960 --> 00:25:31.630
the sun has slowed it down as much as it


00:25:31.640 --> 00:25:35.110
can how much speed has it got left and


00:25:35.120 --> 00:25:37.669
two objects that were found in the last


00:25:37.679 --> 00:25:39.830
decade met this criteria of being


00:25:39.840 --> 00:25:42.470
Interstellar they were umu which came


00:25:42.480 --> 00:25:44.549
through in 2017 and despite what a


00:25:44.559 --> 00:25:47.470
certain eminent um person at Harvard and


00:25:47.480 --> 00:25:48.909
I'm trying to choose my words carefully


00:25:48.919 --> 00:25:50.830
here because I have a certain opinion um


00:25:50.840 --> 00:25:52.950
despite what he keeps trying to tell you


00:25:52.960 --> 00:25:54.310
to sell his books and make a lot of


00:25:54.320 --> 00:25:56.389
money that was not an alien spaceship it


00:25:56.399 --> 00:25:58.310
never would be an alien spaceship it


00:25:58.320 --> 00:26:00.909
absolutely was not aliens that was just


00:26:00.919 --> 00:26:04.070
a lump of rock and debris we then had


00:26:04.080 --> 00:26:06.630
comic borisov back in 2019 which was our


00:26:06.640 --> 00:26:09.269
second Interstellar object yeah we found


00:26:09.279 --> 00:26:10.909
two of them now the odds are that in the


00:26:10.919 --> 00:26:12.950
coming decade we will find hundreds


00:26:12.960 --> 00:26:14.669
because the Vera Rubin observatories are


00:26:14.679 --> 00:26:17.070
going to come online ver ruin


00:26:17.080 --> 00:26:18.549
Observatory of course named for one of


00:26:18.559 --> 00:26:21.230
the great astronomers of 20th century


00:26:21.240 --> 00:26:24.230
who was a woman in astronomy and that's


00:26:24.240 --> 00:26:25.750
a challenging thing to discuss at the


00:26:25.760 --> 00:26:27.350
moment with what's going on in the US I


00:26:27.360 --> 00:26:29.110
will just mention in passing that that


00:26:29.120 --> 00:26:31.789
is itself a controversy this week


00:26:31.799 --> 00:26:33.430
because with the new government in the


00:26:33.440 --> 00:26:35.590
US they've been forced to change the


00:26:35.600 --> 00:26:39.389
biography of Vera Rubin on the website


00:26:39.399 --> 00:26:40.750
because one of the things that she was


00:26:40.760 --> 00:26:42.430
very active on was advocating for women


00:26:42.440 --> 00:26:44.389
in science and you know setting up


00:26:44.399 --> 00:26:45.830
schemes to try and help women get more


00:26:45.840 --> 00:26:47.430
involved in astronomy and now you can't


00:26:47.440 --> 00:26:49.750
talk about that anyway that that's an


00:26:49.760 --> 00:26:51.750
aside but it's a bit of a frustration of


00:26:51.760 --> 00:26:53.950
the human element of this yeah but ver


00:26:53.960 --> 00:26:55.909
Rubin Observatory named after this


00:26:55.919 --> 00:26:57.710
incredible astronomer is going to come


00:26:57.720 --> 00:26:59.669
online in the next year or two and is


00:26:59.679 --> 00:27:01.789
forast to find tens or hundreds of these


00:27:01.799 --> 00:27:03.269
objects because we'll just be much


00:27:03.279 --> 00:27:06.269
better at spotting them what the new


00:27:06.279 --> 00:27:08.789
research is is some computer modeling a


00:27:08.799 --> 00:27:10.430
group has had this same idea that we're


00:27:10.440 --> 00:27:12.190
just talking about and said let's model


00:27:12.200 --> 00:27:14.430
this let's try and get a handle on just


00:27:14.440 --> 00:27:17.510
how much stuff May by star systems are


00:27:17.520 --> 00:27:19.750
throwing our way to fill the space


00:27:19.760 --> 00:27:23.070
around us and they looked at our nearest


00:27:23.080 --> 00:27:25.190
companions the alpha centor system which


00:27:25.200 --> 00:27:27.830
is the binary SAR of alpha centor a andb


00:27:27.840 --> 00:27:29.710
and then the Red Dwarf Proxima which is


00:27:29.720 --> 00:27:31.190
currently a bit closer towards of the


00:27:31.200 --> 00:27:32.430
two bigger


00:27:32.440 --> 00:27:34.909
stars there run some simulations very


00:27:34.919 --> 00:27:36.830
much of the ilk that I do in my D job


00:27:36.840 --> 00:27:39.230
running on the superc Computing cluster


00:27:39.240 --> 00:27:43.350
here saying if this star system has the


00:27:43.360 --> 00:27:44.870
kind of objects in it we'd expect for


00:27:44.880 --> 00:27:47.509
system of that age how many are getting


00:27:47.519 --> 00:27:49.190
ejected in our general direction and


00:27:49.200 --> 00:27:51.470
what they have found is that their


00:27:51.480 --> 00:27:53.389
simulation suggests there could be as


00:27:53.399 --> 00:27:55.830
many as a million objects bigger than


00:27:55.840 --> 00:27:58.630
100 meters across passing through our


00:27:58.640 --> 00:28:01.990
solar system at the current time that


00:28:02.000 --> 00:28:03.830
departed from the alpha centor system


00:28:03.840 --> 00:28:06.710
now the cirley here is a lot of the time


00:28:06.720 --> 00:28:08.470
when we talk about passing through the


00:28:08.480 --> 00:28:10.230
solar system we think of our local part


00:28:10.240 --> 00:28:11.750
of the solar system the orbits of the


00:28:11.760 --> 00:28:13.990
planets but in reality the volume of


00:28:14.000 --> 00:28:15.509
space we're considering to be the solar


00:28:15.519 --> 00:28:17.950
system here is the entirety of the out


00:28:17.960 --> 00:28:20.269
Cloud so this is a volume of space


00:28:20.279 --> 00:28:22.590
something like two light years in every


00:28:22.600 --> 00:28:24.509
direction from it so it's an


00:28:24.519 --> 00:28:27.789
unimaginably vast sphere of space that


00:28:27.799 --> 00:28:30.029
has these objects passing through it so


00:28:30.039 --> 00:28:31.669
the likelihood of one getting closer to


00:28:31.679 --> 00:28:33.350
first to detect in the near future is


00:28:33.360 --> 00:28:35.710
pretty low but it's not be on the


00:28:35.720 --> 00:28:37.710
balance of possibility and again when


00:28:37.720 --> 00:28:41.230
Vera Rubin comes online if any of these


00:28:41.240 --> 00:28:43.389
are in you know the domain of the


00:28:43.399 --> 00:28:44.789
planets they're coming close enough to


00:28:44.799 --> 00:28:47.830
the Sun that they are detectable ver


00:28:47.840 --> 00:28:51.669
Rubin will find them now a million


00:28:51.679 --> 00:28:53.269
objects spread over the out Cloud to be


00:28:53.279 --> 00:28:55.149
honest means that it's very unlikely one


00:28:55.159 --> 00:28:57.190
of them will be close enough to see but


00:28:57.200 --> 00:28:58.789
these things are going to be TR faster


00:28:58.799 --> 00:29:01.509
than the escape velocity of the Sun so


00:29:01.519 --> 00:29:03.630
they'll come through fairly quickly and


00:29:03.640 --> 00:29:04.950
that means if they're moving through


00:29:04.960 --> 00:29:06.350
just because we don't see them M doesn't


00:29:06.360 --> 00:29:07.909
mean if we look again in 5 years time


00:29:07.919 --> 00:29:09.870
there wouldn't be one that's appeared


00:29:09.880 --> 00:29:11.710
the other thing that came out of this is


00:29:11.720 --> 00:29:13.110
that they talked about the smaller


00:29:13.120 --> 00:29:15.389
particles are more common and it's quite


00:29:15.399 --> 00:29:17.070
likely that there may be as many as 10


00:29:17.080 --> 00:29:20.110
meteors per year on the earth that are


00:29:20.120 --> 00:29:21.750
bits of dust from the alpha centor


00:29:21.760 --> 00:29:24.430
system hitting our planet now 10 per


00:29:24.440 --> 00:29:26.190
year across the entire surface of the


00:29:26.200 --> 00:29:27.870
Earth means you're very unlikely to find


00:29:27.880 --> 00:29:28.710
them


00:29:28.720 --> 00:29:30.590
but it reminded me of stories that go


00:29:30.600 --> 00:29:32.230
back much further because we have these


00:29:32.240 --> 00:29:34.110
wonderful networks of cameras across the


00:29:34.120 --> 00:29:37.710
Earth that look up at shooting s and try


00:29:37.720 --> 00:29:39.909
and get multi-session observations so


00:29:39.919 --> 00:29:41.630
you can do trigonometry and figure out


00:29:41.640 --> 00:29:42.990
what their orbit was how they were


00:29:43.000 --> 00:29:45.110
moving and they've detected over the


00:29:45.120 --> 00:29:46.549
years a very small number of


00:29:46.559 --> 00:29:49.310
definitively interstellar meteors so


00:29:49.320 --> 00:29:51.070
meteors coming into the Earth atmosphere


00:29:51.080 --> 00:29:52.830
with a speed significantly higher than


00:29:52.840 --> 00:29:55.710
72 km a second which means that they


00:29:55.720 --> 00:29:57.190
can't have been bound to the solar


00:29:57.200 --> 00:29:58.870
system


00:29:58.880 --> 00:30:00.590
one of the things that those papers


00:30:00.600 --> 00:30:02.029
discussed for a long time is that there


00:30:02.039 --> 00:30:04.470
is one dominant source of dust through


00:30:04.480 --> 00:30:06.750
our solar system that gives us more than


00:30:06.760 --> 00:30:09.990
all of sources combined it's famous star


00:30:10.000 --> 00:30:11.190
called beta


00:30:11.200 --> 00:30:14.070
pictoris which back in 1983 was one of


00:30:14.080 --> 00:30:16.149
three stars the infrared astronomical


00:30:16.159 --> 00:30:18.430
satellite was confused about because it


00:30:18.440 --> 00:30:20.190
found an infrared excess around that


00:30:20.200 --> 00:30:22.950
star soory light years away it's more


00:30:22.960 --> 00:30:24.509
massive than the Sun and hotton but it's


00:30:24.519 --> 00:30:26.549
very young and it's still got a disc of


00:30:26.559 --> 00:30:28.590
debris around it forming planets it's


00:30:28.600 --> 00:30:30.310
got planets in that disc that we've


00:30:30.320 --> 00:30:32.389
discovered but that incredibly active


00:30:32.399 --> 00:30:34.269
Stellar Wind that that massive star has


00:30:34.279 --> 00:30:36.630
is blowing lots of the Dust into Space


00:30:36.640 --> 00:30:38.190
streaming off in all


00:30:38.200 --> 00:30:41.269
directions and enough of that dust is


00:30:41.279 --> 00:30:44.630
traveling to reach us 63 light years


00:30:44.640 --> 00:30:47.110
away that we can detect that as a


00:30:47.120 --> 00:30:50.110
distinct source of debris crashing into


00:30:50.120 --> 00:30:52.630
the Earth atmosphere that really boggles


00:30:52.640 --> 00:30:55.070
my mind that a star that far away can be


00:30:55.080 --> 00:30:57.470
putting dust into our atmosphere at a


00:30:57.480 --> 00:30:59.430
sufficient level that people have


00:30:59.440 --> 00:31:02.549
detected that dust stre yeah it is it's


00:31:02.559 --> 00:31:05.029
amazing and this must be happening just


00:31:05.039 --> 00:31:07.470
about everywhere we we we've probably


00:31:07.480 --> 00:31:11.070
got systems exchanging junk constantly


00:31:11.080 --> 00:31:13.669
yeah absolutely and it it ties into the


00:31:13.679 --> 00:31:15.629
panspermia idea that we've talked about


00:31:15.639 --> 00:31:17.750
before as well yeah if you are


00:31:17.760 --> 00:31:19.590
constantly ejecting dust and debris from


00:31:19.600 --> 00:31:22.070
every planetary system if you have


00:31:22.080 --> 00:31:24.470
somewhere with life in that system


00:31:24.480 --> 00:31:27.230
eventually that life has the potential


00:31:27.240 --> 00:31:28.789
to travel


00:31:28.799 --> 00:31:31.190
and you know yeah most of it will most


00:31:31.200 --> 00:31:32.629
of the debris ejected from the earth


00:31:32.639 --> 00:31:34.590
Will Never Land on any other world it'll


00:31:34.600 --> 00:31:36.909
just float in space for forever more but


00:31:36.919 --> 00:31:40.230
enough has been ejected that eventually


00:31:40.240 --> 00:31:41.710
something ejected from the earth will


00:31:41.720 --> 00:31:44.310
land on a planet around another s or


00:31:44.320 --> 00:31:46.230
will be incorporated in a planet forming


00:31:46.240 --> 00:31:47.990
region around the S that's just being


00:31:48.000 --> 00:31:50.750
bought you put enough material out there


00:31:50.760 --> 00:31:53.070
with enough bacteria buried in it it's


00:31:53.080 --> 00:31:54.990
very reasonable to imagine that you


00:31:55.000 --> 00:31:57.230
could get a situation where some point


00:31:57.240 --> 00:31:59.029
in the distant future there is a planet


00:31:59.039 --> 00:32:01.310
that has life on it and that life is


00:32:01.320 --> 00:32:02.789
having the discussion of how did life


00:32:02.799 --> 00:32:04.710
get started and someone suggest well


00:32:04.720 --> 00:32:06.230
maybe life came from the stars and


00:32:06.240 --> 00:32:07.430
everybody says well that's a lot of


00:32:07.440 --> 00:32:09.629
rubbish stop watching Star Trek and


00:32:09.639 --> 00:32:12.110
after was URS because it's Earth life


00:32:12.120 --> 00:32:14.950
yes indeed and this story also proves


00:32:14.960 --> 00:32:16.070
that you shouldn't get upset with your


00:32:16.080 --> 00:32:17.870
neighbors for throwing the grass


00:32:17.880 --> 00:32:20.669
clippings over your fence because it


00:32:20.679 --> 00:32:23.070
happens right through the cosmos


00:32:23.080 --> 00:32:24.710
absolutely I mean ties into the other


00:32:24.720 --> 00:32:27.070
space andruff thing actually so this is


00:32:27.080 --> 00:32:28.870
the the whole connection here of course


00:32:28.880 --> 00:32:30.310
is the Stars shaking their head and


00:32:30.320 --> 00:32:32.029
comets flying through space essentially


00:32:32.039 --> 00:32:34.310
the beautiful analogy there but anytime


00:32:34.320 --> 00:32:36.669
you're walking around outside or anytime


00:32:36.679 --> 00:32:38.230
you're doing the dusting in your house a


00:32:38.240 --> 00:32:39.549
certain amount of the dust that is


00:32:39.559 --> 00:32:41.629
falling on your shoulders or there is a


00:32:41.639 --> 00:32:44.070
crewing in your house is dust from


00:32:44.080 --> 00:32:46.389
outter space we have these tiny little


00:32:46.399 --> 00:32:48.070
particles of dust which are sometimes


00:32:48.080 --> 00:32:50.750
called brownly particles they are small


00:32:50.760 --> 00:32:52.389
enough that they are slowed down by the


00:32:52.399 --> 00:32:54.870
very tenous outer atmosphere before they


00:32:54.880 --> 00:32:56.029
get into a thick enough layer of


00:32:56.039 --> 00:32:58.310
atmosphere that they get a bled before


00:32:58.320 --> 00:33:00.430
they burn up so there's this steady


00:33:00.440 --> 00:33:03.310
little SLE of micro micro microscopic


00:33:03.320 --> 00:33:05.230
dust particles from space running down


00:33:05.240 --> 00:33:07.470
on the Earth all the time so when you do


00:33:07.480 --> 00:33:09.990
the dusting or when you go outside on a


00:33:10.000 --> 00:33:12.149
on a day and you're getting dust on you


00:33:12.159 --> 00:33:14.190
a tiny fraction of that is space so


00:33:14.200 --> 00:33:15.870
you've got space and refraining down on


00:33:15.880 --> 00:33:18.710
you at all times yeah it is fascinating


00:33:18.720 --> 00:33:21.029
to think about uh I think we have


00:33:21.039 --> 00:33:22.830
touched on that story once before a


00:33:22.840 --> 00:33:25.070
while ago but uh yeah


00:33:25.080 --> 00:33:27.870
fascinating um I think if we're quick we


00:33:27.880 --> 00:33:30.190
can squeeze in one more little story if


00:33:30.200 --> 00:33:32.230
you want to chase up the Space dandr


00:33:32.240 --> 00:33:35.470
story livescience.com uh carries that


00:33:35.480 --> 00:33:39.990
one uh one last yarn and this one is


00:33:40.000 --> 00:33:42.029
something we um I think we touched on in


00:33:42.039 --> 00:33:43.430
the last couple of weeks about you know


00:33:43.440 --> 00:33:45.350
where does a planet store start and a


00:33:45.360 --> 00:33:49.110
brown dwarf begin and we talked about 13


00:33:49.120 --> 00:33:52.950
um Jupiter masses uh well now a new


00:33:52.960 --> 00:33:56.310
planet has popped up in a study that has


00:33:56.320 --> 00:33:59.669
sparked debate on that issue yes so what


00:33:59.679 --> 00:34:01.870
we tend to do as humans in all walks of


00:34:01.880 --> 00:34:04.430
life is try and understand the universe


00:34:04.440 --> 00:34:06.110
that's just very fundamentally human


00:34:06.120 --> 00:34:08.270
thing to do and to do that we break


00:34:08.280 --> 00:34:10.710
things that are continual up into


00:34:10.720 --> 00:34:13.470
discrete packets into discrete fractions


00:34:13.480 --> 00:34:15.149
and we do this with a human lifetime you


00:34:15.159 --> 00:34:17.109
know you grow up and then suddenly one


00:34:17.119 --> 00:34:18.629
magical morning you wake up and you're


00:34:18.639 --> 00:34:20.829
legally able to drive or you're legally


00:34:20.839 --> 00:34:22.349
able to drink so long as you're not


00:34:22.359 --> 00:34:24.270
driving you know you have these magical


00:34:24.280 --> 00:34:26.149
thresholds where we've said one day


00:34:26.159 --> 00:34:28.270
you're an adult the day before you were


00:34:28.280 --> 00:34:30.310
a child you're not fundamentally any


00:34:30.320 --> 00:34:32.149
different across that barrier but we're


00:34:32.159 --> 00:34:33.829
grouping like with like and keeping


00:34:33.839 --> 00:34:35.389
different things


00:34:35.399 --> 00:34:37.230
separated that's what's happened with


00:34:37.240 --> 00:34:38.829
definitions of planets you know this was


00:34:38.839 --> 00:34:41.470
all the rage all the controversy two


00:34:41.480 --> 00:34:43.389
decades ago with the demotion of Pluto


00:34:43.399 --> 00:34:45.389
it was a same thing it was trying to


00:34:45.399 --> 00:34:46.990
group objects that are similar with each


00:34:47.000 --> 00:34:49.589
other in groups so that you can study


00:34:49.599 --> 00:34:52.069
that and one of the great areas where


00:34:52.079 --> 00:34:54.829
this has happened is you've got planets


00:34:54.839 --> 00:34:56.669
you've got stars and in between them


00:34:56.679 --> 00:34:58.230
you've got these curious objects that


00:34:58.240 --> 00:35:00.550
people call Brown dwarfs which are


00:35:00.560 --> 00:35:02.109
things that they viewed as being too big


00:35:02.119 --> 00:35:03.630
and too massive to be considered a


00:35:03.640 --> 00:35:05.910
typical Planet but they're not massive


00:35:05.920 --> 00:35:07.750
enough to have hydrogen fusion and to


00:35:07.760 --> 00:35:10.030
shine and become a sar so the boundary


00:35:10.040 --> 00:35:11.870
to be a sar is fairly clear upup if you


00:35:11.880 --> 00:35:14.829
get hydrogen Fusion going you're a sar


00:35:14.839 --> 00:35:16.710
which leads to the slightly quirky thing


00:35:16.720 --> 00:35:19.589
that white dwarfs and neutron stars are


00:35:19.599 --> 00:35:21.870
not Stars they're cell remnants so


00:35:21.880 --> 00:35:24.790
they're dead stars which is a turle


00:35:24.800 --> 00:35:28.030
asite but between a planet and a star


00:35:28.040 --> 00:35:29.390
there's this domain where you are not


00:35:29.400 --> 00:35:31.829
massive enough to burn hydrogen but the


00:35:31.839 --> 00:35:33.390
temperature in your core will get high


00:35:33.400 --> 00:35:34.870
enough that you will temporarily be able


00:35:34.880 --> 00:35:37.030
to burn deuterium which is heavy


00:35:37.040 --> 00:35:39.030
hydrogen there's not much of that so


00:35:39.040 --> 00:35:40.790
you'll get a very short period of dyum


00:35:40.800 --> 00:35:42.230
burning and then you'll just fizzle out


00:35:42.240 --> 00:35:44.030
and be a little glowing


00:35:44.040 --> 00:35:47.630
Ember now where that boundary is with


00:35:47.640 --> 00:35:49.470
the star is very clearcut it's a


00:35:49.480 --> 00:35:50.910
hydrogen fusion and it's a very


00:35:50.920 --> 00:35:53.030
observable thing but the boundary at the


00:35:53.040 --> 00:35:55.109
lower end where you no longer have


00:35:55.119 --> 00:35:57.790
enough Mass to burn the uteran is much


00:35:57.800 --> 00:36:00.390
woer and if people do modeling it


00:36:00.400 --> 00:36:02.270
depends on the composition of the object


00:36:02.280 --> 00:36:04.190
and how much solid material it's got and


00:36:04.200 --> 00:36:06.270
how much uterum it's got and all sorts


00:36:06.280 --> 00:36:09.069
of things going on so what's happened


00:36:09.079 --> 00:36:10.550
historically because we didn't really


00:36:10.560 --> 00:36:11.990
have the capacity to find low mass


00:36:12.000 --> 00:36:13.190
objects is people just put this


00:36:13.200 --> 00:36:15.790
arbitrary boundary of 13 Jupiter masses


00:36:15.800 --> 00:36:18.390
there to say anything more massive than


00:36:18.400 --> 00:36:20.430
that is a brown wolf anything less


00:36:20.440 --> 00:36:23.030
massive is a planet so that is setting


00:36:23.040 --> 00:36:25.230
this boundary purely on the physical


00:36:25.240 --> 00:36:27.630
Mass it's taking no account of the


00:36:27.640 --> 00:36:29.069
composition of the object or how it


00:36:29.079 --> 00:36:31.390
formed and as we finally got the ability


00:36:31.400 --> 00:36:32.950
to find objects in this Mass people have


00:36:32.960 --> 00:36:36.069
started to question that because the


00:36:36.079 --> 00:36:37.750
formation mechanism the composition


00:36:37.760 --> 00:36:39.670
matters a planet like Jupiter has about


00:36:39.680 --> 00:36:41.910
30 Earth masses of solid material as a


00:36:41.920 --> 00:36:45.910
core because of the way it formed a star


00:36:45.920 --> 00:36:48.910
doesn't have that same kind of structure


00:36:48.920 --> 00:36:50.870
so there's a growing argument that maybe


00:36:50.880 --> 00:36:53.190
we should divide it by formation


00:36:53.200 --> 00:36:55.270
mechanism and something that formed like


00:36:55.280 --> 00:36:57.069
a planet is a planet even if it's more


00:36:57.079 --> 00:36:59.030
massive than risk limit and it probably


00:36:59.040 --> 00:37:00.750
wouldn't undergo utaran fusion because a


00:37:00.760 --> 00:37:03.270
lot of the mass is solid material so


00:37:03.280 --> 00:37:06.030
it's got less utaran alternatively if it


00:37:06.040 --> 00:37:08.270
Formed like a star even if it's less


00:37:08.280 --> 00:37:10.950
massive than 13 juk to masses maybe it


00:37:10.960 --> 00:37:12.790
should be considered a brand W rather


00:37:12.800 --> 00:37:14.230
than a planet because of the formation


00:37:14.240 --> 00:37:16.470
mechanism and it's a debate that's only


00:37:16.480 --> 00:37:17.710
just starting to kick off because we're


00:37:17.720 --> 00:37:19.550
only really able to find these objects


00:37:19.560 --> 00:37:22.150
now it's being fired up here by the


00:37:22.160 --> 00:37:24.710
discovery of what's known as Gia 4B so


00:37:24.720 --> 00:37:26.190
the guy spacecraft we talked about


00:37:26.200 --> 00:37:28.069
earlier is this incredible miss that was


00:37:28.079 --> 00:37:29.829
measuring the positions and the Motions


00:37:29.839 --> 00:37:32.870
of a billion stars with Incredible


00:37:32.880 --> 00:37:35.230
Precision two billion stars absolutely


00:37:35.240 --> 00:37:37.670
ridiculous and what guia has promised


00:37:37.680 --> 00:37:39.910
for a long time is that it would find


00:37:39.920 --> 00:37:42.030
100,000 to a million planets under the


00:37:42.040 --> 00:37:45.030
stars that was part of the marketing so


00:37:45.040 --> 00:37:48.230
far it has found four or five um more


00:37:48.240 --> 00:37:49.470
will come because they're still doing


00:37:49.480 --> 00:37:51.309
their big de list so it will give us a


00:37:51.319 --> 00:37:53.870
deluge of planets at some point but the


00:37:53.880 --> 00:37:55.710
reason it can do this is that it


00:37:55.720 --> 00:37:57.710
measures the positions of the Stars the


00:37:57.720 --> 00:38:00.150
sky so accurately that it can see them


00:38:00.160 --> 00:38:02.950
wobbling as they move as a result of the


00:38:02.960 --> 00:38:05.870
planets pulling them around so this is a


00:38:05.880 --> 00:38:07.470
counterpart to our radial velocity


00:38:07.480 --> 00:38:09.790
method radial velocity sees a movement


00:38:09.800 --> 00:38:12.109
back and forth on a line of sight Gia


00:38:12.119 --> 00:38:14.309
sees the movement at right angles to


00:38:14.319 --> 00:38:17.230
that so it's been looking at this star


00:38:17.240 --> 00:38:19.270
this star is less massive than the sun


00:38:19.280 --> 00:38:21.510
about 2third of the mass of the Sun and


00:38:21.520 --> 00:38:23.109
this star is moving across the night sky


00:38:23.119 --> 00:38:24.589
because it's moving through the Galaxy


00:38:24.599 --> 00:38:26.589
separately to us it's what what we call


00:38:26.599 --> 00:38:28.790
proper motion and guy has identified


00:38:28.800 --> 00:38:29.910
that instead of that proper motion


00:38:29.920 --> 00:38:31.589
ministra line it's following a Corp


00:38:31.599 --> 00:38:34.750
group path across the sky zigzagging and


00:38:34.760 --> 00:38:36.550
that's a Telltale sign it's got a planet


00:38:36.560 --> 00:38:39.470
going around it now because this Stars a


00:38:39.480 --> 00:38:41.550
bit like the sun it's a bit cooler you


00:38:41.560 --> 00:38:43.790
can do radio velocity observations which


00:38:43.800 --> 00:38:45.390
means you can measure the line of sight


00:38:45.400 --> 00:38:47.589
wobble as well which means you can


00:38:47.599 --> 00:38:49.309
perfectly constrain what's going around


00:38:49.319 --> 00:38:51.829
it and the evidence here is that this is


00:38:51.839 --> 00:38:55.630
an object 11.8 times the mass of Jupiter


00:38:55.640 --> 00:38:57.230
so it's just underneath that threshold


00:38:57.240 --> 00:38:58.430
to be a brown dwarf we would


00:38:58.440 --> 00:39:00.630
traditionally call it a planet yeah and


00:39:00.640 --> 00:39:03.430
job on the complexity comes out that


00:39:03.440 --> 00:39:05.750
this SAR is less massive than the Sun


00:39:05.760 --> 00:39:07.470
and it's got a roughly similar


00:39:07.480 --> 00:39:10.030
composition to the Sun what that means


00:39:10.040 --> 00:39:12.589
is the pl material the planets around it


00:39:12.599 --> 00:39:14.829
would have formed from would have been


00:39:14.839 --> 00:39:17.150
similar to that around the sun it's not


00:39:17.160 --> 00:39:18.710
particularly metal Rich so it wouldn't


00:39:18.720 --> 00:39:20.670
have had far more solid material around


00:39:20.680 --> 00:39:22.870
it than the sun did which means there's


00:39:22.880 --> 00:39:24.710
a really difficult question to answer


00:39:24.720 --> 00:39:26.470
which is how can a sty less massive than


00:39:26.480 --> 00:39:28.870
the Sun which presumably forms from a


00:39:28.880 --> 00:39:30.589
less massive cloud of material than the


00:39:30.599 --> 00:39:33.309
sun how can it form a planet 12 times


00:39:33.319 --> 00:39:34.990
more massive than the biggest planet we


00:39:35.000 --> 00:39:37.750
have in our system that just doesn't


00:39:37.760 --> 00:39:40.069
make much sense it's really counter to


00:39:40.079 --> 00:39:41.630
our planet formation models which is


00:39:41.640 --> 00:39:43.750
more massive stars form more massive


00:39:43.760 --> 00:39:45.870
planets so that then brings up the


00:39:45.880 --> 00:39:47.390
suggestion that maybe this thing didn't


00:39:47.400 --> 00:39:49.990
form as a planet at all maybe instead


00:39:50.000 --> 00:39:51.470
what we're seeing is a failed binary


00:39:51.480 --> 00:39:55.069
star system and this 11.8 Jupiter Mass


00:39:55.079 --> 00:39:57.390
object formed in the same way that


00:39:57.400 --> 00:40:00.790
binary Stars would form that it wasn't


00:40:00.800 --> 00:40:02.309
cor Recreation you didn't get a load of


00:40:02.319 --> 00:40:04.430
solid material grow to 30 times the mass


00:40:04.440 --> 00:40:05.990
of the Earth or 10 times the mass of the


00:40:06.000 --> 00:40:08.150
Earth and then start Gathering gas


00:40:08.160 --> 00:40:10.190
because of the gravitational pole that


00:40:10.200 --> 00:40:11.750
instead it formed through gravitational


00:40:11.760 --> 00:40:13.430
instability in the cloud like another


00:40:13.440 --> 00:40:15.910
star would fall right and therefore this


00:40:15.920 --> 00:40:18.630
could be considered a failed star in


00:40:18.640 --> 00:40:20.870
which case it should be called a brown


00:40:20.880 --> 00:40:22.430
dwarf even though it's not massive


00:40:22.440 --> 00:40:24.309
enough because it didn't form as a


00:40:24.319 --> 00:40:26.750
planet it may even be because it's so


00:40:26.760 --> 00:40:28.190
close to the threshold that it could


00:40:28.200 --> 00:40:29.950
have almost got to the detarium burning


00:40:29.960 --> 00:40:32.390
limit it could have had that happen now


00:40:32.400 --> 00:40:35.190
we don't really know if we could go


00:40:35.200 --> 00:40:37.190
there if we could borrow Captain Kirk's


00:40:37.200 --> 00:40:39.710
spaceship and engage what RAV and go


00:40:39.720 --> 00:40:41.150
there we'd be able to answer this after


00:40:41.160 --> 00:40:42.750
a little while we'd put a mission up


00:40:42.760 --> 00:40:45.109
like Juno that's going around Jupiter


00:40:45.119 --> 00:40:46.829
that would allow you to map the interior


00:40:46.839 --> 00:40:48.349
of the object a bit like the earthquakes


00:40:48.359 --> 00:40:50.430
we were talking about in the first topic


00:40:50.440 --> 00:40:52.190
and figure out if it had a car or not


00:40:52.200 --> 00:40:53.230
and that would tell you about its


00:40:53.240 --> 00:40:55.589
formation but we can't do that we just


00:40:55.599 --> 00:40:57.790
can't get there so at the minute it's


00:40:57.800 --> 00:40:59.550
purely in the domain of speculation but


00:40:59.560 --> 00:41:02.829
it's a sufficiently odd discovery that


00:41:02.839 --> 00:41:04.670
it is just restarting that old


00:41:04.680 --> 00:41:06.910
discussion about at what point do we


00:41:06.920 --> 00:41:08.870
need to look at this again I guess at


00:41:08.880 --> 00:41:11.750
what point do we need to discuss whether


00:41:11.760 --> 00:41:13.950
we get a more physically motivated


00:41:13.960 --> 00:41:15.470
difference between brand woles and


00:41:15.480 --> 00:41:17.430
planets or whether we're happy to


00:41:17.440 --> 00:41:19.670
sticking with this arbitrary Mass limit


00:41:19.680 --> 00:41:21.790
and as the years go on gu is going to


00:41:21.800 --> 00:41:24.190
discover far more objects we continue to


00:41:24.200 --> 00:41:27.390
find planets using all the other methods


00:41:27.400 --> 00:41:29.030
there will be more objects that straddle


00:41:29.040 --> 00:41:30.390
that boundary because nature forms


00:41:30.400 --> 00:41:32.790
things of all sizes it doesn't say I'm


00:41:32.800 --> 00:41:34.510
going to leave a gap here to make it


00:41:34.520 --> 00:41:35.750
nice and easy for you there'll be things


00:41:35.760 --> 00:41:38.069
of all masses and there will be things


00:41:38.079 --> 00:41:39.790
of identical masses that formed in


00:41:39.800 --> 00:41:42.190
different ways and so it's going to be


00:41:42.200 --> 00:41:43.589
an ongoing question I'm sure we could


00:41:43.599 --> 00:41:44.829
have a chat in a couple of years time


00:41:44.839 --> 00:41:46.150
and they'd still be having the same


00:41:46.160 --> 00:41:48.750
debates but it's great when you get to


00:41:48.760 --> 00:41:51.589
the point where our ability to find


00:41:51.599 --> 00:41:53.270
things is such that it pushes the


00:41:53.280 --> 00:41:54.750
boundaries of how we Define things and


00:41:54.760 --> 00:41:56.550
we have to revisit them that's how


00:41:56.560 --> 00:41:58.550
science works and I really love it even


00:41:58.560 --> 00:42:00.309
if it means you get cranky people waving


00:42:00.319 --> 00:42:01.950
flags and going Pluto should still be a


00:42:01.960 --> 00:42:03.870
planet yes yes and that's still


00:42:03.880 --> 00:42:06.109
happening two years oh


00:42:06.119 --> 00:42:08.430
indeed yeah all right uh if you would


00:42:08.440 --> 00:42:13.510
like to um look U look into guia 4B and


00:42:13.520 --> 00:42:16.470
5B they've posted a report in the


00:42:16.480 --> 00:42:18.790
astronomical Journal uh it's a


00:42:18.800 --> 00:42:20.430
fascinating Discovery and I imagine the


00:42:20.440 --> 00:42:22.230
more we look the more unusual things


00:42:22.240 --> 00:42:24.270
we'll find and yes we probably will have


00:42:24.280 --> 00:42:25.069
to


00:42:25.079 --> 00:42:27.829
redefine where a brown War starts and a


00:42:27.839 --> 00:42:29.870
planet finishes in the future it might


00:42:29.880 --> 00:42:32.230
come down to that but uh at the moment


00:42:32.240 --> 00:42:35.549
we just go with what we know until proof


00:42:35.559 --> 00:42:38.230
sends us in a different direction uh we


00:42:38.240 --> 00:42:41.390
are just about done JY thank you so much


00:42:41.400 --> 00:42:42.630
that's absolute pleasure thank you for


00:42:42.640 --> 00:42:44.950
having me always a pleasure and we'll


00:42:44.960 --> 00:42:47.109
see you real soon uh Professor jonty


00:42:47.119 --> 00:42:49.710
horer from the University of Southern


00:42:49.720 --> 00:42:51.829
Queensland and thanks to Hugh in the


00:42:51.839 --> 00:42:53.910
studio who couldn't be with us today


00:42:53.920 --> 00:42:55.870
he's very embarrassed he's got a severe


00:42:55.880 --> 00:42:57.790
case of space dandr


00:42:57.800 --> 00:42:59.710
uh don't forget to visit us online as


00:42:59.720 --> 00:43:02.230
well at SPAC nuts podcast.com or SPAC


00:43:02.240 --> 00:43:04.589
nuts. and from me Andrew Dunley thanks


00:43:04.599 --> 00:43:06.109
for joining us we'll see you on the very


00:43:06.119 --> 00:43:09.829
next episode of space uh Space Nuts


00:43:09.839 --> 00:43:12.950
coming soon until then


00:43:12.960 --> 00:43:15.630
bye-bye you'll be listening to the Space


00:43:15.640 --> 00:43:17.309
Nuts


00:43:17.319 --> 00:43:20.390
podcast available at Apple podcasts


00:43:20.400 --> 00:43:23.390
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00:43:23.400 --> 00:43:25.670
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00:43:25.680 --> 00:43:27.829
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00:43:27.839 --> 00:43:29.750
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00:43:29.760 --> 00:43:33.599
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