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Meteorite Myths, Fireballs, and the Enigmatic 3I Atlas
In this thrilling episode of Space Nuts, hosts Andrew Dunkley and Professor Jonti Horner dive into a variety of fascinating cosmic topics, from the truth behind a supposed meteorite impact on a car to the latest developments surrounding the comet 3I Atlas. This episode is packed with intriguing insights and lively discussions that will leave you pondering the mysteries of the universe.
Episode Highlights:
- Meteorite or Not? Andrew and Jonti examine a peculiar incident involving a car in South Australia that was thought to have been struck by a meteorite. They explore the evidence, including an impressive impact crater on the windscreen, and discuss the likelihood that it was merely debris from a passing truck instead.
- Daylight Fireball: The hosts report on a recent fireball sighting over southeastern Australia that captivated witnesses in broad daylight. They analyze the characteristics of this event and the implications it might have for potential meteorite recovery.
- Updates on 3I Atlas: The episode features an update on the comet 3I Atlas, which recently passed perihelion. Andrew and Jonti discuss its unusual behavior, including rapid brightening and the theories behind its activity as it travels through the solar system.
- Supermassive Black Holes in Tiny Galaxies: The discovery of a supermassive black hole in the ultra-faint dwarf galaxy Segue One raises intriguing questions about galaxy formation and evolution. The hosts delve into the implications of this finding and what it reveals about the nature of dark matter and galaxy interactions.
- Life After Asteroid Impacts: A fascinating study from Finland sheds light on how life can rebound after an asteroid impact. The research team investigates the timeline of microbial recolonization in a crater formed 78 million years ago, revealing insights into the resilience of life on Earth.
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Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
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00:00:00 --> 00:00:02 Andrew Dunkley: Hi there. Thanks for joining us on Space Nuts
00:00:02 --> 00:00:04 where we talk astronomy and space science. My
00:00:04 --> 00:00:07 name is Andrew Dunkley and hope, uh, you're.
00:00:07 --> 00:00:10 Well, coming up in this episode we are going
00:00:10 --> 00:00:12 to, uh, look at, oh, there's a whole bunch of
00:00:12 --> 00:00:14 stuff. We might not fit it all in. We'll do
00:00:14 --> 00:00:17 our very best. Uh, a meteorite versus a
00:00:17 --> 00:00:19 windscreen. Did it happen the way people
00:00:19 --> 00:00:21 think? We'll tell you. And over the
00:00:21 --> 00:00:24 weekend, uh, there was a fireball seen over,
00:00:25 --> 00:00:27 uh, southeastern states, uh, Victoria, New
00:00:27 --> 00:00:30 South Wales. The act. We'll talk about that.
00:00:31 --> 00:00:32 Uh, there's been a bit of chatter on social
00:00:32 --> 00:00:35 media, including the Space nuts podcast group
00:00:35 --> 00:00:38 about 3i Atlas. So we'll have
00:00:38 --> 00:00:41 an update on that. And time permitting, we
00:00:41 --> 00:00:44 will be looking at a huge black hole and a
00:00:44 --> 00:00:46 tiny galaxy. I mean tiny as in
00:00:46 --> 00:00:49 maybe only hundreds or thousands of stars. It
00:00:49 --> 00:00:52 sounds unusual, doesn't it? And life
00:00:52 --> 00:00:55 after an asteroid impact. That's all coming
00:00:55 --> 00:00:58 up on this episode of Space Nuts.
00:00:58 --> 00:01:00 15 seconds. Guidance is internal.
00:01:00 --> 00:01:03 10, 9, ignition
00:01:03 --> 00:01:04 sequence time.
00:01:04 --> 00:01:07 Jonti Horner: Uh, Space Nuts. 5, 4, 3, 2.
00:01:07 --> 00:01:09 Andrew Dunkley: 1, 2, 3, 4, 5, 5, 4, 3,
00:01:09 --> 00:01:12 2, 1. Space Nuts astronauts report
00:01:12 --> 00:01:13 it feels good.
00:01:14 --> 00:01:17 And with Fred still away, we are, uh,
00:01:17 --> 00:01:19 thrilled to welcome again Jonti Horner,
00:01:19 --> 00:01:21 professor of astrophysics at the University
00:01:21 --> 00:01:23 of Southern Queensland. Hello, Jonny.
00:01:24 --> 00:01:25 Jonti Horner: Good morning. How are you going?
00:01:25 --> 00:01:28 Andrew Dunkley: I am well. Good to see you. Nice backdrop
00:01:28 --> 00:01:29 too, by the way. What do you got there?
00:01:29 --> 00:01:31 Jonti Horner: Um, so another of the picks I've been playing
00:01:31 --> 00:01:33 around with with the telescope I bought about
00:01:33 --> 00:01:35 12 months ago. This is supplied ease I can
00:01:35 --> 00:01:36 slap out of shot.
00:01:36 --> 00:01:38 Andrew Dunkley: Um, very nice.
00:01:38 --> 00:01:40 Jonti Horner: My chair immediately interferes. The chair
00:01:40 --> 00:01:41 caption. Human being.
00:01:41 --> 00:01:43 Andrew Dunkley: But that was the, that was the Chair Nebula.
00:01:44 --> 00:01:47 Jonti Horner: Absolutely. But yes, I get the angle of the
00:01:47 --> 00:01:49 chair just right. The AI doesn't recognize it
00:01:49 --> 00:01:51 as a human being and we get to see it. Yeah,
00:01:51 --> 00:01:53 pretty good. But I'm going to have to have
00:01:53 --> 00:01:55 another go at that site. It doesn't quite
00:01:55 --> 00:01:56 feel right. It looks a little uncanny valley
00:01:56 --> 00:01:58 to me. So I may have to take some more photos
00:01:58 --> 00:02:00 later in the ah, year if the wonderful
00:02:00 --> 00:02:02 thunderstorms we're getting at the minute
00:02:02 --> 00:02:03 kind of stop because we've had some
00:02:03 --> 00:02:05 interesting weather appear again over the
00:02:05 --> 00:02:08 last few days. Um, there was a possible
00:02:08 --> 00:02:10 tornado within 30km of my house, which is
00:02:10 --> 00:02:13 cool. And some places got 10 centimeter
00:02:13 --> 00:02:16 diameter hail and lots of damage and
00:02:16 --> 00:02:18 yeah, tasty stuff going on and we might get a
00:02:18 --> 00:02:20 little bit more today and tomorrow. So it's
00:02:20 --> 00:02:22 another of those events which is spectacular
00:02:22 --> 00:02:24 and fun to watch. But you also sympathise
00:02:24 --> 00:02:25 with those who are directly in the thyroid
00:02:25 --> 00:02:26 line.
00:02:26 --> 00:02:28 Andrew Dunkley: Yeah, I saw those, uh, tornado
00:02:28 --> 00:02:30 forecasts pop up. And, uh,
00:02:31 --> 00:02:34 the bureau does not often go that far,
00:02:34 --> 00:02:36 uh, with their forecasting, but they were
00:02:36 --> 00:02:39 pretty confident. So, yeah, we get a few of
00:02:39 --> 00:02:40 those down our way too.
00:02:40 --> 00:02:42 Jonti Horner: It is an interesting one. I mean, growing up
00:02:42 --> 00:02:44 in the uk, I grew up in the country or one of
00:02:44 --> 00:02:46 the few countries that has the most tornadoes
00:02:46 --> 00:02:49 per year, which shocks everybody. But they're
00:02:49 --> 00:02:51 really, really itty bitty diddy ones that are
00:02:51 --> 00:02:53 associated with frontal systems. And I think
00:02:53 --> 00:02:55 a lot of Americans say, oh, no, they're not
00:02:55 --> 00:02:57 tornadoes, they're just gusnados or something
00:02:57 --> 00:02:59 like that. But in terms of the really
00:02:59 --> 00:03:01 damaging thunderstorms around the world,
00:03:02 --> 00:03:04 you've got the Great Plains in the US and
00:03:04 --> 00:03:05 then you've got the kind of area around
00:03:05 --> 00:03:08 Bangladesh, I think. But after that kind of
00:03:08 --> 00:03:09 Southeast Queensland, northeast New South
00:03:09 --> 00:03:12 Wales is the New South Wales is the third
00:03:12 --> 00:03:14 best place in the world for these kind of
00:03:14 --> 00:03:17 storms. And we get fewer tornadoes than
00:03:17 --> 00:03:18 the Great Plains because we get less wind
00:03:18 --> 00:03:21 shear at high altitudes. But we get
00:03:21 --> 00:03:24 equivalent amounts of mega hail and guerrilla
00:03:24 --> 00:03:25 hail is what they're calling it nowadays when
00:03:25 --> 00:03:28 you're bigger than giant hail. So we do get
00:03:28 --> 00:03:29 some really tasty and interesting stuff. And
00:03:29 --> 00:03:32 I did have one day not long after we built
00:03:32 --> 00:03:34 this house and moved in where the garage was
00:03:34 --> 00:03:37 still full of boxes, um, which is always a
00:03:37 --> 00:03:38 good thing. And this thunderstorm came in and
00:03:38 --> 00:03:40 suddenly there's the roaring of a freight
00:03:40 --> 00:03:42 train kind of noise, which was so weird, and
00:03:42 --> 00:03:45 hailstones, hailstones as my fist started
00:03:45 --> 00:03:47 coming down and I had to run out with
00:03:47 --> 00:03:50 blankets and a doona, uh, to cover the
00:03:50 --> 00:03:51 windscreen of my car to prevent it getting
00:03:51 --> 00:03:53 damaged. And unfortunately it didn't. Well,
00:03:53 --> 00:03:54 fortunately it didn't get much worse than
00:03:54 --> 00:03:56 that. But it was an interesting experience
00:03:56 --> 00:03:57 for someone who grew up in the uk, where the
00:03:57 --> 00:03:59 worst weather gets a bit of drizzle and a lot
00:03:59 --> 00:04:00 of wind.
00:04:00 --> 00:04:02 Andrew Dunkley: Yeah, yeah, it can get pretty volatile, uh,
00:04:02 --> 00:04:04 in Australia, and especially in the eastern
00:04:04 --> 00:04:05 parts.
00:04:06 --> 00:04:08 Uh, speaking of volatile, our first story
00:04:08 --> 00:04:11 is about, um,
00:04:12 --> 00:04:14 what people thought was a meteorite hitting
00:04:14 --> 00:04:17 the windscreen of a car. And when you see the
00:04:17 --> 00:04:19 photo, it's. It's one heck of a crack. It's,
00:04:19 --> 00:04:22 um, it's come in hard, whatever it was. Uh,
00:04:22 --> 00:04:23 what is the story here?
00:04:24 --> 00:04:27 Jonti Horner: It's a slightly weird one. Um, there's a
00:04:27 --> 00:04:30 guy driving along. Um, he's a vet down
00:04:30 --> 00:04:32 in South Australia, goes by the name of
00:04:32 --> 00:04:35 Melville Smith. It's his name, Andrew M.
00:04:35 --> 00:04:37 Melville Smith. Driving along in his
00:04:37 --> 00:04:39 Tesla. And the Tesla part is important to the
00:04:39 --> 00:04:42 story. Apparently about 40km out from
00:04:42 --> 00:04:45 a place called Port Garmin, when suddenly
00:04:45 --> 00:04:46 there's a really loud smash on his
00:04:46 --> 00:04:49 windscreen. Um, him and his partner in the
00:04:49 --> 00:04:52 front seats get showered with glass from this
00:04:52 --> 00:04:54 shattered windscreen and there's an impact
00:04:54 --> 00:04:57 crater on the windscreen. Um, and
00:04:57 --> 00:04:59 obviously the car just kept on driving
00:04:59 --> 00:05:01 because it's a Tesla and they don't seem to
00:05:01 --> 00:05:03 notice when they hit things, they just carry
00:05:03 --> 00:05:05 on. Um, all is good
00:05:07 --> 00:05:09 now. He thought it was weird, so he reached
00:05:09 --> 00:05:12 out to the museum in South Australia with
00:05:12 --> 00:05:14 the idea that this could have been a
00:05:14 --> 00:05:17 meteorite hitting a car. And that would be
00:05:17 --> 00:05:19 very unusual. Now we've had occasions in the
00:05:19 --> 00:05:22 past, um, most famously the Peekskill
00:05:22 --> 00:05:23 meteorite, and I think it was 1994, where
00:05:23 --> 00:05:26 meteorites have hit parked cars and done a
00:05:26 --> 00:05:28 lot of damage. And I think in the case of the
00:05:28 --> 00:05:31 Peekskill meteorite, it was a fairly hefty
00:05:31 --> 00:05:33 iron ore, stony iron meteorite that basically
00:05:33 --> 00:05:36 wrote off the rear end of the car. And the
00:05:36 --> 00:05:37 person who owned the car was very upset until
00:05:37 --> 00:05:39 a museum bought the car for a six figure sum,
00:05:39 --> 00:05:42 which kind of the blow. This, um,
00:05:42 --> 00:05:45 case, part of the reason that they thought it
00:05:45 --> 00:05:47 was a meteorite was that there was melting of
00:05:47 --> 00:05:50 the windscreen as well as just shattering of
00:05:50 --> 00:05:53 the windscreen. And this, the people at South
00:05:53 --> 00:05:55 Australia Museum basically came out with a
00:05:55 --> 00:05:56 fairly neutral statement and said, we're
00:05:56 --> 00:05:58 going to investigate this. It sounds really
00:05:58 --> 00:06:00 weird. The melting sounds odd. We're not sure
00:06:00 --> 00:06:03 what's going on. To me as an
00:06:03 --> 00:06:04 astronomer though, it speaks to one of the
00:06:04 --> 00:06:07 kind of really big Hollywood movie driven
00:06:07 --> 00:06:10 myths, I think, about meteorites.
00:06:10 --> 00:06:12 There's this idea that if a meteorite falls
00:06:12 --> 00:06:13 through the atmosphere and you pick it up
00:06:13 --> 00:06:15 immediately, it'll burn your hands, it'll be
00:06:15 --> 00:06:18 super, super hot. And that just really
00:06:18 --> 00:06:20 isn't the case now. I mean, it would be the
00:06:20 --> 00:06:23 case if something like the dinosaur killing
00:06:23 --> 00:06:25 asteroid hit the Earth. Uh, that'd get really
00:06:25 --> 00:06:26 hot, but you wouldn't be picking it up
00:06:26 --> 00:06:29 because you'd be vaporized and dead. Right.
00:06:29 --> 00:06:31 Um, for the smaller things that hit the, uh,
00:06:31 --> 00:06:34 Earth but can make it to the ground intact,
00:06:35 --> 00:06:37 they typically are slowed down by the
00:06:37 --> 00:06:39 atmosphere such that by the time they're 10
00:06:39 --> 00:06:41 or 20 kilometers above the ground, they've
00:06:41 --> 00:06:44 slowed down to below the speed of sound. And
00:06:44 --> 00:06:45 so that's why when you see the fireball for
00:06:45 --> 00:06:48 these things, that fireball terminates still
00:06:48 --> 00:06:50 quite high in the atmosphere. And while it
00:06:50 --> 00:06:51 might look like it was just over the next
00:06:51 --> 00:06:54 hill from you. The thing was still 20 or 30
00:06:54 --> 00:06:56 kilometers up. That's because the air
00:06:56 --> 00:06:58 resistance has been enough to slow them down.
00:06:58 --> 00:07:00 And at that point, they're falling at just a
00:07:00 --> 00:07:02 couple of hundred kilometers per hour at
00:07:02 --> 00:07:04 terminal velocity. Now, that's still pretty
00:07:04 --> 00:07:06 fast. And I mean, I wouldn't want to fall at
00:07:06 --> 00:07:09 200km an hour into the ground. No, but it
00:07:09 --> 00:07:11 means that from a height of 20 or 30 km, it
00:07:11 --> 00:07:13 takes a few minutes to reach the ground.
00:07:14 --> 00:07:16 What that means is that there's time for the
00:07:16 --> 00:07:19 rock to equilibrate to get
00:07:20 --> 00:07:22 the temperature equalized across this entire
00:07:22 --> 00:07:24 object. Now, the object's been held in space
00:07:24 --> 00:07:27 in cold storage for millions of years. Years.
00:07:27 --> 00:07:29 So the interior of the rock is bitterly,
00:07:29 --> 00:07:32 bitterly, bitterly cold. And, um, they've got
00:07:32 --> 00:07:35 rocky asteroids, rocky meteorites have a
00:07:35 --> 00:07:38 fairly high thermal inertia. They're not very
00:07:38 --> 00:07:40 conductive. And so what
00:07:40 --> 00:07:42 happens is that the thin outer layer gets
00:07:42 --> 00:07:44 super hot when it's coming through the
00:07:44 --> 00:07:46 atmosphere and it's luminous and that's
00:07:46 --> 00:07:48 getting ablated away. But very little
00:07:48 --> 00:07:51 of that heat actually is conducted to the
00:07:51 --> 00:07:53 interior. Once this thing slows down,
00:07:54 --> 00:07:56 it just keeps falling. And you've got a huge
00:07:56 --> 00:07:58 amount of cold material and a very, very tiny
00:07:58 --> 00:08:01 thin layer of hot material. So by the time it
00:08:01 --> 00:08:03 reaches the ground, meteorites are typically
00:08:03 --> 00:08:05 cold to the touch. And you're more likely to
00:08:05 --> 00:08:08 see frost forming on them or water vapor
00:08:08 --> 00:08:10 condensing on them. It's a bit like maybe
00:08:10 --> 00:08:12 deep fried ice cream. You deep fry the ice
00:08:12 --> 00:08:14 cream, you get a hot layer on the outside,
00:08:14 --> 00:08:16 but the ice cream in the middle stays cold.
00:08:16 --> 00:08:19 Same kind of idea. The one caveat to that
00:08:19 --> 00:08:21 is if you get an iron meteorite, a metal
00:08:21 --> 00:08:23 meteorite, that'll have a much higher thermal
00:08:23 --> 00:08:25 conductivity. So that can be quite warm when
00:08:25 --> 00:08:28 it reaches the ground. But rather than being
00:08:28 --> 00:08:30 super hot like the atmosphere, it's probably
00:08:30 --> 00:08:31 going to be nearer to room temperature.
00:08:32 --> 00:08:35 That's fine. What was pointed out to me,
00:08:35 --> 00:08:38 um, famous astronomer called Rob McNaught got
00:08:38 --> 00:08:39 in touch with me after he heard me on the
00:08:39 --> 00:08:41 radio talking about this one. Because I got
00:08:41 --> 00:08:43 called out, I got cold about this while I was
00:08:43 --> 00:08:45 driving back from the airport, having picked
00:08:45 --> 00:08:48 up colleague talked about it and Rob got
00:08:48 --> 00:08:50 in touch and pointed out that space junk,
00:08:51 --> 00:08:53 because it comes in at a much shallower
00:08:53 --> 00:08:56 angle, it actually ablates in the atmosphere
00:08:56 --> 00:08:58 for much, much, much longer. And it's usually
00:08:58 --> 00:09:00 much more conductive material. So you put
00:09:00 --> 00:09:03 those two things together and if a bit of
00:09:03 --> 00:09:05 space junk were to reach the Ground,
00:09:06 --> 00:09:08 there is a good chance that would be hot to
00:09:08 --> 00:09:11 the touch at the time you get to it. So one
00:09:11 --> 00:09:12 of the. Another thing that you could possibly
00:09:12 --> 00:09:14 use to differentiate, uh, between whether
00:09:14 --> 00:09:16 this is a meteorite or a bit of SpaceX
00:09:16 --> 00:09:19 material. All of that put together
00:09:19 --> 00:09:21 means that the melting of the windscreen and
00:09:21 --> 00:09:24 this rock being hot to me, actually kind of
00:09:24 --> 00:09:26 rules out it being a meteorite.
00:09:26 --> 00:09:26 Andrew Dunkley: Yeah.
00:09:26 --> 00:09:29 Jonti Horner: What adds to my argument that it's almost
00:09:29 --> 00:09:30 certainly not a meteorite is it was a
00:09:30 --> 00:09:32 nighttime event, the skies were clear in the
00:09:32 --> 00:09:34 area, nobody saw a fireball. There are no
00:09:34 --> 00:09:37 reports of a bright fireball, added to
00:09:37 --> 00:09:40 which are also no reports of sonic events
00:09:40 --> 00:09:42 or tremors, you know, things that would show
00:09:42 --> 00:09:44 up in the seismograph. So I think we can
00:09:44 --> 00:09:47 fairly definitively rule out a meteorite as
00:09:47 --> 00:09:49 the source of this impact on this car.
00:09:50 --> 00:09:52 Um, there is the amusing option that it could
00:09:52 --> 00:09:54 have been a SpaceX on Tesla impact, which
00:09:54 --> 00:09:56 would have been very entertaining. You know,
00:09:56 --> 00:09:57 it could have been a bit of space debris
00:09:58 --> 00:10:00 falling through the atmosphere and almost be
00:10:00 --> 00:10:02 friendly fire. But again, that would have
00:10:02 --> 00:10:04 created a very bright fireball that people
00:10:04 --> 00:10:05 would have seen. So I think we can rule that
00:10:05 --> 00:10:07 out as well. And the thing that to me
00:10:08 --> 00:10:11 tells the story here and will point me in a
00:10:11 --> 00:10:12 direction of investigation is in his
00:10:12 --> 00:10:15 interview, um, Dr. Melville Smith
00:10:15 --> 00:10:18 says a truck went past. Five or ten seconds
00:10:18 --> 00:10:20 later, there was an enormous explosion. Now,
00:10:20 --> 00:10:22 I've been hit by bits of gravel falling off
00:10:22 --> 00:10:24 trucks before and had my windscreen damaged.
00:10:24 --> 00:10:26 Yep. Quite possible that this was a rock that
00:10:26 --> 00:10:29 fell off that truck that went past, or that
00:10:29 --> 00:10:31 the truck kicked up a bit of rock from the
00:10:31 --> 00:10:32 surface of the road that bounced along the
00:10:32 --> 00:10:35 road and hit the windscreen. I still
00:10:35 --> 00:10:38 find it hard to see how that would have
00:10:38 --> 00:10:40 generated heat from the thing that hit the
00:10:40 --> 00:10:42 windscreen that will cause a bit of melting.
00:10:42 --> 00:10:44 Even though it's been really hot there, the
00:10:44 --> 00:10:46 road surface could have been hot. You still
00:10:46 --> 00:10:48 don't expect the surface of the road to be
00:10:48 --> 00:10:51 hot enough to melt glass. But the
00:10:51 --> 00:10:53 kinetic energy of an impact, if you've got a
00:10:53 --> 00:10:55 more massive impactor coming in a bit more
00:10:55 --> 00:10:57 slowly, you still can put a lot of energy in.
00:10:57 --> 00:10:59 And it may well just be that what they're
00:10:59 --> 00:11:02 mistaking for melting is actually this
00:11:02 --> 00:11:04 deformation, this crater in the windscreen,
00:11:04 --> 00:11:06 with all of the material in the windscreen
00:11:06 --> 00:11:08 that is designed to stop your windscreen
00:11:08 --> 00:11:10 shattering. And that's done a really good
00:11:10 --> 00:11:11 job. I know when I've had cracks in my
00:11:11 --> 00:11:13 windscreen, I'm always surprised how you get
00:11:13 --> 00:11:15 a break but it doesn't shatter, doesn't
00:11:15 --> 00:11:18 create a whole windscreen. Modern windscreens
00:11:18 --> 00:11:20 are designed to be like this multi layer
00:11:20 --> 00:11:22 thing that stops them doing that. And I'm
00:11:22 --> 00:11:25 wondering if what they think looked as signs
00:11:25 --> 00:11:27 of melting was actually the structure of the
00:11:27 --> 00:11:29 wind windscreen behaving as it's expected to,
00:11:29 --> 00:11:32 with a bigger impact. And um, because this is
00:11:32 --> 00:11:33 substantial, I mean it's bigger than some of
00:11:33 --> 00:11:35 the pictures of hail damage I saw over the
00:11:35 --> 00:11:37 weekend, for example. And it's bigger than
00:11:37 --> 00:11:39 the usual chip you see kicked up off the
00:11:39 --> 00:11:42 road. It's at a size that people might not
00:11:42 --> 00:11:44 expect it to look like that. So my take on
00:11:44 --> 00:11:47 this one is very confident it's not a rock
00:11:47 --> 00:11:48 from space, but it might have been a rock
00:11:48 --> 00:11:49 from truck.
00:11:49 --> 00:11:52 Andrew Dunkley: Yes, well, the timing sounds about right. And
00:11:52 --> 00:11:55 um, yeah, good picture of you on the ABC
00:11:55 --> 00:11:56 story on the website too, by the way.
00:11:57 --> 00:11:59 Jonti Horner: Yeah, back when I was younger and slimmer.
00:11:59 --> 00:12:01 Andrew Dunkley: Yeah, they generally use those photos for us.
00:12:01 --> 00:12:04 It's very nice. But yeah, it
00:12:04 --> 00:12:07 reminds me once when um, we, we had a brand
00:12:07 --> 00:12:09 new car and we decided to take it for a run
00:12:09 --> 00:12:12 and we were approaching roadworks and we were
00:12:12 --> 00:12:14 teaching our son to drive at the time. So
00:12:14 --> 00:12:17 he's hammering along at the minimum,
00:12:17 --> 00:12:20 you know, maximum, minimum speed of a, ah, a
00:12:20 --> 00:12:23 learner. And I told him to hit the brakes
00:12:23 --> 00:12:25 because I didn't want to hit that road work
00:12:25 --> 00:12:27 when a truck approached and that's exactly
00:12:27 --> 00:12:30 what happened. We got showered in gravel.
00:12:30 --> 00:12:33 That brand new car had so much,
00:12:33 --> 00:12:35 you know, chipping on the front. We were
00:12:35 --> 00:12:36 very, very upset.
00:12:37 --> 00:12:39 Jonti Horner: To say it's shocking. I mean, one of the good
00:12:39 --> 00:12:41 things is, and it's not often that you can
00:12:41 --> 00:12:44 readily praise insurance companies, but I got
00:12:44 --> 00:12:47 a big chip on my windscreen at the turn of
00:12:47 --> 00:12:50 the year last year and um, got in touch with
00:12:50 --> 00:12:52 my insurance company and they soldered a
00:12:52 --> 00:12:55 windscreen replacement free of charge without
00:12:55 --> 00:12:57 it impacting my excess or anything like that.
00:12:57 --> 00:12:58 Now, well, I guess it's not free of charge
00:12:58 --> 00:13:00 because I'm paying the insurance premiums.
00:13:00 --> 00:13:02 But you know, it didn't impact my insurance
00:13:02 --> 00:13:05 rates, it didn't cause an excess. And I'm
00:13:05 --> 00:13:06 guessing that's because if you don't fix
00:13:06 --> 00:13:08 that, uh, it can become a much bigger problem
00:13:08 --> 00:13:10 and cause them a much bigger accident. So
00:13:10 --> 00:13:11 from their point of view, it's a very
00:13:11 --> 00:13:14 valuable investment. But it does mean that
00:13:14 --> 00:13:16 when we get these kind of events, we can get
00:13:16 --> 00:13:18 our windscreens fixed fairly easily and
00:13:18 --> 00:13:20 probably means that the trucks that are
00:13:20 --> 00:13:21 driving around shedding their loads get off A
00:13:21 --> 00:13:23 little bit scot free compared to having
00:13:23 --> 00:13:25 people chasing them down to pay for repairs.
00:13:25 --> 00:13:28 Andrew Dunkley: Yes, yes indeed. Okay,
00:13:28 --> 00:13:31 so probably not a meteorite, but probably
00:13:31 --> 00:13:32 a rock. Um.
00:13:35 --> 00:13:36 Jonti Horner: Roger, you're allowed to clear also.
00:13:37 --> 00:13:40 Andrew Dunkley: Space nuts to another event that uh,
00:13:40 --> 00:13:42 happened over uh, Victoria, New South Wales
00:13:43 --> 00:13:46 and the act, which, which are next door
00:13:46 --> 00:13:48 to each other, a fireball, um,
00:13:49 --> 00:13:51 as recently as yesterday as we
00:13:51 --> 00:13:52 speak.
00:13:52 --> 00:13:55 Jonti Horner: Yes. So this is very much breaking news. So
00:13:55 --> 00:13:57 I'm aware this doesn't air immediately. So
00:13:57 --> 00:13:59 this was a fireball that was seen on Sunday
00:13:59 --> 00:14:02 2nd November, which as we're recording at
00:14:02 --> 00:14:04 the minute, this was actually about 18 hours
00:14:04 --> 00:14:07 ago from now, roughly. And so that means
00:14:07 --> 00:14:10 information's still coming in. It was at uh,
00:14:10 --> 00:14:13 just about 20 to 5 in the evening,
00:14:13 --> 00:14:16 which means it was broad daylight. So this is
00:14:16 --> 00:14:18 a daylight fireball. And to me that's always
00:14:18 --> 00:14:21 a really exciting flag that this could be a
00:14:21 --> 00:14:23 bigger event because to be bright enough to
00:14:23 --> 00:14:25 be seen in broad daylight, and particularly
00:14:25 --> 00:14:27 to be bright enough to be seen widely in
00:14:27 --> 00:14:29 broad daylight by the general public means
00:14:29 --> 00:14:31 that this was a fairly substantial thing
00:14:31 --> 00:14:33 coming into the atmosphere. There are
00:14:33 --> 00:14:35 observations of this in New South Wales, in
00:14:35 --> 00:14:38 the act, the Australian Capital Territory
00:14:38 --> 00:14:41 and down into Victoria. Um, it's also
00:14:41 --> 00:14:43 a sonic boom and rumbles have been heard
00:14:43 --> 00:14:46 across Victoria recorded on seismograph
00:14:46 --> 00:14:49 in Nurbuchen in eastern Victoria.
00:14:50 --> 00:14:52 So it kind of sounds really promising from
00:14:52 --> 00:14:54 the point of view of something that is big
00:14:54 --> 00:14:56 enough to potentially drop a meteorite.
00:14:56 --> 00:14:58 There's a lot of good footage popping up on
00:14:58 --> 00:15:00 Facebook groups like the Australian Meteor
00:15:00 --> 00:15:03 Reports Facebook group. And the
00:15:03 --> 00:15:05 one thing that gives me a little bit of
00:15:05 --> 00:15:06 caution about something making it to the
00:15:06 --> 00:15:09 ground here is on some of those videos I've
00:15:09 --> 00:15:11 seen, this single looks like it was a very
00:15:11 --> 00:15:13 fast moving object. Now
00:15:13 --> 00:15:16 typically really fast moving things
00:15:16 --> 00:15:18 coming into the atmosphere have a lower
00:15:18 --> 00:15:20 likelihood of leaving anything to make it to
00:15:20 --> 00:15:22 the ground. Couple of reasons for that.
00:15:22 --> 00:15:25 Firstly, they tend to detonate higher up in
00:15:25 --> 00:15:27 the atmosphere and ah, more things get
00:15:27 --> 00:15:29 destroyed. But the other thing which I think
00:15:29 --> 00:15:31 is more to the point is things that come in
00:15:31 --> 00:15:34 really, really fast are typically moving on
00:15:34 --> 00:15:36 more comet like orbits and asteroid like
00:15:36 --> 00:15:39 orbits and therefore are more likely to be
00:15:39 --> 00:15:41 cometary material than asteroidal material,
00:15:41 --> 00:15:43 which means they're likely to be more
00:15:43 --> 00:15:45 friable, more fragile, more dust and
00:15:45 --> 00:15:48 ice rather than rock and metal. And that
00:15:48 --> 00:15:50 means that uh, when you see something coming
00:15:50 --> 00:15:51 in at really high speed, like some of these
00:15:51 --> 00:15:54 videos seem to show, that possibly
00:15:54 --> 00:15:56 means that there is a lower chance of
00:15:56 --> 00:15:59 something surviving to the surface. Doesn't
00:15:59 --> 00:16:02 mean that there won't be a meteorite found
00:16:02 --> 00:16:04 from this. Particularly because this, like I
00:16:04 --> 00:16:06 said, was bright enough to see in broad
00:16:06 --> 00:16:08 daylight and bright enough to be quite widely
00:16:08 --> 00:16:11 observed. The fact that the explosion, the
00:16:11 --> 00:16:13 terminal detonation, the air burst happened
00:16:13 --> 00:16:15 low enough for people to hear the sonic booms
00:16:15 --> 00:16:17 and for it to pick up on seismographs, all of
00:16:17 --> 00:16:19 these things are kind of things that we'd
00:16:19 --> 00:16:21 look for to say this is a promising event.
00:16:22 --> 00:16:23 The one thing that's giving me some caution
00:16:23 --> 00:16:26 is a very high speed. So this is very much a
00:16:26 --> 00:16:28 developing story. It might be that by the
00:16:28 --> 00:16:31 time people listen to this episode, they can
00:16:31 --> 00:16:32 go online and have a look and there'll be
00:16:32 --> 00:16:35 more information available. I'm honestly
00:16:35 --> 00:16:36 quite surprised that there's not been more
00:16:36 --> 00:16:38 media interest in this this morning. Usually
00:16:38 --> 00:16:40 when there's a bright event like this,
00:16:40 --> 00:16:42 journalists are ringing up and saying, what
00:16:42 --> 00:16:44 do you think? And what's happened? Yeah, so
00:16:44 --> 00:16:46 it may be a little bit of a slow burn, but
00:16:46 --> 00:16:48 it'll be interesting to see what develops on
00:16:48 --> 00:16:50 this in the next week or two. Maybe that
00:16:50 --> 00:16:52 nothing had always found, but it could be yet
00:16:52 --> 00:16:53 another rock dropping to the surface of
00:16:53 --> 00:16:55 Australia to give us something to study.
00:16:55 --> 00:16:58 Andrew Dunkley: Yeah, indeed. Yeah, yeah. Um, I've never
00:16:58 --> 00:17:00 seen one myself, but we've, we've had a few
00:17:00 --> 00:17:03 over the years, um, crossing the. The
00:17:03 --> 00:17:06 sky in Dubbo. One particular daytime
00:17:06 --> 00:17:09 one that someone filmed many, many years ago.
00:17:09 --> 00:17:11 And, uh, yeah, quite spectacular.
00:17:12 --> 00:17:14 Okay, uh, this is Space Nuts with
00:17:14 --> 00:17:17 Andrew Dunkley and John de Horner.
00:17:21 --> 00:17:22 Jonti Horner: Space Nuts.
00:17:22 --> 00:17:25 Andrew Dunkley: Uh, now this next story takes, um,
00:17:26 --> 00:17:28 us back to 3I Atlas, the, um,
00:17:29 --> 00:17:31 exo comet, I
00:17:31 --> 00:17:34 suppose, um, that's currently moving through
00:17:34 --> 00:17:37 our solar system. Uh, the reason it's
00:17:37 --> 00:17:39 sort of gained more traction is because
00:17:39 --> 00:17:42 things have changed and it's
00:17:42 --> 00:17:44 doing weird things. And of course, that's
00:17:44 --> 00:17:46 brought out the popular press and a few of
00:17:46 --> 00:17:48 those other comments that we're not going to
00:17:48 --> 00:17:50 talk about, but, um, bit of chatter on
00:17:50 --> 00:17:52 Facebook through the Space Nuts podcast
00:17:52 --> 00:17:55 group. Uh, what's happening with 3i
00:17:55 --> 00:17:55 Atlas?
00:17:57 --> 00:18:00 Jonti Horner: Well, the latest update is that it got a lot
00:18:00 --> 00:18:02 of coverage last week. Not really because
00:18:02 --> 00:18:04 anything special was happening, but because
00:18:04 --> 00:18:06 last week was the point at which Comet Atlas
00:18:06 --> 00:18:08 went through perihelion. Yeah, so that was
00:18:08 --> 00:18:09 the time it was closest to the sun.
00:18:09 --> 00:18:11 Perihelion was on about 30 October,
00:18:12 --> 00:18:15 so people are obviously interested. Um, I see
00:18:15 --> 00:18:17 the astronomer who Shall Not Be Named and
00:18:17 --> 00:18:19 they'll call him Voldemort for now, has come
00:18:19 --> 00:18:21 out with new stories saying that this Thing
00:18:21 --> 00:18:23 is changing direction and the aliens are
00:18:23 --> 00:18:25 definitely invading and rocket engines have
00:18:25 --> 00:18:28 kicked off. And, um, all this stuff,
00:18:28 --> 00:18:30 um, and it clearly isn't, you know, we are
00:18:30 --> 00:18:31 safe, we're not going to be invaded by
00:18:31 --> 00:18:33 aliens. You don't have to worry and protect
00:18:33 --> 00:18:35 yourself and buy some wine, Cokes or whatever
00:18:35 --> 00:18:38 you need to do. Um, does open up the question
00:18:38 --> 00:18:40 at what point this guy lost his credibility
00:18:40 --> 00:18:42 with the scientific community. The best part
00:18:42 --> 00:18:44 of a decade ago. But I wonder at what point
00:18:45 --> 00:18:47 the Boy who Cried Wolf syndrome will kick in
00:18:47 --> 00:18:49 to such an extent to overwhelm the Harvard
00:18:49 --> 00:18:52 affiliation and that the stories this
00:18:52 --> 00:18:54 guy puts out will stop getting oxygen. That's
00:18:54 --> 00:18:56 going to be an interesting study in the,
00:18:57 --> 00:18:59 um, I guess the scientific literacy of
00:18:59 --> 00:19:01 journalists at the lowest common denominator
00:19:01 --> 00:19:03 publications. That might be the way I put it,
00:19:04 --> 00:19:05 but it is definitely not aliens. But what is
00:19:05 --> 00:19:08 happening with Comet 3i Atlas is it's giving
00:19:08 --> 00:19:11 us this unprecedented window into the
00:19:11 --> 00:19:12 behavior of a comet that formed around
00:19:12 --> 00:19:15 another star. It's also a comet that's coming
00:19:15 --> 00:19:17 in and traveling through the solar system at
00:19:17 --> 00:19:19 a higher speed than typical comets do. And
00:19:19 --> 00:19:20 that's of course, how we know it's from
00:19:20 --> 00:19:23 another star. What that means, though, is
00:19:23 --> 00:19:26 that, uh, the typical process by which
00:19:26 --> 00:19:29 comets do their thing will happen
00:19:29 --> 00:19:30 in a slightly different way for this object,
00:19:30 --> 00:19:32 naturally, because it's coming through
00:19:32 --> 00:19:34 quicker. So things happen at an accelerated
00:19:34 --> 00:19:37 rate. And that might be what's happening.
00:19:37 --> 00:19:39 That ties into a paper that's just been
00:19:39 --> 00:19:41 published that you can read on the archive,
00:19:41 --> 00:19:43 the preprint server that we as astronomers
00:19:43 --> 00:19:46 use to spread the word of our work and
00:19:46 --> 00:19:48 circumvent the exorbitant prices that
00:19:48 --> 00:19:50 journals charge for you to read. Then we put
00:19:50 --> 00:19:52 all our papers on Arxiv as well and say,
00:19:52 --> 00:19:54 don't pay the journal, read it for free here,
00:19:54 --> 00:19:57 because we're nice like that. Um, this paper
00:19:57 --> 00:20:00 has been looking at the light curve of this
00:20:00 --> 00:20:02 comet, so how it's brightening over time.
00:20:02 --> 00:20:05 And what it's found is that, ah3i Atlas has
00:20:05 --> 00:20:08 been brightening faster than typical OC cloud
00:20:08 --> 00:20:10 comets do at this distance from the sun.
00:20:11 --> 00:20:13 So when you've got a comet coming in from the
00:20:13 --> 00:20:16 sun, it brightens in
00:20:16 --> 00:20:18 a slightly predictable rate. And the reason I
00:20:18 --> 00:20:21 say slightly predictable rate is, uh, there's
00:20:21 --> 00:20:23 a famous quote from a comet astronomer called
00:20:23 --> 00:20:25 David Levy that says comets are like cats.
00:20:26 --> 00:20:28 They have tails and they do whatever the hell
00:20:28 --> 00:20:30 they want. And there's a truth in that. So
00:20:30 --> 00:20:33 what we tend to do is when we first find a
00:20:33 --> 00:20:36 comet, we can work out Fairly quickly, what
00:20:36 --> 00:20:39 orbit it's moving on around the sun to some
00:20:39 --> 00:20:41 degree, how far away it is from the sun and
00:20:41 --> 00:20:43 how quickly it's moving. And, um, by knowing
00:20:43 --> 00:20:45 how far away it is and how bright it is, when
00:20:45 --> 00:20:47 we find it, we can work out
00:20:48 --> 00:20:50 an absolute magnitude for it, which is a
00:20:50 --> 00:20:52 quantity that characterizes whether it's a
00:20:52 --> 00:20:54 big, bright comet or a small, faint comet.
00:20:55 --> 00:20:57 And we can use that and, um, the orbit it's
00:20:57 --> 00:20:59 going around the sun to make a first
00:20:59 --> 00:21:00 prediction of how the comet will brighten or
00:21:00 --> 00:21:03 fade. Then, as we observe it over a little
00:21:03 --> 00:21:06 bit of time, we can characterize how its
00:21:06 --> 00:21:08 activity is changing and work out not only
00:21:08 --> 00:21:10 whether it's a big comet or a small comet,
00:21:10 --> 00:21:12 but whether it's an active comet or whether
00:21:12 --> 00:21:15 it's a very quiescent comet. So whether it's
00:21:15 --> 00:21:18 brightening rapidly or brightening slowly
00:21:18 --> 00:21:20 for a comet of that size. And over time, this
00:21:20 --> 00:21:22 allows people to predict the brightness of
00:21:22 --> 00:21:25 the comet going forward. And assuming the
00:21:25 --> 00:21:27 comet doesn't do anything unusual, like
00:21:27 --> 00:21:29 fragmenting or having an outburst or
00:21:29 --> 00:21:32 something like this, we can get a fairly good
00:21:32 --> 00:21:35 handle several months ahead of time, of how
00:21:35 --> 00:21:37 bright the comet's going to be with a certain
00:21:37 --> 00:21:39 degree of uncertainty. And so we've got a
00:21:39 --> 00:21:42 fairly good feeling for how a comet coming in
00:21:42 --> 00:21:44 from the Oort Cloud that is about the size of
00:21:44 --> 00:21:46 Comet ATLAS should brighten.
00:21:47 --> 00:21:48 Now, some comets brighten a bit quicker
00:21:48 --> 00:21:50 because they're more active. Some brighten a
00:21:50 --> 00:21:53 bit slower. What's happened with Comet ATLAS
00:21:53 --> 00:21:55 is it started to brighten significantly
00:21:55 --> 00:21:58 quicker than we'd expect a typical Oort cloud
00:21:58 --> 00:22:00 comet to brighten at the same distance from
00:22:00 --> 00:22:02 the Sun. And that's what this paper's all
00:22:02 --> 00:22:04 about. Basically, the comet's brightening
00:22:04 --> 00:22:06 unusually quickly. Now, there's a
00:22:06 --> 00:22:08 variety of possible explanations for that,
00:22:08 --> 00:22:11 and we won't know which answer is true until
00:22:11 --> 00:22:13 we do more study. The most common reason
00:22:13 --> 00:22:16 for a comet to brighten unusually quickly
00:22:16 --> 00:22:18 is often linked to the comet's head becoming
00:22:18 --> 00:22:20 a bit more diffuse because it's a comet
00:22:20 --> 00:22:23 fragmentation event. So the comet's
00:22:23 --> 00:22:25 falling apart. You release a lot of
00:22:25 --> 00:22:27 dust as the comet falls apart, but you also
00:22:27 --> 00:22:29 increase the surface area exposed to
00:22:29 --> 00:22:31 sunlight, which means you increase the
00:22:31 --> 00:22:33 activity. And the analogy here will be the
00:22:33 --> 00:22:34 difference. If you've ever had the
00:22:34 --> 00:22:36 effervescent tablets you put in water and you
00:22:36 --> 00:22:39 let them dissolve. If you get two of them and
00:22:39 --> 00:22:41 you put one in a glass of water fully intact,
00:22:41 --> 00:22:43 and you crumble the other one up and drop in
00:22:43 --> 00:22:45 the crumbled one, the crumbled one reacts
00:22:45 --> 00:22:47 much quicker, and it foams up really quickly.
00:22:48 --> 00:22:49 The solid one takes a while to go.
00:22:51 --> 00:22:53 That could be the case. We'll only know if we
00:22:53 --> 00:22:54 observe for a little bit of time. And that
00:22:54 --> 00:22:56 wouldn't necessarily be that unsurprising.
00:22:56 --> 00:22:58 There is a suspicion that this comet, 3i
00:22:58 --> 00:23:01 atlas never actually got close enough to its
00:23:01 --> 00:23:03 parent star to be active as a comet. So it
00:23:03 --> 00:23:05 will be more equivalent to what we call the
00:23:05 --> 00:23:07 new Oort cloud comets coming through for the
00:23:07 --> 00:23:09 very first time, rather than one that's had
00:23:09 --> 00:23:12 multiple perihelion passages. And, um, we do
00:23:12 --> 00:23:14 know that new comets have a tendency to
00:23:14 --> 00:23:16 fragment more often than older comets that
00:23:16 --> 00:23:18 have been more baked in, essentially. So
00:23:18 --> 00:23:19 that's one possible explanation.
00:23:19 --> 00:23:21 But I think another one that's really
00:23:21 --> 00:23:23 interesting and would probably fit quite well
00:23:23 --> 00:23:26 is that our models of cometary
00:23:26 --> 00:23:29 activity have built within them. Though, uh,
00:23:29 --> 00:23:31 we don't normally think about it, the time at
00:23:31 --> 00:23:34 which activity driven by different ices
00:23:34 --> 00:23:36 kicks in. So as the comet gets closer to the
00:23:36 --> 00:23:39 sun and it gets hotter, different ices on
00:23:39 --> 00:23:41 the surface will reach the temperature where
00:23:41 --> 00:23:43 they can no longer be ices, and they turn
00:23:43 --> 00:23:45 from ice to gas in a process called
00:23:45 --> 00:23:46 sublimation. And that's what drives the
00:23:46 --> 00:23:49 activity of the comet. And as a comet heats
00:23:49 --> 00:23:51 up, different ices turn on, effectively.
00:23:52 --> 00:23:55 Now, when you're far from the sun, water ice
00:23:55 --> 00:23:57 is really cold and stays as water ice. But
00:23:57 --> 00:24:00 other volatile materials like carbon monoxide
00:24:00 --> 00:24:02 and carbon dioxide are, uh, what drive the
00:24:02 --> 00:24:04 activity of a comet when it's further from
00:24:04 --> 00:24:07 the Sun. Now, as it comes in closer, it
00:24:07 --> 00:24:09 heats up and water turns on. And certainly
00:24:09 --> 00:24:11 within a few astronomical units of the sun.
00:24:11 --> 00:24:13 Water is usually the dominant driving factor
00:24:13 --> 00:24:16 of comet reactivity. With Comet
00:24:16 --> 00:24:19 atlas, this brightening is happening
00:24:19 --> 00:24:21 interior to the distance where most comets
00:24:21 --> 00:24:23 would have turned on their water emission.
00:24:23 --> 00:24:26 But Comet ATLAS is coming in quicker, and
00:24:26 --> 00:24:29 so therefore, it is heating up
00:24:29 --> 00:24:31 due to the radiation from the Sun. But as
00:24:31 --> 00:24:34 it's coming in quicker, maybe it was closer
00:24:34 --> 00:24:36 to the sun by the time that the heat from the
00:24:36 --> 00:24:39 sun got to be enough to penetrate the surface
00:24:39 --> 00:24:41 material and start kicking on the water
00:24:41 --> 00:24:43 activity. But then that heating is happening
00:24:43 --> 00:24:45 really quickly because the distance to the
00:24:45 --> 00:24:48 sun is dropping quite fast. And so therefore,
00:24:48 --> 00:24:49 you've had this spike in temperature and
00:24:49 --> 00:24:52 therefore a spike in activity as the water
00:24:52 --> 00:24:55 activity is turned on, not so much as a
00:24:55 --> 00:24:57 trickle, but as a flood. And that ties in
00:24:57 --> 00:24:59 actually quite nicely to some of the recent
00:24:59 --> 00:25:01 stories in the last few weeks about the water
00:25:01 --> 00:25:03 vapor, uh, and the water being emitted from
00:25:03 --> 00:25:06 the comet I saw some article about the comet
00:25:06 --> 00:25:09 emitting a jet of water like a firehose. So
00:25:09 --> 00:25:11 this is one of those narratives that seems to
00:25:11 --> 00:25:13 fit together really, really well. And it
00:25:13 --> 00:25:14 could just be that the high speed of the
00:25:14 --> 00:25:16 comet means that it got closer in before the
00:25:16 --> 00:25:19 water turned on. And now it's catching up for
00:25:19 --> 00:25:22 lost time. What this means for the future is
00:25:22 --> 00:25:24 that, in all honesty, we are
00:25:24 --> 00:25:26 less confident in predicting the future
00:25:26 --> 00:25:28 brightness of the comet than we normally
00:25:28 --> 00:25:30 would be. Because it's all this cometary
00:25:30 --> 00:25:32 activity going on. It's effectively having a
00:25:32 --> 00:25:35 bit of an outburst. When we were talking
00:25:35 --> 00:25:36 about it months ago, we always said it would
00:25:36 --> 00:25:38 never get brighter than about magnitude 11,
00:25:38 --> 00:25:41 magnitude 12. There's a chance it might get a
00:25:41 --> 00:25:42 little bit brighter than that now. But it's
00:25:42 --> 00:25:44 really hard to model. We don't know whether
00:25:45 --> 00:25:46 the comet will brighten further than
00:25:46 --> 00:25:49 expected, brighten really rapidly, go back to
00:25:49 --> 00:25:52 behaving as normal. It might fade away
00:25:52 --> 00:25:54 because suddenly it's had this outburst. It's
00:25:54 --> 00:25:56 clogged itself up. It might even go out
00:25:56 --> 00:25:58 relatively quickly like a bit of a snuff
00:25:58 --> 00:26:00 torch if it has fully fragmented and
00:26:00 --> 00:26:03 disintegrated. And we saw that with the great
00:26:03 --> 00:26:06 comet earlier this year, Comet Atlas, which
00:26:06 --> 00:26:07 was really bright and spectacular. And then
00:26:07 --> 00:26:09 became the headless comet because its head
00:26:09 --> 00:26:12 just totally disintegrated. And all you were
00:26:12 --> 00:26:14 left was this tail gradually drifting through
00:26:14 --> 00:26:17 space with no comet to call its own. Yeah, so
00:26:17 --> 00:26:19 we just, honestly, we just don't, um, know
00:26:19 --> 00:26:22 There's a lot more to learn. And, yeah, this
00:26:22 --> 00:26:24 is getting a lot of hyperbolic stories
00:26:25 --> 00:26:27 about it and people arguing that it's
00:26:27 --> 00:26:29 actually the mass driver engine that's turned
00:26:29 --> 00:26:31 on as it will reroute itself to the Earth.
00:26:31 --> 00:26:33 Courtesy Harvard astronomer of doom.
00:26:34 --> 00:26:36 But in reality, this is why these objects are
00:26:36 --> 00:26:38 so exciting, because they give us a window
00:26:38 --> 00:26:40 into comets with different compositions that
00:26:40 --> 00:26:42 formed around different stars. And also how
00:26:42 --> 00:26:44 comets behave at higher speed. You know,
00:26:45 --> 00:26:46 this is why it's cool.
00:26:46 --> 00:26:49 Andrew Dunkley: Yeah. Uh, I must say I'm surprised that this
00:26:49 --> 00:26:52 one's receiving so much attention. But I
00:26:52 --> 00:26:54 shouldn't be surprised because it is a little
00:26:54 --> 00:26:56 bit different to most.
00:26:56 --> 00:26:59 And, um, being an ex. Extra, um,
00:27:00 --> 00:27:03 solar comet, um,
00:27:03 --> 00:27:05 it just, Just makes it that much more
00:27:05 --> 00:27:07 interesting. So, yeah, um, lots to learn,
00:27:07 --> 00:27:10 really. Uh, so, yeah, this one, uh, will no
00:27:10 --> 00:27:13 doubt, uh, be getting some attention for some
00:27:13 --> 00:27:16 time to come. Um, would be a pity if
00:27:16 --> 00:27:17 it kind of, you know,
00:27:19 --> 00:27:21 lost itself in our solar
00:27:21 --> 00:27:24 system. But, um, that's just the way it goes
00:27:24 --> 00:27:24 sometimes.
00:27:26 --> 00:27:26 Jonti Horner: Absolutely.
00:27:26 --> 00:27:27 Andrew Dunkley: Well, there it is.
00:27:28 --> 00:27:28 Jonti Horner: Yeah.
00:27:29 --> 00:27:31 I was going to say, while we're on the topic
00:27:31 --> 00:27:32 of comets, I should just flag up to everyone,
00:27:32 --> 00:27:34 particularly the Northern Hemisphere people,
00:27:34 --> 00:27:37 but also us in the Southern Hemisphere, a
00:27:37 --> 00:27:39 tiny little bit. Comet Lemon, which is
00:27:39 --> 00:27:41 getting a lot of media coverage, is at its
00:27:41 --> 00:27:44 brightest pretty much bang at the minute.
00:27:44 --> 00:27:46 It's about magnitude 4.3, which means
00:27:46 --> 00:27:47 technically it's visible to the naked eye.
00:27:47 --> 00:27:50 But in reality, because comets are diffuse
00:27:50 --> 00:27:52 objects, it'll be a very hard spot unless
00:27:52 --> 00:27:54 you're somewhere incredibly dark. But it is
00:27:54 --> 00:27:57 very photogenic comet. It is most visible to
00:27:57 --> 00:27:59 people in the Northern Hemisphere. For those
00:27:59 --> 00:28:02 of us in Australia, it's basically lost in
00:28:02 --> 00:28:04 the glare of twilight, even though it's at a
00:28:04 --> 00:28:06 declination where it could be visible if it
00:28:06 --> 00:28:08 was in a dark sky. It's too near the sun in
00:28:08 --> 00:28:10 the sky. But these few days around now,
00:28:10 --> 00:28:12 the next week or so, it's the best chance
00:28:12 --> 00:28:15 we'll get to see it from Australia while it's
00:28:15 --> 00:28:17 bright. And, um, that'll be very low in the
00:28:17 --> 00:28:20 west after sunset, um, as the sky
00:28:20 --> 00:28:22 gets darker. Have a look on
00:28:22 --> 00:28:24 planetarium programs like Stellarium to find
00:28:24 --> 00:28:27 the location. But my memory is that, uh, the
00:28:27 --> 00:28:29 planet Mercury is going to be visible low to
00:28:29 --> 00:28:30 the west after sunset. And if you can find
00:28:30 --> 00:28:33 Mercury and you go to the right of Mercury,
00:28:33 --> 00:28:35 it's about the same height as Mercury on the
00:28:35 --> 00:28:38 7th or 8th of November. So worth
00:28:38 --> 00:28:41 looking at. It is not the best comet of the
00:28:41 --> 00:28:42 year. We already have that back in January,
00:28:42 --> 00:28:44 despite what some of the articles said. But
00:28:44 --> 00:28:45 if you do want to see a comet that's
00:28:46 --> 00:28:47 borderline bright enough to see the naked
00:28:47 --> 00:28:49 eye, that's your one. It should be quite good
00:28:49 --> 00:28:52 in binoculars and certainly for people doing
00:28:52 --> 00:28:54 astrophotography. Have a look online. Some of
00:28:54 --> 00:28:55 the photos of this thing are really
00:28:55 --> 00:28:57 spectacular. There's people who've done, um,
00:28:57 --> 00:28:59 yeah, pretty clever things imaging it with
00:28:59 --> 00:29:02 lovely foreground views like lakes or rocks
00:29:02 --> 00:29:04 or castles or whatever. So there's lovely
00:29:04 --> 00:29:07 images of this comet out there if you want to
00:29:07 --> 00:29:08 feast your eyes on what people who are
00:29:08 --> 00:29:09 talented photographers can do.
00:29:10 --> 00:29:13 Andrew Dunkley: Yes, very good. Uh, that's Three Eye, Three
00:29:13 --> 00:29:15 Eye Atlas. Uh, now, um,
00:29:16 --> 00:29:18 oh, and you can, you can read, uh, about
00:29:18 --> 00:29:21 that, uh, on, um, the archive website,
00:29:21 --> 00:29:22 as Jonti mentioned.
00:29:25 --> 00:29:25 Jonti Horner: Okay.
00:29:25 --> 00:29:27 Andrew Dunkley: We checked all four systems and being with a
00:29:27 --> 00:29:30 girl, space nats, uh, let's move on to
00:29:30 --> 00:29:33 this really interesting story. An enormous
00:29:33 --> 00:29:36 black hole has been found. But what's really
00:29:36 --> 00:29:39 interesting is the galaxy that it's in is
00:29:39 --> 00:29:42 tiny. And when I, when I read into the
00:29:42 --> 00:29:45 details of this Story. We're talking about a
00:29:45 --> 00:29:47 galaxy with very few stars,
00:29:48 --> 00:29:49 surprisingly few stars.
00:29:50 --> 00:29:52 Jonti Horner: And, um, this fascinated me reading it now. I
00:29:52 --> 00:29:54 always say, particularly when we're doing the
00:29:54 --> 00:29:56 questions, and we get lots of cosmology type
00:29:56 --> 00:29:58 questions. I'm not a cosmologist, I'm not a
00:29:58 --> 00:30:01 galactic type astronomer. Uh, my expertise
00:30:01 --> 00:30:03 and my focus is very much on the things
00:30:03 --> 00:30:05 closer to home. So I tend to try and pick
00:30:05 --> 00:30:07 stories where I can talk from a position of
00:30:07 --> 00:30:09 some authority rather than no authority, if
00:30:09 --> 00:30:12 that makes sense. But this story was so cool,
00:30:12 --> 00:30:14 I thought we had to include it, even if, um,
00:30:14 --> 00:30:16 it might be a little bit of the blind leading
00:30:16 --> 00:30:17 the blind in a way. But this is one of the
00:30:17 --> 00:30:19 Milky Way's satellite galaxies. And our
00:30:19 --> 00:30:22 galaxy has many, many satellites, from the
00:30:22 --> 00:30:24 incredibly large and bright, large and Small
00:30:24 --> 00:30:27 Magellanic Clouds, which we can see here in
00:30:27 --> 00:30:28 the Southern Hemisphere, really high in the
00:30:28 --> 00:30:31 sky at the minute, really spectacular, down
00:30:31 --> 00:30:33 to really, really tiny satellite galaxies
00:30:33 --> 00:30:36 that almost push our understanding of what it
00:30:36 --> 00:30:39 means to be a galaxy. And this galaxy
00:30:39 --> 00:30:41 is one such galaxy. It's what's described as
00:30:41 --> 00:30:44 an ultra faint dwarf galaxy. And there are
00:30:44 --> 00:30:47 likely an enormous number of these in space
00:30:47 --> 00:30:49 that we just don't find. I guess the analogy
00:30:49 --> 00:30:51 I'd use here is that if you go out and look
00:30:51 --> 00:30:53 at the stars in the night sky, the stars that
00:30:53 --> 00:30:55 you're seeing are very much the superstars of
00:30:55 --> 00:30:57 our galaxy. They're stars that are much more
00:30:57 --> 00:30:59 massive than the sun that we're seeing from
00:30:59 --> 00:31:02 great distances. The most common stars in
00:31:02 --> 00:31:05 the galaxy are the dim little red dwarfs like
00:31:05 --> 00:31:07 Proxima Centauri. And Proxima is fairly
00:31:07 --> 00:31:10 massive and fairly luminous for a red dwarf.
00:31:10 --> 00:31:12 It is the closest star to the solar system,
00:31:12 --> 00:31:14 and it's too fancy with the naked eye by a
00:31:14 --> 00:31:17 factor of 100 times. So there's lots and lots
00:31:17 --> 00:31:19 of very small, faint things that until we
00:31:19 --> 00:31:21 have telescopes, we couldn't find at all.
00:31:21 --> 00:31:23 There are always more small things than big
00:31:23 --> 00:31:26 things. So it seems likely that there are,
00:31:26 --> 00:31:28 uh, many, many, many faint,
00:31:28 --> 00:31:31 ultra faint dwarf galaxies that have simply
00:31:31 --> 00:31:33 not been discovered even in our local area,
00:31:33 --> 00:31:36 never mind at the far parts of the cosmos.
00:31:36 --> 00:31:38 When we talk about galaxies that are many
00:31:38 --> 00:31:40 hundreds of millions of light years away,
00:31:40 --> 00:31:41 we're only seeing the superstars. We're not
00:31:41 --> 00:31:44 seeing the little baby ones like this. The
00:31:44 --> 00:31:47 galaxy in the story here is called Segue one.
00:31:47 --> 00:31:50 And I must admit that I don't think I'd ever
00:31:50 --> 00:31:51 heard of this, or I'd only ever heard of it
00:31:51 --> 00:31:54 in passing before this story came out. It is
00:31:54 --> 00:31:57 really tiny and very Anonymous. It's about
00:31:57 --> 00:31:59 75 light years from the Earth.
00:32:00 --> 00:32:01 Like I say, it's one of our satellite
00:32:01 --> 00:32:03 galaxies. And, uh, our, uh, best
00:32:03 --> 00:32:05 observations. There's a photograph in the
00:32:05 --> 00:32:07 Space.com article which is fabulous. It says,
00:32:07 --> 00:32:09 you know, here's this dwarf galaxy with only
00:32:09 --> 00:32:11 a handful of stars, and I'm not sure where
00:32:11 --> 00:32:13 the galaxy is because there's so little in
00:32:13 --> 00:32:15 the photograph. That's what it's like. And so
00:32:15 --> 00:32:17 you're talking here of just a few hundred or
00:32:17 --> 00:32:20 a few thousand stars held together.
00:32:21 --> 00:32:23 Now, that's been a puzzle for galaxy
00:32:23 --> 00:32:25 astronomers for a long time, because so few
00:32:25 --> 00:32:28 stars have so little mass that the
00:32:28 --> 00:32:30 galaxy shouldn't hold itself together. The
00:32:30 --> 00:32:33 galaxy should have dispersed over time. And
00:32:33 --> 00:32:35 for a long time, the best explanation people
00:32:35 --> 00:32:37 have had for this is that these are kind of
00:32:37 --> 00:32:40 dark matter galaxies, that they've got a
00:32:40 --> 00:32:42 massive dark matter agglomerated as a big
00:32:42 --> 00:32:45 dark matter halo, giving you enough mass
00:32:45 --> 00:32:47 there that we can't see to provide enough
00:32:47 --> 00:32:49 gravity to hold this very small number of
00:32:49 --> 00:32:51 stars together to keep them kind of whizzing
00:32:51 --> 00:32:54 around one another. And that kind of makes
00:32:54 --> 00:32:57 sense. We know that a lot of galaxies have
00:32:57 --> 00:32:58 big amounts of dark matter. In fact, all
00:32:58 --> 00:33:01 galaxies do. So you could almost have dark
00:33:01 --> 00:33:02 matter galaxies where you've got a clump of
00:33:02 --> 00:33:04 dark matter with very few stars. That kind of
00:33:04 --> 00:33:07 made sense. But the new story
00:33:08 --> 00:33:10 comes from improved observations of this
00:33:10 --> 00:33:12 galaxy, coupled with some computational
00:33:12 --> 00:33:14 numerical orbital modeling. And what they've
00:33:14 --> 00:33:16 found is that the stars near the middle of
00:33:16 --> 00:33:19 Segue one are, uh, going round the middle
00:33:19 --> 00:33:21 really, really quickly. Now, that allows us
00:33:21 --> 00:33:24 to take a measurement of the mass that is
00:33:24 --> 00:33:26 closer to the middle of the galaxy than those
00:33:26 --> 00:33:29 stars are. So anything feels
00:33:29 --> 00:33:31 gravity from the things closer to the middle
00:33:31 --> 00:33:34 than they do fundamentally. So what this
00:33:34 --> 00:33:36 means is by observing those stars that are in
00:33:36 --> 00:33:38 the middle of this galaxy, seeing them move,
00:33:38 --> 00:33:41 we can weigh the very innermost parts of that
00:33:41 --> 00:33:44 galaxy. And, um, what that tells us is that
00:33:44 --> 00:33:46 there is about 450 times
00:33:46 --> 00:33:48 more mass in the middle of that galaxy than
00:33:48 --> 00:33:51 the mass of our sun that we cannot see.
00:33:51 --> 00:33:51 Andrew Dunkley: Yeah.
00:33:51 --> 00:33:54 Jonti Horner: Which makes this a black hole, and it makes
00:33:54 --> 00:33:57 this a supermassive black hole, albeit a
00:33:57 --> 00:33:59 relatively low mass supermassive black hole
00:33:59 --> 00:34:01 compared to the one in the middle of Milky
00:34:01 --> 00:34:04 Way. Now, that in itself is not hugely
00:34:04 --> 00:34:06 unexpected. Pretty much all big galaxies have
00:34:06 --> 00:34:08 supermassive black holes, but we've not
00:34:08 --> 00:34:10 really seen them in teeny, tiny little
00:34:10 --> 00:34:13 galaxies like this before. Even
00:34:13 --> 00:34:16 more so, we've not really seen cases where
00:34:16 --> 00:34:18 there are galaxies whose black hole is, is
00:34:18 --> 00:34:20 more than 10 times the mass of all of the
00:34:20 --> 00:34:23 stars we can see in that galaxy. Feels like a
00:34:23 --> 00:34:25 really kind of weird imbalance. The black
00:34:25 --> 00:34:27 hole is more massive than the galaxy around
00:34:27 --> 00:34:29 it seems to suggest there would have been
00:34:29 --> 00:34:31 enough material for. But it's
00:34:32 --> 00:34:34 really weird from a few reasons, but really
00:34:34 --> 00:34:36 cool in the same way in that it's suggesting
00:34:36 --> 00:34:38 that this galaxy is not held together by dark
00:34:38 --> 00:34:40 matter, it's held together by this
00:34:40 --> 00:34:43 supermassive black hole at the middle. That
00:34:43 --> 00:34:45 maybe gives us an insight into how other
00:34:45 --> 00:34:48 ultra faint dwarf galaxies behave. This is
00:34:48 --> 00:34:50 probably not alone suggesting that there
00:34:50 --> 00:34:52 could be a lot more of these supermassive
00:34:52 --> 00:34:54 black holes out there in the cosmos than we
00:34:54 --> 00:34:56 thought. It also possibly is a bit of a
00:34:56 --> 00:34:59 hint that segue one was once a more massive
00:34:59 --> 00:35:01 galaxy. You know, if you think about the
00:35:01 --> 00:35:03 idea of the mass of this supermassive black
00:35:03 --> 00:35:05 hole and think, well, what kind of galaxy
00:35:05 --> 00:35:08 would normally expect to have a mass massive
00:35:08 --> 00:35:10 black hole like that in its center? How many
00:35:10 --> 00:35:13 stars should it have had? Maybe Segue one was
00:35:13 --> 00:35:15 like that in the past, but because it's so
00:35:15 --> 00:35:18 close to the Milky Way, it has been
00:35:18 --> 00:35:20 continually stripped and denuded of its stars
00:35:20 --> 00:35:23 from the outside inwards by our galaxy,
00:35:23 --> 00:35:25 essentially playing Pac man and gobbling it
00:35:25 --> 00:35:27 up going nom nom, nom, essentially, which is
00:35:27 --> 00:35:29 how galaxies grow. Galaxies grow through
00:35:29 --> 00:35:31 cannibalizing their neighbors. And we see
00:35:31 --> 00:35:33 that to an extent even with our largest
00:35:33 --> 00:35:35 satellite galaxies which have been disrupted
00:35:35 --> 00:35:37 and devoured a bit by the Milky Way and will
00:35:37 --> 00:35:39 eventually be gone. So there's a lot in this,
00:35:39 --> 00:35:42 it is a really fascinating story, albeit one,
00:35:42 --> 00:35:44 like I say, where I'm much further from being
00:35:44 --> 00:35:46 an expert than a lot of the other stuff that
00:35:46 --> 00:35:48 we talk about. Um, but you can find more
00:35:48 --> 00:35:50 about it online. And it is just a really cool
00:35:50 --> 00:35:53 little story, you know, it may well totally
00:35:53 --> 00:35:54 revolutionize our understanding of how the
00:35:54 --> 00:35:56 smallest galaxies work.
00:35:56 --> 00:35:59 Andrew Dunkley: Yes, indeed. Um, I, I, you kind of took the
00:35:59 --> 00:36:01 question out of my mouth, but I wasn't
00:36:01 --> 00:36:03 thinking of a neighboring galaxy stripping
00:36:03 --> 00:36:06 the, the stars away from segue. I was
00:36:06 --> 00:36:08 thinking the black hole might be devouring
00:36:08 --> 00:36:10 the stars within galaxy, but.
00:36:11 --> 00:36:13 Jonti Horner: Uh, you'd probably get a bit of that as well
00:36:13 --> 00:36:16 because the thing with the black hole is
00:36:16 --> 00:36:18 that uh, its gravitational pull is exactly
00:36:18 --> 00:36:20 the same as, ah, a group of objects of the
00:36:20 --> 00:36:23 same mass would have. Um, so it doesn't
00:36:23 --> 00:36:24 really pull things in any harder than the
00:36:24 --> 00:36:27 material that was there beforehand. But if
00:36:27 --> 00:36:28 you've got a neighboring galaxy like the
00:36:28 --> 00:36:31 Milky Way stirring up and um, numbing
00:36:31 --> 00:36:33 on this galaxy. It will also stir up the
00:36:33 --> 00:36:36 orbits of the stars in that galaxy, making
00:36:36 --> 00:36:38 some of them sufficiently elongated that they
00:36:38 --> 00:36:40 could fall onto that central black hole. So
00:36:40 --> 00:36:42 it's likely that the process of the Milky Way
00:36:42 --> 00:36:45 eating this galaxy has also led to the black
00:36:45 --> 00:36:47 hole in the middle of it getting a bit of a
00:36:47 --> 00:36:50 feed as well. A bit like the, um, white dwarf
00:36:50 --> 00:36:52 we were talking about last week, getting fed
00:36:52 --> 00:36:54 asteroids by the planets going around it.
00:36:54 --> 00:36:54 Same kind of idea.
00:36:55 --> 00:36:57 Andrew Dunkley: Yeah. It sounds like these stars, uh, in
00:36:57 --> 00:36:59 segue, are like a school of fish being
00:36:59 --> 00:37:02 attacked from all sides by predators, and
00:37:02 --> 00:37:05 eventually they'll just all be gone. Uh,
00:37:05 --> 00:37:07 yeah, you can read all about that@space.com
00:37:07 --> 00:37:10 or, or you can look at the paper that was
00:37:10 --> 00:37:12 published in astrophysical journal letters.
00:37:15 --> 00:37:18 3, 2, 1.
00:37:18 --> 00:37:19 Space nuts.
00:37:20 --> 00:37:22 I think we've got time for one more quick
00:37:22 --> 00:37:25 yarn, Jonti. And this is a story
00:37:25 --> 00:37:28 that I find fascinating, uh, and certainly
00:37:28 --> 00:37:31 relates to, um, the history of Earth in many
00:37:31 --> 00:37:33 ways. Uh, life after an
00:37:33 --> 00:37:36 asteroid impact. Now, a big
00:37:36 --> 00:37:39 asteroid conking the Earth, uh, can
00:37:39 --> 00:37:41 have cataclysmic effects, as
00:37:41 --> 00:37:44 we've seen in our history. And the,
00:37:44 --> 00:37:47 um, geology certainly backs that up.
00:37:47 --> 00:37:50 But, um, you know, fast forward a few
00:37:50 --> 00:37:53 gazillion years or whatever the number is,
00:37:53 --> 00:37:56 uh, and life does return. Um,
00:37:57 --> 00:37:59 they've been looking into this effect,
00:37:59 --> 00:37:59 haven't they?
00:38:00 --> 00:38:02 Jonti Horner: Now, this is some lovely research that's come
00:38:02 --> 00:38:05 out of Finland, where there's a beautiful
00:38:05 --> 00:38:07 impact crater. And I will apologize for
00:38:07 --> 00:38:08 anybody listening who speaks a beautiful
00:38:08 --> 00:38:11 Finnish language. Um, but there's a beautiful
00:38:11 --> 00:38:13 impact crater, uh, in Finland called Lake
00:38:13 --> 00:38:16 Lapijavi, which is an impact
00:38:16 --> 00:38:19 basin about 23 kilometers across that was
00:38:19 --> 00:38:22 formed 78 million years ago. It's a
00:38:22 --> 00:38:24 fairly hefty impact. It's the kind of thing
00:38:24 --> 00:38:26 that would be a bit of a drama if you lived
00:38:26 --> 00:38:28 in that part of the world, but not large
00:38:28 --> 00:38:30 enough to cause a global mass extinction
00:38:30 --> 00:38:32 event. So this is nothing like the one that
00:38:32 --> 00:38:35 killed the dinosaurs 65, 66 million
00:38:35 --> 00:38:37 years ago. This is a bit smaller, a bit more
00:38:37 --> 00:38:40 run of the mill. Now, there's a vague rough
00:38:40 --> 00:38:43 rule of thumb for impacts that if an impact
00:38:43 --> 00:38:45 happens, the size of the crater is about 19
00:38:45 --> 00:38:48 times the diameter of the impactor. So that
00:38:48 --> 00:38:50 tells me that the rock that hit to create
00:38:50 --> 00:38:53 this crater was probably a bit more than a
00:38:53 --> 00:38:56 kilometer across. So it's fairly substantial.
00:38:56 --> 00:38:59 That's the kind of impact that statisticians
00:38:59 --> 00:39:00 would argue would kill about a quarter of the
00:39:00 --> 00:39:03 world's human population. So not an
00:39:03 --> 00:39:05 extinction event, but a very bad day.
00:39:06 --> 00:39:09 The Team that have looked into this were
00:39:09 --> 00:39:11 really interested in how quickly
00:39:11 --> 00:39:14 life can reestablish itself in the
00:39:14 --> 00:39:16 rocks left behind from an impact. Because you
00:39:16 --> 00:39:19 have an impact happen, it superheats
00:39:19 --> 00:39:21 and sterilize the rocks. This would have
00:39:21 --> 00:39:23 sterilized the rocks in the impact site by
00:39:23 --> 00:39:25 heating them to more than 2 degrees C.
00:39:25 --> 00:39:28 That's 3 Fahrenheit for the American.
00:39:29 --> 00:39:31 Enough to kind of really sterilize the place
00:39:31 --> 00:39:34 it hit. It would have also, though, caused
00:39:34 --> 00:39:36 huge temperature gradients. It would have
00:39:36 --> 00:39:38 shattered the rocks, and it would have driven
00:39:38 --> 00:39:40 some interesting chemistry. So that means
00:39:40 --> 00:39:43 that, uh, once the clouds clear and there's
00:39:43 --> 00:39:45 time for things to settle down, you have a
00:39:45 --> 00:39:48 site here that is similar to the kind of
00:39:48 --> 00:39:50 conditions at, uh, locations where people
00:39:50 --> 00:39:52 think the first life on Earth may have got
00:39:52 --> 00:39:54 started. So there's some interesting
00:39:55 --> 00:39:58 what happened after. So to study that,
00:39:58 --> 00:40:01 this team have gone to the, um,
00:40:01 --> 00:40:03 store of drill cores that they can get to in
00:40:03 --> 00:40:06 Finland, where there are, uh, results,
00:40:06 --> 00:40:08 resources left behind from drilling
00:40:08 --> 00:40:11 expeditions that dug into this crater lake
00:40:11 --> 00:40:14 back in the 1980s, 1990s. Now this is a
00:40:14 --> 00:40:15 really good example, incidentally, of how
00:40:16 --> 00:40:19 legacy materials continue to have
00:40:19 --> 00:40:20 worth. And we've talked about that with the
00:40:21 --> 00:40:22 rocks from the Apollo missions, where they
00:40:22 --> 00:40:24 put a lot of them and preserve them for
00:40:24 --> 00:40:27 future use, because our technology improves
00:40:27 --> 00:40:29 all the time. So we can go back and look at
00:40:29 --> 00:40:30 things that were collected in the past and
00:40:30 --> 00:40:33 get new insights. So the team
00:40:33 --> 00:40:35 went back to these rocks that, uh, were dug
00:40:35 --> 00:40:38 up back in the 80s and 90s from drill
00:40:38 --> 00:40:41 cores that dug down all the way into this
00:40:41 --> 00:40:43 crater lake, into the floor of it. And they
00:40:43 --> 00:40:45 got 33 different drill core samples from
00:40:45 --> 00:40:48 different locations, looked at them
00:40:48 --> 00:40:49 essentially with a microscope and a pair of
00:40:49 --> 00:40:52 tweezers, and, um, plucked out a number of
00:40:52 --> 00:40:55 crystals of calcite and. And
00:40:55 --> 00:40:56 what was the other rock? There were a couple
00:40:56 --> 00:40:59 of things, calcite and pyrite, these rocks.
00:40:59 --> 00:41:01 And they use these for chemical analyses. And
00:41:01 --> 00:41:03 what they were interested in doing was
00:41:03 --> 00:41:06 getting a chronology of what happened in the
00:41:06 --> 00:41:09 years after this crater was formed.
00:41:09 --> 00:41:11 Now, similar work has been done before for
00:41:11 --> 00:41:13 the Rhys Crater in Germany and the Horton
00:41:13 --> 00:41:16 Crater in Canada, which suggested for those
00:41:16 --> 00:41:19 craters, the material under and around the
00:41:19 --> 00:41:21 crater cooled fairly quickly in geological
00:41:21 --> 00:41:24 times. For those craters, it cooled to about
00:41:24 --> 00:41:26 50 degrees C within a quarter of a million
00:41:26 --> 00:41:28 years. For the Reese Crater and for the
00:41:28 --> 00:41:30 Horton Crater in Canada for about 50
00:41:30 --> 00:41:32 years. So that cooled down fairly quickly.
00:41:33 --> 00:41:35 But this Finnish team, looking at these
00:41:35 --> 00:41:38 crystals from, um, this beautiful Lake
00:41:38 --> 00:41:41 Lapiavi, found that it took about 4 million
00:41:41 --> 00:41:44 years for the rocks to cool to 50 degrees C,
00:41:44 --> 00:41:47 which to me is astonishingly long time.
00:41:47 --> 00:41:49 That's very slow cool. And they're saying, we
00:41:49 --> 00:41:51 don't really understand why it took so long,
00:41:51 --> 00:41:52 but it's probably to do with the kind of
00:41:52 --> 00:41:54 rocks that were around and the kind of
00:41:54 --> 00:41:57 insulating properties. But what they did
00:41:57 --> 00:41:59 then was that they looked at the chemistry of
00:41:59 --> 00:42:01 these samples. They used mass spectrometry
00:42:01 --> 00:42:04 to look at basically the different isotopes
00:42:04 --> 00:42:07 of oxygen, carbon and sulfur in the rock.
00:42:07 --> 00:42:09 And they were doing that because microbes
00:42:09 --> 00:42:12 tend to process oxygen, carbon and sulfur and
00:42:12 --> 00:42:14 preferentially use one isotope over the
00:42:14 --> 00:42:16 other. So they can put this very distinctive
00:42:16 --> 00:42:19 chemical signature in to what's left behind.
00:42:19 --> 00:42:22 So the team were very much looking for, in
00:42:22 --> 00:42:25 addition to this cooling data, uh, the point
00:42:25 --> 00:42:27 at which you started to get the fingerprints
00:42:27 --> 00:42:29 of microbial life once again. And what they
00:42:29 --> 00:42:31 found was that, uh, 4 million year point when
00:42:31 --> 00:42:34 it cooled to about 50 degrees C. That was
00:42:34 --> 00:42:36 when you started to get life there again. And
00:42:36 --> 00:42:38 you started to get life that was turning
00:42:38 --> 00:42:41 sulfates into sulfides. I think that was
00:42:41 --> 00:42:43 the chemical terminology there.
00:42:44 --> 00:42:47 So there were processing materials and
00:42:47 --> 00:42:50 life had recolonized effectively, yes,
00:42:50 --> 00:42:53 sulfate into sulfide. That was after 4
00:42:53 --> 00:42:55 million years. 10 million years after that,
00:42:55 --> 00:42:57 the temperature dropped to about 30 degrees
00:42:57 --> 00:42:59 C. And you got the kind of microbes that make
00:42:59 --> 00:43:02 methane recolonize there. So you've now got
00:43:02 --> 00:43:04 this really nice chronological timeline of
00:43:04 --> 00:43:07 the recolonization of this site. And, um,
00:43:07 --> 00:43:09 they talk about this being a surprisingly
00:43:09 --> 00:43:12 quick time. To me, this is surprisingly slow
00:43:12 --> 00:43:14 given how much life we've got around on the
00:43:14 --> 00:43:17 Earth. So obviously they are more expert than
00:43:17 --> 00:43:20 I am, and I'm happy to take their
00:43:20 --> 00:43:21 word that this is a very quick
00:43:21 --> 00:43:24 recolonisation. But to me, it's interesting
00:43:24 --> 00:43:26 that it took it so long to cool down and for
00:43:26 --> 00:43:29 life to get going again afterwards. That's
00:43:29 --> 00:43:30 maybe telling us something about the kind of
00:43:30 --> 00:43:33 rocks the impact happened in. I don't know
00:43:33 --> 00:43:34 whether it could also be telling us something
00:43:34 --> 00:43:36 about the underlying geology of the area at
00:43:36 --> 00:43:39 the time. I'm just not expert enough. But
00:43:39 --> 00:43:42 it's a really fascinating study and it's a
00:43:42 --> 00:43:45 really good example of how the science of
00:43:45 --> 00:43:47 astrobiology, which is the science of the
00:43:47 --> 00:43:49 search for life elsewhere and the science of
00:43:49 --> 00:43:51 the question of how we learn in the universe
00:43:51 --> 00:43:53 and of how did life get started on Earth, all
00:43:53 --> 00:43:56 those really thorny questions. That's not a
00:43:56 --> 00:43:57 science that can be answered by just one
00:43:57 --> 00:44:00 discipline within astronomy. It's a really
00:44:00 --> 00:44:02 multidisciplinary area where you need people
00:44:02 --> 00:44:04 from an incredibly wide and diverse
00:44:06 --> 00:44:08 variety of areas in the sciences to come
00:44:08 --> 00:44:10 together because no one area has the
00:44:10 --> 00:44:11 knowledge and the skill set and the
00:44:11 --> 00:44:14 methodology and the samples to provide an
00:44:14 --> 00:44:17 answer on their own. It's why conference
00:44:17 --> 00:44:19 on this kind of topic are so, uh, fascinating
00:44:19 --> 00:44:21 to me because you go to talks from biology
00:44:21 --> 00:44:24 and chemistry and geophysics rather than just
00:44:24 --> 00:44:26 a lot of talks from astronomers on astronomy
00:44:26 --> 00:44:29 things. And um, this is the kind of study no
00:44:29 --> 00:44:30 one I work with directly would have been able
00:44:30 --> 00:44:33 to do. But these people have been able to
00:44:33 --> 00:44:35 drill down, do this awesome work and get some
00:44:35 --> 00:44:38 really fascinating results. So I'm looking
00:44:38 --> 00:44:40 forward to hearing more about this. And to be
00:44:40 --> 00:44:41 honest, this would almost set the scene for
00:44:41 --> 00:44:43 groups elsewhere in the world to start
00:44:43 --> 00:44:45 drilling down into other creators to see if
00:44:45 --> 00:44:47 we can get a feel for. Is this unusual? Is
00:44:47 --> 00:44:50 this common? And, um, the other two unusual,
00:44:50 --> 00:44:52 essentially, what's going on?
00:44:52 --> 00:44:54 Andrew Dunkley: Yeah, yeah. And uh, as you said, it's just
00:44:54 --> 00:44:57 great that historical studies,
00:44:57 --> 00:45:00 uh, being dredged back up and
00:45:00 --> 00:45:03 reused with modern, um,
00:45:03 --> 00:45:06 techniques and technology to, to uh, find out
00:45:06 --> 00:45:08 more. I think that's amazing. And uh,
00:45:08 --> 00:45:11 keeping rocks for future reference,
00:45:11 --> 00:45:14 um, when we can do things even
00:45:14 --> 00:45:17 better, um, may reveal more answers.
00:45:17 --> 00:45:19 So, ah, that's. That. That in itself is a
00:45:19 --> 00:45:22 terrific part of that particular story.
00:45:22 --> 00:45:25 Uh, and I was just wondering about the Tim
00:45:25 --> 00:45:28 Horton, the uh, Horton crater. It couldn't
00:45:28 --> 00:45:30 be named after Tim Horton the famous ice
00:45:30 --> 00:45:31 hockey player, could it?
00:45:32 --> 00:45:34 Jonti Horner: Ice hockey player. Are there not some famous
00:45:34 --> 00:45:37 pancakes? Uh, Tim Hortons.
00:45:37 --> 00:45:37 Andrew Dunkley: Yeah.
00:45:37 --> 00:45:38 Jonti Horner: Well, that's. Yeah.
00:45:38 --> 00:45:40 Andrew Dunkley: I mean you can't go to Canada and not go to
00:45:40 --> 00:45:41 Tim Hortons.
00:45:41 --> 00:45:43 Jonti Horner: Um, I think the spelling may be different.
00:45:43 --> 00:45:46 This is Horton. H, A, U, G, H. Right.
00:45:46 --> 00:45:48 So probably a distant relative.
00:45:48 --> 00:45:51 Andrew Dunkley: You never know. Uh, okay, that brings us to
00:45:51 --> 00:45:52 the end. Johnny, thank you so much.
00:45:53 --> 00:45:54 Jonti Horner: Matt, it's an absolute pleasure. Thank you.
00:45:55 --> 00:45:57 Andrew Dunkley: Good, uh, to see you. Jonti Horner, professor
00:45:57 --> 00:45:59 of Astrophysics at the University of Southern
00:45:59 --> 00:46:02 Queensland, joining us. Don't forget to visit
00:46:02 --> 00:46:05 us online, uh, at our website and check
00:46:05 --> 00:46:06 everything out. You can, uh, send us
00:46:06 --> 00:46:09 questions via the uh, website as well and
00:46:09 --> 00:46:11 check out the shop and maybe, uh, sign up to
00:46:11 --> 00:46:14 become a supporter. Whatever floats your
00:46:14 --> 00:46:16 boat. Uh, it's@Space
00:46:16 --> 00:46:19 Nutspodcast.com uh, and
00:46:19 --> 00:46:21 thanks to Huw in the studio who couldn't be
00:46:21 --> 00:46:22 with us today. I don't know if you know this
00:46:22 --> 00:46:25 about Huw, but he's a bit old. He doesn't use
00:46:25 --> 00:46:27 satnav, but he heard about this great new
00:46:27 --> 00:46:29 book and he's gone to a bookshop to try and
00:46:29 --> 00:46:32 get it today. Uh, it's, um. It's the
00:46:32 --> 00:46:33 Three Eye Atlas book.
00:46:35 --> 00:46:38 Um, I'm not going to tell him. And from me,
00:46:38 --> 00:46:39 Andrew Dunkley, thanks for your company.
00:46:39 --> 00:46:41 We'll see you on the next episode of Space
00:46:41 --> 00:46:43 Nuts. Bye. Bye. You'll be
00:46:43 --> 00:46:45 listening to the Space Nuts.
00:46:45 --> 00:46:48 Jonti Horner: Podcast, available at
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00:46:50 --> 00:46:53 iHeartRadio or your favorite podcast player.
00:46:53 --> 00:46:56 You can also stream on demand@bytes.com M.
00:46:57 --> 00:46:59 Andrew Dunkley: This has been another quality podcast
00:46:59 --> 00:47:01 production from bytes.com.