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Comets, Meteor Showers, and Mysteries of Uranus
In this engaging episode of Space Nuts, hosts Andrew Dunkley and Professor Jonti Horner explore the latest cosmic happenings, from the intriguing updates on interstellar comet 3I Atlas to the meteor showers lighting up our skies. They also delve into the fascinating story of Uranus's moon Ariel, which hints at a hidden ocean in its past, and the potential threat posed by asteroids influenced by Venus.
Episode Highlights:
- 3I Atlas Update: Andrew and Jonti discuss the latest observations of comet 3I Atlas, the third interstellar object observed, and its rapid journey through our solar system. With a close approach to the sun and Mars, the comet presents unique opportunities for data collection, despite being temporarily out of view from Earth.
- Exciting Comet Discoveries: The hosts share news about other comets, including C 2025 R2 Swan and A6 Lemon, highlighting their visibility and potential for amateur astronomers. They discuss the thrill of unexpected comet appearances and the importance of ongoing observation.
- Meteor Showers in Focus: Andrew and Jonti provide insights into the upcoming Orionid and Draconid meteor showers, including optimal viewing times and conditions. They discuss the rarity of meteor storms and the impact of moonlight on visibility.
- Ariel and Its Hidden Ocean: The episode takes a deeper look at Uranus's moon Ariel, revealing new findings that suggest the presence of a subsurface ocean in its past due to tidal heating. The discussion emphasizes the implications for understanding the potential for life beyond Earth.
- Venus and Asteroid Dynamics: The hosts conclude with a thought-provoking discussion about near-Earth asteroids that may be influenced by Venus's gravity, exploring how these objects could pose a long-term threat to Earth in the future.
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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: Hello again. Thanks for joining us on another
00:00:02 --> 00:00:04 episode of Space Nuts. Where we talk
00:00:04 --> 00:00:06 astronomy and space science. My name is
00:00:06 --> 00:00:08 Andrew Dunkley, your host, and it's good to
00:00:08 --> 00:00:11 have your company. Coming up on this
00:00:11 --> 00:00:14 episode, we will be doing an update on
00:00:14 --> 00:00:16 3i Atlas. Yes, I did pronounce it correctly.
00:00:16 --> 00:00:19 This week we'll also take, uh, a look at a
00:00:19 --> 00:00:21 few other comets. That are skimming around
00:00:21 --> 00:00:24 our, uh, region at the moment. Um,
00:00:24 --> 00:00:27 from comets to meteor showers that are making
00:00:27 --> 00:00:30 the news. And including the Draconids media
00:00:30 --> 00:00:33 shower. And the, uh, the
00:00:33 --> 00:00:36 moon of Uranus called Ariel, or
00:00:36 --> 00:00:38 Ariel is making the news. This is a really
00:00:38 --> 00:00:40 interesting story. And we'll be talking about
00:00:40 --> 00:00:43 asteroids being thrown at us by Venus
00:00:43 --> 00:00:45 in the next few thousand years. That's all
00:00:45 --> 00:00:48 coming up on this episode of space
00:00:48 --> 00:00:49 nuts.
00:00:49 --> 00:00:51 Jonti Horner: 15 seconds. Guidance is internal.
00:00:51 --> 00:00:54 10, 9. Ignition
00:00:54 --> 00:00:57 sequence start. Space nuts. 5, 4,
00:00:57 --> 00:00:59 3, 2, 1, 2, 3.
00:01:01 --> 00:01:02 Space nuts.
00:01:02 --> 00:01:04 Andrew Dunkley: Astronauts report at Neil's. Good.
00:01:06 --> 00:01:08 And as you would be aware, Professor Fred
00:01:08 --> 00:01:11 Watson is on the road or on a plane or
00:01:11 --> 00:01:14 on a bus or something. Uh, but he'll be away
00:01:14 --> 00:01:17 for several weeks. And in his
00:01:17 --> 00:01:19 stead is Professor Jonti Horner. Professor of
00:01:19 --> 00:01:22 astrophysics at the University of Southern
00:01:22 --> 00:01:24 Queensland, joining us again. Hello, Jonti.
00:01:24 --> 00:01:25 Jonti Horner: Good morning. How are you getting on?
00:01:25 --> 00:01:27 Andrew Dunkley: I'm getting on quite well. What about you?
00:01:28 --> 00:01:30 Jonti Horner: Um, oh, not too bad. I've never been a great
00:01:30 --> 00:01:33 fan of mornings, but I'm. I'm powering
00:01:33 --> 00:01:35 through and mainlining coffee and doing all
00:01:35 --> 00:01:36 those kind of healthy things to try and be
00:01:36 --> 00:01:37 coherent today.
00:01:38 --> 00:01:40 Andrew Dunkley: Mainlining m Coffee. I love that I should try
00:01:40 --> 00:01:42 it. But, uh, yeah, it's good to have you
00:01:42 --> 00:01:43 back. We've had a few people asking, you
00:01:43 --> 00:01:45 know, is he. Is he coming back? When.
00:01:45 --> 00:01:45 Jonti Horner: When will we.
00:01:45 --> 00:01:48 Andrew Dunkley: When will we see him again? Well, today. So
00:01:48 --> 00:01:50 great to have you back, Jonti. And, uh, and.
00:01:50 --> 00:01:52 And we're going to get straight into it
00:01:52 --> 00:01:54 because we got a lot to talk about.
00:01:54 --> 00:01:55 Jonti Horner: And.
00:01:55 --> 00:01:57 Andrew Dunkley: And we'll start off with a, um, an update on
00:01:58 --> 00:02:00 the comet. Uh, the Exo
00:02:00 --> 00:02:02 Comet, I suppose you'd call it. I don't know,
00:02:02 --> 00:02:04 3I Atlas. What's happening there?
00:02:05 --> 00:02:07 Jonti Horner: Well, it keeps getting lots and lots of
00:02:07 --> 00:02:09 media. And unfortunately, it keeps getting
00:02:09 --> 00:02:10 lots and lots of bad media as well. Thanks to
00:02:10 --> 00:02:12 a certain, uh, astronomer in the US who
00:02:13 --> 00:02:15 should probably remain nameless. And I wish
00:02:15 --> 00:02:18 he would remain nameless. It is the
00:02:18 --> 00:02:20 object, of course, that was found a few
00:02:20 --> 00:02:22 months ago. Speeding through the solar
00:02:22 --> 00:02:24 system. Much, much faster than a speeding
00:02:24 --> 00:02:26 bullet. Everybody uses a speeding bullet
00:02:26 --> 00:02:28 analogy. And in kind of solar system terms,
00:02:28 --> 00:02:30 bullets are really slow. So pretty much
00:02:30 --> 00:02:32 everything's faster than speeding bullet. But
00:02:32 --> 00:02:34 anyway, this thing's tearing through our
00:02:34 --> 00:02:37 solar system at such a speed that even when
00:02:37 --> 00:02:39 it gets so far away from the sun that it
00:02:39 --> 00:02:41 doesn't notice the sun anymore, it will still
00:02:41 --> 00:02:43 be going at more than 58 kilometers a second.
00:02:43 --> 00:02:46 Wow. Which is pretty remarkable all
00:02:46 --> 00:02:48 told. And it's been coming through the solar
00:02:48 --> 00:02:51 system on this slightly curved path
00:02:51 --> 00:02:53 because the sun will deflect it, it's going
00:02:53 --> 00:02:55 to change its direction coming through. And
00:02:55 --> 00:02:57 um, we've been getting a good view of it and
00:02:57 --> 00:03:00 it's the third ever interstellar object that
00:03:00 --> 00:03:03 we've got to see after Ummao MAU and Borisov.
00:03:03 --> 00:03:05 And it's a relatively small, fairly run of
00:03:05 --> 00:03:08 the mill comet, except for the fact that it's
00:03:08 --> 00:03:09 a comet that formed around a star that isn't
00:03:09 --> 00:03:10 the sun.
00:03:10 --> 00:03:11 Andrew Dunkley: Yeah.
00:03:11 --> 00:03:14 Jonti Horner: And that is pretty awesome and really
00:03:14 --> 00:03:16 fantastic. And because we found it so early,
00:03:17 --> 00:03:19 people have had a lot of time to study it.
00:03:19 --> 00:03:21 Get some really good data now, unfortunately
00:03:21 --> 00:03:23 from the Earth, it's now ducked out of view.
00:03:23 --> 00:03:26 It's passing closest to the sun on the 29th
00:03:26 --> 00:03:28 of this month. It's just come very close to
00:03:28 --> 00:03:30 Mars, which I'll come to in a minute, but
00:03:30 --> 00:03:32 it's swinging in towards its closest approach
00:03:32 --> 00:03:34 to the sun, getting more active, all looking
00:03:34 --> 00:03:36 good, but it's passing through on the far
00:03:36 --> 00:03:38 side of the sun. So it's now from the Earth's
00:03:38 --> 00:03:40 point of view, effectively lost to view for a
00:03:40 --> 00:03:43 couple of months. It's ducked out of sight
00:03:43 --> 00:03:45 and we can't really see it.
00:03:45 --> 00:03:47 Fortunately we're still going to get
00:03:47 --> 00:03:49 something of a view of it though, because as
00:03:49 --> 00:03:51 I just mentioned, it's just passed close to
00:03:51 --> 00:03:54 Mars. Came within about 30 million
00:03:54 --> 00:03:56 kilometers of Mars, very roughly speaking.
00:03:56 --> 00:03:59 Mhm. Which means if you were on Mars
00:03:59 --> 00:04:01 and you weren't worried about getting home,
00:04:01 --> 00:04:03 you still wouldn't be able to see it with the
00:04:03 --> 00:04:06 naked eye. It's genuinely quite a dim,
00:04:06 --> 00:04:08 faint comet from that point of view. So from
00:04:08 --> 00:04:10 Mars at the minute will probably be about
00:04:10 --> 00:04:12 factor of 100 times 2. Fancy with the naked
00:04:12 --> 00:04:14 eye, but we have all these spacecraft both
00:04:14 --> 00:04:17 orbiting Mars and on Mars surface that can
00:04:17 --> 00:04:20 look up and hopefully gather some data. So
00:04:20 --> 00:04:22 I saw actually a Reddit thread this morning
00:04:22 --> 00:04:24 claiming to show the first images from the
00:04:24 --> 00:04:27 Perseverance rover of the comet. Now
00:04:27 --> 00:04:29 I'm a little bit skeptical about this because
00:04:29 --> 00:04:31 I saw it on a Reddit thread that someone had
00:04:31 --> 00:04:33 posted a random image rather than on the NASA
00:04:33 --> 00:04:36 website. But at this close approach,
00:04:37 --> 00:04:39 there's been a concerted effort for both the
00:04:39 --> 00:04:41 European Space Agency's missions and the
00:04:41 --> 00:04:44 NASA spacecraft around and, uh, on Mars
00:04:44 --> 00:04:46 to actually try and get some data and try and
00:04:46 --> 00:04:48 get some images of this object. Now, we've
00:04:48 --> 00:04:51 not got any of that back yet, notwithstanding
00:04:51 --> 00:04:53 the claimed first image from perseverance.
00:04:54 --> 00:04:55 But this is going to be really, really useful
00:04:55 --> 00:04:57 because it allows us to peer at this object
00:04:58 --> 00:05:00 as it's getting closest to the sun, when it
00:05:00 --> 00:05:01 should technically be most active and
00:05:01 --> 00:05:03 therefore there'd be the most to learn about
00:05:03 --> 00:05:06 it. It's giving off the most gas, so there's
00:05:06 --> 00:05:08 the most to observe while it's hidden out of
00:05:08 --> 00:05:11 view. From our point of view, that's going to
00:05:11 --> 00:05:13 be really, really interesting. It's
00:05:13 --> 00:05:16 unfortunate that the shutdown in the US is
00:05:16 --> 00:05:17 happening at the minute. I mean, it's
00:05:17 --> 00:05:19 unfortunate for many, many reasons, but one
00:05:19 --> 00:05:21 of them is that a lot of staff working with
00:05:21 --> 00:05:24 NASA are currently furloughed and not able to
00:05:24 --> 00:05:26 work. And that will probably delay the
00:05:26 --> 00:05:28 results coming out. But it doesn't stop the
00:05:28 --> 00:05:30 spacecraft working. They just get on with it.
00:05:30 --> 00:05:32 So we will get to see the results at some
00:05:32 --> 00:05:35 point, but sadly not quite yet.
00:05:35 --> 00:05:38 And however we're going to get them. It's
00:05:38 --> 00:05:39 not the end of the story in terms of
00:05:39 --> 00:05:41 spacecraft looking at this thing though,
00:05:41 --> 00:05:43 because there's a couple of other spacecraft
00:05:43 --> 00:05:44 that will probably be able to snag some good
00:05:44 --> 00:05:47 photos as it moves further through the solar
00:05:47 --> 00:05:50 system. We've got the wonderful name Juice,
00:05:50 --> 00:05:52 which is a Jupiter Icy Moons explorer, which
00:05:52 --> 00:05:54 is currently winging its way out towards
00:05:54 --> 00:05:57 Jupiter. That will get a really good view of
00:05:57 --> 00:05:59 Three Eye Atlas over the next month or so
00:05:59 --> 00:06:01 as it goes one way and ATLAS goes the other
00:06:01 --> 00:06:04 way. Effectively not as close as Mars is to
00:06:04 --> 00:06:06 it. But the advantage is Juice will be
00:06:06 --> 00:06:09 inside, closer to the sun than the comet. So
00:06:09 --> 00:06:11 it will be looking away from the sun, get a
00:06:11 --> 00:06:13 decent view now, but it'll get an even better
00:06:13 --> 00:06:15 view in about a month's time when it's a bit
00:06:15 --> 00:06:17 further from the sun and can therefore
00:06:17 --> 00:06:18 observe for longer without overheating the
00:06:18 --> 00:06:21 spacecraft effectively. Yeah, so we're going
00:06:21 --> 00:06:22 to get that data, uh, and it's going to be
00:06:22 --> 00:06:24 really interesting to see what comes of this.
00:06:24 --> 00:06:26 I think it's going to be one of these cases
00:06:26 --> 00:06:28 where the data we get
00:06:29 --> 00:06:31 now from Mars, from Juice and all the data we
00:06:31 --> 00:06:34 gather from Earth will be yielding results
00:06:35 --> 00:06:36 that have been discussed for years to come.
00:06:37 --> 00:06:39 You know, we'll talk a little bit later about
00:06:39 --> 00:06:42 results about Jupiter's moon, about, sorry,
00:06:42 --> 00:06:45 about Uranus's. Moon aerial, which are, uh,
00:06:45 --> 00:06:47 based in part on observations that were taken
00:06:47 --> 00:06:49 40 years ago. So these things have a really
00:06:49 --> 00:06:52 long lifetime and it takes a long time for
00:06:52 --> 00:06:54 everybody to pick through them to get all of
00:06:54 --> 00:06:56 the wonderful juicy bits of gossip out,
00:06:56 --> 00:06:58 essentially all the wonderful information we
00:06:58 --> 00:07:00 can learn. So I think all this data is going
00:07:00 --> 00:07:02 to give us stuff that will be yielding
00:07:02 --> 00:07:05 awesome scientific results, new stories,
00:07:05 --> 00:07:08 new discussions on space nuts for 5, 10 years
00:07:08 --> 00:07:09 to come at least.
00:07:09 --> 00:07:12 Andrew Dunkley: Yeah, we're starting to see a lot of, um,
00:07:12 --> 00:07:14 that happen these days with new technology
00:07:14 --> 00:07:17 that you'd be able to reanalyze old data and
00:07:17 --> 00:07:20 come up with new concepts and sometimes new
00:07:20 --> 00:07:22 answers. Uh, another factor that you just
00:07:22 --> 00:07:25 mentioned was, uh, the photo on Reddit. Uh,
00:07:25 --> 00:07:28 we are now reaching a point where
00:07:28 --> 00:07:30 it's difficult to trust
00:07:31 --> 00:07:33 what's happening because of AI. And that's a
00:07:33 --> 00:07:36 discussion for another day. But I suppose the
00:07:36 --> 00:07:38 way around that is to go to reputable
00:07:38 --> 00:07:41 sources, which you mentioned NASA. So that's,
00:07:41 --> 00:07:44 yeah, it's, it's, it's getting, uh, like I
00:07:44 --> 00:07:46 spend a lot of time on social media and
00:07:46 --> 00:07:48 sometimes I look at an image and, or a video
00:07:48 --> 00:07:50 and go, hang on a minute. That,
00:07:50 --> 00:07:53 that's not. Yeah, but it looks so convincing.
00:07:53 --> 00:07:56 And that's, that's the problem. Uh, so that's
00:07:56 --> 00:07:58 three I atlas and we'll have more to talk
00:07:58 --> 00:08:00 about, uh, in the not too distant future. Few
00:08:00 --> 00:08:03 other comments that we might, uh, skim over.
00:08:03 --> 00:08:03 Jonti Horner: Boom, boom.
00:08:04 --> 00:08:06 Andrew Dunkley: Uh, with, um, within our,
00:08:06 --> 00:08:09 um, perimeters, I suppose, or our, um, uh,
00:08:09 --> 00:08:10 close to Earth.
00:08:10 --> 00:08:13 And the first One is, uh, C 2025
00:08:13 --> 00:08:13 R2.
00:08:13 --> 00:08:15 Jonti Horner: Swan. Yes.
00:08:15 --> 00:08:16 Andrew Dunkley: Uh, what's happening with that one?
00:08:16 --> 00:08:19 Jonti Horner: Quickly, this one was a big
00:08:19 --> 00:08:21 surprise. You know, people like me who are
00:08:21 --> 00:08:23 dead keen on going out and looking at comets,
00:08:23 --> 00:08:25 it's um, they're not really my kind of main
00:08:25 --> 00:08:27 professional focus. But there's something
00:08:27 --> 00:08:29 I've always loved since I was a little kid as
00:08:29 --> 00:08:30 an amateur astronomer. So I get really
00:08:30 --> 00:08:32 excited and hyped up when we get a good
00:08:32 --> 00:08:34 comet. So I've always got this kind of
00:08:34 --> 00:08:36 background awareness of what bright comets
00:08:36 --> 00:08:38 are coming up. I check a couple of really
00:08:38 --> 00:08:40 good websites I keep an eye on and I go to
00:08:40 --> 00:08:41 those every couple of weeks and just see if
00:08:41 --> 00:08:44 anything new's cropped up. And I'm also in a
00:08:44 --> 00:08:47 Facebook comic group, um, purely as an
00:08:47 --> 00:08:49 observer, I've got to say I don't really post
00:08:49 --> 00:08:51 in there because I'm not an expert and I see
00:08:51 --> 00:08:53 people posting in there when new discoveries
00:08:53 --> 00:08:56 are made. And normally when we get A comet
00:08:56 --> 00:08:58 that gets bright enough to be visible with
00:08:58 --> 00:08:59 the naked eye, we get at least a few months
00:08:59 --> 00:09:02 notice. We're getting better and better at
00:09:02 --> 00:09:04 finding these things further and further out.
00:09:04 --> 00:09:06 And that of course is going to get even more
00:09:06 --> 00:09:08 the case in the years to come with the
00:09:08 --> 00:09:11 incredible Vera Rubin Observatory. But if you
00:09:11 --> 00:09:13 go back to uh, kind of our, ah, parents or
00:09:13 --> 00:09:16 grandparents, generations, there was this
00:09:16 --> 00:09:18 real possibility for bright comet to just
00:09:18 --> 00:09:20 suddenly pop up out of nowhere and
00:09:20 --> 00:09:23 totally unexpected. A really good example of
00:09:23 --> 00:09:26 this is back in 1910 when everybody was
00:09:26 --> 00:09:28 hyped up, looking forward to an apparition of
00:09:28 --> 00:09:29 Comet Hallie, which appeared in May that
00:09:29 --> 00:09:32 year. And, um, was really good that time. It
00:09:32 --> 00:09:34 wasn't like 1986 when it was, to be honest,
00:09:34 --> 00:09:36 pretty ropey. It was pretty awful.
00:09:36 --> 00:09:37 Andrew Dunkley: I remember that.
00:09:37 --> 00:09:39 Jonti Horner: Yeah, that was the worst apparition of Comet
00:09:39 --> 00:09:42 Hallie for 2000 years. It will be better next
00:09:42 --> 00:09:43 time around. And just to make you and I feel
00:09:43 --> 00:09:45 old, it's now closer to the next apparition
00:09:45 --> 00:09:47 of Comet Hallie than the last. So it is
00:09:47 --> 00:09:50 nearer to 2061 than 1986. But
00:09:50 --> 00:09:53 back in 1910 everybody was hyped up and
00:09:53 --> 00:09:55 looking forward to Comet Hallie, which was
00:09:55 --> 00:09:57 going to put on a really good show. And then
00:09:57 --> 00:10:00 in January 1910, suddenly this comet was
00:10:00 --> 00:10:02 discovered by miners in the Transvaal when
00:10:02 --> 00:10:04 they were leaving the mine first thing in the
00:10:04 --> 00:10:06 morning in South Africa. Visible with a
00:10:06 --> 00:10:09 naked eye as bright as the brightest stars
00:10:09 --> 00:10:12 in the dawn sky before sunrise. Um, that
00:10:12 --> 00:10:15 was the Great Comet of 1910 and it was
00:10:15 --> 00:10:18 first visible when it was at perihelion
00:10:18 --> 00:10:20 because it sneaked up on us from the far side
00:10:20 --> 00:10:23 of the sun, effectively. Um, and now that was
00:10:23 --> 00:10:25 really quite close to the sun. It was visible
00:10:25 --> 00:10:28 in broad daylight for four days continuously.
00:10:28 --> 00:10:30 That's how it was one of the brightest comets
00:10:30 --> 00:10:31 of the 20th century.
00:10:32 --> 00:10:35 Which brings us to this one, 2025 R
00:10:35 --> 00:10:38 AH2 Swan. It is not as bright as
00:10:38 --> 00:10:40 a Great Comet of 1910. If it was, everybody
00:10:40 --> 00:10:42 would know about it. Yes, but back
00:10:42 --> 00:10:44 bizarrely about three weeks ago now,
00:10:45 --> 00:10:48 it went from being unknown to being the
00:10:48 --> 00:10:50 brightest comet in the night sky at the time
00:10:50 --> 00:10:53 it was discovered, which is unheard of. And
00:10:53 --> 00:10:55 it was almost naked eye visibility when it
00:10:55 --> 00:10:57 was discovered. Um, it was about magnitude 7
00:10:57 --> 00:11:00 and a half, so a factor of two to three times
00:11:00 --> 00:11:02 too faint to see with the naked eye. If
00:11:02 --> 00:11:04 you've got good eyesight and a really dark
00:11:04 --> 00:11:07 sky, it is still on the cusp
00:11:07 --> 00:11:09 of naked eye visibility. Some of the
00:11:09 --> 00:11:11 observations people are sending in of it
00:11:11 --> 00:11:12 report it being just Bright enough to see
00:11:12 --> 00:11:15 with the naked eye, others just a little bit
00:11:15 --> 00:11:17 too faint. This one is still
00:11:17 --> 00:11:19 better seen for people in the Southern
00:11:19 --> 00:11:21 hemisphere than the Northern hemisphere,
00:11:21 --> 00:11:23 which, it's seems to be a recurring theme for
00:11:23 --> 00:11:26 comets, but it's not always the case. And um,
00:11:26 --> 00:11:28 there's been some absolutely glorious photos
00:11:28 --> 00:11:30 coming of it, particularly in the first few
00:11:30 --> 00:11:32 days after it was discovered actually because
00:11:32 --> 00:11:34 it was discovered very near to the bright
00:11:34 --> 00:11:36 star Spiker in the constellation Virgo,
00:11:37 --> 00:11:40 near Mars, which was close to Spiker at
00:11:40 --> 00:11:42 the time. So you've got these glorious photos
00:11:42 --> 00:11:44 taken by some of the world's best comet
00:11:44 --> 00:11:47 photographers that show this beautiful comet
00:11:47 --> 00:11:49 with a lovely long iron tail next to the
00:11:49 --> 00:11:52 bright red star Mars, the bright blue, bright
00:11:52 --> 00:11:54 red planet Mars, sorry, bright blue star
00:11:54 --> 00:11:56 Spiker in Virgo. And uh, just putting on an
00:11:56 --> 00:11:59 incredible shot. And it stayed. It's not
00:11:59 --> 00:12:01 brightened much more because we discovered it
00:12:01 --> 00:12:03 when it was about as bright as it was going
00:12:03 --> 00:12:05 to get. But it's hovering on the edge of
00:12:05 --> 00:12:07 naked eye. Visibility will remain so for
00:12:07 --> 00:12:10 another few weeks because it's been moving
00:12:10 --> 00:12:12 away from the sun but towards the uh, Earth.
00:12:12 --> 00:12:14 And that's been balancing out effectively.
00:12:14 --> 00:12:16 Yeah, so that's been putting on a fabulous
00:12:16 --> 00:12:19 show particularly for astrophotographers down
00:12:19 --> 00:12:21 here in the Southern hemisphere. Seems that
00:12:21 --> 00:12:22 it's a comet that comes around about every
00:12:22 --> 00:12:24 thousand years or so. There were even
00:12:24 --> 00:12:26 suggestions that uh, the Earth could get a
00:12:26 --> 00:12:28 minor meteor shower from this comet
00:12:29 --> 00:12:31 around today or yesterday as we cross where
00:12:31 --> 00:12:34 the comet is going to be in a few weeks time.
00:12:34 --> 00:12:36 We cross its orbit today. That seems
00:12:36 --> 00:12:39 unlikely. Although, um, totally in passing, I
00:12:39 --> 00:12:41 have seen notifications that uh, there has
00:12:41 --> 00:12:43 been a brand new meteor shower observed for
00:12:43 --> 00:12:45 the very first time just over the last couple
00:12:45 --> 00:12:48 of weeks deep in our southern sky by
00:12:48 --> 00:12:50 these old sky camera networks. Now, probably
00:12:50 --> 00:12:53 not related at all, but it's interesting how
00:12:53 --> 00:12:54 all these things happen at once. So that's
00:12:54 --> 00:12:56 been a really interesting comment and it's a
00:12:56 --> 00:12:59 real reminder that we might not
00:12:59 --> 00:13:01 necessarily get really good warning the next
00:13:01 --> 00:13:03 time we get a really good comment. We
00:13:03 --> 00:13:05 probably will, especially with Vera Rubin.
00:13:05 --> 00:13:07 But there's always a possibility that
00:13:07 --> 00:13:09 something like this will come along where
00:13:09 --> 00:13:12 effectively due to the quirks of
00:13:12 --> 00:13:15 celestial mechanics, it approaches the sun
00:13:16 --> 00:13:19 swinging in on a curved orbit whilst
00:13:19 --> 00:13:21 hiding behind the sun from our point of view,
00:13:21 --> 00:13:24 staying within about 30 or 40 degrees of the
00:13:24 --> 00:13:25 sun in the sky, which means it's lost in the
00:13:25 --> 00:13:28 twilight glare and it only pops up, it swings
00:13:28 --> 00:13:31 around the sun to our side of the Sun. That's
00:13:31 --> 00:13:32 what's happened here that's what happened
00:13:32 --> 00:13:35 with the Great Comet in 1910 as well. It just
00:13:35 --> 00:13:37 happened to come in. In such a direction that
00:13:37 --> 00:13:40 as it moved, it stayed hidden. You know,
00:13:40 --> 00:13:42 bit like a small child playing peekaboo, I
00:13:42 --> 00:13:43 guess, kind of trying to stay hidden behind
00:13:43 --> 00:13:44 the thing as you move around.
00:13:44 --> 00:13:47 Andrew Dunkley: Yep. Okay, so that's Swan,
00:13:47 --> 00:13:50 and, uh, it's a. It's around for a little
00:13:50 --> 00:13:52 while longer. Uh, the other two that are in
00:13:52 --> 00:13:54 the news at the moment are a six lemon and
00:13:54 --> 00:13:57 R3 pan stars. What's happening there?
00:13:58 --> 00:14:00 Jonti Horner: A three lemon is one that was discovered back
00:14:00 --> 00:14:03 in January. So with these comet names,
00:14:03 --> 00:14:04 they're a little bit like a calendar that can
00:14:04 --> 00:14:06 tell you exactly when comets are found. So if
00:14:06 --> 00:14:08 you hear a Comet described as
00:14:08 --> 00:14:11 C2025A6, which is what
00:14:11 --> 00:14:14 we've got with Comet Lemon, the C tells you
00:14:14 --> 00:14:17 that it's a comet that is not a short period
00:14:17 --> 00:14:18 comet. It's not been seen at multiple
00:14:18 --> 00:14:21 apparitions. In this case, it's a comet with
00:14:21 --> 00:14:22 a period of more than a thousand years, but
00:14:22 --> 00:14:25 less than 10 years, probably about 1400.
00:14:25 --> 00:14:25 Andrew Dunkley: Mhm.
00:14:26 --> 00:14:28 Jonti Horner: The 2025 tells you it was discovered in the
00:14:28 --> 00:14:31 year 2025. And, um, the letter tells you
00:14:31 --> 00:14:33 which fortnight of the year it was discovered
00:14:33 --> 00:14:35 in. So the letter A here tells you the first
00:14:35 --> 00:14:37 two weeks of January. Right. So this comet
00:14:37 --> 00:14:39 was found right at the start of this year.
00:14:39 --> 00:14:41 And, um, it looked like it was going to be
00:14:41 --> 00:14:44 promising, but it wasn't heralded as
00:14:44 --> 00:14:46 being the equivalent of kind of Comet Atlas
00:14:46 --> 00:14:47 we had at the start of the year, or Comet
00:14:47 --> 00:14:49 Church in Shan Atlas last year, which were
00:14:49 --> 00:14:51 great comets. I'd classify them as they were
00:14:51 --> 00:14:54 really bright, easily visible from even
00:14:54 --> 00:14:56 brightly light polluted areas. They were
00:14:56 --> 00:14:59 really spectacular. This comet is currently
00:14:59 --> 00:15:01 best visible from the northern hemisphere. We
00:15:01 --> 00:15:03 don't really get to see it down south just
00:15:03 --> 00:15:05 yet, but it's swinging into perihelion. It's
00:15:05 --> 00:15:08 currently about the same brightness as the
00:15:08 --> 00:15:10 comet I just discussed, Comet R2, Swan.
00:15:11 --> 00:15:13 But this one is still brightening, and at its
00:15:13 --> 00:15:15 brightest it will, unless it does something
00:15:15 --> 00:15:18 unexpected. You know, comets famous saying
00:15:18 --> 00:15:20 says comets are like cats. They have tails
00:15:20 --> 00:15:22 and they do whatever they want. There's
00:15:22 --> 00:15:24 always a chance that this thing could undergo
00:15:24 --> 00:15:26 a fragmentation event and brighten by a
00:15:26 --> 00:15:28 factor of 100. That kind of thing does
00:15:28 --> 00:15:31 happen. Not necessarily all that likely,
00:15:31 --> 00:15:33 but if it continues brightening as it
00:15:33 --> 00:15:35 currently is, and it's behaving really well
00:15:35 --> 00:15:37 at the minute, it will probably at its
00:15:37 --> 00:15:39 brightest, be comparably bright to the
00:15:39 --> 00:15:41 Andromeda Galaxy. So Visible, uh, with the
00:15:41 --> 00:15:44 naked eye from dark sky sites, if you know
00:15:44 --> 00:15:46 where to look, but not visible from the
00:15:46 --> 00:15:49 middle of like polluted Sydney or Brisbane or
00:15:49 --> 00:15:51 somewhere like that, unless you've got
00:15:51 --> 00:15:53 binoculars. But it's going to be the
00:15:53 --> 00:15:56 brightest comet in our sky since Comet Atlas
00:15:56 --> 00:15:58 back in January. It's going to be a fairly
00:15:58 --> 00:16:00 good site. Again, there are some absolutely
00:16:00 --> 00:16:02 astonishingly good photographs coming in from
00:16:02 --> 00:16:03 the northern hemisphere of this. It's really
00:16:03 --> 00:16:06 photogenic and it's going to be above the
00:16:06 --> 00:16:08 threshold for naked eye visibility for about
00:16:08 --> 00:16:11 two months, building up to that peak and then
00:16:11 --> 00:16:13 fading away again. So it's going to be a
00:16:13 --> 00:16:15 really good site. Currently, it is best
00:16:15 --> 00:16:18 visible from the Northern hemisphere, I
00:16:18 --> 00:16:20 believe it's currently quite high in the
00:16:20 --> 00:16:23 northern sky, edging towards the,
00:16:23 --> 00:16:25 the southern outskirts of Ursa Major, that
00:16:25 --> 00:16:27 kind of part of the sky. But it's then going
00:16:27 --> 00:16:30 to start ducking southwards and by the
00:16:30 --> 00:16:32 time it's at its brightest, which is going to
00:16:32 --> 00:16:34 be the start of November, it will be visible
00:16:34 --> 00:16:37 from both hemispheres, albeit I think,
00:16:37 --> 00:16:39 easier to see from the Northern hemisphere
00:16:39 --> 00:16:41 still. But this is going to be a naked eye
00:16:41 --> 00:16:44 comet. Naked eye caveat,
00:16:44 --> 00:16:46 not that spectacular, but visible if you know
00:16:46 --> 00:16:49 where to look. Um, for those who go out and
00:16:49 --> 00:16:51 look at comets and that therefore it's
00:16:51 --> 00:16:53 probably a little bit brighter than Pons
00:16:53 --> 00:16:56 Brooks was last year. Pons Brooks was, you
00:16:56 --> 00:16:58 know, captors of Devil's Comet and all those
00:16:58 --> 00:17:00 kind of weird names that these things seem to
00:17:00 --> 00:17:02 get in the media. If you saw that one with
00:17:02 --> 00:17:05 the naked eye, this comet should be a bit
00:17:05 --> 00:17:07 brighter than that and a bit easier to spot.
00:17:07 --> 00:17:08 But it's probably a really good opportunity
00:17:08 --> 00:17:11 for people to dust off their camera gear, do
00:17:11 --> 00:17:13 a little bit of planning and go take some
00:17:13 --> 00:17:16 photos. So it's going to be pretty good. And
00:17:16 --> 00:17:18 nobody complains about a naked eye comet.
00:17:18 --> 00:17:18 Andrew Dunkley: No, they don't.
00:17:18 --> 00:17:21 And R3 pan starrs, I'm guessing from its
00:17:21 --> 00:17:23 name, is a very recent discovery.
00:17:23 --> 00:17:25 Jonti Horner: It is. This was discovered very, very
00:17:25 --> 00:17:27 recently and we still know surprisingly
00:17:27 --> 00:17:30 little about it, actually. I mean, if I go to
00:17:30 --> 00:17:32 the place I normally look at the light curves
00:17:32 --> 00:17:34 for these comets from where it aggregates all
00:17:34 --> 00:17:36 the observations and tries to predict forward
00:17:36 --> 00:17:38 how bright it's going to be. That has a
00:17:38 --> 00:17:41 really nice light curve for this object, but
00:17:41 --> 00:17:44 it has no observations on the light curve at
00:17:44 --> 00:17:46 the minute. So this is very new. It is still
00:17:46 --> 00:17:48 very faint. I mean, with this one we're
00:17:48 --> 00:17:50 talking about something that's probably a
00:17:50 --> 00:17:53 factor of 50 times too fancy with the
00:17:53 --> 00:17:56 naked eye at uh, the minute, very recent
00:17:56 --> 00:17:58 discovery by that wonderful automated
00:17:58 --> 00:18:00 search facility on the top of Hawaii Pan
00:18:00 --> 00:18:03 starts. The reason this has got my attention
00:18:03 --> 00:18:05 is that it is going to pass
00:18:05 --> 00:18:08 incredibly close to the line between the sun
00:18:08 --> 00:18:11 and the Earth, uh, which we've seen with
00:18:11 --> 00:18:13 those two great comets we had in the last 12
00:18:13 --> 00:18:15 months. And when you get an object that
00:18:15 --> 00:18:17 passes directly between the sun and the
00:18:17 --> 00:18:19 Earth, if it happens to be a particularly
00:18:19 --> 00:18:21 dusty comet and shedding a lot of dust,
00:18:21 --> 00:18:23 there's a phenomenon called forward
00:18:23 --> 00:18:25 scattering which we in Australia are fairly
00:18:25 --> 00:18:27 familiar with on, um, dusty days because near
00:18:27 --> 00:18:29 sunset the sky is unbearably bright and it's
00:18:29 --> 00:18:32 awful driving west at sunset, which is
00:18:32 --> 00:18:33 something people in Toowoomba, um, are very
00:18:33 --> 00:18:35 familiar with because our roads are kind of
00:18:35 --> 00:18:37 east, west, north, south. And so around the
00:18:37 --> 00:18:40 equinoxes you drive towards the sunset and
00:18:40 --> 00:18:43 get snow blind effects. Skiers are familiar
00:18:43 --> 00:18:45 with it for the same reason. You know, on a
00:18:45 --> 00:18:47 kind of day where there's a lot of small ice
00:18:47 --> 00:18:49 crystals in the air, the sky can be very
00:18:49 --> 00:18:52 bright in the direction of the Sun. This
00:18:52 --> 00:18:54 phenomenon of forward scattering can make
00:18:54 --> 00:18:57 comets brighten by more than a
00:18:57 --> 00:18:59 factor of 100, depending on the orientation
00:19:00 --> 00:19:03 when they're close to the sun in the sky, um,
00:19:03 --> 00:19:04 or when they're close to that line between
00:19:04 --> 00:19:07 the Earth and Sun. Now this object Pan stars,
00:19:07 --> 00:19:09 it looks like it's a fairly small comet, but
00:19:09 --> 00:19:11 we've not got much information about it yet.
00:19:11 --> 00:19:14 But its orbit's fairly well constrained and
00:19:14 --> 00:19:16 it is going to come very close to the sun in
00:19:16 --> 00:19:18 the sky from our point of view. For a time,
00:19:18 --> 00:19:19 people were even suggesting it could transit
00:19:19 --> 00:19:21 the disk of the sun, um, even though we
00:19:21 --> 00:19:22 wouldn't see anything because it'd be too
00:19:22 --> 00:19:25 small to be visible, it could pass so
00:19:25 --> 00:19:26 perfectly between us, it will cross across
00:19:26 --> 00:19:28 the disc of the sun from our point of view.
00:19:29 --> 00:19:32 What that all means is that if this
00:19:32 --> 00:19:34 comet becomes fairly active,
00:19:35 --> 00:19:37 there's a chance that it could become quite
00:19:37 --> 00:19:40 bright in April next year. Now,
00:19:40 --> 00:19:43 how bright is utterly unknown at the
00:19:43 --> 00:19:44 minute, but it's worth flagging up because
00:19:44 --> 00:19:46 it's an interesting one. The light curve I'm
00:19:46 --> 00:19:49 looking at as I talk about this is, in
00:19:49 --> 00:19:51 all honesty, with the lack of observations,
00:19:51 --> 00:19:53 we've got something of a fiction. It could
00:19:53 --> 00:19:54 get a lot brighter than this or fainter than
00:19:54 --> 00:19:57 this. But it suggests that without this
00:19:57 --> 00:19:59 forward scattering process, this comet will
00:19:59 --> 00:20:01 be too small to be visible with a naked eye.
00:20:01 --> 00:20:03 But with forward scattering, it could get as
00:20:03 --> 00:20:06 bright or brighter than Comet Lemon. So it
00:20:06 --> 00:20:08 could get brighter than the andromeda Galaxy,
00:20:08 --> 00:20:09 albeit when it's quite close to the sun in
00:20:09 --> 00:20:12 the sky and therefore it could be visible to
00:20:12 --> 00:20:14 the naked eye for a week or two. Now if it
00:20:14 --> 00:20:16 turns out to be a larger, more substantial
00:20:16 --> 00:20:19 comet than those first observations suggests,
00:20:19 --> 00:20:21 that all ramps up and it could be even
00:20:21 --> 00:20:24 better. There's a small chance I'd say that
00:20:24 --> 00:20:25 this thing could be visible with the naked
00:20:25 --> 00:20:28 eye in April, but it's just again one, once
00:20:28 --> 00:20:31 again a reminder of as we get better at uh,
00:20:31 --> 00:20:33 these kind of all sky surveys, we're going to
00:20:33 --> 00:20:36 find interesting comets earlier. We're
00:20:36 --> 00:20:38 eventually going to get to the point where an
00:20:38 --> 00:20:40 object like Comet R2 Swan that we've got at
00:20:40 --> 00:20:43 the minute can't surprise us because we'll
00:20:43 --> 00:20:44 get our telescopes good enough that we'd find
00:20:44 --> 00:20:46 it a really long way away before it hides
00:20:46 --> 00:20:49 behind the sun. And so uh,
00:20:49 --> 00:20:51 you know, it wouldn't surprise me if the next
00:20:51 --> 00:20:53 great comet was found months ahead of time
00:20:53 --> 00:20:55 rather than weeks ahead of time. And we get
00:20:55 --> 00:20:58 prior artists, um, and because it's
00:20:58 --> 00:21:01 observed that early, we might have this level
00:21:01 --> 00:21:03 of uncertainty in an object that's a bit
00:21:03 --> 00:21:06 brighter than this and people will either
00:21:06 --> 00:21:09 be calm and cautious or hyperbolic
00:21:09 --> 00:21:11 and excited. And then we get to see that's
00:21:11 --> 00:21:12 part of the fun of it.
00:21:13 --> 00:21:14 Andrew Dunkley: M. Yeah, indeed.
00:21:14 --> 00:21:16 Okay, so plenty, uh, or potentially plenty
00:21:16 --> 00:21:19 for skywatchers to look forward to and a lot
00:21:19 --> 00:21:21 going on at the moment. And while you've been
00:21:21 --> 00:21:22 talking about those comments, I've been
00:21:22 --> 00:21:24 looking up some of the media pictures and
00:21:24 --> 00:21:26 it's interesting to see that um, the quality
00:21:26 --> 00:21:29 of the outlet dictates the
00:21:30 --> 00:21:32 genuineness uh, of the photo. Let me just say
00:21:32 --> 00:21:35 that this, this is Space
00:21:35 --> 00:21:37 Nuts with Andrew Dunkley and John de Horner.
00:21:38 --> 00:21:40 Jonti Horner: 3, 2, 1.
00:21:40 --> 00:21:43 Andrew Dunkley: Space nuts from comets to
00:21:43 --> 00:21:46 meteor showers. And there's uh, there's a
00:21:46 --> 00:21:47 few making the news at the moment.
00:21:47 --> 00:21:50 Jonti Horner: Jonti, there are. It's a good time of the
00:21:50 --> 00:21:53 year for meteor observers, um, particularly
00:21:53 --> 00:21:55 in the Northern hemisphere. Whilst comets
00:21:55 --> 00:21:57 seem to get a slightly better deal in the
00:21:57 --> 00:21:59 Southern hemisphere over long periods of
00:21:59 --> 00:22:01 time. The Northern hemisphere gets the better
00:22:01 --> 00:22:03 of the meteor showers. We're getting a fair
00:22:03 --> 00:22:05 bit of coverage already about the Orionid
00:22:05 --> 00:22:08 meteor shower which is already
00:22:08 --> 00:22:10 active but is building to a peak around the
00:22:10 --> 00:22:13 20th, 21st of October. Now the
00:22:13 --> 00:22:16 Orionids are uh, a meteor shower that's
00:22:16 --> 00:22:18 caused by Comet Hallie which has been
00:22:18 --> 00:22:19 whizzing around the sun on its current
00:22:20 --> 00:22:22 roughly 76 year orbit for thousands, if not
00:22:22 --> 00:22:25 tens of thousands of years. It's a very big
00:22:25 --> 00:22:27 cometary nucleus Laying down lots of dust.
00:22:27 --> 00:22:30 And that dust has spread out to such an
00:22:30 --> 00:22:32 extent that every year the Earth, uh, crosses
00:22:32 --> 00:22:34 through that tube of dust left behind by the
00:22:34 --> 00:22:36 comet on two separate occasions. Yeah, we get
00:22:36 --> 00:22:39 the Etraquarian meteor shower in May, which
00:22:39 --> 00:22:42 is one of the year's best meteor showers. But
00:22:42 --> 00:22:44 it's really hard to see. Um, you need to be
00:22:44 --> 00:22:46 up in a couple of hours before dawn to see
00:22:46 --> 00:22:47 anything. And that favors Southern Hemisphere
00:22:47 --> 00:22:49 observers. So it's not as well known, not as
00:22:49 --> 00:22:52 well observed. Then you have the Orionids
00:22:52 --> 00:22:55 in October. And, um, the Orionids are not as
00:22:55 --> 00:22:58 good as the Aquarids. They're probably in the
00:22:58 --> 00:23:00 second kind of tier of meteor showers. So
00:23:00 --> 00:23:02 you've got the big three in the form of the
00:23:02 --> 00:23:05 Quadrantids in January, the Perseids in
00:23:05 --> 00:23:07 August, and, um, the Geminids, which are the
00:23:07 --> 00:23:09 best meteor shower in a typical year in
00:23:09 --> 00:23:11 December. And they're reliable every
00:23:11 --> 00:23:13 year, uh, really good rates. And they're the
00:23:13 --> 00:23:15 ones that, uh, you tell your friends who are
00:23:15 --> 00:23:17 not into astronomy to go out and look at
00:23:17 --> 00:23:18 because they're good enough that someone
00:23:18 --> 00:23:20 who's not that excited already will still see
00:23:20 --> 00:23:23 a good show. The Orion into the, like, the
00:23:23 --> 00:23:25 next tier down, they are. If you're someone
00:23:25 --> 00:23:27 who's really keen on astronomy and you're
00:23:27 --> 00:23:29 happy to spend an hour or two sitting out in
00:23:29 --> 00:23:31 the middle of the night, you'll see a
00:23:31 --> 00:23:33 reasonable number and they're lovely to see,
00:23:33 --> 00:23:35 but they're probably not active enough that
00:23:35 --> 00:23:37 someone who's not that keen on astronomy will
00:23:37 --> 00:23:40 get a real buzz out of it, if that makes
00:23:40 --> 00:23:42 sense. So if you're somewhere in
00:23:42 --> 00:23:44 Northern Europe and North America, where
00:23:44 --> 00:23:47 you've got long dark nights at the minute and
00:23:47 --> 00:23:49 you were out all night, you might see 15 or
00:23:49 --> 00:23:52 20 of these per hour in the early morning
00:23:52 --> 00:23:54 hours in late October, you know,
00:23:54 --> 00:23:57 the kind of 19th, 20th, 21st, 22nd
00:23:58 --> 00:24:00 from Australia, the rates are a bit lower
00:24:00 --> 00:24:02 because a point in the sky these meters come
00:24:02 --> 00:24:04 from the radiant is lower in the sky at its
00:24:04 --> 00:24:07 highest. And geometry means, therefore, the
00:24:07 --> 00:24:09 same number of meteors are spread over a
00:24:09 --> 00:24:11 larger volume of atmosphere. So you'll see a
00:24:11 --> 00:24:13 smaller number of them from wherever you're
00:24:13 --> 00:24:15 sat. But you can still see if you're in kind
00:24:15 --> 00:24:18 of the top end of Australia, I'd say 10 or 15
00:24:18 --> 00:24:19 per hour. If you're down at the southern end,
00:24:20 --> 00:24:21 a little bit less than that. The further
00:24:21 --> 00:24:23 south you go, the worse it'll get. This year,
00:24:23 --> 00:24:25 though, is particularly good because it's New
00:24:25 --> 00:24:28 Moon. And so what that means is you've Got
00:24:28 --> 00:24:30 ideal viewing conditions. You don't have
00:24:31 --> 00:24:34 the glowing orb of doom scattering light in
00:24:34 --> 00:24:36 the sky and basically blocking the view of
00:24:36 --> 00:24:38 all the interesting stuff. I've always been,
00:24:38 --> 00:24:40 as an amateur astronomer that side of my
00:24:40 --> 00:24:42 life. Frustrated by the Moon because it stops
00:24:42 --> 00:24:44 us seeing all the good stuff. But, um, that's
00:24:44 --> 00:24:47 particularly true of meteor showers. That's
00:24:47 --> 00:24:49 iron. It's. They're getting a lot of
00:24:49 --> 00:24:51 coverage. Um, what I would say with it is
00:24:51 --> 00:24:54 unless you're a really avid meteor observer
00:24:54 --> 00:24:56 or unless you're going out anyway, don't buy
00:24:56 --> 00:24:59 into the hype. There'll be a lot of overblown
00:24:59 --> 00:25:00 articles. And I'm seeing them already from
00:25:00 --> 00:25:02 some of the less reputable media outlets
00:25:02 --> 00:25:05 online. Talking about the skies falling. And
00:25:05 --> 00:25:06 this will be the best thing you'll ever see.
00:25:06 --> 00:25:08 And that just sets people up for
00:25:08 --> 00:25:10 disappointment. So it was a little bit sad.
00:25:10 --> 00:25:12 But if you do want to go out and see the
00:25:12 --> 00:25:15 Orionids. Around the 20th of October
00:25:15 --> 00:25:18 is the best time. Unlike
00:25:18 --> 00:25:21 most meteor showers, the Orionids and the
00:25:21 --> 00:25:23 Aquarids in May, both these Comet Hallie
00:25:23 --> 00:25:26 meteor showers have quite a broad maximum. So
00:25:26 --> 00:25:28 if it's cloudy on the night of the peak.
00:25:28 --> 00:25:30 You'll still get a decent show for two or
00:25:30 --> 00:25:32 three nights either side. It's a much flatter
00:25:32 --> 00:25:34 plateau, effectively. And they do sometimes
00:25:34 --> 00:25:37 throw a bit of a surprise our way. They are
00:25:37 --> 00:25:39 fast meteors, um, have a tendency to produce
00:25:39 --> 00:25:41 quite a few bright ones as well. And you see
00:25:41 --> 00:25:43 them best if you're out in the early hours of
00:25:43 --> 00:25:45 the morning, after midnight. That's kind of
00:25:45 --> 00:25:46 the best time. With the best rates being just
00:25:46 --> 00:25:49 before dawn. But they are visible from about
00:25:49 --> 00:25:50 10:30 at night.
00:25:51 --> 00:25:51 Andrew Dunkley: Okay.
00:25:51 --> 00:25:54 Now, um, the other meteor shower
00:25:54 --> 00:25:56 that you wanted to talk about, uh, that could
00:25:56 --> 00:25:58 be worth a look is the Draconids. I don't
00:25:58 --> 00:25:59 know much about this one.
00:26:00 --> 00:26:02 Jonti Horner: This is a really fun little shower. Because
00:26:02 --> 00:26:05 it's illustrative of how meteor showers are
00:26:05 --> 00:26:08 really changeable over time. The
00:26:08 --> 00:26:11 way a meteor shower forms is you've got a
00:26:11 --> 00:26:13 comet going around the sun. And a comet is a
00:26:13 --> 00:26:15 dirty snowball, a snowy dirt ball. So when
00:26:15 --> 00:26:17 it's far from the sun, it just looks like an
00:26:17 --> 00:26:19 asteroid. Nothing's happening. It's a tiny
00:26:19 --> 00:26:21 speck of light, few kilometers across.
00:26:22 --> 00:26:24 When it gets close to the sun, the surface
00:26:24 --> 00:26:26 gets hot. And all the ices on the surface
00:26:26 --> 00:26:29 sublime. They turn to gas, erupt from the
00:26:29 --> 00:26:32 surface in jets. Because they only sublime if
00:26:32 --> 00:26:34 they're exposed to enough heat to get off.
00:26:34 --> 00:26:36 And a lot of the surface is caked up and
00:26:36 --> 00:26:38 blocked up. So you get these little active
00:26:38 --> 00:26:40 areas casting jets of material into space
00:26:41 --> 00:26:43 and carrying with them a lot of dust.
00:26:44 --> 00:26:46 So comets, when they're closer to the sun,
00:26:46 --> 00:26:47 shed gas and dust. And that's why they get
00:26:47 --> 00:26:49 the coma and the tails that make them
00:26:49 --> 00:26:51 brighter and easier to see and so
00:26:51 --> 00:26:54 spectacular. The dust that they shed
00:26:54 --> 00:26:56 is ejected from them at, uh, speeds of
00:26:56 --> 00:26:59 meters or tens of meters or maybe hundreds of
00:26:59 --> 00:27:02 meters per second. But typically 1 or
00:27:02 --> 00:27:04 10 meters a second while the comet's going
00:27:04 --> 00:27:06 around the sun at a speed measured in tens of
00:27:06 --> 00:27:09 kilometers per second. So that means that the
00:27:09 --> 00:27:10 dust will end up moving on essentially the
00:27:10 --> 00:27:13 same orbit as the comet. It won't move on to
00:27:13 --> 00:27:16 a drastically different orbit. The
00:27:16 --> 00:27:18 smallest grains of dust are blown away by the
00:27:18 --> 00:27:20 sun and the solar wind and radiation
00:27:20 --> 00:27:22 pressure. But the bigger bits of dust kind of
00:27:22 --> 00:27:24 stay moving around the sun on an orbit
00:27:24 --> 00:27:26 similar to that of the comet. But because of
00:27:26 --> 00:27:29 that ejection speed, some of the dust grains
00:27:29 --> 00:27:31 move on orbits that have a shorter period
00:27:31 --> 00:27:33 than the comet. Some move on periods slightly
00:27:33 --> 00:27:35 longer than the comet. So over time, they
00:27:35 --> 00:27:37 spread out ahead and behind the comet in its
00:27:37 --> 00:27:40 orbit until eventually the orbit is clogged
00:27:40 --> 00:27:42 with dust all the way around. So if you go
00:27:42 --> 00:27:44 across the orbit when the comet isn't there,
00:27:44 --> 00:27:45 you'll still run into dust because there'll
00:27:45 --> 00:27:48 always be something there. Then when you
00:27:48 --> 00:27:50 get the Earth, uh, running across one of
00:27:50 --> 00:27:52 these orbits, if they intersect in space
00:27:52 --> 00:27:54 every year, we'll go through that dust and
00:27:54 --> 00:27:56 we'll get a meteor shower. Now, comets,
00:27:56 --> 00:27:59 orbits are constantly changing. And that's
00:27:59 --> 00:28:01 particularly true of a family of comets we
00:28:01 --> 00:28:03 call the Jupiter family comets, or the short
00:28:03 --> 00:28:05 period comets. These are comets captured by
00:28:05 --> 00:28:06 Jupiter, flung into the inner solar system,
00:28:07 --> 00:28:09 moving on orbits that are kind of five, six,
00:28:09 --> 00:28:12 seven years long. So you'll get a comet
00:28:12 --> 00:28:14 will be nudged, dropped onto a new orbit, and
00:28:14 --> 00:28:17 it will start laying down dust on that orbit.
00:28:17 --> 00:28:18 But it might not be there particularly long
00:28:18 --> 00:28:20 until it's flung onto a different orbit. The
00:28:20 --> 00:28:22 orbit's constantly being tweaked and changed.
00:28:23 --> 00:28:25 That means that you get these dust trails
00:28:25 --> 00:28:27 that build up over time, but you can even
00:28:27 --> 00:28:29 orphan them. You can take the comet away and
00:28:29 --> 00:28:30 the dust trail remains, which is the case of
00:28:30 --> 00:28:33 some of our meteor showers. It also means,
00:28:33 --> 00:28:36 uh, that when a comet is relatively newly
00:28:36 --> 00:28:39 placed onto a given orbit, that
00:28:39 --> 00:28:41 orbit won't have fully clogged up with dust
00:28:41 --> 00:28:43 yet. So most years when we cross where that
00:28:43 --> 00:28:45 orbit will be, we'll get very few meteors
00:28:45 --> 00:28:47 because the dust just hasn't had time to
00:28:47 --> 00:28:50 spread out yet. But if you catch it on a year
00:28:50 --> 00:28:52 when the comet is relatively nearby, you
00:28:52 --> 00:28:55 might run into dust. The final little
00:28:55 --> 00:28:57 piece of all this puzzle that I'm talking
00:28:57 --> 00:28:59 through is that dust, uh, that was emitted,
00:28:59 --> 00:29:01 uh, at the last few apparitions of the comet
00:29:02 --> 00:29:04 will not have had time to spread out a huge
00:29:04 --> 00:29:06 amount laterally. So you get these almost
00:29:06 --> 00:29:09 like javelins. Very thin, very long
00:29:09 --> 00:29:12 filaments of dust that are much
00:29:12 --> 00:29:15 denser. And if the Earth goes through one of
00:29:15 --> 00:29:16 those, suddenly, you can get a really big
00:29:16 --> 00:29:18 meteor outburst. And, um, instead of getting
00:29:18 --> 00:29:20 one or two meters an hour, you might get
00:29:20 --> 00:29:23 hundreds or thousands. Wow. So that's a
00:29:23 --> 00:29:24 lengthy bit of background exposition to kind
00:29:24 --> 00:29:26 of explain what's happening in the background
00:29:26 --> 00:29:29 here. The Draconig meteor shower is one that
00:29:29 --> 00:29:32 kind of shot to fame in the year, uh, 1933,
00:29:32 --> 00:29:34 when there was an incredible meteor storm,
00:29:34 --> 00:29:37 um, where people saw literally
00:29:37 --> 00:29:40 thousands of meteors per hour. That's more
00:29:40 --> 00:29:42 than one a second raining down,
00:29:42 --> 00:29:45 Absolutely incredibly spectacular.
00:29:45 --> 00:29:47 All radiating out from this point in the
00:29:47 --> 00:29:48 night sky. Near the Northern hemisphere
00:29:48 --> 00:29:51 constellation of Draco. There was a slightly
00:29:51 --> 00:29:53 less spectacular but still very intense
00:29:53 --> 00:29:55 meteor storm from this shower in
00:29:55 --> 00:29:58 1946. And since then,
00:29:58 --> 00:30:01 most years you get two or three meters an
00:30:01 --> 00:30:02 hour from this meteor shower. They're very
00:30:02 --> 00:30:05 slow meteors. They're typically fairly faint
00:30:05 --> 00:30:07 as well. But there's always a little bit
00:30:07 --> 00:30:10 going on. But every six years or so,
00:30:11 --> 00:30:13 the comet comes back to perihelion, and
00:30:13 --> 00:30:15 there's a chance of us getting an outburst.
00:30:15 --> 00:30:17 Now, whether we get one or not depends on the
00:30:17 --> 00:30:19 gravity of all the other planets pulling the
00:30:19 --> 00:30:20 comet's orbit. And these debris streams
00:30:20 --> 00:30:23 around, Sometimes they'll miss us underneath
00:30:23 --> 00:30:24 or they'll miss us above. And we don't run
00:30:24 --> 00:30:27 through them. But it's become an active thing
00:30:27 --> 00:30:29 of trying to figure out what's going to
00:30:29 --> 00:30:32 happen next. Could we ever get another
00:30:32 --> 00:30:34 meteor storm from this shower? Now, we've
00:30:34 --> 00:30:37 had a few outbursts that are not storms, but
00:30:37 --> 00:30:38 are good. A few years ago, there was an
00:30:38 --> 00:30:40 outburst where there were a hundred meters an
00:30:40 --> 00:30:41 hour visible for a couple of hours, which is
00:30:41 --> 00:30:44 a pretty good meteor shower. Yeah. That's
00:30:44 --> 00:30:47 led to, uh, people using this meteor shower
00:30:47 --> 00:30:49 as a really good test bed for how we model
00:30:49 --> 00:30:52 how these things work. Trying to improve our
00:30:52 --> 00:30:54 computer models of how all the dust moves,
00:30:54 --> 00:30:56 where it's all going to be so that we can
00:30:56 --> 00:30:58 predict forward and say what's going to
00:30:58 --> 00:31:00 happen at the next operation. And a paper
00:31:00 --> 00:31:03 came out literally just a couple of days ago
00:31:04 --> 00:31:07 that explored this in some depth it's from
00:31:07 --> 00:31:09 some of the leading meteor astronomers in the
00:31:09 --> 00:31:12 world. Doing modeling of the Draconids. And
00:31:12 --> 00:31:13 what it suggested is that this week,
00:31:14 --> 00:31:16 literally the week that we're recording this.
00:31:17 --> 00:31:19 There is a potential for the Draconis to have
00:31:19 --> 00:31:22 a fairly good outburst. On Wednesday
00:31:22 --> 00:31:24 night. Into Thursday morning Australian time.
00:31:24 --> 00:31:27 So that's around the 8th of November, the
00:31:27 --> 00:31:29 evening of the 8th of November, universal
00:31:29 --> 00:31:32 time, early hours of the morning. 9th, sorry,
00:31:32 --> 00:31:35 October 8th of October, universal time,
00:31:35 --> 00:31:37 early hours of the morning of the 9th of
00:31:37 --> 00:31:38 October, for us here in Australia.
00:31:39 --> 00:31:41 That there'll be a bit of an outburst. Now,
00:31:41 --> 00:31:44 this is probably not going to be an outburst.
00:31:44 --> 00:31:46 That's particularly spectacular visually.
00:31:47 --> 00:31:49 Reason for that is its full Moon. So it
00:31:49 --> 00:31:51 brings us back to the Moon. Getting in our
00:31:51 --> 00:31:53 way and spoiling all of our fun. If the full
00:31:53 --> 00:31:56 Moon wasn't the full Moon. It's likely that
00:31:56 --> 00:31:58 this outburst. Could be somewhere between 30
00:31:58 --> 00:32:01 meters per hour and 100, maybe even 200 per
00:32:01 --> 00:32:03 hour. But the Draconids tend to come in
00:32:03 --> 00:32:05 fairly slow. And they tend to be small, faint
00:32:05 --> 00:32:07 meteors. So almost all of them will be lost
00:32:07 --> 00:32:10 to the naked eye in the moonlight.
00:32:10 --> 00:32:12 Unless they're not, because this is just a
00:32:12 --> 00:32:14 prediction. So something could happen that is
00:32:14 --> 00:32:17 better than we expect. What's most likely to
00:32:17 --> 00:32:18 happen, though, is that, uh, people will see
00:32:18 --> 00:32:21 a few meteors through the moonlight. And that
00:32:21 --> 00:32:23 will tell you there's a lot more going on
00:32:23 --> 00:32:25 than you can see. But the
00:32:25 --> 00:32:28 astronomers doing observations with radar
00:32:29 --> 00:32:32 will see an outburst. And it will probably be
00:32:32 --> 00:32:34 the strongest radar meteor shower of the
00:32:34 --> 00:32:37 year. So these are people almost doing
00:32:37 --> 00:32:40 kind of, uh. Beyond the horizon. Radio
00:32:40 --> 00:32:41 listening. One of the most common ways you
00:32:41 --> 00:32:44 can listen to meteors in radio
00:32:44 --> 00:32:45 wavelengths.
00:32:45 --> 00:32:48 Is to look at an angle low to the
00:32:48 --> 00:32:50 horizon. When you're in a country where there
00:32:50 --> 00:32:52 are, uh, other countries far enough away.
00:32:52 --> 00:32:55 That their radio broadcasts can bounce off
00:32:55 --> 00:32:57 the ionized trails left behind by the meteors
00:32:57 --> 00:32:59 80 kilometers up. And bounce back down to
00:32:59 --> 00:33:01 you. So, obviously, for a lot of places, this
00:33:01 --> 00:33:03 just doesn't work. Because you're looking out
00:33:03 --> 00:33:05 over the ocean. But people in Europe or
00:33:05 --> 00:33:08 people in North America. Quite often there's
00:33:08 --> 00:33:10 a city at about the right distance. It's
00:33:10 --> 00:33:12 quite a big bit of wiggle room. That if
00:33:12 --> 00:33:14 you're pointing your detector roughly in that
00:33:14 --> 00:33:16 direction. Every time there's a meteor.
00:33:16 --> 00:33:18 You'll suddenly get this reflective ionized
00:33:18 --> 00:33:21 trail 80 km up. Radio waves that would
00:33:21 --> 00:33:23 have normally escaped the atmosphere. And
00:33:23 --> 00:33:25 gone on into space. Will bounce off that and
00:33:25 --> 00:33:26 bounce down to you. And you'll get a little
00:33:26 --> 00:33:29 burst of radio noise. And so that means
00:33:29 --> 00:33:31 people can count meteors. And it's likely
00:33:31 --> 00:33:33 that this draconian outburst will be
00:33:33 --> 00:33:35 confirmed not by people looking with the
00:33:35 --> 00:33:38 naked ey, but by people listening with radio
00:33:38 --> 00:33:40 antennas. And they're saying in terms of
00:33:40 --> 00:33:42 radio signals, you could get more than a
00:33:42 --> 00:33:44 thousand per hour. So it could be a fairly
00:33:44 --> 00:33:47 intense outburst, just not one that is really
00:33:47 --> 00:33:50 visible with a naked eye. It's worth flagging
00:33:50 --> 00:33:52 up though, is it's a good insight into how we
00:33:52 --> 00:33:54 do the science of this, that kind of
00:33:54 --> 00:33:56 beautiful interplay of theory and experiment
00:33:56 --> 00:33:59 and observation where we predict something,
00:33:59 --> 00:34:00 we test that prediction, and that allows us
00:34:00 --> 00:34:02 to improve our models to make the next
00:34:02 --> 00:34:04 prediction, prediction even better. But it's
00:34:04 --> 00:34:06 also worth flagging up because the one
00:34:06 --> 00:34:08 prediction you can make is that all
00:34:08 --> 00:34:10 predictions will be wrong. And so while we're
00:34:10 --> 00:34:12 saying that it'll probably be only 40 or 50
00:34:12 --> 00:34:15 per hour or 20 per hour with the naked eye,
00:34:15 --> 00:34:17 and the Moon will hide most of them, you
00:34:17 --> 00:34:18 can't rule out that it'll be better than
00:34:18 --> 00:34:20 that. So if you're up in the early hours of
00:34:20 --> 00:34:23 the morning on Wednesday night into
00:34:23 --> 00:34:25 Thursday morning, it's worth having a bit of
00:34:25 --> 00:34:27 a look. The forecast peak is forecast to be
00:34:27 --> 00:34:30 at 3pm Universal Time, between 3 and 4pm
00:34:30 --> 00:34:33 Universal Time, which is Greenwich Mean Time.
00:34:33 --> 00:34:35 So you can work out from that what time it'll
00:34:35 --> 00:34:37 be for you. For many people it'll be in the
00:34:37 --> 00:34:39 daytime. So sorry, but this time kind of
00:34:39 --> 00:34:41 favors people in East Asia and Australia,
00:34:41 --> 00:34:44 that kind of area. So we might see something,
00:34:44 --> 00:34:46 we might not. But it's worth a look.
00:34:46 --> 00:34:48 Andrew Dunkley: Okie doke. Yeah. Uh, if you want to read
00:34:48 --> 00:34:50 about that, uh, you can do so at the Harvard
00:34:51 --> 00:34:53 Edu website or go to the Arxiv
00:34:54 --> 00:34:56 website where the paper was published. And
00:34:57 --> 00:34:59 I'd read out, I'd read out the whole thing,
00:34:59 --> 00:35:02 but you'll never remember it.
00:35:02 --> 00:35:04 Jonti Horner: I was going to say one thing I should mention
00:35:04 --> 00:35:07 with that is the draconids are best seen from
00:35:07 --> 00:35:08 the northern hemisphere. So if you're in the
00:35:08 --> 00:35:10 southern hemisphere and you want to see this
00:35:10 --> 00:35:12 nearer to the equator, you are the better.
00:35:12 --> 00:35:15 And in reality, I'd say that people south
00:35:15 --> 00:35:17 of the line about at, uh, Brisbane's
00:35:17 --> 00:35:19 latitude, it's not even worth bothering
00:35:19 --> 00:35:21 because the radiant will be so low in the sky
00:35:21 --> 00:35:23 that you will see nothing at all really is
00:35:23 --> 00:35:24 more of a Northern Hemisphere thing. So I
00:35:24 --> 00:35:26 want, you know, want to make sure that we
00:35:26 --> 00:35:28 don't get somebody down in New Zealand going
00:35:28 --> 00:35:30 out looking for it and saying, I saw nothing.
00:35:30 --> 00:35:32 But, well, you saw nothing because you can't
00:35:32 --> 00:35:34 see anything from there. I'm really sorry.
00:35:34 --> 00:35:36 Andrew Dunkley: Yes, that's the way it goes though. That's
00:35:36 --> 00:35:37 the way it goes. Yeah.
00:35:37 --> 00:35:37 Jonti Horner: Yes.
00:35:37 --> 00:35:40 Andrew Dunkley: All right, uh, this is Space Nuts with Andrew
00:35:40 --> 00:35:42 Dunkley and Professor Jonti Horner.
00:35:42 --> 00:35:43 Jonti Horner: Space Nuts.
00:35:44 --> 00:35:46 Andrew Dunkley: All right, let's move on to Uranus and
00:35:46 --> 00:35:49 the Moon. Ariel. This is a really
00:35:49 --> 00:35:51 fascinating story about, uh, what might have
00:35:51 --> 00:35:54 been, uh, in its past. A
00:35:54 --> 00:35:56 hidden ocean on, on a rather small object.
00:35:57 --> 00:36:00 Jonti Horner: It is, and it's part of this ongoing
00:36:00 --> 00:36:02 journey, discovery that we're getting where
00:36:02 --> 00:36:05 fundamentally the kind of world that I grew
00:36:05 --> 00:36:08 up in as a kid excited by astronomy in the
00:36:08 --> 00:36:10 80s and 90s just isn't the same anymore.
00:36:10 --> 00:36:13 I was growing up and the kind of accepted
00:36:13 --> 00:36:15 wisdom was that water was incredibly rare and
00:36:15 --> 00:36:18 liquid water particularly rare, and therefore
00:36:18 --> 00:36:20 life would be uncommon in the cosmos. And
00:36:20 --> 00:36:21 this was one of the kind of centerpieces of
00:36:21 --> 00:36:24 the rare Earth hypothesis, which basically
00:36:24 --> 00:36:25 said don't even bother looking for life
00:36:25 --> 00:36:27 elsewhere because where all there is. And
00:36:27 --> 00:36:30 I've never particularly put much stock in
00:36:30 --> 00:36:32 that idea. But what we've seen in the last 30
00:36:32 --> 00:36:35 years or so is that, uh, water is actually
00:36:35 --> 00:36:38 incredibly more common than people would
00:36:38 --> 00:36:40 have thought. And that's not a surprise. You
00:36:40 --> 00:36:43 know, if you look at, uh, the universe as a
00:36:43 --> 00:36:45 whole, Hydrogen is by far the most common
00:36:45 --> 00:36:47 atom. Oxygen is the third most common atom.
00:36:47 --> 00:36:49 And if you put them together, you get water.
00:36:50 --> 00:36:52 And we see in the after solar system, we see
00:36:52 --> 00:36:53 in the form of these comets we talked about
00:36:53 --> 00:36:56 earlier on. Water ice is incredibly abundant
00:36:56 --> 00:36:59 and in fact of the solid material in the
00:36:59 --> 00:37:02 solar system, water ice is by far the
00:37:02 --> 00:37:05 largest amount of mass of everything.
00:37:05 --> 00:37:07 Once you're out at Jupiter's orbit and
00:37:07 --> 00:37:09 further out, all the icy moons, all the
00:37:09 --> 00:37:12 comets, all the trans neptunian objects are
00:37:12 --> 00:37:13 uh, basically lots of water ice with a bit of
00:37:13 --> 00:37:16 other stuff going on. So solid water is
00:37:16 --> 00:37:19 really common. Liquid water though, people
00:37:19 --> 00:37:21 said, well, we've got a lot of it on Earth,
00:37:21 --> 00:37:22 but elsewhere it's not that common. And then
00:37:22 --> 00:37:25 we found liquid water in Mars as polar caps.
00:37:25 --> 00:37:27 And we've found all these deeply buried
00:37:27 --> 00:37:30 subsurface oceans, the kind of poster child
00:37:30 --> 00:37:33 of which is Europa. And you know, even in the
00:37:33 --> 00:37:34 kind of wonderful films, you know, all these
00:37:34 --> 00:37:36 worlds are yours except Europa. Attempt no
00:37:36 --> 00:37:38 landing there, that whole kind of thing.
00:37:39 --> 00:37:41 So we found all these subsurface oceans and
00:37:41 --> 00:37:43 the more we look, the more we find them.
00:37:43 --> 00:37:45 There was a story earlier this year that the
00:37:45 --> 00:37:47 dwarf planet series in the Ashram asteroid
00:37:47 --> 00:37:49 belt had a subsurface ocean in the past.
00:37:49 --> 00:37:50 Yeah.
00:37:50 --> 00:37:53 And now we come to Ariel. Ariel is one
00:37:53 --> 00:37:55 of Uranus's moons. And Uranus's moons we got
00:37:55 --> 00:37:58 some lovely images of, from the Voyager 2
00:37:58 --> 00:38:00 spacecraft back when, back when I was a wee
00:38:00 --> 00:38:02 band back in kind of 1985,
00:38:03 --> 00:38:05 1986 time. Voyager 2
00:38:05 --> 00:38:08 flew past Uranus as part of its grand tour of
00:38:08 --> 00:38:10 the outer solar system. And
00:38:10 --> 00:38:13 as we always say, it flew past faster than a
00:38:13 --> 00:38:15 speeding bullet. So it didn't have very long
00:38:15 --> 00:38:18 to hang around and take images. And because
00:38:18 --> 00:38:21 Uranus is tipped over on its side and
00:38:21 --> 00:38:24 its moon's orbit above Uranus's equator,
00:38:24 --> 00:38:26 they're all tipped over on their side. So you
00:38:26 --> 00:38:28 had basically mid summer at Uranus there.
00:38:28 --> 00:38:30 And all of these moons had one hemisphere
00:38:30 --> 00:38:33 illuminated and one hemisphere dark, which
00:38:33 --> 00:38:36 meant that as Voyager 2 flew through,
00:38:36 --> 00:38:38 we got all these beautiful pictures of
00:38:38 --> 00:38:40 Uranus's moons. But for all those moons, we
00:38:40 --> 00:38:42 only saw one side of them. We saw the
00:38:42 --> 00:38:45 southern hemisphere illuminated by daylight,
00:38:45 --> 00:38:47 but we didn't get to see the other side. Uh,
00:38:47 --> 00:38:49 and we saw these really unusual objects.
00:38:49 --> 00:38:51 Miranda is kind of the most famous for this,
00:38:51 --> 00:38:53 which almost looks like somebody's taken a
00:38:53 --> 00:38:55 moon and smashed it apart with a hammer and
00:38:55 --> 00:38:58 then rebuilt it haphazardly. You've got all
00:38:58 --> 00:38:59 these very different features next to each
00:38:59 --> 00:39:02 other. It looks really odd. Ariel
00:39:02 --> 00:39:05 is a bit bigger than Miranda and also, um,
00:39:05 --> 00:39:07 looks really odd. It's got areas on its
00:39:07 --> 00:39:09 surface that are clearly very, very old.
00:39:09 --> 00:39:12 They're fairly relatively low albedo, they're
00:39:12 --> 00:39:14 not that reflective, and they're incredibly
00:39:14 --> 00:39:17 heavily cratered. But it also has these
00:39:17 --> 00:39:19 areas that are much more reflective,
00:39:20 --> 00:39:23 much smoother. They have far fewer craters.
00:39:23 --> 00:39:25 And they've also got these incredibly large
00:39:25 --> 00:39:28 canyons, fishering Valley type features on
00:39:28 --> 00:39:31 them. And, um, again, it looks a very
00:39:32 --> 00:39:34 odd world, a bit like Miranda. You've got
00:39:34 --> 00:39:36 very different surfaces relatively close to
00:39:36 --> 00:39:38 each other that look very different to one
00:39:38 --> 00:39:40 another geologically. They look like they've
00:39:40 --> 00:39:43 got very different histories. That's 40 years
00:39:43 --> 00:39:44 ago. And this is a really good example of
00:39:44 --> 00:39:47 what we talked about earlier, where data
00:39:47 --> 00:39:50 from the past continues to have value as our
00:39:50 --> 00:39:52 tools improve so we can better understand
00:39:52 --> 00:39:55 it. Because a new result that's come out in
00:39:55 --> 00:39:58 the last couple of weeks is a result of
00:39:58 --> 00:40:01 really impressive computer modeling trying to
00:40:01 --> 00:40:03 figure out what's going on with Arial. Why
00:40:03 --> 00:40:05 does it look so unusual?
00:40:06 --> 00:40:08 Typically, when we see smooth surfaces with
00:40:08 --> 00:40:11 far fewer craters, we consider
00:40:11 --> 00:40:14 them to be younger because impact craters are
00:40:14 --> 00:40:16 happening all the time. And so the longer you
00:40:16 --> 00:40:18 have to be exposed to space, the more craters
00:40:18 --> 00:40:20 you'll get. Which leads to this kind of
00:40:21 --> 00:40:23 science of crater counting, where you can
00:40:23 --> 00:40:25 estimate the edge of a surface by seeing how
00:40:25 --> 00:40:27 many craters it's got per square kilometer or
00:40:27 --> 00:40:30 whatever. Yeah. So the fact that
00:40:30 --> 00:40:33 aerial surface is in places smoother
00:40:33 --> 00:40:35 and brighter suggests that that surface is
00:40:35 --> 00:40:37 younger, um, and that there's been
00:40:37 --> 00:40:39 significant resurfacing there. And the idea
00:40:39 --> 00:40:41 is that there was probably cryovolcanism,
00:40:41 --> 00:40:44 where molten water was erupting over the
00:40:44 --> 00:40:46 surface and then freezing in just the same
00:40:46 --> 00:40:48 way that molten rock on Earth erupts and then
00:40:48 --> 00:40:50 sets in volcanic eruptions.
00:40:51 --> 00:40:54 But that was a bit speculative. What
00:40:54 --> 00:40:56 this new modeling has done is it's looked at
00:40:56 --> 00:40:59 the history of the orbit of Ariel and
00:40:59 --> 00:41:01 suggested that in the past, Ariel's orbit was
00:41:01 --> 00:41:03 probably a little bit more eccentric than it
00:41:03 --> 00:41:05 is now. Probably an eccentricity up to about
00:41:05 --> 00:41:08 0.04, which is a bit more eccentric
00:41:08 --> 00:41:10 than the orbit of the Earth, but less
00:41:10 --> 00:41:12 eccentric than the orbit of Mars. On an
00:41:12 --> 00:41:15 orbit that is just slightly eccentric like
00:41:15 --> 00:41:17 that. Ariel, which is sandwiched in between
00:41:17 --> 00:41:19 all these other moons and, um, is near a
00:41:19 --> 00:41:21 pretty massive planet in the form of Uranus,
00:41:21 --> 00:41:23 would have been subject to fairly intense
00:41:23 --> 00:41:26 tidal forces that would have squashed and
00:41:26 --> 00:41:29 squeezed it. And that's very much
00:41:29 --> 00:41:30 equivalent to what's happening in the Jupiter
00:41:30 --> 00:41:33 system with IO and Europa, these
00:41:33 --> 00:41:35 moons that are squashed and squeezed by
00:41:35 --> 00:41:37 Jupiter's gravity in the nearby moons, which
00:41:37 --> 00:41:39 dumps a lot of heat into the interior of
00:41:39 --> 00:41:42 these moons, keeping them hot, driving
00:41:42 --> 00:41:45 volcanism, allowing that deeply buried
00:41:45 --> 00:41:47 ocean in Europa. Uh, well said, deeply
00:41:47 --> 00:41:49 buried, probably under about 10km of ice to
00:41:49 --> 00:41:51 stay liquid because it's an internal heat
00:41:51 --> 00:41:54 source driven by this tidal heating. Yeah.
00:41:54 --> 00:41:56 What this work has said is that Ariel, too,
00:41:56 --> 00:41:59 probably had a lot of internal heat from
00:41:59 --> 00:42:01 tidal heating. It's a big object that's
00:42:01 --> 00:42:03 primarily made of water ice. And when you
00:42:03 --> 00:42:05 heat water ice, what happens is it melts. And
00:42:05 --> 00:42:07 so the idea is that, uh, for a very long
00:42:07 --> 00:42:09 period of time, probably hundreds of millions
00:42:09 --> 00:42:12 of years, if not billions of years, buried
00:42:12 --> 00:42:13 under the surface of Ariel, and possibly even
00:42:13 --> 00:42:16 relatively shallow at some times, was this
00:42:16 --> 00:42:19 ocean of liquid water that, again,
00:42:19 --> 00:42:21 just like Europa, probably contained more
00:42:21 --> 00:42:24 liquid water than there is on the entirety of
00:42:24 --> 00:42:25 the planet Earth.
00:42:25 --> 00:42:25 Andrew Dunkley: Wow.
00:42:26 --> 00:42:28 Jonti Horner: That water would have behaved like the mantle
00:42:28 --> 00:42:31 of the Earth, with volcanic eruptions of
00:42:31 --> 00:42:34 water breaking through cracks in the surface,
00:42:35 --> 00:42:37 resurfacing these areas of Ariel, giving us
00:42:37 --> 00:42:40 the clues that we see now, probably
00:42:40 --> 00:42:42 more than a billion years after this ocean
00:42:42 --> 00:42:44 for a solid, Ariel's orbit settled down.
00:42:44 --> 00:42:47 Tidal forces Lessened on, uh, it. It cooled
00:42:47 --> 00:42:50 down, Everything froze solid. But we're left
00:42:50 --> 00:42:52 with these fossilized clues that are
00:42:52 --> 00:42:55 evidence of this much more interesting past,
00:42:55 --> 00:42:57 potentially when you have this moon with a
00:42:57 --> 00:43:00 soft central liquid center. Yeah, and it's,
00:43:00 --> 00:43:02 it's interesting in itself. It's interesting
00:43:02 --> 00:43:04 because of this interplay between observation
00:43:04 --> 00:43:07 and theory and, um, how it shows you that
00:43:07 --> 00:43:09 observations may not bear fruit for
00:43:09 --> 00:43:12 decades. It might be that the observations we
00:43:12 --> 00:43:15 make now are not fully understood for 10, 20,
00:43:15 --> 00:43:17 30 years as our technology and m. Our
00:43:17 --> 00:43:19 modeling and our theories develop in that
00:43:19 --> 00:43:22 time. But it's also interesting from the
00:43:22 --> 00:43:24 whole question of, are we alone in the
00:43:24 --> 00:43:27 universe? Is there life elsewhere? Because
00:43:27 --> 00:43:29 it's reminding us that liquid water is much
00:43:29 --> 00:43:31 more commonplace in the cosmos than we think
00:43:31 --> 00:43:34 it is now. Finding life on
00:43:34 --> 00:43:37 buried oceans is challenging
00:43:37 --> 00:43:39 in the solar system. It's not really
00:43:39 --> 00:43:40 something that's feasible going forward,
00:43:41 --> 00:43:43 looking at planets around other stars. But it
00:43:43 --> 00:43:45 is a reminder that there might be an
00:43:45 --> 00:43:47 incredible diversity of potential habitats
00:43:47 --> 00:43:50 for life to become, develop and thrive
00:43:51 --> 00:43:53 all, all through the solar system, all out
00:43:53 --> 00:43:55 there in the cosmos, and certainly in the
00:43:55 --> 00:43:57 solar system. These are the kind of locations
00:43:57 --> 00:43:59 that we can visit. There's a really growing
00:43:59 --> 00:44:02 push among, um, planetary scientists that
00:44:02 --> 00:44:04 Uranus should be the next place to get a
00:44:04 --> 00:44:07 probe. We've seen incredible
00:44:07 --> 00:44:10 science done by orbiters like Galileo and
00:44:10 --> 00:44:12 Juno that went to Jupiter, like cne that went
00:44:12 --> 00:44:15 Saturn. But for Uranus, we've only seen one
00:44:15 --> 00:44:17 face of the planet, one face of all its moons
00:44:18 --> 00:44:20 as we flew through on a drive by,
00:44:20 --> 00:44:23 essentially. And the argument is,
00:44:23 --> 00:44:25 if we could send a spacecraft there, that did
00:44:25 --> 00:44:28 for Uranus what Cassini did for Saturn, what
00:44:29 --> 00:44:32 Galileo and Juno did for Jupiter. There is
00:44:32 --> 00:44:34 so much we'd learn. And Uranus is such an
00:44:34 --> 00:44:35 oddity among the planets with its satellite
00:44:35 --> 00:44:38 system, with everything all tipped over. It's
00:44:38 --> 00:44:40 got a very different history to the other
00:44:40 --> 00:44:43 planets. There's some violent event in
00:44:43 --> 00:44:45 the past, quite possibly something more
00:44:45 --> 00:44:47 massive than the Earth, uh, hitting Uranus,
00:44:47 --> 00:44:49 knocking it over, disrupting the satellite
00:44:49 --> 00:44:52 system, giving us the moons we see as a
00:44:52 --> 00:44:53 secondary satellite system. The original
00:44:53 --> 00:44:56 moons were destroyed, formed a disk of
00:44:56 --> 00:44:58 material, and new moons formed from them.
00:44:58 --> 00:45:00 It's a very wonderful narrative
00:45:01 --> 00:45:03 that is our best explanation for what we see.
00:45:03 --> 00:45:05 But it may not be the right one. And, um, the
00:45:05 --> 00:45:06 only way we'll find out, the only way we'll
00:45:06 --> 00:45:09 learn more about this is to go there, send
00:45:09 --> 00:45:12 a spacecraft there. So this is
00:45:12 --> 00:45:15 so exciting for people that it's actually the
00:45:15 --> 00:45:18 top priority of the planetary science decadal
00:45:18 --> 00:45:21 plan. In the US Trying to argue for
00:45:21 --> 00:45:23 funding to build a mission. Now, if that
00:45:23 --> 00:45:26 mission was approved, it will probably be
00:45:26 --> 00:45:28 another 20 years before it gets there, uh, if
00:45:28 --> 00:45:30 not more. And um, that's one of the
00:45:30 --> 00:45:32 challenges that people face because you are
00:45:32 --> 00:45:34 dealing with governments that change on
00:45:34 --> 00:45:36 timescales of three or four years, who
00:45:37 --> 00:45:39 often seem to have the policy that whatever
00:45:39 --> 00:45:41 the previous government decided was wrong. So
00:45:41 --> 00:45:43 therefore we need to cancel it. And you've
00:45:43 --> 00:45:45 got to navigate those waters to try and get a
00:45:45 --> 00:45:48 mission to happen where the development alone
00:45:48 --> 00:45:50 can be 10 or 20 years. So it's really
00:45:50 --> 00:45:51 challenging, especially in the current
00:45:51 --> 00:45:54 climate. But the hopes of planetary
00:45:54 --> 00:45:57 scientists across the world are that at some
00:45:57 --> 00:45:59 point a mission like this will get approved
00:45:59 --> 00:46:00 and we'll get to go back there and find out
00:46:00 --> 00:46:01 what's actually going on.
00:46:02 --> 00:46:04 Andrew Dunkley: Yes, indeed. But, um, what I'm finding
00:46:04 --> 00:46:06 fascinating is that, um, the more we look and
00:46:06 --> 00:46:09 the more information we gather and
00:46:09 --> 00:46:11 analyze, uh, these ice
00:46:11 --> 00:46:14 moons, these subsurface ocean moons in
00:46:14 --> 00:46:16 the outer solar system are starting to become
00:46:17 --> 00:46:18 the norm really.
00:46:21 --> 00:46:23 They're identifying more and more of them, or
00:46:23 --> 00:46:25 at least they're suspicious that some of them
00:46:25 --> 00:46:28 are there that we weren't thinking about
00:46:28 --> 00:46:30 before that are starting to show those kinds
00:46:30 --> 00:46:33 of tendencies. And his is yet another
00:46:33 --> 00:46:36 one. So, uh, yeah, there's plenty to, to look
00:46:36 --> 00:46:39 for out, uh, out around that, uh, that
00:46:39 --> 00:46:41 where the gas giants are and beyond. Really
00:46:41 --> 00:46:42 fascinating stuff.
00:46:43 --> 00:46:46 Uh, now finally, let's uh, do this one. Uh,
00:46:46 --> 00:46:48 asteroids controlled by Venus and what that
00:46:48 --> 00:46:50 means for Earth, our sister planet, might
00:46:50 --> 00:46:53 start throwing stuff at us in a few thousand
00:46:53 --> 00:46:54 years time.
00:46:54 --> 00:46:57 Jonti Horner: Oh, absolutely. This is a story that's all
00:46:57 --> 00:47:00 about few objects that have been discovered
00:47:00 --> 00:47:02 relatively recently that are very, very hard
00:47:02 --> 00:47:05 to spot that fall under the broad heading
00:47:05 --> 00:47:06 of near Earth asteroids. They're things
00:47:07 --> 00:47:09 moving in the inner solar system on unstable
00:47:09 --> 00:47:12 orbits. And obviously we've seen deep impact,
00:47:12 --> 00:47:14 we've seen Armageddon. We know that these
00:47:14 --> 00:47:16 things can pose as a threat. And there's a
00:47:16 --> 00:47:19 big growing push to find them and to peer
00:47:19 --> 00:47:21 through the growing numbers of starlink
00:47:21 --> 00:47:23 satellites that make it harder and harder for
00:47:23 --> 00:47:25 us to do that. And it's one of the things
00:47:25 --> 00:47:26 Vera Rubin is going to be great at. Vera
00:47:26 --> 00:47:28 Rubin is going to be great at everything, to
00:47:28 --> 00:47:30 be honest. But it'll be fabulous. NEAR EARTH
00:47:30 --> 00:47:33 ASTEROID FINDING MACHINE but these ones
00:47:33 --> 00:47:35 are going to be challenging even for Rubin.
00:47:36 --> 00:47:38 These are asteroids that spend their entire
00:47:38 --> 00:47:41 orbits closer to the sun than us. I've seen
00:47:41 --> 00:47:44 them described as apaheel asteroids as their
00:47:44 --> 00:47:46 family name. These are things where even when
00:47:46 --> 00:47:48 they're furthest from the sun, they're still
00:47:48 --> 00:47:50 closer to the sun than we are. And what that
00:47:50 --> 00:47:52 means is that they're always to some degree
00:47:52 --> 00:47:55 lost in the Sun's glare. They're hard to
00:47:55 --> 00:47:57 spot. Now there's a growing
00:47:58 --> 00:48:00 population of these that have been found that
00:48:00 --> 00:48:01 are moving, uh, on orbits with a similar
00:48:01 --> 00:48:04 orbital period to Venus, maybe even trapped
00:48:04 --> 00:48:06 in one to one resonance with Venus. So they
00:48:06 --> 00:48:08 complete one lap of the sun in the time it
00:48:08 --> 00:48:11 takes Venus to complete one lap. And we found
00:48:11 --> 00:48:14 a few of these. All of the ones we found are
00:48:14 --> 00:48:16 on relatively eccentric orbits,
00:48:16 --> 00:48:18 eccentricities of about 0.38 or greater,
00:48:19 --> 00:48:21 which means that the point at ah, which
00:48:21 --> 00:48:23 they're furthest from The sun is 38% bigger
00:48:23 --> 00:48:25 than their mean distance, their semi major
00:48:25 --> 00:48:27 axis and the point at which they're closest
00:48:27 --> 00:48:29 to the sun is 38% smaller,
00:48:30 --> 00:48:32 basically. So if you know the semi major
00:48:32 --> 00:48:35 axis, call that letter A, the
00:48:35 --> 00:48:37 distance between these objects and the sun at
00:48:37 --> 00:48:39 their aphelion, their furthest point is
00:48:39 --> 00:48:42 equal to 1 plus the eccentricity
00:48:42 --> 00:48:45 multiplied by semi major axis. So next entry
00:48:45 --> 00:48:47 of 0.38 gives you
00:48:47 --> 00:48:49 1.38 times the semi major axis. That's
00:48:49 --> 00:48:52 basically the way this works out. So what
00:48:52 --> 00:48:54 that means is if you're on an orbit that is
00:48:55 --> 00:48:57 a semi major axis, the same as Venus, which
00:48:57 --> 00:48:59 is a little bit more than 0.7 astronomical
00:48:59 --> 00:49:02 units, if you have an eccentricity of about
00:49:02 --> 00:49:05 0.38 or more, you'll get close to the
00:49:05 --> 00:49:06 Earth's orbit when you're furthest from the
00:49:06 --> 00:49:09 sun, uh, and that means that you're further
00:49:09 --> 00:49:10 from the sun in the sky and you're easier to
00:49:10 --> 00:49:13 find. So we've got an observation bias.
00:49:14 --> 00:49:16 If we find a lot of objects then in the one
00:49:16 --> 00:49:18 to one resonance with Venus that are on
00:49:18 --> 00:49:20 eccentric orbits, we can suggest that
00:49:20 --> 00:49:22 there are going to be far more of them that
00:49:22 --> 00:49:24 are not on eccentric orbits because they're
00:49:24 --> 00:49:26 harder to find. So we're finding the law
00:49:26 --> 00:49:29 hanging fruit. So the idea is that there is a
00:49:29 --> 00:49:31 population of hundreds of these objects,
00:49:31 --> 00:49:33 possibly even thousands of them, m ranging in
00:49:33 --> 00:49:35 size up to hundreds of meters, maybe even a
00:49:35 --> 00:49:38 few kilometers in size, that are uh, near
00:49:38 --> 00:49:40 Earth asteroids that have evolved quite a
00:49:40 --> 00:49:42 long time in their orbits, moved into the
00:49:42 --> 00:49:44 inner solar system and bounce down to Venus
00:49:44 --> 00:49:46 and they're kind of held in a freezer there.
00:49:46 --> 00:49:48 They're kind of held out of our way in a
00:49:48 --> 00:49:51 reservoir. Not to be worried about. The
00:49:51 --> 00:49:53 new work is that people have done some
00:49:53 --> 00:49:55 orbital simulations of the kind that I do in
00:49:55 --> 00:49:58 my day. To day life. And um, they've looked
00:49:58 --> 00:50:00 at what will happen to these things over
00:50:00 --> 00:50:01 time. Because moving on orbits in the inner
00:50:01 --> 00:50:04 solar system is an inherently unstable
00:50:04 --> 00:50:06 situation. You're vulnerable to the
00:50:06 --> 00:50:08 whims of the gravity of all the other
00:50:08 --> 00:50:10 planets. And that means your orbit gets
00:50:10 --> 00:50:11 bounced around, you have close encounters
00:50:11 --> 00:50:14 with the planets. Um, that means that things
00:50:14 --> 00:50:17 are not stable in that one to one resonance
00:50:17 --> 00:50:18 with Venus on really long timescales, they'll
00:50:18 --> 00:50:21 eventually escape and move around. And what
00:50:21 --> 00:50:23 this study has shown is that uh, for these
00:50:23 --> 00:50:25 objects that we currently cannot see, they're
00:50:25 --> 00:50:27 currently most of them hidden from view.
00:50:29 --> 00:50:31 They are on orbits that can evolve to become
00:50:31 --> 00:50:34 Earth crossing once again, maybe even within
00:50:34 --> 00:50:36 just a few thousand years. And so that this
00:50:36 --> 00:50:39 is a previously, um, unthought of
00:50:39 --> 00:50:42 reservoir of potentially hazardous asteroids
00:50:43 --> 00:50:45 that we can't easily detect with our normal
00:50:45 --> 00:50:47 methods. And um, that Vera Rubin, with all
00:50:47 --> 00:50:50 its brilliant abilities will be challenged to
00:50:50 --> 00:50:53 pick up. And so it's flagging up another
00:50:53 --> 00:50:55 area of objects that uh, they don't pose a
00:50:55 --> 00:50:58 threat to us right now. Probably
00:50:58 --> 00:50:59 there might be some of them on orbits that
00:50:59 --> 00:51:01 just reach the Earth, so they could do. But
00:51:01 --> 00:51:03 most of these don't pose an immediate threat,
00:51:03 --> 00:51:06 but they pose a longer term threat. And the
00:51:06 --> 00:51:08 kind of, I guess, punchline of all of this is
00:51:08 --> 00:51:10 that we need to become better, we need to be
00:51:10 --> 00:51:12 creative and think about how we can find
00:51:12 --> 00:51:14 asteroids like this are hidden in the sun's
00:51:14 --> 00:51:17 glare. What we can do in order to try
00:51:17 --> 00:51:19 and quantify the ones that are there and
00:51:19 --> 00:51:20 figure out if any of them pose a threat,
00:51:20 --> 00:51:23 that's kind of their punchline. And I think
00:51:23 --> 00:51:26 it is just a really great reminder of the
00:51:26 --> 00:51:27 fact that we always think we now know so
00:51:27 --> 00:51:30 much, we know so much more than we used to
00:51:30 --> 00:51:31 do. And you always have this niggling
00:51:32 --> 00:51:34 impression at the back of your mind that our
00:51:34 --> 00:51:35 knowledge is almost complete. There are no
00:51:35 --> 00:51:37 surprises still to come. And that's just not
00:51:37 --> 00:51:40 the case. Uh, part of the reason that I love
00:51:40 --> 00:51:41 science, part of the reason that most
00:51:41 --> 00:51:44 scientists still do their job is not because
00:51:44 --> 00:51:45 we know everything, but because we know
00:51:45 --> 00:51:47 nothing. We still got so much more to learn.
00:51:47 --> 00:51:49 And it's the surprises, it's the unknowns
00:51:49 --> 00:51:51 that really motivate people and get people
00:51:51 --> 00:51:53 excited. And this is just a really good
00:51:53 --> 00:51:55 example of that, that here's all these
00:51:55 --> 00:51:57 objects that uh, we weren't even talking
00:51:57 --> 00:52:00 about 10 years ago that are a potential
00:52:00 --> 00:52:01 threat to us and we need to learn more about
00:52:01 --> 00:52:03 them. How do we do that? And that will drive
00:52:03 --> 00:52:05 technology and exploration in the years to
00:52:05 --> 00:52:05 come.
00:52:05 --> 00:52:08 Andrew Dunkley: Yes, indeed. And, uh, if we've got a few
00:52:08 --> 00:52:10 thousand years of wiggle room before it
00:52:10 --> 00:52:12 starts throwing rocks at us, we may be able
00:52:12 --> 00:52:15 to put probes out there to monitor it
00:52:16 --> 00:52:18 and get those early warnings. So we may
00:52:18 --> 00:52:21 develop the technology to, uh, defend
00:52:21 --> 00:52:23 ourselves down the track. But if you want to
00:52:23 --> 00:52:26 read about that, uh, the paper is available
00:52:26 --> 00:52:28 through, uh, Astronomy and Astrophysics, the
00:52:28 --> 00:52:31 journal, or you can look at it on the
00:52:31 --> 00:52:34 space.com website. Fascinating
00:52:34 --> 00:52:37 stuff. And Jonti, thanks for joining us.
00:52:37 --> 00:52:39 Great to have you back for a few weeks and,
00:52:39 --> 00:52:41 uh, we'll catch you on the next episode.
00:52:41 --> 00:52:42 Jonti Horner: Look forward to it.
00:52:42 --> 00:52:43 Thanks for having me back, professor, uh.
00:52:44 --> 00:52:46 Andrew Dunkley: Jonti Horner, professor of Astrophysics at
00:52:46 --> 00:52:48 the University of Southern Queensland. Thanks
00:52:48 --> 00:52:51 to him. And I, uh, would have thanked Huw in
00:52:51 --> 00:52:53 the studio, but he forgot to set his clock
00:52:53 --> 00:52:54 forward for daylight saving in New South
00:52:54 --> 00:52:56 Wales yesterday and couldn't join us. And
00:52:56 --> 00:52:58 from me, Andrew Dunkley, thanks for your
00:52:58 --> 00:53:00 company. See you on the next episode of Space
00:53:00 --> 00:53:03 Nuts. Until then, bye bye. Uh,
00:53:03 --> 00:53:05 you'll be listening to the Space Nuts
00:53:05 --> 00:53:08 podcast, available
00:53:08 --> 00:53:10 at Apple Podcasts, Spotify,
00:53:10 --> 00:53:13 iHeartRadio or your favorite podcast
00:53:13 --> 00:53:13 player.
00:53:13 --> 00:53:16 Jonti Horner: You can also stream on demand@bytes.com.
00:53:17 --> 00:53:19 Andrew Dunkley: This has been another quality podcast
00:53:19 --> 00:53:21 production from sites.um com.