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Revealing the Secrets of Space and the Cosmos: Insights from Space Nuts
Join Andrew Dunkley and Professor Fred Watson as they explore the fascinating universe—from a historic telescope in Melbourne to the latest discoveries in black hole physics and our own solar system. This episode offers a blend of awe-inspiring science, historical stories, and future possibilities that make astronomy accessible and thrilling.
In this episode:
The extraordinary history and restoration of the Melbourne Telescope, crafted in 1869, and its cultural significance.
The record-breaking detection of the loudest gravitational wave from colliding black holes and what it reveals about event horizons.
China's ambitious plans to expand its space station, including new modules and a cutting-edge space telescope.
Recent insights into a star passing close to our solar system, potentially disturbing comet orbits and shaping our cosmic history.
Upcoming solar observatories, including the ESA's Solar Orbiter and the Chinese Shun Tian telescope.
The incredible speed of the Parker Solar Probe and future missions to study the Sun's atmosphere.
How scientists analyze lunar impacts and cosmic rays using imagery and human eye observations.
The long-standing mystery of Earth's atmosphere and the role of tectonic cycles in its stability.
Resources & Links:
The Melbourne Telescope's History and Restoration (Note: Placeholder, search for Melbourne Telescope history)
LIGO and Virgo Gravitational Wave Observatory
NASA's Parker Solar Probe
ESA's Solar Orbiter
Chinese Space Station and Modules
The Daniel K. Inouye Solar Telescope
Fiz.org Physics Articles on Black Holes and Gravitational Waves
The Gaia Mission and Star Orbits
Preprint Article on Black Hole Gravitational Waves
Connect with Fred Watson:
LinkedIn
Twitter
Feel inspired by space science's latest breakthroughs and historic stories, knowing that curiosity drives understanding. With a confident yet approachable tone, this episode pushes the boundaries of knowledge while making complex ideas understandable and engaging for all.
Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support (https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support?utm_source=rss&utm_medium=rss&utm_campaign=rss) .
Episode link: https://play.headliner.app/episode/34309936?utm_source=youtube
00:00:00 --> 00:00:02 Hello there. Thanks for joining us. This
00:00:02 --> 00:00:05 is Space Nuts, where we talk astronomy
00:00:05 --> 00:00:07 and space science. My name is Andrew
00:00:07 --> 00:00:09 Dunley. Great to have your company on
00:00:09 --> 00:00:12 this the 600 millionth episode. It's
00:00:12 --> 00:00:13 maybe not that many, but we've done
00:00:13 --> 00:00:16 quite a few. What is it? 6 643 we're up
00:00:16 --> 00:00:19 to. Blimey. All right. Uh what are we
00:00:19 --> 00:00:21 talking about? We're talking about a um
00:00:21 --> 00:00:24 an old clapped out telescope. Uh Fred
00:00:24 --> 00:00:26 happens to be its patron. He's old and
00:00:26 --> 00:00:29 clapped out, too. Uh we're also going to
00:00:29 --> 00:00:32 uh look at um a new black hole discovery
00:00:32 --> 00:00:34 which was made after
00:00:34 --> 00:00:36 um two black holes collided and they
00:00:36 --> 00:00:39 recorded the loudest crash of gravit
00:00:39 --> 00:00:41 gravitational waves ever. So what's it
00:00:41 --> 00:00:44 going to tell us? Uh also uh China is
00:00:44 --> 00:00:46 going to upgrade its space station and
00:00:46 --> 00:00:50 launch a new space telescope and a star
00:00:50 --> 00:00:52 that got close to our sun may have
00:00:52 --> 00:00:53 caused a bit of a disturbance in the
00:00:54 --> 00:00:56 force. We'll tell you all about it on
00:00:56 --> 00:00:58 this episode of Space Nuts.
00:00:58 --> 00:01:03 >> 15 seconds. Guidance is internal. 10 9
00:01:03 --> 00:01:05 Ignition sequence start.
00:01:05 --> 00:01:06 >> Space Nuts.
00:01:06 --> 00:01:11 >> 5 4 3 2 1 2 3 4 5 5 4 3 2 1
00:01:11 --> 00:01:12 >> Space Nuts.
00:01:12 --> 00:01:14 >> Astronauts report. It feels good.
00:01:14 --> 00:01:17 >> And he's back again as always. It's
00:01:17 --> 00:01:19 Professor Fred Watson, astronomer at
00:01:19 --> 00:01:20 large. Hello, Fred.
00:01:20 --> 00:01:22 >> Hello, Andrew. Hello. Uh, thank you for
00:01:22 --> 00:01:26 that nice introduction. It's uh nice to
00:01:26 --> 00:01:29 hear a welcome like that.
00:01:29 --> 00:01:31 >> You know it. I know I only said it a few
00:01:31 --> 00:01:33 seconds ago, but I forgot what I said
00:01:33 --> 00:01:34 and then it dawned on me that I'd
00:01:34 --> 00:01:36 actually insulted you. Yes.
00:01:36 --> 00:01:37 >> Oh, I forgot about that. Yeah. No,
00:01:37 --> 00:01:38 that's all right. I'm uh
00:01:38 --> 00:01:40 >> That's all right. You last week.
00:01:40 --> 00:01:42 >> I am old and clapped out. There's no
00:01:42 --> 00:01:44 question about that.
00:01:44 --> 00:01:45 >> Aren't we all?
00:01:45 --> 00:01:49 >> Aren't we all? Um now uh before we get
00:01:49 --> 00:01:51 into uh today's stories, um the old
00:01:51 --> 00:01:53 clapped out telescope I referred to is
00:01:54 --> 00:01:56 actually uh a wonderful device uh that
00:01:56 --> 00:01:59 I've actually seen in person when we
00:01:59 --> 00:02:01 were down in Melbourne a few years ago.
00:02:02 --> 00:02:05 >> Uh it's the Melbourne telescope, dates
00:02:05 --> 00:02:07 back to 1869. And you're its patron
00:02:07 --> 00:02:09 because you were there when they put the
00:02:09 --> 00:02:11 first screw in it.
00:02:11 --> 00:02:13 >> I got you again.
00:02:13 --> 00:02:15 >> Yeah. So the the link and the reason why
00:02:15 --> 00:02:17 I'm well there's a number of reasons why
00:02:17 --> 00:02:18 this telescope is very close to my
00:02:18 --> 00:02:22 heart. One is that uh it was I was still
00:02:22 --> 00:02:24 at school when I found a picture of it
00:02:24 --> 00:02:26 in Henry King's history of the
00:02:26 --> 00:02:30 telescope, a very famous uh book on the
00:02:30 --> 00:02:31 history of telescopes published I think
00:02:31 --> 00:02:33 in 1955.
00:02:33 --> 00:02:35 Um I had a copy of that in the school
00:02:35 --> 00:02:36 library and there's this telescope
00:02:36 --> 00:02:38 there, the great Melbourne telescope and
00:02:38 --> 00:02:41 I thought that is that is a telescope.
00:02:41 --> 00:02:43 That's what I want. one like it looks it
00:02:43 --> 00:02:46 just looks like you'd expect one to
00:02:46 --> 00:02:46 look, doesn't it?
00:02:46 --> 00:02:48 >> You can tell it's a telescope. It's got
00:02:48 --> 00:02:51 um with decorative bits like the the
00:02:51 --> 00:02:53 lattis work tube which is uh very
00:02:53 --> 00:02:56 unusual, almost unique. Anyway, that was
00:02:56 --> 00:03:00 my first um encounter with it uh and
00:03:00 --> 00:03:01 sort of followed up as much as I could.
00:03:01 --> 00:03:03 I didn't realize that by then it was
00:03:03 --> 00:03:06 actually in CRA at Mount Stromlo. had
00:03:06 --> 00:03:09 been refurbished um having left
00:03:09 --> 00:03:14 Melbourne in 1944. But uh one h 100red
00:03:14 --> 00:03:18 years exactly after work started on the
00:03:18 --> 00:03:22 manufacturer of that telescope in 1867
00:03:22 --> 00:03:25 100 years later I joined the company
00:03:25 --> 00:03:30 that built it. Uh so it was uh it's 20th
00:03:30 --> 00:03:33 century equivalent. It was uh Howard
00:03:33 --> 00:03:35 Grub Dublin when uh it was the telescope
00:03:35 --> 00:03:37 was built. By the time I got there it
00:03:37 --> 00:03:39 was Sir Howard Grub Parsons and Company
00:03:39 --> 00:03:41 Limited, but it was basically the same
00:03:41 --> 00:03:44 company amalgamated in 1926 with the
00:03:44 --> 00:03:47 Parson's company. So um so I continued
00:03:47 --> 00:03:50 my kinship with that telescope and uh uh
00:03:50 --> 00:03:53 of course when I came to Australia was
00:03:53 --> 00:03:56 interested to see it at Stromlo. Then in
00:03:56 --> 00:03:59 2003, uh the Stromlo observatory had
00:03:59 --> 00:04:01 that terrible fire, bush fire that went
00:04:01 --> 00:04:03 through, destroyed all the heritage
00:04:03 --> 00:04:06 buildings, including the one that uh
00:04:06 --> 00:04:10 that telescope sat in uh and basically
00:04:10 --> 00:04:13 melted uh a lot of the well melted the
00:04:13 --> 00:04:14 dome onto the telescope. The dome was
00:04:14 --> 00:04:17 aluminium uh and the telescope was
00:04:17 --> 00:04:18 wrecked, its mirror was smashed and all
00:04:18 --> 00:04:22 the rest of it. Uh so I when I so I
00:04:22 --> 00:04:23 wrote a book on the history of
00:04:23 --> 00:04:25 telescopes which was published I think
00:04:25 --> 00:04:29 just after that fire because um I wrote
00:04:29 --> 00:04:31 at the end I had a whole chapter on this
00:04:31 --> 00:04:33 telescope and I wrote something to the
00:04:33 --> 00:04:35 effect that
00:04:35 --> 00:04:36 >> uh the best we could hope to see would
00:04:36 --> 00:04:40 be for it to be a static exhibit in in a
00:04:40 --> 00:04:42 museum just the remnants
00:04:42 --> 00:04:45 >> uh which was for a while. Well, it
00:04:45 --> 00:04:47 wasn't. No, it stayed put in Strummlow.
00:04:47 --> 00:04:49 And it was 5 years after the fire, 2008,
00:04:50 --> 00:04:52 when this consortium of uh museums
00:04:52 --> 00:04:54 Victoria, the Astronomical Society of
00:04:54 --> 00:04:57 Victoria, uh Royal Botanic Gardens,
00:04:57 --> 00:04:59 Melbourne, because that's where it
00:04:59 --> 00:05:00 started its career.
00:05:00 --> 00:05:01 >> Yeah.
00:05:01 --> 00:05:04 >> Uh and uh and the uh I think the Bureau
00:05:04 --> 00:05:06 of Meteorology were involved as well. Uh
00:05:06 --> 00:05:09 and they got together a plan to to
00:05:10 --> 00:05:14 basically restore it. M uh and uh so I
00:05:14 --> 00:05:17 did play a role in that in 2015. We we
00:05:18 --> 00:05:20 actually had a held a workshop which I
00:05:20 --> 00:05:22 chaired which was about how you could
00:05:22 --> 00:05:24 update the optics of the telescope
00:05:24 --> 00:05:27 because the mechanical stuff could be re
00:05:27 --> 00:05:30 refurbished uh but the optics were a
00:05:30 --> 00:05:32 different matter uh and a sort of
00:05:32 --> 00:05:35 optical prescription was was drawn up.
00:05:35 --> 00:05:36 Now those optics are still in the
00:05:36 --> 00:05:39 process of being manufactured. Uh but
00:05:40 --> 00:05:44 the telescope itself is now essentially
00:05:44 --> 00:05:46 mechanically complete. It is as complete
00:05:46 --> 00:05:49 as it was when it was built and and the
00:05:49 --> 00:05:52 work that's been done and more than 100
00:05:52 --> 00:05:54 volunteers and staff from Museums
00:05:54 --> 00:05:56 Victoria and the Astronomical Society of
00:05:56 --> 00:05:58 Victoria, it's well over a hundred have
00:05:58 --> 00:06:01 worked on it. And so last week there was
00:06:01 --> 00:06:05 a little party to celebrate that. and uh
00:06:05 --> 00:06:07 some of the museum's dignitaries said a
00:06:07 --> 00:06:08 few words, I said a few words. The chap
00:06:08 --> 00:06:10 who's been leading the project, Simon
00:06:10 --> 00:06:12 Brink, over the last few years, he said
00:06:12 --> 00:06:14 a few words. He's actually coming to
00:06:14 --> 00:06:16 coming to lunch with us on Saturday. Oh,
00:06:16 --> 00:06:18 >> lovely. Even though he's he's in
00:06:18 --> 00:06:20 Melbourne, he's coming up um which is
00:06:20 --> 00:06:23 nice. So, we've um so we had a
00:06:23 --> 00:06:26 celebration. So, and to be honest, what
00:06:26 --> 00:06:27 they've done is nothing short of
00:06:27 --> 00:06:30 miraculous because there weren't any
00:06:30 --> 00:06:32 diagrams of all the bits and pieces of
00:06:32 --> 00:06:34 this telescope. There were engineering
00:06:34 --> 00:06:37 diagrams of the thing complete. Uh they
00:06:37 --> 00:06:39 were published in a journal. But the
00:06:39 --> 00:06:42 individual parts and probably thousands
00:06:42 --> 00:06:47 of components, screws, washers, uh
00:06:47 --> 00:06:49 pulleys, cog wheels of various different
00:06:49 --> 00:06:52 sized, all of that, no idea what they
00:06:52 --> 00:06:55 look like. And by scouring photographs
00:06:55 --> 00:06:59 of the telescope uh from many sources
00:06:59 --> 00:07:03 and working out things like the numbers
00:07:03 --> 00:07:05 of teeth you need on a cog wheel to make
00:07:05 --> 00:07:08 the things work properly. Uh they've
00:07:08 --> 00:07:09 done a great job with all that and now
00:07:10 --> 00:07:11 it's in basically in perfect working
00:07:12 --> 00:07:14 order except it doesn't have its main
00:07:14 --> 00:07:17 mirror yet that's being fabricated. Um
00:07:17 --> 00:07:19 it's at the moment still at Science
00:07:19 --> 00:07:21 Works which is the science museum in
00:07:21 --> 00:07:23 Victoria and it's a
00:07:23 --> 00:07:24 >> which is worth a visit especially with
00:07:24 --> 00:07:25 the kids.
00:07:25 --> 00:07:28 >> Yeah, it's a great place to go. Uh and
00:07:28 --> 00:07:30 anybody who does go to Melbourne and
00:07:30 --> 00:07:31 sees science works definitely have a
00:07:31 --> 00:07:33 look at the great Melbourne telescope.
00:07:33 --> 00:07:35 The hope is that one day it will be in
00:07:35 --> 00:07:37 its original building which still exists
00:07:37 --> 00:07:40 in the Royal Botanic Gardens. uh but um
00:07:40 --> 00:07:42 there's quite a bit of work needs to be
00:07:42 --> 00:07:46 done to make that uh ONS uh satisfactory
00:07:46 --> 00:07:50 for 2026 or where whenever it happens
00:07:50 --> 00:07:52 compared with the um you know the health
00:07:52 --> 00:07:55 and safety regulations in 1869 when
00:07:55 --> 00:07:58 people came and went u just had a look
00:07:58 --> 00:08:00 through the telescope that's the idea
00:08:00 --> 00:08:02 that it will eventually be a working
00:08:02 --> 00:08:03 telescope for the public for people to
00:08:04 --> 00:08:05 come and look through
00:08:05 --> 00:08:07 >> wonderful and uh if you can't get down
00:08:07 --> 00:08:09 to see it in Melbourne and uh just do a
00:08:09 --> 00:08:10 search for the Melbourne Telescope
00:08:10 --> 00:08:12 online and have a look at it and you'll
00:08:12 --> 00:08:13 know what we're talking about. Um the
00:08:14 --> 00:08:16 lattis work is just beautiful. Just it
00:08:16 --> 00:08:19 is a glorious piece of equipment
00:08:19 --> 00:08:21 >> and I stumbled across it. I didn't even
00:08:21 --> 00:08:22 know it was at Science Works when we
00:08:22 --> 00:08:24 went there and we just went for a wander
00:08:24 --> 00:08:26 and found it and I went, "Oh, Fred will
00:08:26 --> 00:08:28 love this." And then it turns out you
00:08:28 --> 00:08:30 were the patron. So that's right.
00:08:30 --> 00:08:31 >> Yeah.
00:08:31 --> 00:08:34 >> Yeah. It's um it is it's quite
00:08:34 --> 00:08:36 staggering. It's how big it is, isn't
00:08:36 --> 00:08:36 it? When you
00:08:36 --> 00:08:37 >> Oh, yeah. just went
00:08:38 --> 00:08:40 >> blows your mind. You just stand there in
00:08:40 --> 00:08:40 awe.
00:08:40 --> 00:08:43 >> Big telescope. It was the biggest fully
00:08:43 --> 00:08:45 steerable telescope in the world at the
00:08:45 --> 00:08:47 time when it was when it was built. It
00:08:47 --> 00:08:48 wasn't the biggest, but it biggest
00:08:48 --> 00:08:49 telescope in the world, but it wasn't
00:08:49 --> 00:08:50 far off.
00:08:50 --> 00:08:52 >> Yeah, as a good friend of mine often
00:08:52 --> 00:08:54 says, it's a great piece of kit.
00:08:54 --> 00:08:56 >> It was a great piece of kit, and
00:08:56 --> 00:08:58 hopefully it will be again one day.
00:08:58 --> 00:08:59 Fingers crossed.
00:08:59 --> 00:09:00 >> All right.
00:09:00 --> 00:09:02 >> Uh, moving on. We're talking black
00:09:02 --> 00:09:04 holes. Very unusual. We don't usually
00:09:04 --> 00:09:05 talk about things like this, but uh this
00:09:05 --> 00:09:07 this is an interesting one because they
00:09:07 --> 00:09:09 they've made a bit of a discovery. They
00:09:09 --> 00:09:11 they've recorded the loudest crash of
00:09:11 --> 00:09:14 gravitational waves ever heard, and it
00:09:14 --> 00:09:16 was because of two black holes that
00:09:16 --> 00:09:19 decided uh to play bills with each
00:09:19 --> 00:09:22 other. And boom. Uh but it's what
00:09:22 --> 00:09:24 they've discovered from the in the
00:09:24 --> 00:09:26 aftermath of all this that's getting
00:09:26 --> 00:09:27 interesting.
00:09:28 --> 00:09:32 >> Uh yes, it is. Um so yeah we black um
00:09:32 --> 00:09:34 gravitational waves from colliding
00:09:34 --> 00:09:38 objects have been detectable by humans
00:09:38 --> 00:09:39 since 2015
00:09:40 --> 00:09:43 um with uh the LIGO gravit laser
00:09:43 --> 00:09:44 interferometer gravitational wave
00:09:44 --> 00:09:47 observatory in America and that now
00:09:47 --> 00:09:51 works with uh Virgo which is an Italian
00:09:51 --> 00:09:54 uh uh gravitational wave observatory and
00:09:54 --> 00:09:57 Kagra which is the kamioa gravitational
00:09:57 --> 00:09:59 wave detector in Japan. And so those
00:09:59 --> 00:10:01 three telescopes work together to pick
00:10:01 --> 00:10:05 up the vibrations of space uh which are
00:10:05 --> 00:10:08 transmitted from very distant collisions
00:10:08 --> 00:10:10 usually and it's usually neutron stars
00:10:10 --> 00:10:13 and black holes uh with collisions
00:10:13 --> 00:10:15 between either neutron stars and neutron
00:10:15 --> 00:10:17 stars or black holes and black holes or
00:10:17 --> 00:10:20 neutron stars and black holes. um those
00:10:20 --> 00:10:22 all produce gravitational wave signals
00:10:22 --> 00:10:25 that are actually in the frequency range
00:10:25 --> 00:10:27 detectable by uh these telescopes
00:10:27 --> 00:10:30 because that's a key part of it. The the
00:10:30 --> 00:10:32 amount of energy that's involved tells
00:10:32 --> 00:10:33 you what the frequency of the
00:10:34 --> 00:10:36 gravitational waves is going to be. And
00:10:36 --> 00:10:39 as we've noted before, Andrew, it's
00:10:39 --> 00:10:41 curious that um the gravitational waves
00:10:42 --> 00:10:44 that these telescopes are sensitive to
00:10:44 --> 00:10:46 are actually in the audio frequency
00:10:46 --> 00:10:48 regime. Uh basically if you just
00:10:48 --> 00:10:50 amplified them uh you would have an
00:10:50 --> 00:10:52 audio signal and that's basically what
00:10:52 --> 00:10:54 they do except they're doing it in a
00:10:54 --> 00:10:57 very much more sophisticated way. Um the
00:10:57 --> 00:11:01 um the the amount of um shaking of space
00:11:01 --> 00:11:05 that they can they can detect is
00:11:05 --> 00:11:08 absolutely infinite decimal. Uh but
00:11:08 --> 00:11:10 these things are sensitive enough that
00:11:10 --> 00:11:13 they can measure a distance that is a
00:11:13 --> 00:11:15 thousandth I think it's a 10th
00:11:15 --> 00:11:17 actually of the diameter of a proton. Uh
00:11:18 --> 00:11:20 that's the uh the accuracy with which
00:11:20 --> 00:11:22 they can measure the distance between
00:11:22 --> 00:11:24 two mirrors which is how you do all this
00:11:24 --> 00:11:27 sort of thing. So that's the backstory.
00:11:27 --> 00:11:31 Uh the the up story, the forward story
00:11:31 --> 00:11:35 is that an object or a you don't have an
00:11:35 --> 00:11:36 object, you have a gravitational wave
00:11:36 --> 00:11:39 signal. Uh it's rejoices in the name of
00:11:39 --> 00:11:42 GW25014.
00:11:42 --> 00:11:44 Uh that tells you that it was picked up
00:11:44 --> 00:11:48 on in January uh 2025. Uh that's where
00:11:48 --> 00:11:50 the 25501
00:11:50 --> 00:11:55 comes from. Um uh and it uh basically
00:11:56 --> 00:11:58 uh on analysis
00:11:58 --> 00:12:03 um has been uh detected to be a
00:12:03 --> 00:12:06 collision between two black holes each
00:12:06 --> 00:12:09 of which had around 32 times the mass of
00:12:09 --> 00:12:12 the sun. And so they collided and that
00:12:12 --> 00:12:15 set uh you know set the gravitational
00:12:15 --> 00:12:17 waves on their way because it it it
00:12:17 --> 00:12:19 basically disturbed space. It rippled
00:12:19 --> 00:12:23 space. So what's happened is and and
00:12:23 --> 00:12:24 this as you mentioned at the beginning
00:12:24 --> 00:12:26 is the loudest gravitational wave signal
00:12:26 --> 00:12:28 that's been detected or the certainly
00:12:28 --> 00:12:30 the most uh intense the highest
00:12:30 --> 00:12:32 amplitude one.
00:12:32 --> 00:12:37 >> Yeah. Um so what has happened is uh that
00:12:37 --> 00:12:40 researchers uh have analyzed the audio
00:12:40 --> 00:12:45 signal um and they found in it um a
00:12:45 --> 00:12:47 basically it's been described as a
00:12:47 --> 00:12:50 feature uh which is something called a
00:12:50 --> 00:12:54 direct wave. It's a it's a component of
00:12:54 --> 00:12:57 the signal uh and it's and it's a direct
00:12:57 --> 00:13:01 wave uh that has not that's been seen
00:13:01 --> 00:13:04 before but hasn't nobody's worked out
00:13:04 --> 00:13:08 what it is but apparently it is a
00:13:08 --> 00:13:12 feature that essentially uh in the in
00:13:12 --> 00:13:15 the gravitational wave structure that
00:13:15 --> 00:13:18 comes from this event. You can tell this
00:13:18 --> 00:13:22 direct wave is to do with the event
00:13:22 --> 00:13:25 horizon of the combined black holes.
00:13:25 --> 00:13:27 >> So you've got two black holes, each of
00:13:28 --> 00:13:30 which is has got its own event horizon.
00:13:30 --> 00:13:32 They're spinning around one another
00:13:32 --> 00:13:34 getting ever closer as we've seen that
00:13:34 --> 00:13:36 sort of thing before and the frequency
00:13:36 --> 00:13:38 goes up of the gravitational waves. Um
00:13:38 --> 00:13:41 and then suddenly all stops because that
00:13:41 --> 00:13:43 they've collided and there's no more
00:13:43 --> 00:13:46 accelerations which is what you need to
00:13:46 --> 00:13:49 uh to set up gravitational waves. Um and
00:13:49 --> 00:13:53 but uh at that point the two um
00:13:53 --> 00:13:54 gravitate the sorry the two event
00:13:54 --> 00:13:58 horizons merge. Uh now a recap on event
00:13:58 --> 00:14:01 horizons that's the point of no return.
00:14:01 --> 00:14:03 Basically it's the it's the distance
00:14:03 --> 00:14:07 from the black hole uh where the escape
00:14:07 --> 00:14:08 velocity
00:14:08 --> 00:14:12 uh is more than the speed of light and
00:14:12 --> 00:14:14 so nothing can escape from within the
00:14:14 --> 00:14:17 event horizon uh and in particular light
00:14:17 --> 00:14:18 can't escape. So the event horizon is
00:14:18 --> 00:14:20 black. It's a sphere around the black
00:14:20 --> 00:14:22 hole uh through which you can't see
00:14:22 --> 00:14:25 because nothing escapes including light.
00:14:25 --> 00:14:28 So um that is what the event horizon is
00:14:28 --> 00:14:31 in a sense. It's imaginary. Uh, Andrew,
00:14:31 --> 00:14:33 you know, it's not it's not a real
00:14:33 --> 00:14:34 surface. It's an imaginary surface
00:14:34 --> 00:14:37 because it's just the boundary between
00:14:37 --> 00:14:39 what's visible and what's not vis not
00:14:39 --> 00:14:41 not visible.
00:14:41 --> 00:14:45 >> Now, we know when black holes collide,
00:14:45 --> 00:14:47 uh, I I don't know that much about the
00:14:48 --> 00:14:50 details of these things, but there is a
00:14:50 --> 00:14:52 a period immediately after they've
00:14:52 --> 00:14:55 merged which is called the ringdown. And
00:14:55 --> 00:14:57 it's a time when they sort of
00:14:57 --> 00:15:00 consolidate as one black hole. And that
00:15:00 --> 00:15:02 means their event horizons also
00:15:02 --> 00:15:05 consolidate. And I think this direct
00:15:05 --> 00:15:08 wave that has been detected is basically
00:15:08 --> 00:15:13 a uh an artifact of that ringdown. Uh
00:15:13 --> 00:15:18 and so um what I guess is uh perhaps the
00:15:18 --> 00:15:21 takeaway message from this work is not
00:15:21 --> 00:15:24 that we've learned something miraculous
00:15:24 --> 00:15:27 and and new about the event horizon, but
00:15:27 --> 00:15:28 that we've learned that there might be a
00:15:28 --> 00:15:32 way of in future gravitational wave
00:15:32 --> 00:15:35 events uh might be a way of analyzing
00:15:35 --> 00:15:37 these direct waves to give us more
00:15:37 --> 00:15:40 information on the black hole event
00:15:40 --> 00:15:42 horizon. Because at the moment we've we
00:15:42 --> 00:15:44 don't know much about it. We can we've
00:15:44 --> 00:15:47 seen them in the telescopes, you know,
00:15:47 --> 00:15:49 the um observations from the event
00:15:49 --> 00:15:52 horizon telescope that amalgam of many
00:15:52 --> 00:15:56 radio telescopes, an earth-sized array
00:15:56 --> 00:15:58 uh which has been used to look at the
00:15:58 --> 00:16:00 black holes in center of our own galaxy
00:16:00 --> 00:16:04 and in M57 I think it was uh with um
00:16:04 --> 00:16:08 with a fair fairly high degree of
00:16:08 --> 00:16:10 precision and what we've seen is the
00:16:10 --> 00:16:12 black shadow of the of the event
00:16:12 --> 00:16:14 horizon. Um, but perhaps with these
00:16:14 --> 00:16:17 gravitational waves, these direct waves,
00:16:17 --> 00:16:20 there might be a a way of teasing out
00:16:20 --> 00:16:23 even more detail from these distant and
00:16:23 --> 00:16:25 highly enigmatic objects.
00:16:25 --> 00:16:27 >> Yes, indeed. And another interesting
00:16:27 --> 00:16:28 thing that comes out of this story is
00:16:28 --> 00:16:31 that um that they're suggesting uh the
00:16:32 --> 00:16:35 measurements that that that they've made
00:16:35 --> 00:16:39 could be a step towards um future tests
00:16:39 --> 00:16:42 of general relativity
00:16:42 --> 00:16:44 >> using direct waves. So you know there's
00:16:44 --> 00:16:46 there's all sorts of potential by the
00:16:46 --> 00:16:46 sound of it.
00:16:46 --> 00:16:48 >> That's that's right. Yeah. I mean
00:16:48 --> 00:16:51 exactly and of course this is one of the
00:16:51 --> 00:16:53 holy grails of a of science generally
00:16:53 --> 00:16:56 actually certainly physics to find
00:16:56 --> 00:16:59 chinks in general relativity because at
00:16:59 --> 00:17:01 the moment it behaves exactly as
00:17:01 --> 00:17:03 predicted. Everything that we've seen in
00:17:03 --> 00:17:06 the universe follows the uh the the
00:17:06 --> 00:17:07 rules and regulations of general
00:17:07 --> 00:17:12 relativity uh in a perfect way. So maybe
00:17:12 --> 00:17:14 uh direct waves will as you said give us
00:17:14 --> 00:17:17 a way of testing general relativity. If
00:17:17 --> 00:17:20 we find um things that don't work in
00:17:20 --> 00:17:22 general relativity then that could be an
00:17:22 --> 00:17:24 opening into new physics which is
00:17:24 --> 00:17:26 certainly a hot topic at the moment.
00:17:26 --> 00:17:29 >> Indeed it is. Well, everyone including
00:17:29 --> 00:17:30 Einstein thinks something's wrong with
00:17:30 --> 00:17:32 it. They just they just can't fight
00:17:32 --> 00:17:34 anything at the moment. It keeps coming
00:17:34 --> 00:17:35 up
00:17:35 --> 00:17:37 >> aces every time they test it.
00:17:37 --> 00:17:38 >> Yeah. They think something's wrong with
00:17:38 --> 00:17:40 it because it doesn't it doesn't sit
00:17:40 --> 00:17:42 with quantum mechanics. The two are
00:17:42 --> 00:17:44 incompatible and they both work
00:17:44 --> 00:17:46 perfectly well, but they're
00:17:46 --> 00:17:48 incompatible.
00:17:48 --> 00:17:49 >> Weird, isn't it?
00:17:49 --> 00:17:51 >> Yes. That's very weird. Yeah. The other
00:17:51 --> 00:17:52 thing that I find fascinating about this
00:17:52 --> 00:17:55 story is that from something as simple
00:17:55 --> 00:17:58 as a as a a gravitational wave, they're
00:17:58 --> 00:18:00 able to break it down and find
00:18:00 --> 00:18:04 information that is is
00:18:04 --> 00:18:06 really just,
00:18:06 --> 00:18:08 >> you know, you you can't see any of this.
00:18:08 --> 00:18:10 It's all just data, isn't it?
00:18:10 --> 00:18:11 >> Yeah. Yeah, that's correct. That's
00:18:12 --> 00:18:14 right. But the physics is well
00:18:14 --> 00:18:16 understood because general relativity is
00:18:16 --> 00:18:18 such a reliable tool for people to use
00:18:18 --> 00:18:21 to analyze these things. Um that's how
00:18:21 --> 00:18:23 we can make these statements about it.
00:18:24 --> 00:18:26 And yes um if we can find flaws with
00:18:26 --> 00:18:28 general relativity, it will be very
00:18:28 --> 00:18:30 exciting.
00:18:30 --> 00:18:31 >> Indeed it will. And you can read all
00:18:31 --> 00:18:34 about it at the space.com website. Uh
00:18:34 --> 00:18:37 they published their research uh in the
00:18:37 --> 00:18:40 journal Nature. This is Space Nuts with
00:18:40 --> 00:18:45 Andrew Dunley and Professor Fred Watson.
00:18:45 --> 00:18:46 Let's take a short break from the show
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00:20:33 --> 00:20:35 >> I believe that this nation should commit
00:20:35 --> 00:20:39 itself to achieving the goal before this
00:20:39 --> 00:20:41 decade is out of landing a man on the
00:20:42 --> 00:20:44 moon and returning him safely to the
00:20:44 --> 00:20:44 earth.
00:20:44 --> 00:20:46 >> These muts.
00:20:46 --> 00:20:49 >> Now, Fred, we turn our uh attention
00:20:49 --> 00:20:51 towards China. Of course, they've got a
00:20:51 --> 00:20:54 a very active space station in operation
00:20:54 --> 00:20:57 at the moment. Uh the latest news though
00:20:57 --> 00:21:01 is that they intend to uh make it bigger
00:21:01 --> 00:21:02 and at the same time they're going to
00:21:02 --> 00:21:05 put a new space telescope into uh into
00:21:05 --> 00:21:07 orbit as well. So they're really going
00:21:07 --> 00:21:09 ahead in leaps and bounds, aren't they?
00:21:09 --> 00:21:11 They are. Yes. Uh it's um you know this
00:21:12 --> 00:21:14 is part of the Chinese it's not the
00:21:14 --> 00:21:17 China National uh space agency. Uh I
00:21:17 --> 00:21:19 think it's that they've got a separate
00:21:19 --> 00:21:23 space agency for human space flight. Uh
00:21:23 --> 00:21:25 and that's the organization that
00:21:25 --> 00:21:28 operates the Tangong uh space station
00:21:28 --> 00:21:31 which has been up there since 2021 I
00:21:31 --> 00:21:33 think was when uh we started seeing it
00:21:33 --> 00:21:35 being assembled. It was assembled in a
00:21:35 --> 00:21:37 very similar manner to the International
00:21:37 --> 00:21:39 Space Station by building sort of
00:21:39 --> 00:21:42 modules that you can stick together like
00:21:42 --> 00:21:46 Lego uh up once once these modules are
00:21:46 --> 00:21:46 in orbit.
00:21:46 --> 00:21:48 >> Yeah. At the moment, it's the China
00:21:48 --> 00:21:51 National Space Administration, which
00:21:51 --> 00:21:53 handles the programs, and the China Man
00:21:53 --> 00:21:56 Space Agency, which um oversees human
00:21:56 --> 00:21:57 space flight.
00:21:57 --> 00:21:58 >> That's that that's right. I knew there
00:21:58 --> 00:22:01 were two organizations involved. Thank
00:22:01 --> 00:22:02 you for that.
00:22:02 --> 00:22:02 >> That's all right.
00:22:02 --> 00:22:04 >> Um
00:22:04 --> 00:22:08 so, uh yes. So uh at the moment the the
00:22:08 --> 00:22:11 tangon consists of three modules and
00:22:12 --> 00:22:15 they're arranged in a sort of T-shape uh
00:22:15 --> 00:22:20 with um uh two three the three end
00:22:20 --> 00:22:22 points of the modules if you like coming
00:22:22 --> 00:22:23 coming together in a in a sort of
00:22:23 --> 00:22:26 vestibule where you can uh tunnel your
00:22:26 --> 00:22:28 way from one to the to the other with um
00:22:28 --> 00:22:31 these basically entry and exit hatches
00:22:31 --> 00:22:34 that uh is the way things work on the
00:22:34 --> 00:22:36 International Space Station as Well, but
00:22:36 --> 00:22:38 as you've said, uh what they're now
00:22:38 --> 00:22:41 planning to do is to add three more
00:22:41 --> 00:22:44 modules. Um and the reason they want to
00:22:44 --> 00:22:49 do that is because uh they want to do
00:22:49 --> 00:22:52 more research up there, uh and make more
00:22:52 --> 00:22:56 frequent crew and cargo changes. Um so
00:22:56 --> 00:22:59 they're actually um I think the way to
00:22:59 --> 00:23:01 deal with that is to to make the space
00:23:01 --> 00:23:04 station bigger. Um, and so it's going to
00:23:04 --> 00:23:07 be what they're calling a double T
00:23:07 --> 00:23:09 shape, which I think is probably an H
00:23:09 --> 00:23:11 shape,
00:23:11 --> 00:23:13 if I can put it that way. Um,
00:23:13 --> 00:23:14 >> well, that's what Yeah, it would turn
00:23:14 --> 00:23:15 into that, wouldn't it?
00:23:15 --> 00:23:17 >> You'd expect so. Yes, that's right.
00:23:17 --> 00:23:20 Unless they do something clever,
00:23:20 --> 00:23:22 >> like turn one of the T's round uh at
00:23:22 --> 00:23:24 right angles to the other one. Anyway,
00:23:24 --> 00:23:25 we we don't know what's going to happen
00:23:25 --> 00:23:28 there, but um there is a new um
00:23:28 --> 00:23:31 multi-purpose module and two new
00:23:31 --> 00:23:34 experimental modules that are planned uh
00:23:34 --> 00:23:39 to um essentially uh you know allow
00:23:39 --> 00:23:42 Chinese uh space exploration in low
00:23:42 --> 00:23:46 earth orbit to continue and be extended.
00:23:46 --> 00:23:50 Um um we understand from um some of the
00:23:50 --> 00:23:54 researchers in China that uh it's always
00:23:54 --> 00:23:58 been uh an expectation that this would
00:23:58 --> 00:24:00 uh take place that there be this
00:24:00 --> 00:24:03 extension uh and what it will do in
00:24:03 --> 00:24:06 terms of the mass of the of the um space
00:24:06 --> 00:24:08 station is take it up from its current
00:24:08 --> 00:24:12 90 tons uh up to
00:24:12 --> 00:24:14 180 tons or thereabouts. And there's a
00:24:14 --> 00:24:16 yard stick if I remember rightly and you
00:24:16 --> 00:24:18 might be able to correct me here Andrew
00:24:18 --> 00:24:19 but I think the International Space
00:24:19 --> 00:24:22 Station is about 400 tons in terms of
00:24:22 --> 00:24:26 its mass. I think that is the case. So,
00:24:26 --> 00:24:30 uh, that's, uh, the plan and alongside
00:24:30 --> 00:24:32 that, as you've already mentioned,
00:24:32 --> 00:24:36 Andrew, is the idea of a new, um, space
00:24:36 --> 00:24:39 observatory, an optical telescope,
00:24:39 --> 00:24:41 >> quite similar in some ways to the Hubble
00:24:41 --> 00:24:43 Space Telescope,
00:24:43 --> 00:24:45 >> slightly smaller mirror, two mir 2 m
00:24:45 --> 00:24:48 rather than 2.3 m.
00:24:48 --> 00:24:52 Um, and also with a much wider field of
00:24:52 --> 00:24:54 view. The Hubble has quite a narrow
00:24:54 --> 00:24:57 field of view. Uh and in fact the Nancy
00:24:57 --> 00:25:00 Grace Roman telescope which is also very
00:25:00 --> 00:25:02 similar to the Hubble will have a much
00:25:02 --> 00:25:04 wider field of view than Hubble. That's
00:25:04 --> 00:25:07 being launched later this year I hope.
00:25:07 --> 00:25:11 um this uh uh Chinese telescope uh which
00:25:11 --> 00:25:13 has a name Shuntan I think is probably
00:25:13 --> 00:25:17 how it's how it's pronounced in my
00:25:17 --> 00:25:21 in my um poor Chinese uh poor Mandarin
00:25:21 --> 00:25:24 and poor Chinese. Uh it's um it's got a
00:25:24 --> 00:25:26 much bigger field of view and will
00:25:26 --> 00:25:31 actually give new uh surveys to uh
00:25:31 --> 00:25:33 Chinese astronomers. We'll see a lot
00:25:33 --> 00:25:36 more information about the universe
00:25:36 --> 00:25:37 coming from this telescope. The more
00:25:37 --> 00:25:38 telescopes you've got on the universe,
00:25:38 --> 00:25:42 the better. And uh Shunan will be one of
00:25:42 --> 00:25:45 those uh features when it is launched
00:25:45 --> 00:25:48 and actually commissioned uh that will
00:25:48 --> 00:25:51 we hope um really bring new insights
00:25:51 --> 00:25:52 into our knowledge of space.
00:25:52 --> 00:25:55 >> Yeah. Apparently its field of view is
00:25:55 --> 00:25:58 going to be massive compared to Hubble
00:25:58 --> 00:26:00 at 300 times.
00:26:00 --> 00:26:02 >> Correct. Yes, that's right. So, it's a
00:26:02 --> 00:26:04 wide-angle telescope rather than the the
00:26:04 --> 00:26:06 sort of pinpoint view of the of the
00:26:06 --> 00:26:07 Hubble.
00:26:07 --> 00:26:09 >> Yeah. Quite incredible. You uh you were
00:26:09 --> 00:26:10 right about the International Space
00:26:10 --> 00:26:13 Station. Uh 419
00:26:13 --> 00:26:18 kg is its mass or say 420
00:26:18 --> 00:26:21 >> um tons. Yes, indeed. Um the other
00:26:21 --> 00:26:23 interesting thing that China is working
00:26:23 --> 00:26:28 on uh is a new um delivery system for
00:26:28 --> 00:26:30 their they call them tyonauts, don't
00:26:30 --> 00:26:30 they?
00:26:30 --> 00:26:33 >> Yes, they do. Yeah. Uh they want to they
00:26:33 --> 00:26:35 want to develop a rocket system that
00:26:35 --> 00:26:37 will send seven up at a time.
00:26:37 --> 00:26:39 >> Yes. Yeah.
00:26:39 --> 00:26:41 >> Sponsored by Seven Up. No, I'm joking.
00:26:41 --> 00:26:43 But um they're going Yeah, that's what
00:26:43 --> 00:26:44 they're looking at doing at the moment.
00:26:44 --> 00:26:47 They can only send up three at a time.
00:26:47 --> 00:26:51 Yes. So the the the Chinese um uh
00:26:51 --> 00:26:54 orbital vehicle for getting astronauts
00:26:54 --> 00:26:58 up taken up there and I'm ashamed that I
00:26:58 --> 00:27:00 can't remember what it's called. Uh is
00:27:00 --> 00:27:04 it Shenzho Shenzhao? I I can't remember.
00:27:04 --> 00:27:08 But the that is basically an adaptation
00:27:08 --> 00:27:11 of the old Soyots Russian spacecraft
00:27:11 --> 00:27:12 which is still in service in the
00:27:12 --> 00:27:14 International Space Station developed in
00:27:14 --> 00:27:16 the 1960s.
00:27:16 --> 00:27:19 >> Uh a threeperson uh module. Uh I think
00:27:19 --> 00:27:21 I'm right in saying that the Crew Dragon
00:27:21 --> 00:27:25 can take up to seven astronauts as well.
00:27:25 --> 00:27:26 >> Interesting. Shenzhia.
00:27:26 --> 00:27:29 >> Shencho. Yeah. is the um is the system
00:27:29 --> 00:27:31 they're using right
00:27:31 --> 00:27:32 >> you did
00:27:32 --> 00:27:36 >> um so uh yes so that will go from 3 to 7
00:27:36 --> 00:27:38 it's understandable you know if you you
00:27:38 --> 00:27:40 want to keep the crews coming and going
00:27:40 --> 00:27:41 I think this is a really important
00:27:41 --> 00:27:44 development because um if nothing else
00:27:44 --> 00:27:47 it's going to I think spur
00:27:48 --> 00:27:51 uh the private sector on to pick up the
00:27:51 --> 00:27:54 baton of what you might call western
00:27:54 --> 00:27:56 international space stations or the
00:27:56 --> 00:27:58 western international space station
00:27:58 --> 00:27:59 because that's scheduled at the moment
00:28:00 --> 00:28:02 to to be decommissioned in 2030. That
00:28:02 --> 00:28:03 might change. Yeah.
00:28:04 --> 00:28:06 >> Uh but it's a possibility that we will
00:28:06 --> 00:28:09 lose the ISS in 2030. Uh and we've seen
00:28:09 --> 00:28:11 problems with, you know, the leakage
00:28:11 --> 00:28:13 that we had in one of the modules a
00:28:13 --> 00:28:16 couple of weeks ago where the crew was
00:28:16 --> 00:28:18 evacuated, not not evacuated, but moved
00:28:18 --> 00:28:22 the the American crew uh the NASA end of
00:28:22 --> 00:28:25 the spacecraft were moved into a crew
00:28:25 --> 00:28:29 dragon capsule to uh just be certain
00:28:29 --> 00:28:31 that nothing untored was going to happen
00:28:31 --> 00:28:35 if uh if there was a a a catastrophic
00:28:35 --> 00:28:37 leak. Uh when the Ross Cosmos
00:28:38 --> 00:28:39 Cosmonauts, they were actually trying to
00:28:39 --> 00:28:41 fix the leak, uh they moved the other
00:28:41 --> 00:28:44 crew into the um into the Crew Dragon
00:28:44 --> 00:28:46 capsule for safety.
00:28:46 --> 00:28:49 >> Yeah. Uh in terms of replacing the ISS,
00:28:49 --> 00:28:51 uh there are no firm plans at the
00:28:51 --> 00:28:53 moment, but they're they're kind of
00:28:54 --> 00:28:56 thinking about um I think you mentioned
00:28:56 --> 00:28:58 it, the commercial sector getting
00:28:58 --> 00:29:00 involved. Yeah.
00:29:00 --> 00:29:02 >> So, and and that's that's probably
00:29:02 --> 00:29:04 logical. I I'm I'm pretty sure that uh
00:29:04 --> 00:29:07 Elon would be pretty keen to put a a
00:29:07 --> 00:29:10 space station into orbit and
00:29:10 --> 00:29:12 a few others probably. There's plenty of
00:29:12 --> 00:29:15 people around with me bucks to do it.
00:29:15 --> 00:29:17 >> Yes, that's right. Um Yeah. And but you
00:29:18 --> 00:29:20 know, you might think have to think
00:29:20 --> 00:29:23 carefully about whether you uh take over
00:29:23 --> 00:29:29 the old the old tired and quite dodgy uh
00:29:29 --> 00:29:30 old international space station or
00:29:30 --> 00:29:32 whether you build something new. Mh.
00:29:32 --> 00:29:34 >> Um, and uh, of course, the technology
00:29:34 --> 00:29:36 has moved on enormously since the 1990s
00:29:36 --> 00:29:39 when when that was put together. It's
00:29:39 --> 00:29:41 been continuously continuously occupied
00:29:41 --> 00:29:45 since 2000. Uh, that's 26 years of uh,
00:29:45 --> 00:29:47 tenants coming and going. It's probably
00:29:47 --> 00:29:49 taken a fair beating inside.
00:29:49 --> 00:29:50 >> Yeah, I'm sure they've had a few
00:29:50 --> 00:29:54 parties. Yeah, no doubt about it.
00:29:54 --> 00:29:56 >> If you want to read all about China's
00:29:56 --> 00:29:59 plans, you can do that at space.com.
00:30:00 --> 00:30:01 Uh, this is Space Nuts with Andrew
00:30:01 --> 00:30:06 Dunley and Professor Fred Watson.
00:30:06 --> 00:30:10 Space Nuts. Our final story, Fred, takes
00:30:10 --> 00:30:12 us close to home. And, and this is
00:30:12 --> 00:30:14 really quite a fascinating story because
00:30:14 --> 00:30:18 it talks about a star, not our son,
00:30:18 --> 00:30:20 another star that got up close and
00:30:20 --> 00:30:23 personal with our um with our with our
00:30:23 --> 00:30:27 particular sun um a little while ago.
00:30:27 --> 00:30:29 But uh the the effects of that
00:30:29 --> 00:30:34 interaction uh seem to still exist which
00:30:34 --> 00:30:35 is very odd.
00:30:35 --> 00:30:38 >> Yeah. Well, that's right. Uh yes, it is.
00:30:38 --> 00:30:40 It's a interesting story. It covers, you
00:30:40 --> 00:30:42 know, two quite different bits of
00:30:42 --> 00:30:44 astronomy here that come together to to
00:30:44 --> 00:30:47 sort of work out what was going on. So,
00:30:47 --> 00:30:49 this star in question, it's got the
00:30:50 --> 00:30:53 glorious name of HD797.
00:30:53 --> 00:30:55 HD stands for Henry Draper. It's one of
00:30:55 --> 00:30:57 the early star cataloges uh from the
00:30:57 --> 00:31:00 19th century I think uh the Henry Draper
00:31:00 --> 00:31:04 catalog. Uh and it's a relatively near
00:31:04 --> 00:31:07 star similar to the sun. Uh it's
00:31:07 --> 00:31:08 currently in the constellation of
00:31:08 --> 00:31:11 Cassipia which is um one of my favorite
00:31:11 --> 00:31:13 northern constellations actually. It's
00:31:13 --> 00:31:15 one that we don't see from down here in
00:31:15 --> 00:31:21 Australia. Uh so um how do we know that
00:31:21 --> 00:31:23 HD797
00:31:23 --> 00:31:26 had um a near miss with our solar
00:31:26 --> 00:31:29 system? And the answer is with the GIA
00:31:29 --> 00:31:33 mission. So GIA is a spacecraft uh it
00:31:33 --> 00:31:39 sits at the um uh Sun Earth L2 point.
00:31:39 --> 00:31:41 That's the Lrange point on the opposite
00:31:41 --> 00:31:44 side of the Earth from the Sun. Um, it's
00:31:44 --> 00:31:46 been working for, I think, certainly
00:31:46 --> 00:31:49 more than a decade. And what it's done
00:31:49 --> 00:31:52 is measured star positions with
00:31:52 --> 00:31:55 absolutely exquisite precision. Uh,
00:31:55 --> 00:31:57 you're talking about, I think it's sort
00:31:57 --> 00:32:00 of some accuracies in the region of 100
00:32:00 --> 00:32:02 millionth of an arcsec. These are
00:32:02 --> 00:32:05 phenomenal accuracies. And an arcsec, of
00:32:05 --> 00:32:08 course, is 1 3th of a degree. Uh,
00:32:08 --> 00:32:11 the size of a, here in Australia, a $1
00:32:11 --> 00:32:13 coin held up at 5 kilometers. It's a
00:32:13 --> 00:32:16 tiny angle, but this thing's measuring
00:32:16 --> 00:32:18 millionth of that basically or 100
00:32:18 --> 00:32:21 millions. Uh and what that does is it
00:32:21 --> 00:32:23 allows you if you make these
00:32:23 --> 00:32:24 measurements at different times, it
00:32:24 --> 00:32:29 allows you to plot the motions of stars
00:32:29 --> 00:32:31 uh not just in our own galaxy and in our
00:32:32 --> 00:32:34 own neighborhood but also in the two
00:32:34 --> 00:32:38 melanic clouds, the uh the two nearest
00:32:38 --> 00:32:40 neighbor dwarf galaxies, the big ones,
00:32:40 --> 00:32:44 large and small melanic clouds, 165 and
00:32:44 --> 00:32:47 200 lighty years away respectively.
00:32:47 --> 00:32:50 uh those uh you can detect the motions
00:32:50 --> 00:32:52 of stars in those galaxies and even in
00:32:52 --> 00:32:55 the Andromeda galaxy about 2 and a half
00:32:55 --> 00:32:56 million lighty years away. You can see
00:32:56 --> 00:32:58 evidence of what we call lateral motion
00:32:58 --> 00:33:00 on the sky, the sideways motion of
00:33:00 --> 00:33:02 things. And if you can measure the
00:33:02 --> 00:33:05 radial velocity, that's the velocity
00:33:05 --> 00:33:06 along the line of sight, which is
00:33:06 --> 00:33:08 actually much easier if you can do that
00:33:08 --> 00:33:10 as well, you've got um the
00:33:10 --> 00:33:12 three-dimensional motion of objects in
00:33:12 --> 00:33:18 space. And that is how uh it's HD797
00:33:18 --> 00:33:20 was picked up as having passed close to
00:33:20 --> 00:33:23 the sun about 2 and a half million years
00:33:23 --> 00:33:24 ago
00:33:24 --> 00:33:28 >> as both these stars, the sun and HD797
00:33:28 --> 00:33:30 as they both orbit around the center of
00:33:30 --> 00:33:33 our galaxy. Uh we still don't know
00:33:33 --> 00:33:36 exactly how close. Uh the data from GIA
00:33:36 --> 00:33:41 suggests it was between 4 and 25
00:33:41 --> 00:33:43 astronomical units. And as we've
00:33:43 --> 00:33:45 mentioned before, an astronomical unit
00:33:45 --> 00:33:46 is the distance between the Earth and
00:33:46 --> 00:33:50 the Sun. Convenient measure. It is uh
00:33:50 --> 00:33:52 150 million kilometers.
00:33:52 --> 00:33:57 um they they may have um that we might
00:33:57 --> 00:33:59 be able to tie that uh close approach
00:33:59 --> 00:34:02 down though by other methods and the
00:34:02 --> 00:34:05 methods in question have been employed
00:34:05 --> 00:34:09 by uh some scientists at the University
00:34:09 --> 00:34:13 of Bordeaux. Uh and basically what they
00:34:13 --> 00:34:17 have done is looked not at GIA data to
00:34:17 --> 00:34:19 try and refine uh you know this this
00:34:19 --> 00:34:22 sort of look back in time as to when
00:34:22 --> 00:34:24 these two stars were close together.
00:34:24 --> 00:34:27 They've looked at long period comets.
00:34:27 --> 00:34:29 Comets that uh come in from the very
00:34:29 --> 00:34:31 furthest reaches of the solar system
00:34:31 --> 00:34:34 where we think there is a reservoir of
00:34:34 --> 00:34:37 comets. We call it the or cloud. uh and
00:34:37 --> 00:34:39 it turns out that if you look at long
00:34:40 --> 00:34:43 period comets uh which are have been
00:34:43 --> 00:34:45 measured you know over the past 100
00:34:45 --> 00:34:49 years I guess um then you get uh an an
00:34:49 --> 00:34:53 idea of the distribution of their orbits
00:34:53 --> 00:34:56 and the basically there's a quote here
00:34:56 --> 00:34:59 from one of the authors of the uh of the
00:34:59 --> 00:35:02 paper that we're talking about uh who
00:35:02 --> 00:35:04 says the distribution of comet orbits
00:35:04 --> 00:35:05 suggests we are living through an
00:35:05 --> 00:35:09 unusual time where HD797
00:35:09 --> 00:35:11 has dominated the generation of new
00:35:11 --> 00:35:14 comets and not the larger gravitational
00:35:14 --> 00:35:16 field of the Milky Way as it usually
00:35:16 --> 00:35:19 would. This would also mean we're living
00:35:19 --> 00:35:21 through the late stages of a pretty rare
00:35:21 --> 00:35:24 and powerful comet shower. And so what
00:35:24 --> 00:35:26 they've done is made computer
00:35:26 --> 00:35:30 simulations of uh how comet orbits might
00:35:30 --> 00:35:34 behave as a result of being tipped out
00:35:34 --> 00:35:36 of the or cloud by the passage of this
00:35:36 --> 00:35:38 star HD797.
00:35:38 --> 00:35:40 They've kicked out the or cloud and
00:35:40 --> 00:35:42 heading towards the sun. Uh they've
00:35:42 --> 00:35:45 measured the basically the details of
00:35:45 --> 00:35:48 112 long period comets. Actually,
00:35:48 --> 00:35:49 they've chosen ones that have only been
00:35:49 --> 00:35:52 observed in recent years since 1989
00:35:52 --> 00:35:55 because that's when we could detect
00:35:55 --> 00:35:58 comets coming from uh any part of the
00:35:58 --> 00:36:00 sky. Uh if you if you only limit
00:36:00 --> 00:36:02 yourself to one part of the sky, then
00:36:02 --> 00:36:04 you've got uh as visible, for example,
00:36:04 --> 00:36:06 by a single observatory uh or even as
00:36:06 --> 00:36:08 visible by the northern hemisphere
00:36:08 --> 00:36:11 observatories. You're missing uh half
00:36:11 --> 00:36:13 the objects that you want to see. And
00:36:13 --> 00:36:15 since what you're doing is looking at
00:36:15 --> 00:36:16 the statistical distribution of these
00:36:16 --> 00:36:19 things, you can't afford to um to
00:36:19 --> 00:36:21 eliminate things that way. It's what
00:36:21 --> 00:36:24 would be called a selection effect.
00:36:24 --> 00:36:26 >> Um so yes, these long period comets,
00:36:26 --> 00:36:29 they've got very elongated orbits. Uh
00:36:29 --> 00:36:31 and the suggestion is that the
00:36:31 --> 00:36:33 distribution of those orbits in relation
00:36:33 --> 00:36:37 to the direction that we know HD797
00:36:37 --> 00:36:38 went through the solar system or went
00:36:38 --> 00:36:41 close to the solar system. Uh that's why
00:36:41 --> 00:36:45 they believe uh that the two events uh
00:36:45 --> 00:36:49 the close passage of 797
00:36:49 --> 00:36:52 uh tipped up the comets and caused a lot
00:36:52 --> 00:36:55 more of these comets to come in. And if
00:36:55 --> 00:36:59 you accept their uh their um hypothesis,
00:36:59 --> 00:37:03 then what it does is ties down
00:37:03 --> 00:37:06 rather better the distance that we
00:37:06 --> 00:37:09 estimate HD797.
00:37:09 --> 00:37:12 uh approached the sun at somewhere
00:37:12 --> 00:37:15 between 6 and 10 astronomical
00:37:15 --> 00:37:17 units. A tighter window compared with
00:37:17 --> 00:37:20 the 4 to 25 astronomical units
00:37:20 --> 00:37:22 that Gia suggests.
00:37:22 --> 00:37:22 >> Yes.
00:37:22 --> 00:37:25 >> So, it's a it's a nice tightening up of
00:37:25 --> 00:37:27 our understanding of this uh
00:37:27 --> 00:37:30 hypothesized but probably real event 2
00:37:30 --> 00:37:31 and a half million years ago. And just
00:37:31 --> 00:37:33 to give people a bit of an idea of the
00:37:33 --> 00:37:35 distance, so somewhere between 6 and
00:37:35 --> 00:37:40 10 AU is is where HD797
00:37:40 --> 00:37:42 kind of grazed our solar system.
00:37:42 --> 00:37:43 >> Yes.
00:37:43 --> 00:37:46 >> Voyager 1 is 170 AU
00:37:46 --> 00:37:48 >> from Earth. So
00:37:48 --> 00:37:50 >> we're talking a fair way out.
00:37:50 --> 00:37:51 >> It's a long way off. That's right.
00:37:51 --> 00:37:53 >> Yeah. You're talking probably getting
00:37:53 --> 00:37:55 into the vicinity of the or cloud, which
00:37:55 --> 00:37:57 makes sense given what they're
00:37:57 --> 00:38:00 hypothesizing in this paper.
00:38:00 --> 00:38:03 Exactly right. So, a star passing nearby
00:38:03 --> 00:38:04 the or cloud would
00:38:04 --> 00:38:07 >> definitely upset it and send stuff in
00:38:07 --> 00:38:09 towards the inner solar system.
00:38:09 --> 00:38:09 >> Yes,
00:38:09 --> 00:38:12 >> it's actually um it's a theory that uh
00:38:12 --> 00:38:15 that general mechanism was proposed by
00:38:15 --> 00:38:16 colleagues of mine in the Royal
00:38:16 --> 00:38:18 Observatory in Edinburgh, Victor Club
00:38:18 --> 00:38:21 and Bill Napia back in the late 1970s.
00:38:21 --> 00:38:23 The idea that they were suggesting it
00:38:23 --> 00:38:26 might have needed a bit more mass than a
00:38:26 --> 00:38:29 single star to disturb the cloud. Uh and
00:38:29 --> 00:38:31 they suggested the passage nearby
00:38:31 --> 00:38:33 passage of something called a giant
00:38:33 --> 00:38:35 molecular cloud a kind of stellar
00:38:35 --> 00:38:37 birthplace if one of those goes past the
00:38:37 --> 00:38:39 solar system. They were inferring that
00:38:39 --> 00:38:41 it would disturb the or cloud to the
00:38:41 --> 00:38:43 extent that you would get bombardment of
00:38:43 --> 00:38:45 the inner solar system by comets and
00:38:45 --> 00:38:47 that might be visible in the geological
00:38:47 --> 00:38:49 record on earth. That was their
00:38:49 --> 00:38:51 basically their um uh their you know
00:38:51 --> 00:38:54 their their principal line of attack. Uh
00:38:54 --> 00:38:56 really very interesting science. Uh so
00:38:56 --> 00:38:59 this is not a new idea but this is new
00:38:59 --> 00:39:02 research that suggests that um perhaps
00:39:02 --> 00:39:04 we can learn more by pursuing it. But
00:39:04 --> 00:39:04 now
00:39:04 --> 00:39:07 >> indeed yes um the paper by the way has
00:39:07 --> 00:39:09 been accepted by the planetary science
00:39:09 --> 00:39:11 journal and is available at the moment
00:39:11 --> 00:39:14 on the archive preprint server. You can
00:39:14 --> 00:39:19 also read about it at fizz.org phys.org.
00:39:19 --> 00:39:21 Uh Fred, that brings us to the end of
00:39:21 --> 00:39:23 the show. Thank you so much.
00:39:23 --> 00:39:25 >> Well that went very quickly. Uh, what a
00:39:25 --> 00:39:26 good time we had.
00:39:26 --> 00:39:28 >> We did indeed. Yes. We'll catch you on
00:39:28 --> 00:39:28 the next one.
00:39:28 --> 00:39:30 >> Sounds great. Thank you very much.
00:39:30 --> 00:39:32 >> Professor Fred Watson, astronomer at
00:39:32 --> 00:39:34 large. And don't forget between episodes
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00:40:05 --> 00:40:07 all of that on our website. And thanks
00:40:07 --> 00:40:09 to Hugh in the studio who couldn't be
00:40:09 --> 00:40:11 with us today because he saw a passing
00:40:11 --> 00:40:13 star and chased her down for an
00:40:13 --> 00:40:16 autograph. And from and from me, Andrew
00:40:16 --> 00:40:18 Dunley, thanks for your company. We'll
00:40:18 --> 00:40:20 see you on the next episode of Space
00:40:20 --> 00:40:22 Nuts. Bye-bye. Space Nuts.
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