SOURCES Newfound 'Baby' Planet Smashes Record for Youngest Known World NASA Science, 16 September 2026 - https://science.nasa.gov/universe/newfound-baby-planet-smashes-record-for-youngest-known-world/ Elias 2-24 b discovery paper Bernardi, Cieza et al., The Astrophysical Journal Letters, 16 September 2026, DOI 10.3847/2041-8213/ae9bb6 - https://doi.org/10.3847/2041-8213/ae9bb6 ALMA Observations of Elias 2-24: A Protoplanetary Disk with Multiple Gaps (background) Cieza et al., ApJL 851 L23, 2017, DOI 10.3847/2041-8213/aa9b7b - https://doi.org/10.3847/2041-8213/aa9b7b NASA's Moon Orbiter Spots New, 'Once-in-Century' Moon Crater NASA Science, 16 September 2026 - https://science.nasa.gov/solar-system/moon/nasas-moon-orbiter-spots-new-once-in-century-moon-crater/ New 222-metre lunar crater - mission release W. M. Keck / Intuitive Machines / NASA LROC, 16 September 2026; two papers in Science Advances (Robinson et al., morphology and ejecta; Powell et al., Diviner thermal signature) - https://www.prnewswire.com/news-releases/nasas-lunar-reconnaissance-orbiter-discovers-a-new-222-m-diameter-lunar-crater-302880555.html Mystery of one of the earliest recorded space weather impacts solved Lancaster University / RMIT University, 16 September 2026; Wild, Carter, Hapgood et al., Space Weather (AGU), DOI 10.1029/2026SW005239 - https://doi.org/10.1029/2026SW005239 'Born-again' star offers rare chance to watch stellar evolution in real time The University of Manchester, 16 September 2026; Zijlstra, van Hoof et al., 'The emergence of a [WC] star in Sakurai's object', MNRAS, DOI 10.1093/mnras/stag1533 - https://doi.org/10.1093/mnras/stag1533 Cargo Mission and Crew-13 Updates; Station Research, Maintenance Continue NASA Space Station Blog, 16 September 2026 - https://www.nasa.gov/blogs/spacestation/2026/09/16/cargo-mission-and-crew-13-updates-station-research-maintenance-continue/ International Observe the Moon Night 2026 NASA, Saturday 19 September 2026 - https://science.nasa.gov/moon/observe-the-moon-night/overview Skywatch ephemerides Computed in-session with PyEphem for Sydney, Los Angeles, New York and London, 17-18 September 2026
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This episode includes AI-generated content.
00:00:00 --> 00:00:02 Anna: Every planet you have ever heard of was
00:00:02 --> 00:00:05 already finished when we found it. Grown up,
00:00:06 --> 00:00:08 settled into its orbit. The
00:00:08 --> 00:00:11 disc of gas and dust it was built from
00:00:11 --> 00:00:12 long gone.
00:00:13 --> 00:00:15 Avery: Not this one. Astronomers have found a
00:00:15 --> 00:00:18 planet that is still being built, less than
00:00:18 --> 00:00:21 a million years old, sitting in the gap it is
00:00:21 --> 00:00:23 carving through its own birth cloud.
00:00:24 --> 00:00:26 Anna: Also today, a brand new crater on the
00:00:26 --> 00:00:29 Moon, a Victorian train delay that turns
00:00:29 --> 00:00:32 out to be a solar storm, and a dead star
00:00:32 --> 00:00:35 that has got six times hotter in 30 years.
00:00:36 --> 00:00:37 Avery: I'm Avery.
00:00:37 --> 00:00:39 Anna: And I'm Anna. This is Astronomy
00:00:39 --> 00:00:41 AstroDailyPod. Here is a number that should
00:00:41 --> 00:00:41 stop you.
00:00:42 --> 00:00:44 Every previously confirmed young planet,
00:00:45 --> 00:00:47 every single one held up as an example of a
00:00:47 --> 00:00:50 world caught in the act of forming, was at
00:00:50 --> 00:00:53 least 5 million years old. 5 million years
00:00:53 --> 00:00:55 sounds young. It is young. Our own
00:00:55 --> 00:00:57 solar system is about four and a half
00:00:57 --> 00:01:00 billion. But five million years is also long
00:01:00 --> 00:01:02 enough that the most interesting part is
00:01:02 --> 00:01:05 already over. The gas is mostly gone.
00:01:05 --> 00:01:07 The building is done. You are looking at the
00:01:07 --> 00:01:10 result, not the process. Yesterday in
00:01:10 --> 00:01:13 the Astrophysical Journal Letters, a team led
00:01:13 --> 00:01:15 from Chile published the confirmation of a
00:01:15 --> 00:01:18 planet that is less than 1 million years old,
00:01:18 --> 00:01:21 not 5, less than 1. It is
00:01:21 --> 00:01:24 called Elias 224B. And the most
00:01:24 --> 00:01:26 remarkable thing about it is that we are
00:01:26 --> 00:01:27 watching it being made.
00:01:27 --> 00:01:29 Avery: And this is one of those results where the
00:01:29 --> 00:01:32 storey of how we got there is as good as the
00:01:32 --> 00:01:35 result itself. Because the first hint of
00:01:35 --> 00:01:38 this planet is 9 years old, it
00:01:38 --> 00:01:38 is.
00:01:38 --> 00:01:41 Anna: Let me take you back to 2017. A team
00:01:41 --> 00:01:44 including Lucas Sieza, who is an author on
00:01:44 --> 00:01:47 today's paper as well, pointed Alma,
00:01:47 --> 00:01:50 the Big Millimetre array up on the Chagnantor
00:01:50 --> 00:01:52 Plateau in northern Chile at a young star in
00:01:52 --> 00:01:54 the Ophiuchus molecular cloud.
00:01:54 --> 00:01:57 Ophiuchus is one of the closest active star
00:01:57 --> 00:02:00 forming regions to us, about 450
00:02:00 --> 00:02:02 light years away. And from here in the
00:02:02 --> 00:02:05 southern hemisphere, it rides high across the
00:02:05 --> 00:02:08 winter sky. The star is catalogued as
00:02:08 --> 00:02:10 Elias224. It is a K
00:02:10 --> 00:02:13 type star, roughly the mass of the sun, but
00:02:13 --> 00:02:15 much cooler and much puffier because it has
00:02:15 --> 00:02:18 not finished contracting yet. What Alma saw
00:02:18 --> 00:02:20 was a disc of dust around that star with gaps
00:02:20 --> 00:02:23 in it. Dark rings, clean
00:02:23 --> 00:02:26 circular lanes swept through the dust. And
00:02:26 --> 00:02:28 the standard interpretation of a gap like
00:02:28 --> 00:02:30 that is simple and beautiful. Something
00:02:30 --> 00:02:33 massive is orbiting in there and its gravity
00:02:33 --> 00:02:36 is hurting the dust out of its path. The gap
00:02:36 --> 00:02:38 is the wake, a footprint
00:02:38 --> 00:02:39 Avery: rather than a foot.
00:02:39 --> 00:02:42 Anna: Exactly that. And footprints are frustrating
00:02:42 --> 00:02:44 because a gap can be made by other things.
00:02:44 --> 00:02:46 Ice lines, where a particular molecule
00:02:46 --> 00:02:48 freezes out and changes how the dust sticks
00:02:48 --> 00:02:51 together. Magnetic effects in the disc
00:02:51 --> 00:02:53 turbulence. For nine years,
00:02:53 --> 00:02:56 Elias224 has been a beautiful set of
00:02:56 --> 00:02:59 rings and an unproven assumption. What
00:02:59 --> 00:03:02 Andrea Bernardi at Universidad Diego Portales
00:03:02 --> 00:03:05 in Santiago did was go looking for the foot
00:03:05 --> 00:03:07 and the data had been sitting in an archive
00:03:07 --> 00:03:08 the whole time.
00:03:08 --> 00:03:10 Avery: This is the part I love.
00:03:10 --> 00:03:12 Anna: The W.M. keck Observatory on Mauna
00:03:12 --> 00:03:15 Kea observed this system in 2018
00:03:15 --> 00:03:18 and again in 2020 using a
00:03:18 --> 00:03:21 coronagraph on the NIRC 2
00:03:21 --> 00:03:24 infrared camera. A, uh, coronagraph is a
00:03:24 --> 00:03:26 mask that blocks the light of the star itself
00:03:26 --> 00:03:28 so you can see the much fainter things next
00:03:28 --> 00:03:31 to it. The same basic trick the Roman Space
00:03:31 --> 00:03:33 Telescope's coronagraph is being commissioned
00:03:33 --> 00:03:35 to do right now, which we talked about on
00:03:35 --> 00:03:38 Wednesday. Those Keck observations were
00:03:38 --> 00:03:41 taken, archived and not fully
00:03:41 --> 00:03:44 mined. Bernardi's team went back into them,
00:03:44 --> 00:03:46 reprocessed them and found a point of
00:03:46 --> 00:03:48 infrared light sitting inside one of the
00:03:48 --> 00:03:51 gaps. And here is Bernardi's line, which
00:03:51 --> 00:03:54 is the whole paper in one. The
00:03:54 --> 00:03:56 planets should be found within the gaps since
00:03:56 --> 00:03:57 they are carving them.
00:03:58 --> 00:03:59 And that's exactly where we found
00:03:59 --> 00:04:02 Elias224B, end quote.
00:04:02 --> 00:04:05 Avery: So the prediction and the detection line up.
00:04:05 --> 00:04:08 Anna: They line up and then the confirmation
00:04:08 --> 00:04:11 needed a third instrument. ESO's Very
00:04:11 --> 00:04:14 Large Telescope at Paranal in the Atacama
00:04:14 --> 00:04:16 had also caught a faint point of light in
00:04:16 --> 00:04:18 that gap. Put the three together.
00:04:19 --> 00:04:21 ALMA showing you the gap in millimetre dust.
00:04:21 --> 00:04:24 The the VLT and KECK both showing you an
00:04:24 --> 00:04:26 infrared source sitting in it at two separate
00:04:26 --> 00:04:29 epochs, two years apart. So you can cheque it
00:04:29 --> 00:04:31 is moving with the star rather than being a
00:04:31 --> 00:04:34 background object and you have a planet.
00:04:34 --> 00:04:36 Avery: Bernardi made a point of that in the release.
00:04:37 --> 00:04:39 Something like we usually hear about
00:04:39 --> 00:04:41 telescopes working separately. But this
00:04:41 --> 00:04:44 confirmation was only possible by using
00:04:44 --> 00:04:46 multiple telescopes together, which is worth
00:04:46 --> 00:04:49 sitting with for a second because it is also
00:04:49 --> 00:04:52 a storey about hemispheres. ALMA and
00:04:52 --> 00:04:55 the VLT are both in Chile. Keck is
00:04:55 --> 00:04:58 in Hawaii. Ophiuchus sits at about
00:04:58 --> 00:05:00 24 degrees south, so it is a target
00:05:01 --> 00:05:03 both hemispheres can reach. And it took all
00:05:03 --> 00:05:06 three facilities on both sides of the equator
00:05:06 --> 00:05:09 to nail this down. The southern telescopes
00:05:09 --> 00:05:11 found the gap and the northern telescope had
00:05:11 --> 00:05:14 the planet sitting in its archive. Now
00:05:14 --> 00:05:17 the physics and this is where it gets
00:05:17 --> 00:05:19 genuinely awkward for the textbooks.
00:05:19 --> 00:05:22 Elias224B is roughly the
00:05:22 --> 00:05:25 mass of Jupiter and it is orbiting about
00:05:25 --> 00:05:28 55 times further from its star than Earth
00:05:28 --> 00:05:30 is from the Sun. 55
00:05:30 --> 00:05:33 astronomical units for scale.
00:05:33 --> 00:05:36 Neptune is at 30, Pluto averages
00:05:36 --> 00:05:39 about 39. So this is a Jupiter
00:05:39 --> 00:05:41 mass planet out past where our own Kuiper
00:05:41 --> 00:05:44 Belt starts. And it got there in under a
00:05:44 --> 00:05:47 million years. And the standard way we build
00:05:47 --> 00:05:50 giant planets does not go that fast, that
00:05:50 --> 00:05:51 far out.
00:05:51 --> 00:05:54 Anna: It does not core accretion.
00:05:54 --> 00:05:57 The mainstream model says you assemble
00:05:57 --> 00:05:59 a solid core first by sticking pebbles
00:05:59 --> 00:06:02 together. And once that core is heavy enough,
00:06:02 --> 00:06:05 it starts pulling gas down onto itself and
00:06:05 --> 00:06:08 runs away into a gas giant. The trouble is
00:06:08 --> 00:06:10 that the further out you go, the thinner the
00:06:10 --> 00:06:12 disc is and the slower everything orbits.
00:06:13 --> 00:06:15 So there is less material and fewer
00:06:15 --> 00:06:18 collisions per orbit. Building a Jupiter at
00:06:18 --> 00:06:20 55 au by core accretion is slow.
00:06:21 --> 00:06:23 Estimates run to many millions of years.
00:06:24 --> 00:06:26 This planet did not have many millions of
00:06:26 --> 00:06:28 years. It had at the outside one.
00:06:28 --> 00:06:30 Lucas Sieza put it plainly,
00:06:31 --> 00:06:33 our planet formation models already struggled
00:06:33 --> 00:06:35 to explain the previous record holders.
00:06:36 --> 00:06:39 Elias224B shows us that even our best
00:06:39 --> 00:06:40 models are still missing some important
00:06:40 --> 00:06:43 processes. End quote.
00:06:43 --> 00:06:46 Avery: There is an alternative, isn't there? The
00:06:46 --> 00:06:48 disc fragmenting directly.
00:06:48 --> 00:06:51 Anna: There is gravitational instability.
00:06:51 --> 00:06:53 Instead of building a planet from the bottom
00:06:53 --> 00:06:55 up, you let a patch of the disc become dense
00:06:55 --> 00:06:57 enough that it collapses under its own
00:06:57 --> 00:07:00 gravity all at once and makes a giant
00:07:00 --> 00:07:02 planet more or less the way a star forms.
00:07:03 --> 00:07:05 That is fast, and it works better at large
00:07:05 --> 00:07:08 distances where discs are cooler and more
00:07:08 --> 00:07:10 prone to collapse. A planet like this one,
00:07:10 --> 00:07:13 this young, this far out, is exactly
00:07:13 --> 00:07:15 the sort of object people point to when they
00:07:15 --> 00:07:18 argue that gravitational instability has to
00:07:18 --> 00:07:20 be part of the picture rather than a, uh,
00:07:20 --> 00:07:23 curiosity. But I want to be careful here.
00:07:23 --> 00:07:26 And this is the caveat that does not come out
00:07:26 --> 00:07:29 of the script. Go on directly
00:07:29 --> 00:07:30 Imaged protoplanets have a history.
00:07:31 --> 00:07:34 Candidates around the stars Lkca 15
00:07:34 --> 00:07:37 and AB Orige were both announced as
00:07:37 --> 00:07:39 planets in the making, and both ended up
00:07:39 --> 00:07:41 disputed. In some cases, what looked like a
00:07:41 --> 00:07:43 planet turned out to be a bright knot of disc
00:07:43 --> 00:07:46 material or an artefact of how the starlight
00:07:46 --> 00:07:49 was subtracted. The system PDS 70
00:07:49 --> 00:07:51 is the one everybody agrees on, and that took
00:07:51 --> 00:07:54 years of independent confirmation. So
00:07:54 --> 00:07:56 Elias 224B is a strong detection
00:07:56 --> 00:07:59 with three telescopes behind it. And it is
00:07:59 --> 00:08:01 also a detection that will get tested hard
00:08:01 --> 00:08:04 over the next few years, as it should be.
00:08:04 --> 00:08:06 And the mass number deserves the same care.
00:08:07 --> 00:08:09 At an age under a million years, you cannot
00:08:09 --> 00:08:11 weigh a planet directly. You measure how
00:08:11 --> 00:08:14 bright it is in the infrared, and you convert
00:08:14 --> 00:08:15 that to, uh, a mass using models of how a
00:08:15 --> 00:08:18 young giant planet cools. Those models
00:08:18 --> 00:08:20 disagree with each other most severely at
00:08:20 --> 00:08:23 exactly this age, because they depend on how
00:08:23 --> 00:08:25 much heat the planet held onto from its
00:08:25 --> 00:08:27 formation. And some of the light you are
00:08:27 --> 00:08:29 seeing may not be the planet's surface at
00:08:29 --> 00:08:31 all, but gas falling onto it and glowing as
00:08:31 --> 00:08:34 it lands. So when we say Jupiter mass,
00:08:34 --> 00:08:37 read that as Jupiter ish, with real room on
00:08:37 --> 00:08:40 either side. An earlier kinematic estimate
00:08:40 --> 00:08:42 for whatever is carving that gap put it as
00:08:42 --> 00:08:44 high as five Jupiter masses.
00:08:45 --> 00:08:46 Avery: None of which changes the headline.
00:08:47 --> 00:08:49 Anna: None of which changes the headline. Something
00:08:49 --> 00:08:52 with the mass of a giant planet is
00:08:52 --> 00:08:55 sitting in that gap and the star it
00:08:55 --> 00:08:57 orbits is younger than our species.
00:08:58 --> 00:09:00 We have around 6 confirmed
00:09:00 --> 00:09:03 exoplanets now and almost every one of them
00:09:03 --> 00:09:04 is a finished product.
00:09:05 --> 00:09:08 This is a building site with the scaffolding
00:09:08 --> 00:09:11 still up and it is going to be observed
00:09:11 --> 00:09:14 to death, which is the correct fate for a
00:09:14 --> 00:09:15 result like this one.
00:09:16 --> 00:09:18 Avery: Moving on to storey two, sometime between
00:09:18 --> 00:09:21 11 April and 22 May
00:09:22 --> 00:09:24 2024, something the size of a three
00:09:24 --> 00:09:27 to six storey building hit the moon.
00:09:27 --> 00:09:30 Nobody saw it happen. We found the hole
00:09:30 --> 00:09:33 18 months later and the papers describing it
00:09:33 --> 00:09:35 were published yesterday in Science Advances.
00:09:36 --> 00:09:37 Anna: How big a hole?
00:09:37 --> 00:09:40 Avery: 222 metres across and
00:09:40 --> 00:09:43 about 43 metres deep. That is roughly
00:09:43 --> 00:09:46 two football pitches wide and a 14
00:09:46 --> 00:09:49 storey building deep. And here is the part
00:09:49 --> 00:09:52 that makes it news rather than trivia. It
00:09:52 --> 00:09:54 is about three times wider than the largest
00:09:54 --> 00:09:57 new crater found in the entire 17 years the
00:09:57 --> 00:09:59 lunar Reconnaissance Orbiter has been
00:09:59 --> 00:10:02 watching. The team put an impact this size
00:10:02 --> 00:10:04 at something like one in a hundred and thirty
00:10:04 --> 00:10:07 years. It is on the near side at about
00:10:07 --> 00:10:10 1.4 degrees north, 67
00:10:10 --> 00:10:12 degrees east, out on the outer ring of the
00:10:12 --> 00:10:15 crisium basin, roughly 20 kilometres
00:10:15 --> 00:10:18 east of Mare Speumens, right on the boundary
00:10:18 --> 00:10:21 where the bright highlands meet the dark Mare
00:10:21 --> 00:10:23 plains. It is being referred to informally
00:10:23 --> 00:10:26 by the name of its neighbourhood, Magecheon,
00:10:26 --> 00:10:29 after Thomas Magn, who once directed the
00:10:29 --> 00:10:31 Lunar and Planetary Institute.
00:10:31 --> 00:10:34 Formal naming is the IAU's business
00:10:34 --> 00:10:36 and that is a separate process.
00:10:37 --> 00:10:39 Anna: And nobody was looking at that patch of the
00:10:39 --> 00:10:40 moon at the time.
00:10:40 --> 00:10:41 Avery: Nobody was.
00:10:42 --> 00:10:44 It was found by Robert Wagner, an image
00:10:44 --> 00:10:47 processing specialist at Intuitive Machines,
00:10:47 --> 00:10:50 working with the orbiter's camera team. In
00:10:50 --> 00:10:52 October last year, doing routine data
00:10:52 --> 00:10:55 quality cheques, he was running software that
00:10:55 --> 00:10:58 compares before and after maps of the whole
00:10:58 --> 00:11:00 moon and flags. What has changed?
00:11:01 --> 00:11:03 His description of the moment is my favourite
00:11:03 --> 00:11:06 thing. In the release I just
00:11:06 --> 00:11:08 stopped, dropped everything and started
00:11:08 --> 00:11:10 looking into what that spot was.
00:11:12 --> 00:11:14 What stood out was a bright splash of fresh
00:11:14 --> 00:11:17 ejecta. And the ejecta is the science.
00:11:17 --> 00:11:20 The continuous blanket of thrown out rock
00:11:20 --> 00:11:23 reaches a median of about 258
00:11:23 --> 00:11:26 metres from the centre. Bright disturbance
00:11:26 --> 00:11:28 shows up 15 kilometres out.
00:11:28 --> 00:11:31 Fainter, darker disturbance runs beyond a
00:11:31 --> 00:11:34 hundred kilometres. The biggest boulder they
00:11:34 --> 00:11:36 measured is 13 metres by 9 by 3
00:11:37 --> 00:11:40 from a hole 200 metres wide. The
00:11:40 --> 00:11:42 surface is measurably rearranged over an area
00:11:42 --> 00:11:44 the size of a small country,
00:11:44 --> 00:11:46 Anna: which is a lot of energy, about
00:11:46 --> 00:11:49 Avery: 65 trillion joules on assumptions of a
00:11:49 --> 00:11:52 rocky impactor at 15 kilometres a second.
00:11:53 --> 00:11:55 And the second paper is the one I would not
00:11:55 --> 00:11:56 have predicted.
00:11:56 --> 00:11:59 A team led by Powell went to Diviner,
00:11:59 --> 00:12:02 the orbiter's thermal instrument and found a
00:12:02 --> 00:12:04 cold spot about seven kilometres across,
00:12:04 --> 00:12:07 centred on the crater eight or nine Kelvin,
00:12:07 --> 00:12:10 cooler than its surroundings. That is the
00:12:10 --> 00:12:12 signature of fluffed up soil. The impact
00:12:12 --> 00:12:15 did not just dig a hole, it loosened the top
00:12:15 --> 00:12:18 layer of regolith across seven kilometres.
00:12:18 --> 00:12:21 And loose soil holds heat differently from
00:12:21 --> 00:12:23 packed soil. Mark Robinson, the
00:12:23 --> 00:12:26 camera's chief scientist, framed it as
00:12:26 --> 00:12:28 gardening impacts, as the process that
00:12:28 --> 00:12:31 turns the lunar soil over, churning buried
00:12:31 --> 00:12:34 material up and fresh material down. And
00:12:34 --> 00:12:36 he drew the conclusion people always want
00:12:36 --> 00:12:39 drawn on that turnover rate. The
00:12:39 --> 00:12:41 Apollo footprints will, in his words,
00:12:41 --> 00:12:44 definitely be long gone in about
00:12:44 --> 00:12:45 80
00:12:45 --> 00:12:48 Anna: years, which is not soon. But it
00:12:48 --> 00:12:49 is not forever either.
00:12:49 --> 00:12:51 Avery: That is the thing to take away.
00:12:52 --> 00:12:54 We talk about the moon as the dead unchanging
00:12:54 --> 00:12:57 one, the place where nothing happens. It
00:12:57 --> 00:13:00 is not unchanging. It is changing slowly
00:13:00 --> 00:13:03 and it changed in a big way two years ago.
00:13:03 --> 00:13:06 And the only reason we know is that there is
00:13:06 --> 00:13:08 a spacecraft up there photographing the same
00:13:08 --> 00:13:11 ground over and over. Take the watcher
00:13:11 --> 00:13:13 away and this simply would not be a, ah,
00:13:13 --> 00:13:13 known event.
00:13:14 --> 00:13:17 Anna: Okay, now on to our next storey. This one
00:13:17 --> 00:13:19 is a detective storey and it has an
00:13:19 --> 00:13:22 Australian fingerprint on it for
00:13:22 --> 00:13:25 178 years. The textbook answer
00:13:25 --> 00:13:27 to when did space weather first disrupt
00:13:27 --> 00:13:30 human Technology has been 18
00:13:31 --> 00:13:33 October 1841 in
00:13:33 --> 00:13:36 Devon, in the southwest of England. A
00:13:36 --> 00:13:38 train leaving Exeter at 5 past 10 at night
00:13:38 --> 00:13:41 was held for 16 minutes because the
00:13:41 --> 00:13:43 railway telegraph between Exeter and the
00:13:43 --> 00:13:45 village of Starcross had stopped working
00:13:46 --> 00:13:48 and the signalman could not confirm the line
00:13:48 --> 00:13:49 ahead was clear.
00:13:50 --> 00:13:51 Avery: Sixteen minutes.
00:13:51 --> 00:13:53 Hardly a catastrophe.
00:13:53 --> 00:13:56 Anna: Hardly a catastrophe. And that is precisely
00:13:56 --> 00:13:59 why it is famous. It is the first time we can
00:13:59 --> 00:14:01 point at a piece of critical infrastructure
00:14:01 --> 00:14:04 and say the sun did that. Trains
00:14:04 --> 00:14:06 stopped because of something happening 93
00:14:06 --> 00:14:09 million miles away and the people involved
00:14:09 --> 00:14:12 had no idea. It is quoted in review
00:14:12 --> 00:14:14 papers, in government resilience reports,
00:14:14 --> 00:14:17 in lectures. 1841 is the
00:14:17 --> 00:14:20 date everyone uses yesterday in the
00:14:20 --> 00:14:23 Journal Space Weather. A team led by Jim Wild
00:14:23 --> 00:14:26 at Lancaster University, with Brett Carter at
00:14:26 --> 00:14:28 RMIT in Melbourne, Mike Hapgood at
00:14:28 --> 00:14:31 RAL Space and colleagues at the British
00:14:31 --> 00:14:34 Geological Survey, Natural Resources Canada
00:14:34 --> 00:14:37 and Baylor published the correction. It
00:14:37 --> 00:14:40 did not happen in 1841. It happened on
00:14:40 --> 00:14:41 the 18th of October
00:14:41 --> 00:14:44 Avery: 1848, seven years out.
00:14:44 --> 00:14:47 How does a date like that survive a century
00:14:47 --> 00:14:47 and a half?
00:14:48 --> 00:14:50 Anna: Because nobody went back to the source. The
00:14:50 --> 00:14:53 original account is an anonymous article in
00:14:53 --> 00:14:56 the journal nature, published in 1871,
00:14:56 --> 00:14:59 30 years after the fact. And the
00:14:59 --> 00:15:01 giveaway, once you look, is almost
00:15:01 --> 00:15:04 embarrassing. The railway line between Exeter
00:15:04 --> 00:15:07 and Star Cross did not open until 1846.
00:15:08 --> 00:15:09 The event could not have happened on the line
00:15:09 --> 00:15:12 in 1841, because in 1841 there was
00:15:12 --> 00:15:13 no line.
00:15:14 --> 00:15:15 Avery: So it is a typo.
00:15:16 --> 00:15:18 Anna: It looks like a typo. 1848
00:15:18 --> 00:15:21 misprinted as 1841,
00:15:21 --> 00:15:23 probably by the anonymous author, who the
00:15:23 --> 00:15:25 team think was most likely Nathaniel John
00:15:25 --> 00:15:28 Holmes, a telegraph engineer of the period.
00:15:29 --> 00:15:31 But proving that took real archival work
00:15:32 --> 00:15:34 and this is the part I enjoyed. They went
00:15:34 --> 00:15:36 through old railway timetables to find when a
00:15:36 --> 00:15:39 five past ten evening service from Exeter
00:15:39 --> 00:15:41 actually existed, which narrowed it to a four
00:15:41 --> 00:15:44 month window. They pulled the magnetic
00:15:44 --> 00:15:46 observatory records from Greenwich. They read
00:15:46 --> 00:15:49 the sunspot drawings. They went through
00:15:49 --> 00:15:51 newspaper archives and 18
00:15:51 --> 00:15:53 October 1848 lights up
00:15:54 --> 00:15:56 Greenwich recorded powerful magnetic
00:15:56 --> 00:15:58 disturbance from about 20 past 9 in the
00:15:58 --> 00:16:01 evening Universal Time. There were
00:16:01 --> 00:16:03 aurora sightings right across the United
00:16:03 --> 00:16:05 Kingdom. And there was a large sunspot group
00:16:05 --> 00:16:08 on the disc recorded from Durham. The
00:16:08 --> 00:16:10 timetable, the magnetometer, the aurora
00:16:10 --> 00:16:13 reports and the sunspot all agree on one
00:16:13 --> 00:16:13 night.
00:16:14 --> 00:16:17 Avery: Mike Hapgood had a line about that he
00:16:17 --> 00:16:18 did quote.
00:16:18 --> 00:16:21 Anna: Our research has a hint of a Detective Storey
00:16:21 --> 00:16:24 piecing together a wide range of archived
00:16:24 --> 00:16:26 records to better understand a historically
00:16:26 --> 00:16:27 severe space weather event.
00:16:28 --> 00:16:30 End quote. And there is a reason this matters
00:16:30 --> 00:16:32 beyond tidying up. A footnote.
00:16:33 --> 00:16:35 1848 is 11 years before the Carrington
00:16:35 --> 00:16:38 event of 1859, which is the storm
00:16:38 --> 00:16:41 everyone uses as the worst case. Redating
00:16:41 --> 00:16:44 this one does not just move a date, it puts a
00:16:44 --> 00:16:46 severe infrastructure affecting storm into
00:16:46 --> 00:16:48 the record in a decade where we thought we
00:16:48 --> 00:16:51 had one. How often the really big storms
00:16:51 --> 00:16:53 happen is a question we answer by counting
00:16:53 --> 00:16:55 them in the historical record. And the
00:16:55 --> 00:16:57 historical record is only as good as the
00:16:57 --> 00:16:59 record keeping, which is
00:16:59 --> 00:17:01 Avery: the same trap we keep running into with
00:17:01 --> 00:17:02 catalogues.
00:17:03 --> 00:17:05 Anna: It is exactly the same trap moved from
00:17:05 --> 00:17:08 telescopes to archives and it sits squarely
00:17:08 --> 00:17:10 in a thread we have been pulling all month.
00:17:11 --> 00:17:13 The superflare potential work back On
00:17:13 --> 00:17:16 Saturday the 12th, the cosmic radiation at
00:17:16 --> 00:17:17 aviation altitudes.
00:17:17 --> 00:17:19 On Monday the 14th, same dial.
00:17:20 --> 00:17:22 Jim Wilde's closing thought is the one to
00:17:22 --> 00:17:25 keep Space weather is not a
00:17:25 --> 00:17:27 new threat, but a long standing natural
00:17:27 --> 00:17:30 hazard. Society has been experiencing the
00:17:30 --> 00:17:32 effects of space weather on technology for
00:17:32 --> 00:17:34 almost as long as electrical technologies
00:17:34 --> 00:17:37 have existed. End quote. The Victorians
00:17:37 --> 00:17:39 were not protected from the sun. They just
00:17:39 --> 00:17:40 had less to lose.
00:17:41 --> 00:17:43 Avery: In February 1996, a
00:17:43 --> 00:17:46 Japanese amateur astronomer named Yukio
00:17:46 --> 00:17:48 Sakurai found a new star in
00:17:48 --> 00:17:51 Sagittarius. It was announced through the
00:17:51 --> 00:17:53 usual channel, an IAU circular
00:17:53 --> 00:17:56 on 23 February. At first
00:17:56 --> 00:17:58 everyone assumed it was a nova.
00:17:59 --> 00:17:59 Anna: It wasn't.
00:18:00 --> 00:18:03 Avery: No, it certainly wasn't. What
00:18:03 --> 00:18:05 Sakurai had found was one of the rarest
00:18:05 --> 00:18:08 events in stellar astrophysics. A
00:18:08 --> 00:18:10 star that had already died coming back to
00:18:10 --> 00:18:13 life. It is catalogued as
00:18:13 --> 00:18:14 V4334
00:18:14 --> 00:18:17 Sagittarius and everybody calls it
00:18:17 --> 00:18:20 Sakurai's object. Yesterday, a
00:18:20 --> 00:18:23 team led by Albert Zylstra at the Jodrell
00:18:23 --> 00:18:25 Bank Centre for Astrophysics in Manchester,
00:18:25 --> 00:18:28 with Peter Van Hoof at the Royal Observatory
00:18:28 --> 00:18:31 of Belgium and colleagues at the Valongo
00:18:31 --> 00:18:34 Observatory in Rio de Janeiro published
00:18:34 --> 00:18:36 new measurements of it in monthly notices of
00:18:36 --> 00:18:39 the Royal Astronomical Society. And the
00:18:39 --> 00:18:42 number is. In 30 years, the
00:18:42 --> 00:18:45 the star has become about six times hotter.
00:18:45 --> 00:18:48 Its surface was sun like when Sakurai found
00:18:48 --> 00:18:50 it. It is now somewhere between
00:18:50 --> 00:18:53 27 and 36
00:18:53 --> 00:18:56 kelvin. That is among the fastest heating
00:18:56 --> 00:18:58 rates ever measured on any star.
00:18:59 --> 00:19:01 Anna: Take us through what actually happened to it.
00:19:01 --> 00:19:04 Avery: So this star had finished. It had been a sun
00:19:04 --> 00:19:07 like star. It had run through its fuel,
00:19:07 --> 00:19:09 blown off its outer layers and and settled
00:19:09 --> 00:19:12 down to be a white dwarf, an inert cooling
00:19:12 --> 00:19:15 cinder that is meant to be the end.
00:19:15 --> 00:19:17 But there was still a thin layer of helium
00:19:17 --> 00:19:20 sitting on top of the carbon and oxygen core.
00:19:20 --> 00:19:23 And that layer reignited one
00:19:23 --> 00:19:26 last shell flash after the star had already
00:19:26 --> 00:19:29 become a white dwarf. The technical
00:19:29 --> 00:19:32 term is a very late thermal pulse and
00:19:32 --> 00:19:34 the effect is dramatic. The star
00:19:34 --> 00:19:37 puffs back up into a giant in years rather
00:19:37 --> 00:19:40 than millennia. It ends up hydrogen poor
00:19:40 --> 00:19:43 and enriched in helium and carbon because
00:19:43 --> 00:19:46 the flash has dragged process material up
00:19:46 --> 00:19:49 from deep inside. Astronomers call these
00:19:49 --> 00:19:52 born again stars and we know of only
00:19:52 --> 00:19:53 a handful.
00:19:53 --> 00:19:54 Anna: And then it vanished.
00:19:54 --> 00:19:57 Avery: Didn't, did. And that is the
00:19:57 --> 00:20:00 frustrating part of the storey. By late
00:20:00 --> 00:20:03 1998 the Star had manufactured
00:20:03 --> 00:20:05 so much carbon dust that that it wrapped
00:20:05 --> 00:20:07 itself in an opaque shell and by
00:20:07 --> 00:20:10 1999 it had disappeared from
00:20:10 --> 00:20:12 optical telescopes entirely.
00:20:13 --> 00:20:15 Imagine watching the one event you have been
00:20:15 --> 00:20:18 waiting a career for and the object pulls a
00:20:18 --> 00:20:21 curtain across itself. What this team has
00:20:21 --> 00:20:23 done is get back in. They used
00:20:23 --> 00:20:26 ESO's Very Large Telescope in Chile for
00:20:26 --> 00:20:29 spectroscopy. They used ALMA, and
00:20:29 --> 00:20:32 they compared what they saw against models
00:20:32 --> 00:20:35 built for Wolf Rayet stars, the hot
00:20:35 --> 00:20:37 stripped, fiercely windy stars that show
00:20:37 --> 00:20:40 strong carbon and helium signatures.
00:20:40 --> 00:20:43 And that is what Sakurai's object now looks
00:20:43 --> 00:20:46 like. The paper's title says the
00:20:46 --> 00:20:48 emergence of a WC star in
00:20:48 --> 00:20:51 Sakurai's object. Astronomers write it
00:20:51 --> 00:20:53 in square brackets, which is the notation for
00:20:53 --> 00:20:56 the low mass version. It has the spectrum of
00:20:56 --> 00:20:59 a Wolf Rayet star without being a massive
00:20:59 --> 00:21:00 star at all.
00:21:01 --> 00:21:02 Anna: So the curtain is thinning.
00:21:02 --> 00:21:05 Avery: You could say that. And the star underneath
00:21:05 --> 00:21:07 is a different star from the one that went
00:21:07 --> 00:21:08 behind it.
00:21:08 --> 00:21:11 And the headline result is a disagreement
00:21:11 --> 00:21:13 with theory, which is the useful kind of
00:21:13 --> 00:21:16 result. Zelstra's team find it is
00:21:16 --> 00:21:18 reheating more gradually than some of the
00:21:18 --> 00:21:21 newer models predicted. That is a direct
00:21:21 --> 00:21:24 constraint on how convection and mixing work
00:21:24 --> 00:21:27 inside a star during a shell flash, a
00:21:27 --> 00:21:30 process we normally can only model because it
00:21:30 --> 00:21:33 takes longer than a civilization. Here
00:21:33 --> 00:21:36 it takes about as long as a career. One
00:21:36 --> 00:21:39 honest caveat. The distance to this object
00:21:39 --> 00:21:41 is genuinely poorly known.
00:21:41 --> 00:21:44 Published estimates run from under 2
00:21:44 --> 00:21:47 kiloparsecs to more than 5, which is a
00:21:47 --> 00:21:50 factor of nearly 3. And distance feeds
00:21:50 --> 00:21:53 into luminosity. The temperature measurement
00:21:53 --> 00:21:55 does not depend on it. That comes from the
00:21:55 --> 00:21:56 spectrum.
00:21:56 --> 00:21:58 But be wary of any brightness figure
00:21:58 --> 00:22:01 quoted to more precision than that spread
00:22:01 --> 00:22:02 allows.
00:22:02 --> 00:22:03 Anna: And where is it headed?
00:22:04 --> 00:22:06 Avery: Back where it came from. It will keep
00:22:06 --> 00:22:09 heating, blow away what is left and
00:22:09 --> 00:22:12 settle down to being a white dwarf again.
00:22:12 --> 00:22:14 The same fate reached twice.
00:22:15 --> 00:22:17 Peter van Hoof's summary is the one to end
00:22:17 --> 00:22:20 on. Sakurai's
00:22:20 --> 00:22:23 object offers something far rarer.
00:22:23 --> 00:22:26 It is one of the very few stars known to have
00:22:26 --> 00:22:28 changed dramatically within just a few
00:22:28 --> 00:22:31 decades, end quote. Most
00:22:31 --> 00:22:34 of stellar evolution is a slideshow. We get
00:22:34 --> 00:22:37 one frame of this one is a film.
00:22:37 --> 00:22:39 Anna: A quick update on a storey we left
00:22:39 --> 00:22:42 deliberately unfinished Back On Monday
00:22:42 --> 00:22:45 the 14th we told you Crew 13 had been
00:22:45 --> 00:22:47 stood down, that the cause was an oxidizer
00:22:47 --> 00:22:49 leak found in Dragon's propulsion system
00:22:50 --> 00:22:52 during pre launch processing. That the
00:22:52 --> 00:22:55 Canadian Space Agency had said late September
00:22:55 --> 00:22:57 and that NASA had published no specific date.
00:22:58 --> 00:23:00 We said on air that the absence of a date was
00:23:00 --> 00:23:01 itself the news.
00:23:02 --> 00:23:04 Avery: And now there is one.
00:23:04 --> 00:23:05 Anna: Now there is a window.
00:23:06 --> 00:23:08 NASA's station blog updated yesterday says
00:23:08 --> 00:23:11 the oxidizer valve has been replaced and that
00:23:11 --> 00:23:14 NASA and SpaceX are targeting quote as
00:23:14 --> 00:23:17 soon as early October end quote for the
00:23:17 --> 00:23:19 launch. The extra time is for pre launch
00:23:19 --> 00:23:21 activities. Readiness reviews and
00:23:21 --> 00:23:24 coordinating with station operations. So
00:23:24 --> 00:23:27 still not a calendar date, but a valve that
00:23:27 --> 00:23:29 has been fixed rather than a leak being
00:23:29 --> 00:23:31 investigated and a month you can plan around.
00:23:32 --> 00:23:34 The crew is unchanged. Jessica Watkins
00:23:34 --> 00:23:37 commanding, Luke Delaney as pilot, Joshua
00:23:37 --> 00:23:40 Kutryk for the Canadian Space agency and
00:23:40 --> 00:23:43 Sergey to Teriatnikov for Roscosmos
00:23:43 --> 00:23:46 on a Falcon 9 from Space Launch Complex 40.
00:23:46 --> 00:23:49 Avery: And the station is not going hungry in the
00:23:49 --> 00:23:51 meantime, it is not.
00:23:51 --> 00:23:54 Anna: Progress 96 launched yesterday morning US
00:23:54 --> 00:23:57 time with nearly three tonnes of food,
00:23:57 --> 00:24:00 fuel and cargo for the Expedition 75
00:24:00 --> 00:24:03 crew. And it docks to the POISK module on
00:24:03 --> 00:24:03 Saturday.
00:24:03 --> 00:24:06 Avery: Right, what to actually go outside and look
00:24:06 --> 00:24:06 at.
00:24:07 --> 00:24:09 And there is a genuine event on the calendar
00:24:09 --> 00:24:12 for tomorrow night. Friday the 18th
00:24:12 --> 00:24:15 Venus reaches greatest brilliancy.
00:24:15 --> 00:24:18 That is the single brightest Venus gets in
00:24:18 --> 00:24:21 this entire evening apparition at about
00:24:21 --> 00:24:24 magnitude -4.8. And
00:24:24 --> 00:24:27 tonight it is already within a whisker of it.
00:24:27 --> 00:24:30 So do not wait for permission. The reason the
00:24:30 --> 00:24:32 peak falls now rather than when Venus is
00:24:32 --> 00:24:35 closest or when Venus is fullest, is
00:24:35 --> 00:24:38 worth 30 seconds because it is a lovely bit
00:24:38 --> 00:24:39 of geometry.
00:24:40 --> 00:24:41 Anna: It is a trade off.
00:24:41 --> 00:24:44 Avery: It is exactly a trade off. Brightness is
00:24:44 --> 00:24:47 lit fraction times disc size. As
00:24:47 --> 00:24:50 Venus swings round toward us, it gets bigger.
00:24:51 --> 00:24:54 The disc is now about 39 arc seconds
00:24:54 --> 00:24:56 across, which is enormous, roughly
00:24:56 --> 00:24:59 three times the size it was at the start of
00:24:59 --> 00:25:01 the apparition. But as it comes toward us,
00:25:01 --> 00:25:04 we also see less of its lit face. It
00:25:04 --> 00:25:07 is only about 26% illuminated.
00:25:07 --> 00:25:10 A big thin crescent beats a small full
00:25:10 --> 00:25:13 disc. And tomorrow night the two curves
00:25:13 --> 00:25:14 cross.
00:25:14 --> 00:25:17 Put a pair of binoculars on it, steadied
00:25:17 --> 00:25:19 against a fence or a door frame, and the
00:25:19 --> 00:25:22 crescent shape is obvious. That is not a
00:25:22 --> 00:25:25 subtle target. One note on the date.
00:25:25 --> 00:25:28 Some listings give 22 September for
00:25:28 --> 00:25:30 greatest brilliancy. On a slightly different
00:25:30 --> 00:25:33 definition, we are using the
00:25:33 --> 00:25:33 18th.
00:25:33 --> 00:25:36 The difference is a definition, not a
00:25:36 --> 00:25:39 disagreement about Venus. And either way,
00:25:39 --> 00:25:41 this week and next are spectacular.
00:25:42 --> 00:25:45 Now, where you are standing decides how good
00:25:45 --> 00:25:48 a night you have. And the gap is enormous.
00:25:48 --> 00:25:50 Right now. From Sydney, the Sun sets
00:25:50 --> 00:25:53 at 11 minutes to 6 and Venus is
00:25:53 --> 00:25:56 39 degrees above the western horizon at
00:25:56 --> 00:25:59 that moment, most of the way from the horizon
00:25:59 --> 00:26:02 to overhead. It does not set until
00:26:02 --> 00:26:05 three minutes past nine. That is three
00:26:05 --> 00:26:08 and a quarter hours of Venus after sunset.
00:26:08 --> 00:26:11 Melbourne, Brisbane, Perth, Auckland,
00:26:11 --> 00:26:14 Cape Town, Santiago, same storey.
00:26:15 --> 00:26:17 Anna: And for our, uh, North American listeners,
00:26:17 --> 00:26:19 who are the biggest part of this audience,
00:26:20 --> 00:26:21 considerably tougher.
00:26:21 --> 00:26:24 Avery: And I am not going to pretend otherwise.
00:26:24 --> 00:26:27 From Los angeles, Venus is 14 degrees
00:26:27 --> 00:26:30 up at sunset and sets an hour and
00:26:30 --> 00:26:33 20 minutes later from New York, 10
00:26:33 --> 00:26:35 degrees and an hour and five
00:26:36 --> 00:26:39 from London, three degrees and half an
00:26:39 --> 00:26:42 hour. Genuinely difficult. This is the
00:26:42 --> 00:26:44 ecliptic tilt again and it is at its most
00:26:44 --> 00:26:47 extreme in the weeks around the equinox.
00:26:47 --> 00:26:50 The line the planets follow stands almost
00:26:50 --> 00:26:52 vertically up from the western horizon at
00:26:52 --> 00:26:55 dusk from the southern hemisphere and, and
00:26:55 --> 00:26:57 lies almost flat along it from the northern.
00:26:58 --> 00:27:01 Same planet, same evening, radically
00:27:01 --> 00:27:02 different altitude.
00:27:03 --> 00:27:05 Anna: So what is the practical advice up north?
00:27:05 --> 00:27:08 Avery: Find a clear western horizon, the sea,
00:27:08 --> 00:27:11 a lake, a ridge with nothing on it. And
00:27:11 --> 00:27:14 look 20 to 45 minutes after sunset.
00:27:14 --> 00:27:16 Venus is bright enough to punch through
00:27:16 --> 00:27:19 twilight and you will not mistake it for
00:27:19 --> 00:27:22 anything else. It is worth the effort.
00:27:22 --> 00:27:25 You just cannot be casual about it the way we
00:27:25 --> 00:27:28 can down here. Mercury is the harder
00:27:28 --> 00:27:31 version of the same lesson. From Sydney,
00:27:31 --> 00:27:33 it is 15 degrees up, uh, at sunset,
00:27:33 --> 00:27:36 a genuinely good apparition. And it sets
00:27:36 --> 00:27:38 an hour and a quarter after the Sun.
00:27:39 --> 00:27:42 From Los angeles, it is 8 degrees. From
00:27:42 --> 00:27:44 New York, six from London, three
00:27:45 --> 00:27:48 Southern. Listeners, this is your
00:27:48 --> 00:27:50 Mercury. It sits below and to the
00:27:50 --> 00:27:53 right of Venus, about 24 degrees away
00:27:54 --> 00:27:56 then the Moon. And this is where both
00:27:56 --> 00:27:58 hemispheres get the same present.
00:27:59 --> 00:28:01 It is a fat Crescent tonight, about
00:28:01 --> 00:28:04 37% lit, going to
00:28:04 --> 00:28:07 47% tomorrow. And first quarter
00:28:07 --> 00:28:09 falls on Friday the 18th at 43
00:28:09 --> 00:28:12 minutes past 8 in the evening, universal
00:28:12 --> 00:28:15 time, which is quarter to 7 on Saturday
00:28:15 --> 00:28:18 morning here in Sydney. And that timing
00:28:18 --> 00:28:21 is not an accident because Saturday the
00:28:21 --> 00:28:24 19th is international. Observe the Moon
00:28:24 --> 00:28:26 night, which is deliberately
00:28:26 --> 00:28:27 Anna: scheduled for this phase.
00:28:27 --> 00:28:29 Avery: Deliberately and for the right reason.
00:28:30 --> 00:28:32 A full moon is a flat, glaring,
00:28:32 --> 00:28:35 shadowless disc and it is the worst night of
00:28:35 --> 00:28:38 the month to look at it. At first quarter,
00:28:38 --> 00:28:40 the terminator, the line between lunar day
00:28:40 --> 00:28:43 and lunar night, runs straight down the
00:28:43 --> 00:28:46 middle. The sunlight comes in almost sideways
00:28:46 --> 00:28:49 and every crater, rim and mountain throws
00:28:49 --> 00:28:52 a long shadow. Through even the smallest
00:28:52 --> 00:28:53 telescope.
00:28:53 --> 00:28:55 The Moon stops being a picture and becomes a
00:28:55 --> 00:28:58 landscape. And in the light of our second
00:28:58 --> 00:29:01 storey, have a look at Mare Chrisium, the
00:29:01 --> 00:29:04 dark oval near the eastern limb. It is
00:29:04 --> 00:29:07 obvious in binoculars. Somewhere out on
00:29:07 --> 00:29:09 its outer ring, 20 kilometres east of Mare
00:29:09 --> 00:29:12 Spumans, is the crater that was not there
00:29:12 --> 00:29:15 before the middle of 2024. You
00:29:15 --> 00:29:18 will not see it. 200 metres is far
00:29:18 --> 00:29:20 below anything Earth based equipment can
00:29:20 --> 00:29:23 resolve. And at this phase that region is
00:29:23 --> 00:29:25 fully lit and flat, rather than sitting on
00:29:25 --> 00:29:28 the terminator. But you will be looking at
00:29:28 --> 00:29:30 the right patch of ground and knowing it is
00:29:30 --> 00:29:33 there changes what you are looking at. Before
00:29:33 --> 00:29:36 dawn, the balance flips and this one
00:29:36 --> 00:29:38 belongs to the North Jupiter Is the
00:29:38 --> 00:29:41 prize at the start of nautical Twilight.
00:29:42 --> 00:29:44 Jupiter is 26 degrees up from Los
00:29:44 --> 00:29:46 Angeles, 24 from New York,
00:29:47 --> 00:29:50 21 from London and only 8
00:29:50 --> 00:29:52 1/2 degrees from Sydney.
00:29:52 --> 00:29:55 Still fighting the horizon murk. Mars
00:29:55 --> 00:29:58 is even more lopsided, 48 degrees
00:29:58 --> 00:30:01 up from Los Angeles, 46 from New
00:30:01 --> 00:30:03 York, 40 from London against uh, 20
00:30:03 --> 00:30:06 from Sydney. Mars is faint at the
00:30:06 --> 00:30:09 moment, magnitude 1.2, an
00:30:09 --> 00:30:12 unremarkable orange dot, but the two are
00:30:12 --> 00:30:15 23 degrees apart and closing. They
00:30:15 --> 00:30:17 will be about 12 degrees apart by mid
00:30:17 --> 00:30:20 October and about 2 degrees apart by
00:30:20 --> 00:30:23 mid November. Start watching that gap
00:30:23 --> 00:30:25 now and the shrinking is the whole point.
00:30:26 --> 00:30:28 Saturn is well placed for everybody before
00:30:28 --> 00:30:31 dawn around 23 to 28
00:30:31 --> 00:30:34 degrees up wherever you are and it is worth
00:30:34 --> 00:30:37 getting familiar with because opposition is
00:30:37 --> 00:30:39 on the 4th of October rings about
00:30:39 --> 00:30:42 7 degrees open disc a uh touch
00:30:42 --> 00:30:45 under 20 arc seconds. One note for
00:30:45 --> 00:30:48 the southern zodiacal light hunters, not this
00:30:48 --> 00:30:51 week. The evening sky is moonlit from
00:30:51 --> 00:30:53 here through full moon on the 26th.
00:30:54 --> 00:30:57 That false dusk in the west. The faint cone
00:30:57 --> 00:30:59 of sunlight scattered off interplanetary
00:30:59 --> 00:31:02 dust which is an evening object from the
00:31:02 --> 00:31:05 southern hemisphere and a pre dawn object
00:31:05 --> 00:31:07 from the northern at this time of year comes
00:31:07 --> 00:31:10 back into play in the first week of October
00:31:10 --> 00:31:13 and the equinox Wednesday the
00:31:13 --> 00:31:16 23rd at five minutes past midnight
00:31:16 --> 00:31:18 Universal time which is the evening of
00:31:18 --> 00:31:21 Tuesday the 22nd across the Americas and
00:31:21 --> 00:31:24 mid morning on Wednesday here in Australia.
00:31:24 --> 00:31:27 It is an instant, not a day, so the date
00:31:27 --> 00:31:30 depends on where you are standing. Finally,
00:31:30 --> 00:31:33 and we say this every single episode for a
00:31:33 --> 00:31:35 reason, our space weather storey mentioned a
00:31:35 --> 00:31:37 big sunspot group visible in
00:31:37 --> 00:31:40 1848 and every time we mention
00:31:40 --> 00:31:43 sunspots someone quite reasonably wants to go
00:31:43 --> 00:31:46 and look. Do not point any telescope,
00:31:46 --> 00:31:49 any binoculars or any camera at the sun
00:31:49 --> 00:31:52 without a purpose built solar filter fitted
00:31:52 --> 00:31:54 over the front of the optics. If you are
00:31:54 --> 00:31:57 using eclipse glasses or a handheld solar
00:31:57 --> 00:31:59 viewer they must meet the ISO
00:31:59 --> 00:32:02 123122 international
00:32:02 --> 00:32:05 safety standard cheque for that marking and
00:32:05 --> 00:32:08 cheque the filter for scratches or pinholes
00:32:08 --> 00:32:10 before every single use.
00:32:10 --> 00:32:13 Sunglasses are not a solar filter.
00:32:13 --> 00:32:16 Exposed film, smoked glass and
00:32:16 --> 00:32:19 welding glass below shade 14 are
00:32:19 --> 00:32:21 not solar filters. Eye damage from the
00:32:21 --> 00:32:24 sun is painless and permanent and it does
00:32:24 --> 00:32:26 not announce itself until it is done.
00:32:26 --> 00:32:28 Anna: That is Astronomy AstroDailyPod for Thursday
00:32:29 --> 00:32:31 17th September. A
00:32:31 --> 00:32:34 planet under a million years old caught in
00:32:34 --> 00:32:37 the gap. It is carving a 200
00:32:37 --> 00:32:39 metre hole in the moon that nobody saw
00:32:39 --> 00:32:41 arrive. A Victorian train delay
00:32:41 --> 00:32:44 recovered from the wrong decade and a dead
00:32:44 --> 00:32:46 star getting hotter by the year.
00:32:47 --> 00:32:49 Avery: Show notes Sources and links for everything
00:32:49 --> 00:32:52 we have covered are at astronomydaily
00:32:52 --> 00:32:55 IO and there is a contact form there.
00:32:55 --> 00:32:57 Listener questions have started whole
00:32:57 --> 00:32:59 segments on this show, so use it.
00:33:00 --> 00:33:02 Anna: We are on x, Facebook,
00:33:02 --> 00:33:05 Instagram, TikTok and Tumblr.
00:33:05 --> 00:33:08 AstroDaily Pod Astronomy AstroDailyPod
00:33:08 --> 00:33:11 is part of the Bitesz.com podcast network
00:33:11 --> 00:33:12 produced in Sydney.
00:33:13 --> 00:33:14 Avery: I'm Avery.
00:33:14 --> 00:33:16 Anna: And I'm Anna. Clear Skies.
00:33:18 --> 00:33:19 Mhm.