Become a supporter of this podcast: https://www.spreaker.com/podcast/astronomy-daily-latest-space-news--5648921/support.
Sponsor Details:
Ensure your online privacy by using NordVPN. To get our special listener deal and save a lot of money, visit www.astronomydaily.io/nordvpn. You'll be glad you did!
Get the best secure and private email on the planet. Stop your Government, google and who knows who else spying on every email you write. Do what we did and use ProtonMail. They beleive in privacy and there are no ads in their business model...yet they still provide a free forever service. Check them out and get out special deal at www.astronomydaily.io/protonmail
Become a supporter of Astronomy Daily by joining our Supporters Club. Commercial free episodes daily are only a click way... Click Here
This episode includes AI-generated content.
00:00:00 --> 00:00:02 Anna: Hi, everyone. It's Saturday, the 17th of
00:00:02 --> 00:00:05 October, and this is the weekend wrap from
00:00:05 --> 00:00:06 Astronomy AstroDailyPod. I'm Anna.
00:00:07 --> 00:00:09 Avery: And I'm Avery. On Thursday, in a
00:00:09 --> 00:00:12 palace just outside Paris, the world decided
00:00:12 --> 00:00:15 that its clocks will stop waiting for the
00:00:15 --> 00:00:15 Earth.
00:00:16 --> 00:00:18 Anna: No more leap seconds from May next year. And,
00:00:18 --> 00:00:20 um, in the same session, the first formal
00:00:20 --> 00:00:22 step towards an agreed time for the Moon.
00:00:23 --> 00:00:25 Avery: Then we look back over the week, whether on a
00:00:25 --> 00:00:28 world without a sun, Hera breaking hard for
00:00:28 --> 00:00:31 an asteroid, five flashes on the far side
00:00:31 --> 00:00:34 of the Moon, a cloud on Mars that our
00:00:34 --> 00:00:37 models said couldn't form, and the
00:00:37 --> 00:00:38 first green star.
00:00:39 --> 00:00:40 Anna: And in the sky, watch
00:00:41 --> 00:00:43 Mercury's last good week for the south
00:00:44 --> 00:00:47 Venus about to vanish and why the
00:00:47 --> 00:00:50 Orionids are a, uh, set an alarm shower this
00:00:50 --> 00:00:53 year. Let's get into it. To understand
00:00:53 --> 00:00:55 Thursday's decision, you, you need to know
00:00:55 --> 00:00:57 that the world has been running two clocks
00:00:57 --> 00:01:00 side by side for more than 50 years. The
00:01:00 --> 00:01:03 first is atomic time. Hundreds of
00:01:03 --> 00:01:05 atomic clocks in laboratories around the
00:01:05 --> 00:01:07 world are, uh, averaged together into a
00:01:07 --> 00:01:10 timescale that ticks with extraordinary
00:01:10 --> 00:01:12 steadiness. The civil version of that,
00:01:13 --> 00:01:15 the one your phone ultimately follows, is
00:01:15 --> 00:01:17 coordinated Universal Time UTC.
00:01:18 --> 00:01:20 The second clock is the Earth itself.
00:01:21 --> 00:01:24 Astronomers call it UT1. It's simply
00:01:24 --> 00:01:26 the angle the planet has turned through,
00:01:26 --> 00:01:28 measured against the distant sky. And the
00:01:28 --> 00:01:31 Earth is a terrible clock. Its spin
00:01:31 --> 00:01:34 wobbles with tides, with the weather, with
00:01:34 --> 00:01:37 ocean currents, with the slow sloshing of the
00:01:37 --> 00:01:39 liquid core. Over the long run,
00:01:39 --> 00:01:42 tidal friction from the Moon has been slowing
00:01:42 --> 00:01:42 it down,
00:01:43 --> 00:01:45 Avery: so the two clocks drift apart. Since
00:01:45 --> 00:01:48 1972, the rule has been that UTC is never
00:01:48 --> 00:01:50 allowed to get more than nine tenths of a
00:01:50 --> 00:01:52 second away from the Earth's rotation. When
00:01:52 --> 00:01:55 the gap gets close to that, the International
00:01:55 --> 00:01:57 Earth Rotation and Reference System Service
00:01:57 --> 00:02:00 announces a leap second. And every clock on
00:02:00 --> 00:02:03 the planet that follows UTC has to count a
00:02:03 --> 00:02:06 61st second in one particular minute.
00:02:06 --> 00:02:08 Anna: That has happened 27 times.
00:02:09 --> 00:02:11 The last one was at the end of 2016
00:02:12 --> 00:02:15 in July, the IERS confirmed there won't be
00:02:15 --> 00:02:16 one at the end of this year either. So we'll
00:02:16 --> 00:02:18 reach a full decade without one.
00:02:18 --> 00:02:20 Avery: It's worth remembering that for most of
00:02:20 --> 00:02:23 history, these were the same clock.
00:02:23 --> 00:02:26 Until 1956, the second was defined as
00:02:26 --> 00:02:29 a fraction of the average solar day. Then,
00:02:29 --> 00:02:31 because the day wasn't steady enough, it was
00:02:31 --> 00:02:33 redefined as a fraction of the year. Still
00:02:33 --> 00:02:36 astronomy, only in 1967
00:02:36 --> 00:02:38 did the second leave the sky entirely and
00:02:38 --> 00:02:41 move into the cesium atom. Leap seconds were
00:02:41 --> 00:02:44 the compromise that kept the two loosely tied
00:02:44 --> 00:02:44 together.
00:02:45 --> 00:02:48 Anna: So why now, that decade without
00:02:48 --> 00:02:48 one
00:02:48 --> 00:02:51 Avery: is actually the reason for Thursday's vote.
00:02:51 --> 00:02:53 For most of the leet second era, the Earth
00:02:53 --> 00:02:55 was running slow, so the correction was
00:02:55 --> 00:02:58 always the same. Add a second. But in
00:02:58 --> 00:03:00 recent years, the planet's rotation
00:03:00 --> 00:03:03 Anna: has been running slightly fast, which raises
00:03:03 --> 00:03:05 a possibility. Nobody has ever had to deal
00:03:06 --> 00:03:09 a negative leap a minute with
00:03:09 --> 00:03:11 only 59 seconds in it. The
00:03:11 --> 00:03:14 resolution itself puts a number on it. A
00:03:14 --> 00:03:17 workshop held in March last year by the
00:03:17 --> 00:03:19 Consultative Committee for Time and Frequency
00:03:19 --> 00:03:22 and the iers, including experts
00:03:22 --> 00:03:25 on Earth's rotation, estimated that the
00:03:25 --> 00:03:27 probability of a negative leap second rises
00:03:27 --> 00:03:29 rapidly in the near Future, reaching about
00:03:29 --> 00:03:32 30% by 2035. And the
00:03:32 --> 00:03:34 delegates were blunt about the risk. A
00:03:34 --> 00:03:37 negative leap second has never been applied.
00:03:38 --> 00:03:40 The resolution describes it as a high risk to
00:03:40 --> 00:03:42 critical infrastructure that is largely
00:03:42 --> 00:03:45 unprepared and says the cost of getting ready
00:03:45 --> 00:03:47 would be similar to what industry spent
00:03:47 --> 00:03:49 preparing for the millennium bug.
00:03:49 --> 00:03:52 Avery: There's a quieter problem too. Positive
00:03:52 --> 00:03:54 leap seconds already cause trouble. So big
00:03:54 --> 00:03:56 service providers have each invented their
00:03:56 --> 00:03:59 own workarounds, smearing the extra second
00:03:59 --> 00:04:01 across hours of the day in different ways.
00:04:01 --> 00:04:03 The resolution notes that this leaves
00:04:03 --> 00:04:05 different systems disagreeing with each other
00:04:05 --> 00:04:08 about what time it is, and that some users
00:04:08 --> 00:04:10 were starting to abandon UTC altogether for
00:04:10 --> 00:04:11 satellite navigation time.
00:04:12 --> 00:04:14 Anna: So, um. On Thursday 15th October,
00:04:15 --> 00:04:17 at the 28th General Conference on
00:04:17 --> 00:04:20 Weights and Measures in Versailles, member
00:04:20 --> 00:04:23 states adopted what's called Resolution 5. It
00:04:23 --> 00:04:24 was carried by a majority vote.
00:04:25 --> 00:04:27 Avery: Two decisions. First,
00:04:28 --> 00:04:30 UTC becomes a continuous timescale
00:04:30 --> 00:04:33 on 20 May 2027. No more
00:04:33 --> 00:04:36 leap seconds after that in either direction.
00:04:36 --> 00:04:39 Anna: And second, the allowed gap between
00:04:39 --> 00:04:42 UTC and the Earth's rotation grows from under
00:04:42 --> 00:04:43 a second to one hour,
00:04:44 --> 00:04:47 3600 seconds. The
00:04:47 --> 00:04:50 resolution says that ensures UTC's long term
00:04:50 --> 00:04:52 continuity for several centuries.
00:04:52 --> 00:04:55 Avery: Back in 2022, the same conference had agreed
00:04:55 --> 00:04:58 to do this by 2035. What changed
00:04:58 --> 00:05:00 is that, uh, the negative leap seconds
00:05:00 --> 00:05:02 stopped looking theoretical, so they brought
00:05:02 --> 00:05:03 it forward by eight years.
00:05:04 --> 00:05:06 Anna: The president of the Time Committee, Noel
00:05:06 --> 00:05:08 Demark, said it came after 30 years of
00:05:08 --> 00:05:11 debate. Now, the honest caveats,
00:05:12 --> 00:05:13 because the headlines this week have been a
00:05:13 --> 00:05:16 bit dramatic. First, this is a decision about
00:05:16 --> 00:05:19 the clock, not about the Earth. The planet
00:05:19 --> 00:05:21 will keep turning exactly as it was going to.
00:05:22 --> 00:05:25 Avery: Second, the drift is slow. We're
00:05:25 --> 00:05:28 talking seconds per decade, not minutes.
00:05:28 --> 00:05:30 Nobody will notice the sun rising at the
00:05:30 --> 00:05:33 wrong time in their lifetime. The resolution
00:05:33 --> 00:05:35 itself makes the point that most of us
00:05:35 --> 00:05:38 already live an hour or more away from local
00:05:38 --> 00:05:40 solar time because of time zones and daylight
00:05:40 --> 00:05:41 saving.
00:05:41 --> 00:05:44 Anna: And third, what happens if the
00:05:44 --> 00:05:46 gap Ever approaches that one hour limit
00:05:47 --> 00:05:49 is left to people several centuries from now.
00:05:50 --> 00:05:52 The resolution sets the limit. It doesn't
00:05:52 --> 00:05:53 spell out the fix.
00:05:54 --> 00:05:56 Avery: Here's the bit I find most interesting for
00:05:56 --> 00:05:58 this. Astronomers still need
00:05:58 --> 00:06:01 UT1. If you want to point a telescope at a
00:06:01 --> 00:06:03 star or work out where a satellite is over
00:06:03 --> 00:06:06 the ground, you need to know exactly how far
00:06:06 --> 00:06:09 the Earth has actually turned. That number
00:06:09 --> 00:06:12 keeps being published by the iers and
00:06:12 --> 00:06:14 broadcasts in satellite navigation signals.
00:06:14 --> 00:06:17 It just stops being fed back into your clock
00:06:17 --> 00:06:18 every few years.
00:06:18 --> 00:06:20 Anna: And the way the Earth's rotation is measured
00:06:20 --> 00:06:23 is pure astronomy. The technique
00:06:23 --> 00:06:26 that's unique in its ability to pin down UT1
00:06:26 --> 00:06:29 is very long baseline interferometry.
00:06:29 --> 00:06:31 Radio dishes on different continents all
00:06:31 --> 00:06:34 observe the same distant quasars billions of
00:06:34 --> 00:06:36 light years away and time the arrival of the
00:06:36 --> 00:06:38 signal at each dish.
00:06:38 --> 00:06:41 Avery: Because those quasars are so far away,
00:06:41 --> 00:06:44 they're effectively fixed, they make the most
00:06:44 --> 00:06:47 stable reference frame we have. The tiny
00:06:47 --> 00:06:49 differences in arrival time tell you how the
00:06:49 --> 00:06:51 dishes and, um, the whole Earth under them
00:06:51 --> 00:06:51 have rotated.
00:06:52 --> 00:06:54 Anna: And Australia is part of that network.
00:06:54 --> 00:06:57 Oscope's 12 metre dishes at Hobart in
00:06:57 --> 00:06:59 Tasmania, Catherine in the Northern Territory
00:06:59 --> 00:07:02 and Yerra Gadi in Western Australia. Observe
00:07:02 --> 00:07:05 in the International Geodetic VLBI sessions.
00:07:06 --> 00:07:08 So the length of your day is quite literally
00:07:08 --> 00:07:11 partly measured from Australia against
00:07:11 --> 00:07:12 quasars.
00:07:12 --> 00:07:15 Avery: Which is a nice callback to episode 197,
00:07:15 --> 00:07:17 when we covered the Earth's centre of mass.
00:07:17 --> 00:07:20 Wobbling with the seasons. Same idea.
00:07:20 --> 00:07:22 The ground we stand on is not a fixed
00:07:22 --> 00:07:25 platform and, um, it takes the whole sky to
00:07:25 --> 00:07:25 measure it.
00:07:26 --> 00:07:29 Anna: Resolution 5 got the headlines, but the
00:07:29 --> 00:07:32 same session adopted Resolution 6. And
00:07:32 --> 00:07:34 for space exploration, it may matter more.
00:07:35 --> 00:07:37 It's the first international step towards a
00:07:37 --> 00:07:40 lunar reference timescale, the Moon's
00:07:40 --> 00:07:41 equivalent of utc.
00:07:41 --> 00:07:44 Avery: The problem is relativity. A
00:07:44 --> 00:07:46 clock on the Moon sits in weaker gravity and
00:07:46 --> 00:07:49 moves differently from one on Earth, so it
00:07:49 --> 00:07:52 runs fast. A widely cited estimate puts that
00:07:52 --> 00:07:55 at roughly 56 millionths of a
00:07:55 --> 00:07:56 second a day.
00:07:56 --> 00:07:59 Anna: That sounds tiny, but light
00:07:59 --> 00:08:02 travels about 17 kilometres in 56
00:08:02 --> 00:08:04 microseconds. If you're building navigation
00:08:04 --> 00:08:07 on the Moon, landers and rovers and
00:08:07 --> 00:08:09 astronauts working near each other, an error
00:08:09 --> 00:08:12 that grows by kilometres a day is not
00:08:12 --> 00:08:13 acceptable.
00:08:13 --> 00:08:15 Avery: And, um, several agencies are building lunar
00:08:15 --> 00:08:17 navigation systems at the same time. The
00:08:17 --> 00:08:20 Resolution's stated aim is to avoid a
00:08:20 --> 00:08:22 proliferation of competing lunar
00:08:22 --> 00:08:25 timescales and to keep whatever is chosen
00:08:25 --> 00:08:28 traceable back to utc. For now,
00:08:28 --> 00:08:30 it asks space agencies to share how they
00:08:30 --> 00:08:33 handle the relativistic corrections. It
00:08:33 --> 00:08:36 doesn't define the timescale yet that work is
00:08:36 --> 00:08:36 still to come.
00:08:37 --> 00:08:40 Anna: One more Resolution 4 starts
00:08:40 --> 00:08:42 the groundwork for redefining the second
00:08:42 --> 00:08:45 itself. Since 1967, the second
00:08:45 --> 00:08:47 has been defined by cesium atoms. The best
00:08:47 --> 00:08:50 optical clocks now beat the best cesium
00:08:50 --> 00:08:52 fountain clocks by around a factor of 100,
00:08:53 --> 00:08:54 which means the definition
00:08:54 --> 00:08:56 Avery: has become the limitation, not the
00:08:56 --> 00:08:58 technology. Two options are on the
00:08:59 --> 00:09:02 pick one optical transition or average
00:09:02 --> 00:09:04 several. The aim is a vote at the next
00:09:04 --> 00:09:05 conference in 2030.
00:09:06 --> 00:09:08 Anna: So in a single afternoon in Versailles, the
00:09:08 --> 00:09:11 world agreed to stop chasing the Earth's spin
00:09:11 --> 00:09:13 with its clocks, started building a clock for
00:09:13 --> 00:09:16 the moon and began retiring cesium.
00:09:17 --> 00:09:19 Not bad for a meeting most people have never
00:09:19 --> 00:09:19 heard of.
00:09:19 --> 00:09:21 Avery: And next week we'll be watching a spacecraft
00:09:21 --> 00:09:24 head for Mars moons. More on that in the
00:09:24 --> 00:09:25 outro.
00:09:25 --> 00:09:28 Anna: Next, let's move on to our wrap of the space
00:09:28 --> 00:09:29 news from the past week.
00:09:29 --> 00:09:32 Avery: Monday's lead was wise 0855,
00:09:32 --> 00:09:35 the coldest brown dwarf we know, about seven
00:09:35 --> 00:09:38 and a half light years away, with no star to
00:09:38 --> 00:09:40 warm it. A team led from the University of
00:09:40 --> 00:09:43 Arizona used JWST's NirSpec
00:09:43 --> 00:09:46 to take a spectrum every 15 minutes for 11
00:09:46 --> 00:09:46 hours,
00:09:47 --> 00:09:49 Anna: and the atmosphere changed while they
00:09:49 --> 00:09:51 watched. Carbon monoxide and phosphine rose
00:09:51 --> 00:09:54 and fell together, which points to convection
00:09:54 --> 00:09:57 dredging deep gas upward. Higher up,
00:09:57 --> 00:09:59 patchy water clouds thickened and thinned the
00:09:59 --> 00:10:00 careful bit.
00:10:01 --> 00:10:02 Avery: Some headlines said these were the first
00:10:02 --> 00:10:05 water clouds seen outside the solar system.
00:10:05 --> 00:10:07 They're not water clouds were claimed for
00:10:07 --> 00:10:10 this object in 2014 and 2016.
00:10:11 --> 00:10:13 What's new is seeing them change. The paper
00:10:13 --> 00:10:16 is a Preprint posted about three weeks before
00:10:16 --> 00:10:17 we covered it Tuesday.
00:10:18 --> 00:10:20 Anna: We led on ESA's Hera closing on the
00:10:20 --> 00:10:23 Didymos binary asteroid, the system NASA's
00:10:23 --> 00:10:25 DART mission struck in 2022.
00:10:25 --> 00:10:27 Avery: On 7 October, its second launch
00:10:27 --> 00:10:30 anniversary, Hera caught its target for the
00:10:30 --> 00:10:33 first time. Didymos and its moonlit dimorphos
00:10:33 --> 00:10:36 together as a single pixel from about
00:10:36 --> 00:10:38 236 kilometres away.
00:10:39 --> 00:10:42 Anna: Then early on Thursday the 15th, the big
00:10:42 --> 00:10:44 one three thrusters burning
00:10:44 --> 00:10:47 continuously for 93 minutes to shut a few
00:10:47 --> 00:10:49 hundred metres per second, with ESA's new
00:10:49 --> 00:10:52 Norsha antenna in Western Australia lined up
00:10:52 --> 00:10:54 to pick up the signal afterwards as we
00:10:54 --> 00:10:54 record.
00:10:54 --> 00:10:57 Avery: ESA hasn't yet published the result, which is
00:10:57 --> 00:10:59 normal, while the Flight Dynamics team checks
00:10:59 --> 00:11:01 the new trajectory will bring it to you when
00:11:01 --> 00:11:02 they do.
00:11:02 --> 00:11:04 Anna: Next up is a second shorter burn of about
00:11:04 --> 00:11:07 31 minutes on Thursday the 22nd. Then
00:11:07 --> 00:11:10 three small manoeuvres to bring HERA almost
00:11:10 --> 00:11:13 to a stop beside the asteroids ahead of close
00:11:13 --> 00:11:16 up observations from 25 to 30 kilometres away
00:11:16 --> 00:11:17 in November and December.
00:11:17 --> 00:11:20 Avery: Wednesday, NASA's preliminary lunar science
00:11:20 --> 00:11:22 report from Artemis 2. During a
00:11:22 --> 00:11:25 54 minute stretch when the sun was hidden
00:11:25 --> 00:11:27 behind the moon, the crew watched the dark
00:11:27 --> 00:11:30 lunar surface and reported five faint flashes
00:11:30 --> 00:11:31 of light rocks,
00:11:31 --> 00:11:33 Anna: each only a few centimetres across, hitting
00:11:33 --> 00:11:36 the moon. One of those flashes was marked
00:11:36 --> 00:11:38 independently by all three crew members who
00:11:38 --> 00:11:40 logged them, which is about as good as
00:11:40 --> 00:11:42 eyewitness evidence gets. They may be the
00:11:42 --> 00:11:44 faintest lunar impact flashes ever seen by
00:11:44 --> 00:11:45 human eyes.
00:11:46 --> 00:11:49 Avery: Also on Wednesday, Anmol Aggarwal and Ralph
00:11:49 --> 00:11:51 Schoenrich at UH University College London,
00:11:51 --> 00:11:53 in two papers in the Monthly Notices of the
00:11:53 --> 00:11:56 Royal Astronomical Society, went after one of
00:11:56 --> 00:11:59 the lines of evidence for chemical
00:11:59 --> 00:12:01 fingerprints in very old stars.
00:12:01 --> 00:12:04 Anna: They found that ordinary supernovae enriching
00:12:04 --> 00:12:07 the gas unevenly explain three
00:12:07 --> 00:12:09 of the four stars thought to carry a
00:12:09 --> 00:12:12 hypernova signature. The fourth, a
00:12:12 --> 00:12:14 giant rich in silver and uranium,
00:12:14 --> 00:12:17 fits a neutron star merger plus one
00:12:17 --> 00:12:20 ordinary supernova and the
00:12:20 --> 00:12:20 honest framing.
00:12:20 --> 00:12:23 Avery: That doesn't mean hypernovae don't exist.
00:12:23 --> 00:12:25 Very energetic explosions linked to gamma ray
00:12:25 --> 00:12:28 bursts have been observed directly. What's in
00:12:28 --> 00:12:30 question is whether these old stars require
00:12:30 --> 00:12:31 them.
00:12:31 --> 00:12:34 Anna: Thursday took us to Mars. Every morning
00:12:34 --> 00:12:37 in the southern spring and summer, a thin
00:12:37 --> 00:12:40 cloud up to 1800 kilometres long
00:12:40 --> 00:12:42 streams from the 20 kilometre volcano
00:12:42 --> 00:12:45 Archia Mons, then vanishes
00:12:45 --> 00:12:46 by afternoon.
00:12:46 --> 00:12:48 Avery: For years, the models couldn't make it.
00:12:49 --> 00:12:52 Jorge Hernandez Bernal and colleagues at LMD
00:12:52 --> 00:12:54 in Paris, writing in Nature Geoscience, only
00:12:54 --> 00:12:56 reproduced it by letting ice form directly
00:12:56 --> 00:12:59 from vapour with no dust to seed it.
00:13:00 --> 00:13:03 The air over the volcano cools by around 30
00:13:03 --> 00:13:05 degrees in 10 minutes and the humidity soars
00:13:05 --> 00:13:08 to more than 100 times
00:13:08 --> 00:13:10 everyday earth levels before it freezes.
00:13:11 --> 00:13:13 Anna: It's a modelling result sufficient
00:13:14 --> 00:13:15 not yet observed directly.
00:13:15 --> 00:13:18 Avery: And Friday, colour Mark Hollins and
00:13:18 --> 00:13:20 colleagues at the University of Warwick took
00:13:20 --> 00:13:23 white dwarf spectra astronomers already had
00:13:23 --> 00:13:25 and ran them through a model of human colour
00:13:25 --> 00:13:25 vision.
00:13:25 --> 00:13:29 Anna: Wdj1336435
00:13:30 --> 00:13:32 comes out green chartreuse
00:13:32 --> 00:13:35 because sodium from the rocky remains of its
00:13:35 --> 00:13:38 own planetary system absorbs the orange
00:13:38 --> 00:13:40 light. WDJ 10,
00:13:40 --> 00:13:43 11, 28, 45, 48 light years
00:13:43 --> 00:13:46 away. Maybe the reddest star
00:13:46 --> 00:13:49 ever recorded a deep salmon
00:13:49 --> 00:13:49 pink.
00:13:50 --> 00:13:52 Avery: Two caveats. These colours are computed
00:13:52 --> 00:13:55 not seen. No white dwarf is close enough to
00:13:55 --> 00:13:58 see its colour by eye and the typical white
00:13:58 --> 00:14:00 dwarf turns out to be white. Of the
00:14:00 --> 00:14:03 151 within about 65 light years,
00:14:03 --> 00:14:06 only around 1 in 30 has an unusual colour.
00:14:06 --> 00:14:08 Anna: A few more from the week quickly
00:14:09 --> 00:14:11 Monday VTF
00:14:11 --> 00:14:13 Jo440 uh
00:14:13 --> 00:14:16 5 a red dwarf
00:14:16 --> 00:14:19 pulling gas off a brown dwarf of about 25
00:14:19 --> 00:14:22 Jupiter masses on an 87 minute
00:14:22 --> 00:14:24 orbit. The MIT led team in Nature
00:14:24 --> 00:14:27 Astronomy calls it the first confirmed case
00:14:27 --> 00:14:30 of stable mass transfer from a substellar
00:14:30 --> 00:14:31 object onto a star.
00:14:31 --> 00:14:34 Avery: Also Monday the dead Soviet weather satellite
00:14:34 --> 00:14:37 Meteor2.7, launched in 1981,
00:14:37 --> 00:14:40 broke apart on 5 October about 8,
00:14:40 --> 00:14:43 850 kilometres up and the breakup was picked
00:14:43 --> 00:14:45 up by LeoLab's radar in western Australia.
00:14:45 --> 00:14:47 The cause is still unknown.
00:14:47 --> 00:14:49 Anna: Wednesday Juno found Jupiter's vast
00:14:49 --> 00:14:52 magnetic disc is crumpled, rippling
00:14:52 --> 00:14:55 as it rotates, crossing the spacecraft four
00:14:55 --> 00:14:57 times in 10 minutes in one pass.
00:14:58 --> 00:15:01 And simulations from the Indian Institute of
00:15:01 --> 00:15:04 Science suggested strong magnetic fields
00:15:04 --> 00:15:06 could let a white dwarf grow to around
00:15:06 --> 00:15:09 2.4 solar masses, well past
00:15:09 --> 00:15:10 the usual limit
00:15:10 --> 00:15:13 Avery: near 1.4 Thursday
00:15:13 --> 00:15:16 JWST mapped the edge of the hot
00:15:16 --> 00:15:18 Jupiter WASP 17b, about
00:15:18 --> 00:15:21 860 Kelvin at the morning edge
00:15:21 --> 00:15:24 and 1520 at the evening edge,
00:15:24 --> 00:15:27 the largest contrast yet measured. And
00:15:27 --> 00:15:30 an INF led team found that nearly 300
00:15:30 --> 00:15:33 well measured multiplanet systems fall
00:15:33 --> 00:15:35 Anna: into two distinct families and Friday
00:15:35 --> 00:15:38 a southern one. Reprocessing archived
00:15:38 --> 00:15:40 mrion data from CSIRO's Parkes
00:15:40 --> 00:15:43 telescope turned up six pulsars, five of
00:15:43 --> 00:15:46 them in the Large Magellanic Cloud, plus the
00:15:46 --> 00:15:48 slowest radio pulsar yet found in the Small
00:15:48 --> 00:15:51 Magellanic Cloud. Both are preprints
00:15:51 --> 00:15:53 and both are reminders that old data still
00:15:53 --> 00:15:55 has surprises in it.
00:15:55 --> 00:15:57 Avery: That's the week that was moving on
00:15:57 --> 00:16:00 Anna: to skywatch, starting with the moon. First
00:16:00 --> 00:16:03 quarter is at 16:12 Universal Time on
00:16:03 --> 00:16:06 Sunday. That's 3:12 on Monday morning in
00:16:06 --> 00:16:09 Sydney, 9:12 Sunday morning in Los
00:16:09 --> 00:16:11 Angeles, 12:12 in New York
00:16:12 --> 00:16:14 and 5:12 Sunday afternoon in London.
00:16:15 --> 00:16:17 So all week the moon is in the evening sky
00:16:17 --> 00:16:18 and growing.
00:16:18 --> 00:16:21 Avery: Southern Hemisphere this is Mercury's last
00:16:21 --> 00:16:24 strong week. Tonight From Sydney it's
00:16:24 --> 00:16:26 24 degrees up in the west at sunset
00:16:26 --> 00:16:29 and doesn't set until two hours after the
00:16:29 --> 00:16:32 sun. Even by Wednesday it's still 22
00:16:32 --> 00:16:32 degrees
00:16:32 --> 00:16:35 Anna: up from Los Angeles. It's under 10
00:16:35 --> 00:16:38 degrees at sunset and sets within the hour.
00:16:38 --> 00:16:41 New York 7 degrees, London under
00:16:41 --> 00:16:44 3 Northern. Listeners, you'd need
00:16:44 --> 00:16:47 a flat western horizon and binoculars
00:16:47 --> 00:16:49 and please wait until the sun is fully down.
00:16:49 --> 00:16:51 Avery: Venus is the bigger story from the Northern
00:16:51 --> 00:16:54 Hemisphere. It's already gone below the
00:16:54 --> 00:16:56 horizon by sunset from Sydney Tonight
00:16:56 --> 00:16:59 it's still 11 degrees up at sunset and sets
00:16:59 --> 00:17:01 an hour later. But by Wednesday it's down to
00:17:01 --> 00:17:03 5 degrees in half an hour.
00:17:03 --> 00:17:06 Anna: Venus Reaches inferior conjunction passing
00:17:06 --> 00:17:09 between us and the sun around three
00:17:09 --> 00:17:12 universal time next Saturday the 24th.
00:17:12 --> 00:17:14 That's early Saturday afternoon in Australia
00:17:15 --> 00:17:18 and Friday evening in the Americas. It
00:17:18 --> 00:17:20 slips about six and a half degrees from the
00:17:20 --> 00:17:23 sun then reappears in the morning sky.
00:17:23 --> 00:17:25 Avery: It's the same geometry we keep coming back to
00:17:25 --> 00:17:28 in southern spring. The evening ecliptic uh
00:17:28 --> 00:17:31 stands up steeply so the south keeps Venus
00:17:31 --> 00:17:31 and Mercury
00:17:31 --> 00:17:34 Anna: longer and after dark everyone gets
00:17:34 --> 00:17:37 Saturn. It's only a couple of weeks past
00:17:37 --> 00:17:39 opposition, rising in the east around sunset
00:17:39 --> 00:17:42 and well placed by mid evening from all four
00:17:42 --> 00:17:45 cities. Its rings are tilted only about
00:17:45 --> 00:17:48 7 degrees towards us at the moment. So in a
00:17:48 --> 00:17:50 small telescope they look like a uh, thin
00:17:50 --> 00:17:53 bright line across the planet. They were
00:17:53 --> 00:17:56 exactly edge on in March last year and are
00:17:56 --> 00:17:58 slowly opening again with the south face of
00:17:58 --> 00:18:00 the rings towards us. So each year they'll
00:18:00 --> 00:18:01 look a little wider.
00:18:01 --> 00:18:03 Avery: Now uh, what about the Orionids?
00:18:04 --> 00:18:06 Anna: The Orionid meteor shower peaks on the night
00:18:06 --> 00:18:09 of the 21st into the 22nd. These
00:18:09 --> 00:18:12 are dust grains from Hallie's Comet, the same
00:18:12 --> 00:18:14 comet that gives us the Eta Aquarids in May.
00:18:14 --> 00:18:17 Avery: The catch this year is a bright roughly
00:18:17 --> 00:18:20 80% moon. But it sets in the small
00:18:20 --> 00:18:23 hours about 3:40am in Sydney,
00:18:23 --> 00:18:26 3:20 in Los Angeles, 3:10 in New York
00:18:26 --> 00:18:28 and UM 2:50 in London. That leaves a
00:18:28 --> 00:18:30 dark window before dawn
00:18:30 --> 00:18:33 Anna: and at 4:30am M the radiant in
00:18:33 --> 00:18:36 Orion is around 70
00:18:36 --> 00:18:39 degrees up from Los Angeles, 63 from
00:18:39 --> 00:18:41 New York, 53 from London and
00:18:42 --> 00:18:45 39 from Sydney. So the
00:18:45 --> 00:18:47 north is favoured but the south is perfectly
00:18:47 --> 00:18:50 respectable. Typical rates under dark
00:18:50 --> 00:18:53 skies are around 20 an hour. Go after
00:18:53 --> 00:18:56 moonset, look away from the radiant and give
00:18:56 --> 00:18:58 your eyes 20 minutes while you're up.
00:18:58 --> 00:19:01 Avery: Mars and Jupiter this morning they're 11
00:19:01 --> 00:19:04 and a half degrees apart, closing to under
00:19:04 --> 00:19:06 nine by next weekend and to just over one
00:19:06 --> 00:19:07 degree on the 16th
00:19:07 --> 00:19:10 Anna: of November at nautical dawn. This is a
00:19:10 --> 00:19:13 northern showpiece. Mars around 60
00:19:13 --> 00:19:16 degrees up and Jupiter around 50 from Los
00:19:16 --> 00:19:19 Angeles and New York, 50 and 42
00:19:19 --> 00:19:22 from London. From Sydney they're lower
00:19:22 --> 00:19:24 23 and 19 degrees but easy.
00:19:25 --> 00:19:27 Jupiter is the bright one, Mars is the
00:19:27 --> 00:19:29 orange one above it.
00:19:29 --> 00:19:31 Avery: Finally the sun has woken up a large
00:19:31 --> 00:19:34 active region. AR4551
00:19:34 --> 00:19:36 has developed the most complex magnetic
00:19:36 --> 00:19:39 classification there is Beta Gamma Delta,
00:19:39 --> 00:19:41 which gives it the potential for strong
00:19:41 --> 00:19:44 flares if it launches an Earth directed
00:19:44 --> 00:19:47 eruption. Aurora watchers in Tasmania and
00:19:47 --> 00:19:49 southern Victoria and across Canada, the
00:19:49 --> 00:19:51 northern U.S. and Scotland. We'll want to
00:19:51 --> 00:19:53 check the Bureau of Meteorology, Space
00:19:53 --> 00:19:55 weather Services and NOAA's Space Weather
00:19:55 --> 00:19:57 Prediction Centre. It's a possibility, not a
00:19:57 --> 00:19:58 forecast.
00:19:58 --> 00:20:00 Anna: And if all that sunspot talk tempts you to
00:20:00 --> 00:20:03 look, never look at the sun directly or
00:20:03 --> 00:20:06 through binoculars, a telescope or a camera
00:20:06 --> 00:20:08 without a certified ISO
00:20:08 --> 00:20:10 12312 solar filter
00:20:10 --> 00:20:12 covering the front of the instrument.
00:20:12 --> 00:20:15 Ordinary sunglasses are not safe. Projection
00:20:15 --> 00:20:18 or a properly filtered telescope is the way
00:20:18 --> 00:20:19 to see sunspots.
00:20:19 --> 00:20:21 Avery: On Monday we'll be on launch E for JAXA's
00:20:21 --> 00:20:24 Martian moons exploration mission MMX, which
00:20:24 --> 00:20:27 is aiming to bring back the first sample from
00:20:27 --> 00:20:29 Phobos. With the capsule due to land in South
00:20:29 --> 00:20:32 Australia in 2031, it's a
00:20:32 --> 00:20:35 fitting follow on to today's lead. MMX will
00:20:35 --> 00:20:37 spend years working at Mars, kept on time by
00:20:37 --> 00:20:40 atomic clocks on Earth and tracked by the
00:20:40 --> 00:20:42 deep space stations that serve every mission
00:20:42 --> 00:20:42 out there.
00:20:42 --> 00:20:45 Anna: Launch is set for 441
00:20:45 --> 00:20:48 Tuesday morning Japan time. That's 641
00:20:48 --> 00:20:51 Tuesday morning in Sydney, 1241
00:20:51 --> 00:20:54 Monday lunchtime in Los Angeles, 341
00:20:54 --> 00:20:56 Monday afternoon in New York, and
00:20:56 --> 00:20:58 841 Monday evening in London.
00:20:59 --> 00:21:00 Avery: If you have a question you'd like us to
00:21:00 --> 00:21:02 chase, the contact form is
00:21:02 --> 00:21:05 @Astronomydailyio and you'll find
00:21:05 --> 00:21:07 us@Astrodaily pod. On social media,
00:21:07 --> 00:21:09 Astronomy AstroDailyPod is part of the
00:21:09 --> 00:21:10 bytes.com podcast network.
00:21:11 --> 00:21:12 Anna: Thanks for spending part of your weekend with
00:21:12 --> 00:21:14 us. I'm Anna.
00:21:14 --> 00:21:16 Avery: And I'm Avery Clear Skies and we'll see you
00:21:16 --> 00:21:17 Monday.
00:21:27 --> 00:21:28 Anna: Mhm.
00:21:33 --> 00:21:33 You
00:21:36 --> 00:21:37 Avery: stories we told.