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00:00:00 --> 00:00:02 Anna: Hello everyone, and welcome back to astronomy
00:00:02 --> 00:00:05 daily. Every 7.9 minutes, a
00:00:05 --> 00:00:07 radial pulse arrives from the direction of
00:00:07 --> 00:00:10 Canis Major, the Great Dog. It has
00:00:10 --> 00:00:13 travelled more than 5 light years and
00:00:13 --> 00:00:15 it keeps time like a clock.
00:00:16 --> 00:00:19 Avery: This week a team led from Perth traced that
00:00:19 --> 00:00:22 pulse to its source, a dead star the size
00:00:22 --> 00:00:24 of the Earth circling a star very much like
00:00:24 --> 00:00:27 our sun and on its way to us. The signal
00:00:27 --> 00:00:29 passes through that star's atmosphere and
00:00:29 --> 00:00:30 picks up its weather.
00:00:31 --> 00:00:33 Anna: That's our lead. We'll also look at how a
00:00:33 --> 00:00:36 gravitational wave observatory could end up
00:00:36 --> 00:00:39 finding planets. Then it's the week that was
00:00:39 --> 00:00:42 a moon rover built from a spare, a planet
00:00:42 --> 00:00:44 that stopped transiting, Euclid's first big
00:00:44 --> 00:00:47 data release, and a starship flight that is
00:00:47 --> 00:00:49 still in orbit as we record
00:00:50 --> 00:00:53 Avery: Mars and Jupiter side by side and
00:00:53 --> 00:00:56 the Leonids. This is the weekend wrap.
00:00:56 --> 00:00:58 I'm Avery coming to you from Sydney.
00:00:58 --> 00:01:00 Anna: Let's start with the puzzle this belongs to.
00:01:01 --> 00:01:04 Ordinary pulsars are, ah, spinning neutron
00:01:04 --> 00:01:07 stars. And they're fast. They flash anywhere
00:01:07 --> 00:01:10 from hundreds of times a second to once every
00:01:10 --> 00:01:12 few seconds. Then about five
00:01:12 --> 00:01:15 years ago, radio astronomers began finding
00:01:15 --> 00:01:18 things that pulse far more slowly once
00:01:18 --> 00:01:21 every few minutes or even every few hours.
00:01:21 --> 00:01:24 They're called long period transients.
00:01:24 --> 00:01:26 Avery: And um, slow is a problem, isn't it?
00:01:26 --> 00:01:29 Avery: It is. The standard picture says a
00:01:29 --> 00:01:30 neutron
00:01:30 --> 00:01:32 Anna: star spinning that slowly shouldn't have the
00:01:32 --> 00:01:35 power to make radio beams at all. So the
00:01:35 --> 00:01:38 question has been, what are these things?
00:01:38 --> 00:01:41 Only about a dozen are known. For at least
00:01:41 --> 00:01:43 four of them the answer turned out to be a
00:01:43 --> 00:01:46 white dwarf. The Earth sized ember m of a
00:01:46 --> 00:01:48 dead sun like star paired with
00:01:48 --> 00:01:50 a small cool red dwarf.
00:01:51 --> 00:01:53 Avery: But even there, there was an argument about
00:01:53 --> 00:01:56 which of the two stars was actually doing the
00:01:56 --> 00:01:56 broadcasting
00:01:57 --> 00:01:59 Anna: exactly. Is it the white dwarf,
00:02:00 --> 00:02:03 the red dwarf or the space between them
00:02:03 --> 00:02:05 where their magnetic fields meet?
00:02:06 --> 00:02:08 Hold onto that question because this week's
00:02:08 --> 00:02:10 paper answers it for one system.
00:02:11 --> 00:02:12 Avery: So what did they find?
00:02:12 --> 00:02:15 Anna: The paper came out in Nature astronomy on
00:02:15 --> 00:02:18 Thursday 12th November. The lead author is
00:02:18 --> 00:02:20 Sam McSweeney, who did the work at the Curtin
00:02:20 --> 00:02:23 University Node of the International Centre
00:02:23 --> 00:02:26 for Radio Astronomy Research in Perth with
00:02:26 --> 00:02:29 Natasha Hurley Walker, whose group found the
00:02:29 --> 00:02:31 very first of these objects. This horse has a
00:02:31 --> 00:02:33 catalogue name GPM
00:02:33 --> 00:02:35 J0715
00:02:36 --> 00:02:39 -1141 DPM
00:02:39 --> 00:02:41 stands for Galactic Plane Monitor. A survey
00:02:41 --> 00:02:44 with the Murchison Widefield Array in Outback
00:02:44 --> 00:02:47 Western Australia that scans the whole of the
00:02:47 --> 00:02:48 Milky Way visible from Australia.
00:02:49 --> 00:02:51 Avery: And the Wide Field Array caught the Pulse.
00:02:52 --> 00:02:54 Anna: It did one pulse every
00:02:54 --> 00:02:57 7.9 minutes. Then two more
00:02:57 --> 00:03:00 telescopes came in. Meerkat in South Africa
00:03:00 --> 00:03:03 pinned down the precise position on the sky
00:03:03 --> 00:03:06 and the Keck 1 telescope in Hawaii took a
00:03:06 --> 00:03:08 spectrum of the star sitting at that
00:03:08 --> 00:03:08 position.
00:03:09 --> 00:03:10 Avery: And that's where the surprise was.
00:03:11 --> 00:03:14 Anna: That's the surprise. It isn't a red
00:03:14 --> 00:03:16 dwarf. The spectrum fits a star of about
00:03:16 --> 00:03:19 five and a half thousand Kelvin, a G type
00:03:19 --> 00:03:21 star. That's the sun's own class.
00:03:22 --> 00:03:25 So the system is a low mass white dwarf
00:03:25 --> 00:03:28 and a sun like star going around each other
00:03:28 --> 00:03:30 about once every 1.3 days.
00:03:30 --> 00:03:33 Call it 31 hours. Mhm. It's the first
00:03:33 --> 00:03:36 time radio pulses like this have been tied to
00:03:36 --> 00:03:38 a white dwarf with a sun like partner.
00:03:39 --> 00:03:41 Avery: Now back to the question you told me to hold
00:03:41 --> 00:03:44 onto. Which star is making the pulses?
00:03:45 --> 00:03:48 Anna: Here's the clever part. The team processed
00:03:48 --> 00:03:50 more than 100 hours of radio data at the
00:03:50 --> 00:03:53 Pawsey Supercomputing Research Centre in
00:03:53 --> 00:03:56 Perth and timed the pulses very precisely.
00:03:56 --> 00:03:59 If the thing making the pulses is moving
00:03:59 --> 00:04:01 towards us, each pulse arrives a little
00:04:01 --> 00:04:04 early, moving away a little late.
00:04:04 --> 00:04:06 It's the same trick that found the first
00:04:06 --> 00:04:07 planets around pulsars.
00:04:08 --> 00:04:11 Avery: So the pulses themselves trace out an orbit.
00:04:12 --> 00:04:14 Anna: They do. And the orbit they trace is the
00:04:14 --> 00:04:17 white dwarf's. McSweeney says this is the
00:04:17 --> 00:04:19 first time the pulses from one of these
00:04:19 --> 00:04:21 systems have been clear enough to see the
00:04:21 --> 00:04:23 white dwarf moving around its companion. So
00:04:23 --> 00:04:25 the emission comes from close to the white
00:04:25 --> 00:04:27 dwarf, or possibly from the white dwarf
00:04:27 --> 00:04:28 itself.
00:04:29 --> 00:04:30 Avery: Not from the sun like star.
00:04:31 --> 00:04:33 Anna: Not from the sun like star. But the
00:04:33 --> 00:04:36 paper's conclusion is careful. The white
00:04:36 --> 00:04:39 dwarf seems to need its partner. The
00:04:39 --> 00:04:41 radio emission depends on the interaction
00:04:41 --> 00:04:44 between the two. And the timing suggests the
00:04:44 --> 00:04:46 sun like star isn't spilling gas onto the
00:04:46 --> 00:04:49 white dwarf. So this isn't one star
00:04:49 --> 00:04:50 feeding the other.
00:04:51 --> 00:04:52 Avery: And, uh, then there's the bonus.
00:04:52 --> 00:04:55 Anna: The bonus is my favourite part.
00:04:55 --> 00:04:58 Once every orbit, the white dwarf passes
00:04:58 --> 00:05:01 behind its companion as we see it.
00:05:01 --> 00:05:03 And the pulses have to travel through the
00:05:03 --> 00:05:06 outer atmosphere of the sun like star, its
00:05:06 --> 00:05:09 corona, to reach us. A, uh, corona
00:05:09 --> 00:05:12 is hot magnetised gas and that twists
00:05:12 --> 00:05:14 the polarisation of radio waves passing
00:05:14 --> 00:05:17 through it. It's called Faraday rotation.
00:05:18 --> 00:05:20 Avery: So the pulse is a kind of torch shining
00:05:20 --> 00:05:22 through the other star's atmosphere.
00:05:22 --> 00:05:25 Anna: A torch that flashes every eight
00:05:25 --> 00:05:28 minutes. The team saw that twisting change
00:05:28 --> 00:05:30 rapidly around that part of the orbit, which
00:05:30 --> 00:05:33 is what a corona would do. They also
00:05:33 --> 00:05:36 report flares on the star and one passage
00:05:36 --> 00:05:38 behind, a region of strong magnetic field
00:05:39 --> 00:05:41 that they think is most likely a stellar
00:05:41 --> 00:05:44 prominence. A huge loop of gas arcing off the
00:05:44 --> 00:05:46 surface. Our own sun makes them too
00:05:47 --> 00:05:49 Avery: from 5 light years away.
00:05:49 --> 00:05:52 Anna: Hurley Walker called it amazing that
00:05:52 --> 00:05:55 radio can pick up in her words the
00:05:55 --> 00:05:57 storms on a star at that distance.
00:05:58 --> 00:06:01 Normally, to study the corona of another sun
00:06:01 --> 00:06:03 like star, you want X ray telescopes and
00:06:03 --> 00:06:05 a star that's close by.
00:06:06 --> 00:06:08 Avery: Time for our usual list of what this is not.
00:06:09 --> 00:06:12 Anna: First, it's not the answer to every long
00:06:12 --> 00:06:14 period transient. It's one system
00:06:14 --> 00:06:17 and some of the others may be something else
00:06:17 --> 00:06:19 entirely, neutron stars included.
00:06:20 --> 00:06:23 Second, near or on the white dwarf
00:06:23 --> 00:06:26 is as far as the evidence goes, nobody yet
00:06:26 --> 00:06:28 knows the exact mechanism that makes the
00:06:28 --> 00:06:30 beam. Third, the prominence
00:06:30 --> 00:06:33 is an interpretation, the most likely one,
00:06:33 --> 00:06:36 not a picture of a loop. Fourth,
00:06:36 --> 00:06:39 the distance is given as more than 5
00:06:39 --> 00:06:41 light years and I wouldn't lean on it harder
00:06:41 --> 00:06:44 than that. And fifth, because radial
00:06:44 --> 00:06:46 pulses from space always attract the
00:06:46 --> 00:06:48 question, nothing here suggests anything
00:06:48 --> 00:06:51 artificial. It's a spinning magnet
00:06:51 --> 00:06:54 Avery: and any disclosure on the age of the result
00:06:54 --> 00:06:57 Anna: the Journal received the paper in January and
00:06:57 --> 00:07:00 accepted it in October. So the work itself
00:07:00 --> 00:07:03 is about a year old. We didn't find an
00:07:03 --> 00:07:05 earlier public preprint, so for most of us
00:07:05 --> 00:07:06 it's new this week,
00:07:07 --> 00:07:08 Avery: so why does it matter?
00:07:09 --> 00:07:12 Anna: Two reasons. One, it widens the
00:07:12 --> 00:07:14 family. If a white dwarf can do this with a
00:07:14 --> 00:07:17 sun like star on a day long orbit, and
00:07:17 --> 00:07:19 not only with a red dwarf pressed up close,
00:07:20 --> 00:07:22 there may be many more of these than anyone
00:07:22 --> 00:07:25 has been counting. Two, it's a new tool.
00:07:26 --> 00:07:29 A pulsing white dwarf behind a star is a way
00:07:29 --> 00:07:31 to probe that star's atmosphere and its space
00:07:31 --> 00:07:32 weather.
00:07:32 --> 00:07:35 Avery: And this one is a properly Australian story.
00:07:36 --> 00:07:38 Avery: It is and we don't have to stretch for it.
00:07:39 --> 00:07:41 Anna: Found with the Murchison Wide Field Array on
00:07:41 --> 00:07:44 Wujari Yamaji country in Western Australia.
00:07:45 --> 00:07:48 Lead from Perth processed at Pauzi and the
00:07:48 --> 00:07:51 source sits in canis major about 12
00:07:51 --> 00:07:53 degrees south of the celestial equator. So it
00:07:53 --> 00:07:56 leans south too. From Sydney that patch
00:07:56 --> 00:07:59 of sky climbs 68 degrees high from
00:07:59 --> 00:08:01 London 27
00:08:01 --> 00:08:03 Avery: though you can't see it,
00:08:03 --> 00:08:05 Anna: you can't. This is a radio result
00:08:05 --> 00:08:08 and no backyard telescope will show the
00:08:08 --> 00:08:11 pulse. But you can look at where it
00:08:11 --> 00:08:13 comes from and will point you there in the
00:08:13 --> 00:08:13 skywatch
00:08:14 --> 00:08:15 Avery: M what's next?
00:08:15 --> 00:08:18 Anna: More pulses through more orbits should map
00:08:18 --> 00:08:20 that corona better. And the paper mentions X
00:08:20 --> 00:08:23 ray follow up and the Wide Field Arrays
00:08:23 --> 00:08:26 site is where ska low the low
00:08:26 --> 00:08:28 frequency half of the Square Kilometre Array
00:08:28 --> 00:08:31 is being built. McSweeney is now with its
00:08:31 --> 00:08:33 Science Operations Centre a far more
00:08:33 --> 00:08:35 sensitive telescope on the same ground should
00:08:35 --> 00:08:36 find these in numbers.
00:08:38 --> 00:08:41 Avery: A dead star, a living one, and a
00:08:41 --> 00:08:42 signal that reports on both
00:08:43 --> 00:08:45 Anna: every 7.9 minutes.
00:08:45 --> 00:08:47 Avery: Staying with white dwarfs because it turns
00:08:47 --> 00:08:50 out to be their week. On Tuesday 10 November,
00:08:50 --> 00:08:53 two papers in the Astrophysical Journal, both
00:08:53 --> 00:08:55 led by Casey McGrath of the University of
00:08:55 --> 00:08:57 Maryland, Baltimore county, and NASA's
00:08:57 --> 00:09:00 Goddard Space Flight Centre, set out how a
00:09:00 --> 00:09:02 gravitational wave observatory could find
00:09:02 --> 00:09:02 planets.
00:09:03 --> 00:09:05 Anna: The observatory being lisa.
00:09:06 --> 00:09:08 Avery: Lisa, the Laser Interferometer Space
00:09:08 --> 00:09:11 Antenna, led by the European Space Agency,
00:09:11 --> 00:09:13 with NASA as a partner and slated to launch
00:09:13 --> 00:09:16 in the mid-2030s. Three spacecraft in a
00:09:16 --> 00:09:18 triangle with sides two and a half million
00:09:18 --> 00:09:21 kilometres long, measuring ripples in space
00:09:21 --> 00:09:21 time.
00:09:22 --> 00:09:24 Anna: And its most common target is expected to be
00:09:24 --> 00:09:26 pairs of white dwarfs.
00:09:27 --> 00:09:29 Avery: Right. Two white dwarfs in a tight
00:09:29 --> 00:09:32 orbit give off a steady gravitational wave
00:09:32 --> 00:09:34 humidity, um, at an almost constant pitch.
00:09:34 --> 00:09:37 The Milky Way is thought to hold around 10
00:09:37 --> 00:09:39 million pairs with orbits shorter than an
00:09:39 --> 00:09:42 hour. And LISA is expected to pick out
00:09:42 --> 00:09:44 about 10 of them individually.
00:09:45 --> 00:09:46 Anna: So where does a planet come in?
00:09:47 --> 00:09:49 Avery: Put a big enough planet in orbit around the
00:09:49 --> 00:09:52 pair and its gravity makes the pair wobble
00:09:52 --> 00:09:55 towards us and away from us. That wobble
00:09:55 --> 00:09:57 shifts the pitch of the hum up and down, a
00:09:57 --> 00:10:00 Doppler effect. And in lisa's data, it would
00:10:00 --> 00:10:02 show up as faint extra tones either side of
00:10:02 --> 00:10:05 the main one. The team's comparison is radio,
00:10:05 --> 00:10:08 a carrier frequency with sidebands. And the
00:10:08 --> 00:10:09 sidebands carry the message,
00:10:09 --> 00:10:12 Anna: which is the same idea as our lead
00:10:12 --> 00:10:15 time. A signal carefully enough and it
00:10:15 --> 00:10:17 tells you what its source is. Orbiting
00:10:18 --> 00:10:21 Avery: the same idea with gravity instead of radio,
00:10:22 --> 00:10:24 NASA says LISA could pick up a planet of
00:10:24 --> 00:10:26 about Jupiter's mass this way, out to
00:10:26 --> 00:10:28 thousands of light years. The second paper
00:10:28 --> 00:10:31 adds a crosscheck. A, uh, planet glows in
00:10:31 --> 00:10:33 infrared, so for a nearby system, the James
00:10:33 --> 00:10:35 Webb Space Telescope could see the extra
00:10:35 --> 00:10:38 heat. In their test case, Webb could detect a
00:10:38 --> 00:10:41 planet of about five Jupiter masses at
00:10:41 --> 00:10:42 500 light years.
00:10:42 --> 00:10:44 Anna: And the caveats?
00:10:44 --> 00:10:47 Avery: This is a forecast, not a discovery
00:10:47 --> 00:10:50 LISA hasn't flown. And no planet has
00:10:50 --> 00:10:52 yet been found around a double white dwarf,
00:10:52 --> 00:10:55 so nobody knows how common they are. If they
00:10:55 --> 00:10:57 exist, they're planets that survived the
00:10:57 --> 00:10:59 deaths of two stars.
00:10:59 --> 00:11:01 Anna: Longtime listeners might remember episode
00:11:01 --> 00:11:04 187, when we covered a pair of white dwarfs
00:11:04 --> 00:11:07 orbiting each other every 374
00:11:07 --> 00:11:10 seconds in the far southern sky. Already
00:11:10 --> 00:11:13 lined up as a test source for lisa, this
00:11:13 --> 00:11:15 is what else those hums might carry.
00:11:15 --> 00:11:17 Avery: Let's move on now to our weekly roundup
00:11:18 --> 00:11:21 Anna: time for the week. That was this week's
00:11:21 --> 00:11:23 stories in the order they happened with any
00:11:23 --> 00:11:24 update since
00:11:25 --> 00:11:27 Avery: Tuesday's episode led with NASA's Moon Base
00:11:27 --> 00:11:30 Awards announced on 7 November.
00:11:30 --> 00:11:33 The one to remember is Promise, a nuclear
00:11:33 --> 00:11:36 powered rover for the lunar South Pole, built
00:11:36 --> 00:11:38 from the testbed twin of the Curiosity Mars
00:11:38 --> 00:11:41 rover and a Flight Spare radioisotope
00:11:41 --> 00:11:44 generator. Being nuclear, it can keep working
00:11:44 --> 00:11:46 through the two week lunar night and inside
00:11:46 --> 00:11:48 permanently shadowed craters where the water
00:11:48 --> 00:11:51 ice is thought to be and where a solar rover
00:11:51 --> 00:11:52 would simply stop.
00:11:52 --> 00:11:55 Anna: We also had a theory paper asking whether
00:11:55 --> 00:11:58 gravitational fields can reconnect the way
00:11:58 --> 00:12:00 magnetic fields do in a solar flare.
00:12:01 --> 00:12:04 And a cloud of rubidium atoms cooled
00:12:04 --> 00:12:07 aboard China's Tiangong Space Station to an
00:12:07 --> 00:12:09 equivalent temperature of 9.7
00:12:09 --> 00:12:12 picokelvin. That's trillionths of
00:12:12 --> 00:12:14 a degree above absolute zero.
00:12:15 --> 00:12:16 Avery: Thursday's lead was toy
00:12:17 --> 00:12:19 2535B, a uh, hot Jupiter
00:12:19 --> 00:12:22 about 1000 light years away that crossed the
00:12:22 --> 00:12:24 face of its star every eight and a quarter
00:12:24 --> 00:12:27 days for seven years. Then this March,
00:12:27 --> 00:12:30 it didn't. Samuel Yee and
00:12:30 --> 00:12:33 Eric Pettigura at uh UCLA show da planet
00:12:33 --> 00:12:35 is still there. Its orbit has tilted out of
00:12:35 --> 00:12:38 our line of sight, most likely dragged by an
00:12:38 --> 00:12:40 unseen neighbour at least as massive as
00:12:40 --> 00:12:40 Saturn.
00:12:41 --> 00:12:44 Anna: Also on Thursday, a model from the University
00:12:44 --> 00:12:46 of Texas at Austin that reproduces the
00:12:46 --> 00:12:49 lopsided magnetic fields of Uranus and
00:12:49 --> 00:12:52 Neptune by letting electrical conductivity
00:12:52 --> 00:12:55 rise with depth. And South Africa's
00:12:55 --> 00:12:57 Meerkat measured how hydrogen clusters across
00:12:57 --> 00:13:00 the Universe with all 64 dishes working
00:13:00 --> 00:13:02 as, uh, separate telescopes.
00:13:02 --> 00:13:04 Avery: Friday's episode confirmed that Europe's
00:13:04 --> 00:13:07 Euclid telescope has opened its first major
00:13:07 --> 00:13:09 data release. Dr.1 foundation
00:13:09 --> 00:13:12 about 1900 square degrees of sky and roughly
00:13:12 --> 00:13:15 1.8 petabytes of data with around
00:13:15 --> 00:13:17 1400 of those square degrees in the southern
00:13:17 --> 00:13:20 sky. No dark energy results yet. Those
00:13:20 --> 00:13:22 come with a complete release in the middle of
00:13:22 --> 00:13:23 2027.
00:13:23 --> 00:13:25 Anna: And Caltech's asteroid experiment, about a
00:13:25 --> 00:13:28 cubic metre in size, used a robotic arm to
00:13:28 --> 00:13:30 assemble a section of truss in orbit, which
00:13:30 --> 00:13:31 the team says is a first.
00:13:32 --> 00:13:34 Avery: Friday's lead was the eve of Starship Flight
00:13:34 --> 00:13:37 15 and that story is still unfolding as we
00:13:37 --> 00:13:40 record. Here's what we know Starship
00:13:40 --> 00:13:42 lifted off successfully from Starbase in
00:13:42 --> 00:13:45 Texas at Ah, 5:47pm Eastern Time on Friday
00:13:45 --> 00:13:48 the 13th. That was 9:47 on Saturday morning
00:13:48 --> 00:13:48 in Sydney.
00:13:49 --> 00:13:51 Anna: SpaceX wanted to catch both halves of the
00:13:51 --> 00:13:54 rocket back at the tower. The first half
00:13:54 --> 00:13:56 didn't happen. The super heavy booster
00:13:56 --> 00:13:58 aborted uh, its return to the launch site and
00:13:58 --> 00:14:01 came down in the Gulf of Mexico about six and
00:14:01 --> 00:14:03 a half minutes after liftoff, it was in a
00:14:03 --> 00:14:06 controlled splashdown. SpaceX hasn't yet said
00:14:06 --> 00:14:09 what triggered the abort, and we're not going
00:14:09 --> 00:14:09 to guess
00:14:10 --> 00:14:12 Avery: the ship carried on. It reached orbit only
00:14:12 --> 00:14:15 the second time a Starship has and released
00:14:15 --> 00:14:17 its 26 Starlink satellites,
00:14:17 --> 00:14:19 Anna: and the catch attempt for the ship is still
00:14:19 --> 00:14:22 to come at the time of recording. SpaceX's
00:14:22 --> 00:14:24 timeline puts it at around 21:20 universal
00:14:25 --> 00:14:28 time on Saturday the 14th. That's
00:14:28 --> 00:14:30 about 3:20 in the afternoon in Texas and
00:14:30 --> 00:14:32 about 8:20 on Sunday morning in Sydney.
00:14:33 --> 00:14:36 No starship upper stage has ever been caught.
00:14:36 --> 00:14:38 By the time you hear this, it may have been
00:14:38 --> 00:14:40 tried. We'll have the full story on Monday.
00:14:41 --> 00:14:44 Avery: A few arc updates NASA's twin escapade
00:14:44 --> 00:14:46 spacecraft are both on their way to Mars.
00:14:46 --> 00:14:49 Both powered flybys of Earth worked on the
00:14:49 --> 00:14:51 7th and the 9th and are due to enter Mars
00:14:51 --> 00:14:54 orbit on the 7th and 9th of September 2027.
00:14:55 --> 00:14:58 Anna: Voyager 1 reaches one light day from Earth
00:14:58 --> 00:15:01 this Wednesday the 18th at uh, 10:16
00:15:01 --> 00:15:03 Universal Time. By NASA's estimate
00:15:04 --> 00:15:07 that's 9:16 in the evening in Sydney.
00:15:07 --> 00:15:10 Avery: And BepiColombo is due to be captured into
00:15:10 --> 00:15:12 orbit around Mercury next Saturday the
00:15:12 --> 00:15:15 21st, with HERA's first detailed images of
00:15:15 --> 00:15:18 the asteroid moon Dimorphos due on the
00:15:18 --> 00:15:18 25th
00:15:19 --> 00:15:21 Anna: down to the weak sky from both
00:15:21 --> 00:15:24 hemispheres. As usual, we've calculated
00:15:24 --> 00:15:26 the numbers ourselves for Sydney, Los
00:15:26 --> 00:15:28 Angeles, New York and London.
00:15:29 --> 00:15:31 Avery: The headline is the pairing we've been
00:15:31 --> 00:15:34 counting down to Mars and Jupiter are closest
00:15:34 --> 00:15:36 at 2 Universal Time on Monday 16
00:15:36 --> 00:15:39 November, 1.19 degrees apart by our
00:15:39 --> 00:15:42 calculation. That's a little over two full
00:15:42 --> 00:15:45 moons, but they're within about a degree and
00:15:45 --> 00:15:46 a third of each other on the mornings of the
00:15:46 --> 00:15:49 15th, 16th and 17th wherever you
00:15:49 --> 00:15:52 are, so don't worry about picking the exact
00:15:52 --> 00:15:52 morning.
00:15:53 --> 00:15:55 Anna: Jupiter is the bright 1 at magnitude
00:15:55 --> 00:15:58 -2. Mars is the fainter
00:15:58 --> 00:16:01 orange one beside it, about a, ah, 12th as
00:16:01 --> 00:16:03 bright. Both are in Leo
00:16:04 --> 00:16:07 Avery: and um, this one favours the north. An hour
00:16:07 --> 00:16:09 before sunrise, the pair stands about 68
00:16:09 --> 00:16:12 degrees up from Los Angeles, 63 from New
00:16:12 --> 00:16:15 York and 53 from London from
00:16:15 --> 00:16:17 Sydney they're about 30 degrees up in the
00:16:17 --> 00:16:20 northeast, still an easy naked eyesight.
00:16:20 --> 00:16:21 Just lower
00:16:21 --> 00:16:23 Anna: then Deleanid meteor shower
00:16:24 --> 00:16:26 Published peak dates disagree the night of
00:16:26 --> 00:16:29 the 16th to 17th or the 17th to
00:16:29 --> 00:16:32 18th. The standard prediction ties the
00:16:32 --> 00:16:35 peak to a particular point in Earth's orbit
00:16:35 --> 00:16:37 and by our calculation we reach it at about
00:16:37 --> 00:16:40 23:40 Universal Time on Tuesday the
00:16:40 --> 00:16:43 17th. So the mornings of Tuesday the
00:16:43 --> 00:16:46 17th and Wednesday the 18th are both worth a
00:16:46 --> 00:16:48 look, with Wednesday mornings slightly
00:16:48 --> 00:16:50 favoured in Australia and New Zealand.
00:16:51 --> 00:16:52 Avery: You'll also read that the first quarter moon
00:16:52 --> 00:16:55 spoils it. It doesn't if you go out at the
00:16:55 --> 00:16:58 right time. First quarter is on the 17th and
00:16:58 --> 00:17:00 a first quarter moon sets around the middle
00:17:00 --> 00:17:02 of the night. From Sydney it's down by about
00:17:02 --> 00:17:05 20 to 2 on Wednesday morning. From New York
00:17:05 --> 00:17:07 and London it sets before midnight on
00:17:07 --> 00:17:09 Tuesday. The hours before dawn, which are the
00:17:09 --> 00:17:11 best Leonid hours anyway, are dark.
00:17:12 --> 00:17:14 Anna: Keep expectations modest though.
00:17:14 --> 00:17:17 This is a small shower 10 to 15
00:17:17 --> 00:17:20 meteors an hour under a dark sky with the
00:17:20 --> 00:17:23 radiant overhead in the north. The
00:17:23 --> 00:17:26 radiant in Leo is 60 to 70 degrees
00:17:26 --> 00:17:28 up before dawn. From Sydney
00:17:28 --> 00:17:31 it only reaches about 22 degrees,
00:17:31 --> 00:17:34 so southern observers should expect just a
00:17:34 --> 00:17:37 handful an hour. The upside is that
00:17:37 --> 00:17:40 Mars and Jupiter are sitting right there in
00:17:40 --> 00:17:41 Leo while you wait.
00:17:42 --> 00:17:43 Avery: And for anyone who wants to look towards our
00:17:43 --> 00:17:46 lead story, the eight minute signal comes
00:17:46 --> 00:17:48 from Canis Major, the constellation that
00:17:48 --> 00:17:50 holds Sirius, the brightest star in the night
00:17:50 --> 00:17:53 sky. The Source is about 9 degrees
00:17:53 --> 00:17:55 northeast of Sirius. There's nothing to see
00:17:55 --> 00:17:58 at the spot itself, but Canis Major is up by
00:17:58 --> 00:18:00 about half past 10 in the evening this week
00:18:00 --> 00:18:02 from all four of our cities and Hyatt's
00:18:02 --> 00:18:04 between about half past three and half past
00:18:04 --> 00:18:07 four in the morning, 68 degrees up from
00:18:07 --> 00:18:10 Sydney, 44 from Los Angeles, 38 from New
00:18:10 --> 00:18:12 York and 27 from London.
00:18:12 --> 00:18:15 Anna: And our standing reminder never
00:18:15 --> 00:18:18 look at the sun directly through binoculars
00:18:18 --> 00:18:20 or through a telescope without proper
00:18:20 --> 00:18:23 protection. For any solar viewing,
00:18:23 --> 00:18:25 use only certified solar filters or
00:18:25 --> 00:18:28 eclipse glasses that meet the ISO
00:18:28 --> 00:18:31
00:18:31 --> 00:18:34 international safety standard. And with
00:18:34 --> 00:18:36 planets in the dawn sky, put the binoculars
00:18:36 --> 00:18:38 away before the sun comes up.
00:18:39 --> 00:18:41 Avery: And please take these warnings seriously.
00:18:41 --> 00:18:42 Your eye health is precious.
00:18:43 --> 00:18:46 Anna: That's the weekend wrap our uh, lead a
00:18:46 --> 00:18:49 white dwarf in Canis major pulsing every
00:18:49 --> 00:18:52 7.9 minutes beside a star like
00:18:52 --> 00:18:54 the sun found from Western Australia
00:18:55 --> 00:18:57 with a signal that carries its companions
00:18:57 --> 00:18:57 weather
00:18:58 --> 00:19:00 Avery: plus planets by gravitational wave,
00:19:01 --> 00:19:04 a rover built from a spare, a planet
00:19:04 --> 00:19:07 that tilted out of view, Euclid's data
00:19:07 --> 00:19:10 and a starship still in orbit. Full
00:19:10 --> 00:19:12 coverage of that flight on Monday. If you've
00:19:12 --> 00:19:14 got a question about any of it, the contact
00:19:14 --> 00:19:16 form@astronomydaily IO is the
00:19:16 --> 00:19:17 place
00:19:17 --> 00:19:19 Anna: you'll find show notes, the full back
00:19:19 --> 00:19:21 catalogue and our newsletter at
00:19:21 --> 00:19:24 astronomydaily IO and we're
00:19:25 --> 00:19:27 STROdaily pod on social media.
00:19:27 --> 00:19:29 Avery: We'll be back on Monday. Have a good weekend.
00:19:29 --> 00:19:30 I'm Avery
00:19:30 --> 00:19:32 Anna: and I am Anna. We are skies everyone.
00:19:52 --> 00:19:53