In this episode • The largest galaxy, measured at last. Ultra-deep imaging of IC 1101 in the Abell 2029 cluster has traced its outer edge for the first time: an edge radius of ~260 kpc, a diameter near 520 kpc (~1.7 million light-years), and ~3.4 trillion solar masses in stars — about 17× the width of the Milky Way. Faint outer structures aligned with cluster X-ray disturbances show it is still accreting. Source: Marrero-de la Rosa et al., “How large can galaxies be? Ultra-deep imaging of IC 1101”, accepted A&A (arXiv:2607.15340, 16 Jul 2026); phys.org, 31 Jul 2026; The Debrief, 1 Aug 2026. • Hayabusa2's record asteroid flyby. JAXA confirmed (press conference 30 Jul) that its Hayabusa2 probe passed just 400 m from the surface of near-Earth asteroid Torifune on 5 July — 744 m from centre at >18,000 km/h — the closest asteroid flyby by any mission, plus the first-ever laser ranging of an asteroid during a flyby. Torifune proved to be a contact binary. Source: JAXA press conference, 30 Jul 2026; phys.org / Japan Today (AFP), 31 Jul 2026; autoevolution, 1 Aug 2026. • UK's first orbital launch on hold. Rocket Factory Augsburg de-stacked its RFA One at SaxaVord Spaceport (Unst, Shetland) after finding a vehicle issue during hot-fire test prep (announced 28 Jul). The certified launch window opens 10 August; a successful flight would be the first orbital launch from UK soil. Source: RFA statement (X), 28 Jul 2026; Space.com, 1 Aug 2026; Shetland Times, 28 Jul 2026. • Andromeda is winding down. A new Hubble study mapping ~200 million stars across two-thirds of Andromeda's disk finds star formation has declined over ~500 million years (from ~1 to ~0.2 solar masses/year), with the steepest drop in the last 40 million years — possibly linked to an interaction with satellite galaxy M32. Source: Williams et al., The Astrophysical Journal, 27 Jul 2026; NASA/STScI release, 27 Jul 2026. Skywatch — both hemispheres • Comet 10P/Tempel 2 — perihelion 2 Aug; closest approach to Earth tonight (3 Aug). Binoculars/small scope, dark skies. Best pre-dawn from the Southern Hemisphere; ~9:30–10:30 pm local for mid-northern latitudes before moonrise. • Moon near Saturn tonight (3 Aug) — naked-eye pairing, both hemispheres, up into dawn. • Mercury at greatest western elongation (2 Aug) — low eastern horizon ~1 hr before sunrise, toward Gemini; Mars higher. Better placed for northern observers. • Diary (2 days out): Falcon 9 upper stage (2025-010D) lunar impact near Einstein Crater, 5 Aug ~06:35 UTC — ~2:35 am EDT / 11:35 pm PDT (4 Aug); North America best-timed on the dark limb. Southern Hemisphere: ~4:35 pm AEST (daylight) — await orbiter after-images. • Looking ahead: 12 Aug total solar eclipse (Greenland/Iceland/Spain) + moonless Perseid peak + six-planet dawn alignment. View partial phases only through certified ISO 12312-2 filters. Links & follow • Website, back catalogue, news feed & newsletter: astronomydaily.io • Social: @AstroDailyPod · Part of the Bitesz.com Podcast Network
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This episode includes AI-generated content.
00:00:01 --> 00:00:04 Anna: Here's a question to start your week. How big
00:00:04 --> 00:00:06 can a single thing actually get?
00:00:07 --> 00:00:10 Not a country, not an ocean. One
00:00:10 --> 00:00:12 object held together as one.
00:00:12 --> 00:00:15 Avery: And I'm guessing you don't mean my inbox.
00:00:15 --> 00:00:18 Anna: Bigger. Today, astronomers have
00:00:18 --> 00:00:21 finally put a tape measure around the largest
00:00:21 --> 00:00:23 galaxy we know of and found its edge
00:00:24 --> 00:00:25 for the very first time.
00:00:26 --> 00:00:28 Avery: Plus a Japanese spacecraft that, huh, just
00:00:28 --> 00:00:30 set the record for the closest asteroid flyby
00:00:30 --> 00:00:33 ever flown. A British launch put on hold at
00:00:33 --> 00:00:36 the last minute. And news that our nearest
00:00:36 --> 00:00:38 big neighbor galaxy is quietly powering
00:00:38 --> 00:00:39 down.
00:00:39 --> 00:00:42 Anna: It's Monday 3rd August. This is
00:00:42 --> 00:00:44 Astronomy Daily. I'm Anna.
00:00:44 --> 00:00:46 Avery: And I'm, um, Avery. Let's get into it.
00:00:47 --> 00:00:50 Anna: So let's start with that tape measure. If I
00:00:50 --> 00:00:52 asked you to name the biggest galaxy in the
00:00:52 --> 00:00:55 universe, an astronomer would very likely say
00:00:55 --> 00:00:58 IC1101. And they've
00:00:58 --> 00:01:01 been saying it for decades. But here's the
00:01:01 --> 00:01:03 strange until now, nobody could
00:01:03 --> 00:01:05 actually tell you where it ends.
00:01:06 --> 00:01:09 Avery: How do you not know where a galaxy ends? It's
00:01:09 --> 00:01:10 right there in the pictures.
00:01:10 --> 00:01:12 Anna: You'd think so. IC
00:01:12 --> 00:01:14 1101 sits about
00:01:14 --> 00:01:17 1.15 billion light years away
00:01:17 --> 00:01:20 at the heart of a cluster of galaxies called
00:01:20 --> 00:01:22 Abel 2029. William
00:01:22 --> 00:01:25 Herschel first logged it back in 1790.
00:01:25 --> 00:01:27 Though of course he had no idea it was a
00:01:27 --> 00:01:30 galaxy. Nobody did until the 1920s.
00:01:31 --> 00:01:34 It's what we call a giant elliptical, or
00:01:34 --> 00:01:36 more precisely a, uh, brightest cluster
00:01:36 --> 00:01:39 galaxy a, uh, BCG. And
00:01:39 --> 00:01:41 BCGs are the great white sharks of the
00:01:41 --> 00:01:44 galaxy world. They sit at the center of a
00:01:44 --> 00:01:47 cluster and they grow by swallowing their
00:01:47 --> 00:01:49 neighbors one merger at a time over
00:01:49 --> 00:01:50 billions of years.
00:01:51 --> 00:01:53 Avery: So it's basically been eating the other
00:01:53 --> 00:01:56 Anna: galaxies in its cluster for most of
00:01:56 --> 00:01:59 cosmic history. Yes, and that's exactly
00:01:59 --> 00:02:02 why its edge is so hard to find. When
00:02:02 --> 00:02:04 a galaxy grows by cannibalizing others,
00:02:04 --> 00:02:07 it ends up wrapped in an enormous faint
00:02:07 --> 00:02:10 halo of starsstars flung out into
00:02:10 --> 00:02:13 the space between galaxies. That glow
00:02:13 --> 00:02:16 is so dim, it blurs into the background of
00:02:16 --> 00:02:18 the cluster itself. So the honest answer
00:02:18 --> 00:02:20 to how big is
00:02:20 --> 00:02:23 IC1101? Has for
00:02:23 --> 00:02:26 years been a, uh, shrug. You'll see figures
00:02:26 --> 00:02:28 online anywhere from about 400
00:02:28 --> 00:02:31 light years across to a wild 6
00:02:31 --> 00:02:34 million light years. Nobody could pin it
00:02:34 --> 00:02:34 down.
00:02:35 --> 00:02:37 Avery: That's not a rounding error. That's a factor
00:02:37 --> 00:02:39 of 15. So what changed?
00:02:39 --> 00:02:42 Anna: A team led by Carlos Marrero de la
00:02:42 --> 00:02:45 Rosa took the deepest images ever
00:02:45 --> 00:02:47 captured of this galaxy. Ultra deep
00:02:47 --> 00:02:50 exposures in two colors using the Isaacman
00:02:50 --> 00:02:53 Newton's Wide Field Camera. And when I say
00:02:53 --> 00:02:56 deep I mean, they were sensitive enough to
00:02:56 --> 00:02:59 detect a glow 30 magnitudes per
00:02:59 --> 00:03:02 square arcsecond. Faint in plain
00:03:02 --> 00:03:04 terms, they could pick out starlight roughly
00:03:04 --> 00:03:07 a billion times fainter than the night sky
00:03:07 --> 00:03:08 you'd see with your own eyes.
00:03:09 --> 00:03:11 Avery: And the trick is separating that whisper of
00:03:11 --> 00:03:12 light from everything else.
00:03:13 --> 00:03:16 Anna: That's the whole game. Bright foreground
00:03:16 --> 00:03:18 stars smear light across the image. The
00:03:18 --> 00:03:21 galaxy scatters its own light, too. So they
00:03:21 --> 00:03:24 carefully modeled all that stray light and
00:03:24 --> 00:03:27 subtracted it using a detailed map of
00:03:27 --> 00:03:29 how the telescope spreads out a point of
00:03:29 --> 00:03:32 light. Only then could they trace the
00:03:32 --> 00:03:35 galaxy's true profile all the way out
00:03:35 --> 00:03:37 until it finally melts into the cluster.
00:03:38 --> 00:03:40 And here's what they IC
00:03:40 --> 00:03:43 1101 reaches an edge about
00:03:43 --> 00:03:46 263 light years from
00:03:46 --> 00:03:48 its center, which gives it a diameter of
00:03:48 --> 00:03:50 roughly 520
00:03:50 --> 00:03:52 kiloparsecs. That's about
00:03:52 --> 00:03:55 1.7 million light years from one side
00:03:55 --> 00:03:58 to the other, holding around 3.4
00:03:58 --> 00:04:00 trillion suns worth of stars.
00:04:01 --> 00:04:03 Avery: Okay, I need a yardstick for that. How does
00:04:03 --> 00:04:05 it compare to us? To the Milky Way?
00:04:06 --> 00:04:08 Anna: Our galaxy is about 100 light years
00:04:08 --> 00:04:11 across. So IC1101
00:04:11 --> 00:04:14 is something like 17 times wider
00:04:14 --> 00:04:17 than the Milky Way. And en masse,
00:04:17 --> 00:04:20 our entire galaxy, including all its dark
00:04:20 --> 00:04:23 matter, comes in around one to one and a
00:04:23 --> 00:04:25 half trillion solar masses.
00:04:25 --> 00:04:28 IC1101 has more
00:04:28 --> 00:04:30 than three trillion solar masses in its
00:04:30 --> 00:04:33 stars alone. It is, by any
00:04:33 --> 00:04:36 measure we can now defend with data, the
00:04:36 --> 00:04:37 largest galaxy known.
00:04:38 --> 00:04:41 Avery: You said now defend with data. That word
00:04:41 --> 00:04:42 now is doing some work.
00:04:43 --> 00:04:46 Anna: It is, because the second finding is
00:04:46 --> 00:04:48 almost better than the first. This
00:04:48 --> 00:04:51 galaxy isn't finished. Beyond that
00:04:51 --> 00:04:54 main edge, the team spotted a scatter
00:04:54 --> 00:04:57 of faint, lopsided structures. Eight
00:04:57 --> 00:05:00 of them and two line up neatly with
00:05:00 --> 00:05:02 disturbances astronomers had already seen
00:05:02 --> 00:05:05 in the hot X ray gas of the cluster.
00:05:05 --> 00:05:08 That's the fingerprint of ongoing feeding.
00:05:09 --> 00:05:11 IC1101 is still pulling
00:05:11 --> 00:05:14 material in, still assembling,
00:05:14 --> 00:05:17 probably shaped by a collision with another
00:05:17 --> 00:05:20 group of galaxies 2 to 3 billion years
00:05:20 --> 00:05:22 ago that's still settling down today.
00:05:23 --> 00:05:25 Avery: So it holds the record, and it's still
00:05:25 --> 00:05:28 growing. That feels almost greedy.
00:05:28 --> 00:05:31 Anna: Which brings us to the real question in the
00:05:31 --> 00:05:33 paper's title. How large can
00:05:33 --> 00:05:36 galaxies actually get? Because
00:05:36 --> 00:05:39 IC1101 now sits right at
00:05:39 --> 00:05:42 the extreme upper end of what we call the
00:05:42 --> 00:05:44 mass size relation, the biggest
00:05:44 --> 00:05:47 edge yet measured for any galaxy.
00:05:48 --> 00:05:51 It's not just a trivia record, it's a data
00:05:51 --> 00:05:53 point that tells us the ceiling for how big
00:05:53 --> 00:05:56 a galaxy can grow in the present day
00:05:56 --> 00:05:59 universe. And IC1101 is
00:05:59 --> 00:06:01 sitting up there, brushing against it,
00:06:02 --> 00:06:03 still reaching.
00:06:03 --> 00:06:05 Avery: Can, um, anyone actually see this monster for
00:06:05 --> 00:06:06 themselves?
00:06:07 --> 00:06:10 Anna: You'd want a good telescope. It's a faint
00:06:10 --> 00:06:13 smudge in the constellation Serpents near
00:06:13 --> 00:06:15 the Virgo border. Well placed in the evening
00:06:15 --> 00:06:18 for both hemispheres right now. But
00:06:18 --> 00:06:20 honestly, the wonder here isn't in the
00:06:20 --> 00:06:22 eyepiece. It's the idea.
00:06:23 --> 00:06:25 Somewhere out there is an object nearly
00:06:25 --> 00:06:28 2 million light years wide.
00:06:28 --> 00:06:31 3 trillion stars strong, and it's
00:06:31 --> 00:06:32 still hungry.
00:06:33 --> 00:06:35 Avery: From the largest thing we know to a very
00:06:35 --> 00:06:38 small, very fast one. Japan's space
00:06:38 --> 00:06:41 agency JAXA held a press conference last
00:06:41 --> 00:06:43 Thursday to confirm a result that had
00:06:43 --> 00:06:45 asteroid scientists grinning. Their
00:06:45 --> 00:06:48 Hayabusa2 spacecraft has just flown the
00:06:48 --> 00:06:51 closest asteroid flyby ever attempted
00:06:51 --> 00:06:52 by any mission.
00:06:52 --> 00:06:55 Anna: This is the same spacecraft that brought
00:06:55 --> 00:06:57 samples of asteroid Ryugu back to Earth,
00:06:57 --> 00:06:58 isn't it?
00:06:59 --> 00:07:01 Avery: The very same Hayabusa2, launched back
00:07:01 --> 00:07:04 in 2014, dropped those precious Ryuko
00:07:04 --> 00:07:06 samples in the Australian outback in 2020,
00:07:06 --> 00:07:09 and then, with fuel still in the tank,
00:07:09 --> 00:07:12 kept going. It's now traveled something like
00:07:12 --> 00:07:15 10.7 billion kilometers on
00:07:15 --> 00:07:18 an extended mission. And on 5 July,
00:07:18 --> 00:07:20 it threaded past a near Earth asteroid called
00:07:20 --> 00:07:21 Torifune.
00:07:22 --> 00:07:24 Anna: How close is closest ever?
00:07:25 --> 00:07:28 Avery: 400 meters from the surface. 400.
00:07:28 --> 00:07:31 That's 744 meters from the asteroid's
00:07:31 --> 00:07:34 center. And they did it. While both objects
00:07:34 --> 00:07:37 were screaming along at more than 18
00:07:37 --> 00:07:39 kilometers an hour, about 100 million
00:07:39 --> 00:07:42 kilometers from Earth, they'd plan to pass
00:07:42 --> 00:07:44 800 meters from the center and beat their own
00:07:44 --> 00:07:46 target by clean half.
00:07:46 --> 00:07:49 Anna: At that speed and distance, that's
00:07:49 --> 00:07:50 absurdly precise.
00:07:51 --> 00:07:53 Avery: The operations lead, Yuyemimasu, put it
00:07:53 --> 00:07:56 beautifully. He said the difficulty was like
00:07:56 --> 00:07:59 shooting a 1 yen coin up on the northern
00:07:59 --> 00:08:02 island of Hokkaido from down in Okinawa,
00:08:02 --> 00:08:04 right at the other end of Japan. And they
00:08:04 --> 00:08:06 didn't just take pictures. Hayabusa2
00:08:06 --> 00:08:09 pulled off the first ever laser ranging of an
00:08:09 --> 00:08:12 asteroid during a flyby, bouncing a laser
00:08:12 --> 00:08:15 off the rock to measure the distance in real
00:08:15 --> 00:08:15 time.
00:08:16 --> 00:08:18 Anna: And there was a surprise waiting for them
00:08:18 --> 00:08:18 too.
00:08:19 --> 00:08:21 Avery: There was. Torifune turned out to be a
00:08:21 --> 00:08:24 contact binary. Two lumps of rock stuck
00:08:24 --> 00:08:27 together a bit like a cosmic snowman.
00:08:27 --> 00:08:30 Roughly 450 meters of double lobed
00:08:30 --> 00:08:32 asteroid. They hadn't expected to look like
00:08:32 --> 00:08:33 that at all.
00:08:34 --> 00:08:36 Anna: So why do this? Beyond the lovely
00:08:36 --> 00:08:39 images, planetary defense.
00:08:39 --> 00:08:41 Avery: Learning to navigate a spacecraft that
00:08:41 --> 00:08:44 precisely that close to a moving target
00:08:44 --> 00:08:47 is exactly the skill you'd need to reach,
00:08:47 --> 00:08:49 or one day nudge a genuinely
00:08:49 --> 00:08:52 hazardous asteroid. This was a rehearsal
00:08:52 --> 00:08:55 and the next act is already booked. In
00:08:55 --> 00:08:58 2031, Hayabusa2 will rendezvous with a
00:08:58 --> 00:09:00 tiny asteroid called 1998
00:09:00 --> 00:09:03 KY26. Just 11 meters across.
00:09:04 --> 00:09:06 It might even try to land a
00:09:06 --> 00:09:09 Anna: fridge sized probe landing on something
00:09:09 --> 00:09:11 the size of a house. I love this mission.
00:09:12 --> 00:09:14 Now to a launch that isn't happening quite
00:09:14 --> 00:09:17 yet, but when it does, it'll be a first.
00:09:17 --> 00:09:20 The German company rocket factory Oxford
00:09:20 --> 00:09:23 RFA is aiming to send the first ever
00:09:23 --> 00:09:26 rocket to orbit from UK soil, flying
00:09:26 --> 00:09:29 from Saxavoord Spaceport up on
00:09:29 --> 00:09:31 Unst, the most northerly of Britain's
00:09:31 --> 00:09:33 inhabited islands in Shetland.
00:09:33 --> 00:09:36 Avery: The first orbital launch from the uk. That's
00:09:36 --> 00:09:37 a genuine milestone.
00:09:37 --> 00:09:40 Anna: It really is. Britain has never launched a
00:09:40 --> 00:09:42 satellite to orbit from its own ground.
00:09:43 --> 00:09:46 RFA's rocket, called RFA1,
00:09:46 --> 00:09:48 is a 30 meter three stage vehicle
00:09:48 --> 00:09:51 designed to carry up to 1300
00:09:51 --> 00:09:54 kilograms to a sun synchronous orbit.
00:09:54 --> 00:09:56 But last Monday, while running a test
00:09:56 --> 00:09:59 campaign on the pad ahead of a hot fire of
00:09:59 --> 00:10:01 the engines, the company found what it called
00:10:02 --> 00:10:04 an issue with the vehicle that requires
00:10:04 --> 00:10:07 further investigation. So they've made the
00:10:07 --> 00:10:09 call to de stack to take the fully
00:10:09 --> 00:10:12 assembled rocket apart stage by stage
00:10:12 --> 00:10:13 to get at the problem.
00:10:14 --> 00:10:15 Avery: And they've got a history at that pad,
00:10:15 --> 00:10:16 haven't they?
00:10:16 --> 00:10:19 Anna: They do. Back in August 2024,
00:10:19 --> 00:10:22 an earlier RFA1 first stage was
00:10:22 --> 00:10:25 destroyed in a fireball during a static fire
00:10:25 --> 00:10:28 test at that very site. Nobody hurt,
00:10:28 --> 00:10:30 the pad saved, but the stage lost.
00:10:31 --> 00:10:34 RFA are open about their philosophy. They
00:10:34 --> 00:10:37 develop iteratively, they test hard and
00:10:37 --> 00:10:39 they accept that things sometimes break. This
00:10:39 --> 00:10:42 latest issue sounds far less dramatic. Caught
00:10:42 --> 00:10:45 on the ground exactly where you want to catch
00:10:45 --> 00:10:45 it.
00:10:45 --> 00:10:47 Avery: So what does the timeline look like now?
00:10:47 --> 00:10:50 Anna: AIR certified launch window opens on the 10th
00:10:50 --> 00:10:53 of August. Whether they make that depends on
00:10:53 --> 00:10:55 what the investigation turns up. SACS of
00:10:55 --> 00:10:58 ORD matters here beyond just this one flight.
00:10:59 --> 00:11:01 It's the first fully licensed vertical
00:11:01 --> 00:11:04 orbital launch site in Western Europe and the
00:11:04 --> 00:11:06 only UK spaceport cleared for vertical
00:11:06 --> 00:11:09 launches. With satellite demand the way it
00:11:09 --> 00:11:11 is, Europe is hungry for its own
00:11:11 --> 00:11:14 independent way to orbit. So this is one
00:11:14 --> 00:11:16 to keep an eye on over the next week.
00:11:16 --> 00:11:19 Avery: We opened with a galaxy that's still growing.
00:11:19 --> 00:11:21 Let's close the news with one that's slowing
00:11:21 --> 00:11:24 down. And this one's practically a neighbor.
00:11:24 --> 00:11:27 New Hubble work published last Monday finds
00:11:27 --> 00:11:29 star formation across the Andromeda galaxy
00:11:29 --> 00:11:32 has been fading for the last 500 million
00:11:32 --> 00:11:32 years.
00:11:32 --> 00:11:35 Anna: Andromeda, that's the closest big spiral to
00:11:35 --> 00:11:38 Avery: us, the nearest large spiral, about
00:11:38 --> 00:11:41 2.5 million light years away, roughly a uh,
00:11:41 --> 00:11:44 trillion stars. And on a dark night, you
00:11:44 --> 00:11:46 can see it with your own eyes. A team led by
00:11:46 --> 00:11:48 Benjamin Williams pieced together two
00:11:48 --> 00:11:51 enormous Hubble surveys covering about two
00:11:51 --> 00:11:53 thirds of Andromeda's disk and measured
00:11:53 --> 00:11:56 something like 200 million individual stars.
00:11:57 --> 00:12:00 As Williams put it, the stars are the fossil
00:12:00 --> 00:12:02 record of the galaxy's formation. Read them
00:12:02 --> 00:12:04 carefully and you can reconstruct its
00:12:04 --> 00:12:04 history.
00:12:05 --> 00:12:07 Anna: And that history is one of a galaxy
00:12:07 --> 00:12:09 quieting down steadily.
00:12:09 --> 00:12:12 Avery: Yes, its star forming rate has dropped from
00:12:12 --> 00:12:15 about one sun's worth of new stars a year to
00:12:15 --> 00:12:17 roughly a fifth of that with the sharpest
00:12:17 --> 00:12:20 decline in just the last 40 million years.
00:12:20 --> 00:12:22 Most of what's left is concentrated in a ring
00:12:22 --> 00:12:25 about 32 light years out from the center.
00:12:25 --> 00:12:28 And there may be a culprit. A little
00:12:28 --> 00:12:30 satellite galaxy called M M32
00:12:31 --> 00:12:34 pit and run, possibly a sideswipe.
00:12:34 --> 00:12:36 The region of Andromeda nearest M M32 shows
00:12:36 --> 00:12:39 the most suppressed star formation. And the
00:12:39 --> 00:12:41 slowdown there seems to have kicked off
00:12:41 --> 00:12:43 around 60 million years ago, which could
00:12:43 --> 00:12:46 actually help pin down when M M32 last
00:12:46 --> 00:12:49 barged through Andromeda's disk. It's a
00:12:49 --> 00:12:51 reminder that galaxies aren't serene islands.
00:12:51 --> 00:12:54 They jostle, they collide. And sometimes a
00:12:54 --> 00:12:57 small neighbor leaves a very large mark.
00:12:57 --> 00:12:59 Anna: And you can go and look at the scene of the
00:12:59 --> 00:13:00 crime tonight.
00:13:01 --> 00:13:03 Avery: You can, which is the perfect handover to the
00:13:03 --> 00:13:03 skywatch.
00:13:04 --> 00:13:07 Anna: Skywatch time and a, uh, heads up before we
00:13:07 --> 00:13:09 start. We've just had the full buck moon,
00:13:09 --> 00:13:12 so the moon is a waning gibbous this week,
00:13:12 --> 00:13:15 still bright enough early on to wash out the
00:13:15 --> 00:13:17 faintest targets. It'll get easier as the
00:13:17 --> 00:13:19 week goes and the moon thins toward last
00:13:19 --> 00:13:20 quarter.
00:13:20 --> 00:13:23 Avery: First up, a comet with its moment tonight.
00:13:24 --> 00:13:26 Comet 10P Tempel 2
00:13:27 --> 00:13:29 reached its closest point to the sun
00:13:29 --> 00:13:31 yesterday. And Tonight, Monday the 3rd,
00:13:32 --> 00:13:34 it makes its closest approach to Earth.
00:13:35 --> 00:13:37 Anna: It's not a naked eye showpiece. You'll want
00:13:37 --> 00:13:40 binoculars or a small telescope. And dark
00:13:40 --> 00:13:43 skies from the southern hemisphere. It rides
00:13:43 --> 00:13:46 highest before dawn. So Sydney early
00:13:46 --> 00:13:49 risers have the better geometry. From North
00:13:49 --> 00:13:51 America, it's best hunted in the narrow
00:13:51 --> 00:13:54 window of true darkness after evening
00:13:54 --> 00:13:57 twilight. But before that, gibbous moon
00:13:57 --> 00:13:59 climbs up for mid northern latitudes
00:13:59 --> 00:14:02 roughly 9:30 to 10:30pm
00:14:02 --> 00:14:05 local. Use averted vision and let your
00:14:05 --> 00:14:06 eyes settle.
00:14:06 --> 00:14:08 Avery: Next, an easy one for everyone.
00:14:09 --> 00:14:11 Tonight, the waning gibbous moon sits
00:14:11 --> 00:14:14 right beside Saturn, a lovely naked eye
00:14:14 --> 00:14:17 pairing up through most of the night and into
00:14:17 --> 00:14:20 dawn and visible from both hemispheres.
00:14:20 --> 00:14:22 If you've got a scope, swing it to Saturn
00:14:22 --> 00:14:23 while you're there for the
00:14:23 --> 00:14:26 Anna: rings and for the early risers.
00:14:26 --> 00:14:28 Mercury reached its greatest western
00:14:28 --> 00:14:31 elongation yesterday, so it's about as well
00:14:31 --> 00:14:34 placed in the morning sky as it gets this
00:14:34 --> 00:14:37 round. Look low to the eastern horizon
00:14:37 --> 00:14:39 roughly an hour before sunrise over
00:14:39 --> 00:14:42 toward the stars of Gemini, with Mars a
00:14:42 --> 00:14:45 little higher up. Northern observers get the
00:14:45 --> 00:14:48 cleaner shot at Mercury this time, but it's
00:14:48 --> 00:14:51 worth a try from the south too. You'll need a
00:14:51 --> 00:14:53 flat clear horizon either way.
00:14:53 --> 00:14:56 Avery: Now a uh, diary note we flagged last week and
00:14:56 --> 00:14:59 it's now just two days out on the 5th of
00:14:59 --> 00:15:02 August, a UH Spent Falcon 9 upper stage
00:15:02 --> 00:15:05 is on track to impact the Moon near
00:15:05 --> 00:15:08 Einstein crater on the western limb at about
00:15:08 --> 00:15:10 0635 Universal Time.
00:15:11 --> 00:15:14 Anna: And this one's squarely for our, uh, North
00:15:14 --> 00:15:16 American listeners. You have the best seat in
00:15:16 --> 00:15:19 the house. That impact time works out to
00:15:19 --> 00:15:21 about 2:35 Eastern,
00:15:22 --> 00:15:24 11:35 Pacific the night before.
00:15:24 --> 00:15:27 With the moon up and the impact region on the
00:15:27 --> 00:15:30 dark side of the terminator ideal, you
00:15:30 --> 00:15:32 won't see a flash with the naked eye. But if
00:15:32 --> 00:15:35 you've got a decent telescope and a camera
00:15:35 --> 00:15:37 trained on that limb, you're in the game.
00:15:37 --> 00:15:39 Avery: For us in the southern hemisphere, the
00:15:39 --> 00:15:42 timing's unkind. That's mid afternoon in
00:15:42 --> 00:15:45 Sydney, uh, around 4:35pm with
00:15:45 --> 00:15:48 the moon not favorably placed. So we'll be
00:15:48 --> 00:15:50 waiting on the orbiter after images of the
00:15:50 --> 00:15:52 impact site rather than catching it live.
00:15:53 --> 00:15:55 But it's a great excuse to follow
00:15:55 --> 00:15:58 Anna: along online and looking ahead, a
00:15:58 --> 00:16:00 quick flag for the big month coming.
00:16:00 --> 00:16:03 12 August is a huge date.
00:16:03 --> 00:16:05 A total solar eclipse tracking across
00:16:05 --> 00:16:08 Greenland, Iceland and Spain, paired
00:16:08 --> 00:16:11 for once with a moonless peak of the
00:16:11 --> 00:16:14 Perseid meteor shower. Plus a six
00:16:14 --> 00:16:17 planet lineup in the pre dawn sky. We'll
00:16:17 --> 00:16:19 build all of that out closer to the day.
00:16:19 --> 00:16:22 Avery: 1 um, safety word now though, and we'll say
00:16:22 --> 00:16:25 it every time. If you're anywhere near that
00:16:25 --> 00:16:27 eclipse path, you view the partial phases
00:16:28 --> 00:16:30 only through certified ISO
00:16:30 --> 00:16:33
00:16:33 --> 00:16:35 eclipse glasses or a properly filtered
00:16:35 --> 00:16:38 scope. Never look at the uneclipsed, um, sun
00:16:38 --> 00:16:39 without them.
00:16:39 --> 00:16:41 Anna: That's your Monday briefing. If you want
00:16:41 --> 00:16:44 more. Everything lives at astronomydaily,
00:16:44 --> 00:16:47 IO, the full back catalog, a news
00:16:47 --> 00:16:49 feed that updates through the day, and a spot
00:16:49 --> 00:16:51 to sign up for the daily newsletter.
00:16:52 --> 00:16:54 Avery: You can send us a message from the site too.
00:16:54 --> 00:16:57 Corrections, questions, what you spotted in
00:16:57 --> 00:16:59 your own sky. We read them and we love them.
00:17:00 --> 00:17:02 We even got our first voice message today
00:17:02 --> 00:17:05 from listener Ian Sama in Uganda who
00:17:05 --> 00:17:07 said hi there, I'm Um, Ian from Uganda and I
00:17:07 --> 00:17:10 really enjoy your podcast very much. Thanks a
00:17:10 --> 00:17:13 lot. Thank you, Ian. Um, the feedback is very
00:17:13 --> 00:17:14 much appreciated.
00:17:14 --> 00:17:17 Anna: Yes, thank you, Ian. Very much appreciated by
00:17:17 --> 00:17:20 all of us. We'll be back tomorrow with more
00:17:20 --> 00:17:22 of today's space news. Until then, from
00:17:22 --> 00:17:24 Avery and me, keep
00:17:24 --> 00:17:25 Avery: looking up clear skies.
00:17:32 --> 00:17:32 Anna: Mhm.
00:17:37 --> 00:17:38 The stories.