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00:00:00 --> 00:00:03 Anna: On the most volcanic world on the solar
00:00:03 --> 00:00:06 system, hundreds of erupting mountains have
00:00:06 --> 00:00:08 been hurling light and heat into space
00:00:09 --> 00:00:10 as long as we've been able to watch.
00:00:11 --> 00:00:14 Avery: But that's the surface underneath. In the
00:00:14 --> 00:00:16 first few meters of crust, there was a
00:00:16 --> 00:00:18 temperature nobody had ever actually
00:00:18 --> 00:00:19 measured.
00:00:19 --> 00:00:22 Anna: Until a spacecraft built to study
00:00:22 --> 00:00:24 Jupiter's clouds pointed its instrument
00:00:24 --> 00:00:27 down at a moon and read the heat
00:00:27 --> 00:00:28 beneath the ground.
00:00:29 --> 00:00:31 Avery: Welcome to Astronomy Daily.
00:00:31 --> 00:00:34 Anna: Hello and welcome to Astronomy daily
00:00:34 --> 00:00:36 for Tuesday, the 28th of July,
00:00:37 --> 00:00:39 2026. I'm Anna.
00:00:39 --> 00:00:41 Avery: And I'm Avery. Whether you're under southern
00:00:41 --> 00:00:44 skies here in Australia and New Zealand, or
00:00:44 --> 00:00:45 across North America and the rest of the
00:00:45 --> 00:00:48 Northern Hemisphere, good day and good
00:00:48 --> 00:00:49 evening wherever this finds you.
00:00:50 --> 00:00:52 Anna: Big show. Today, our lead takes us to
00:00:52 --> 00:00:55 IO, Jupiter's fiery moon, and a
00:00:55 --> 00:00:58 genuine first, the temperature below its
00:00:58 --> 00:01:01 surface surface. Then two cosmic puzzles
00:01:01 --> 00:01:04 that might turn out to be the same puzzle. A
00:01:04 --> 00:01:07 fresh way to hunt for alien signals and
00:01:07 --> 00:01:10 a burst of space weather arriving at Earth
00:01:10 --> 00:01:11 just about now.
00:01:11 --> 00:01:13 Avery: Plus a, uh, skywatch with meteor showers
00:01:13 --> 00:01:16 peaking all week. Though the moon has other
00:01:16 --> 00:01:17 ideas. Let's get into it.
00:01:18 --> 00:01:21 Anna: So let's start with the star of the show, and
00:01:21 --> 00:01:23 it's a moon, IO, Jupiter's
00:01:23 --> 00:01:26 innermost large moon and the most
00:01:26 --> 00:01:28 volcanically active body in the entire
00:01:28 --> 00:01:31 solar system. If you've seen the pictures,
00:01:31 --> 00:01:34 it's that slightly unsettling pizza
00:01:34 --> 00:01:37 colored world. Yellows, oranges,
00:01:37 --> 00:01:40 sulfur reds, blotched with hundreds of
00:01:40 --> 00:01:42 volcanoes, some of them throwing plumes
00:01:42 --> 00:01:44 hundreds of kilometers into space.
00:01:45 --> 00:01:47 Avery: It's genuinely hard to overstay how active
00:01:47 --> 00:01:50 IO is. More than 400 active
00:01:50 --> 00:01:53 volcanoes, lava lakes, the works.
00:01:53 --> 00:01:55 Per square meter, it pumps out many times
00:01:55 --> 00:01:57 more heat than Earth does.
00:01:57 --> 00:02:00 Anna: And that's the puzzle at the heart of today's
00:02:00 --> 00:02:03 story. All that volcanism is powered by
00:02:03 --> 00:02:06 something called tidal heating. IO
00:02:06 --> 00:02:08 orbits Jupiter on a slightly stretched
00:02:08 --> 00:02:11 elliptical path. And Jupiter's enormous
00:02:11 --> 00:02:14 gravity is constantly squeezing and
00:02:14 --> 00:02:17 flexing the moon, like bending a paperclip
00:02:17 --> 00:02:20 back and forth until it warms up, except on
00:02:20 --> 00:02:22 a planetary scale. And forever.
00:02:23 --> 00:02:25 Avery: Flex a paperclip fast enough, it gets hot in
00:02:25 --> 00:02:28 your fingers. IO is that paperclip. And
00:02:28 --> 00:02:30 Jupiter never stops bending it.
00:02:30 --> 00:02:33 Anna: Exactly. But here's the thing. For
00:02:33 --> 00:02:36 all the decades we've studied IO, almost
00:02:36 --> 00:02:39 everything we knew about that heat came from
00:02:39 --> 00:02:41 looking at the surface infrared cameras,
00:02:41 --> 00:02:44 which read the temperature of the very top
00:02:44 --> 00:02:46 layer. What we'd never done, what
00:02:46 --> 00:02:49 nobody had ever done for a rocky world other
00:02:49 --> 00:02:52 than Earth, it is measure the temperature
00:02:52 --> 00:02:54 below the surface under the ground.
00:02:55 --> 00:02:57 Avery: And that's exactly what NASA's Juno
00:02:57 --> 00:02:58 spacecraft just did.
00:02:59 --> 00:03:01 Anna: It is. Juno has been orbiting
00:03:01 --> 00:03:04 Jupiter since 2016, and it made
00:03:04 --> 00:03:07 two very close passes of IO in
00:03:07 --> 00:03:10 late December 2023 and early
00:03:10 --> 00:03:13 February 2024, sweeping within
00:03:13 --> 00:03:16 about 1500 kilometers, roughly
00:03:16 --> 00:03:18 930 miles of the surface.
00:03:19 --> 00:03:22 And on both passes, it used an instrument
00:03:22 --> 00:03:24 called the Microwave Radiometer.
00:03:24 --> 00:03:26 MWR for short.
00:03:26 --> 00:03:28 Avery: And this is the part I love, because that
00:03:28 --> 00:03:31 instrument was never designed to do this. The
00:03:31 --> 00:03:34 MWR was built to look down through Jupiter's
00:03:34 --> 00:03:36 thick clouds and read the giant planet's
00:03:36 --> 00:03:39 atmosphere at different depths. It has six
00:03:39 --> 00:03:41 antennas, each tuned to a different
00:03:41 --> 00:03:41 wavelength.
00:03:42 --> 00:03:45 Anna: And that multi wavelength design turns
00:03:45 --> 00:03:47 out to be the whole trick. Different
00:03:47 --> 00:03:50 wavelengths of microwave energy escape from
00:03:50 --> 00:03:52 different depths. So if you point that
00:03:52 --> 00:03:55 instrument at solid ground instead of cloud,
00:03:55 --> 00:03:58 each channel is effectively reading the
00:03:58 --> 00:04:00 temperature at a slightly different depth
00:04:00 --> 00:04:03 below the surface, all at once, all
00:04:03 --> 00:04:06 from orbit, using nothing but the natural
00:04:06 --> 00:04:08 heat the crust is already giving off.
00:04:09 --> 00:04:11 Avery: So it's like a thermometer that reads several
00:04:11 --> 00:04:14 depths at the same time without ever touching
00:04:14 --> 00:04:14 the ground.
00:04:15 --> 00:04:17 Anna: That's a lovely way to put it. And what did
00:04:17 --> 00:04:20 it find? Within just the first few meters of
00:04:20 --> 00:04:23 crust, the temperature climbs by more than 20
00:04:23 --> 00:04:26 degrees Celsius over 40 Fahrenheit.
00:04:26 --> 00:04:28 That might not sound dramatic, but for a
00:04:28 --> 00:04:30 world whose surface sits at around minus
00:04:30 --> 00:04:33 143 Celsius, a rise
00:04:33 --> 00:04:36 that steep, that shallow, tells you there's
00:04:36 --> 00:04:37 serious heat welling up from below.
00:04:38 --> 00:04:40 Avery: Put a number on it. How much heat are we
00:04:40 --> 00:04:41 talking?
00:04:41 --> 00:04:44 Anna: The team estimates a heat flow of roughly 1
00:04:44 --> 00:04:47 to 3 watts per square meter, up to about
00:04:47 --> 00:04:50 30 times Earth's global average, seeping
00:04:50 --> 00:04:52 up through the top 10 meters or so of crust,
00:04:53 --> 00:04:55 most likely from a mix of that tidal heating
00:04:55 --> 00:04:57 and lava still cooling underground.
00:04:58 --> 00:05:00 Avery: 30 times Earth's average welling up through
00:05:00 --> 00:05:02 the ground. That's the engine of all those
00:05:02 --> 00:05:04 volcanoes caught in the act.
00:05:04 --> 00:05:07 Anna: And there was a second surprise in the same
00:05:07 --> 00:05:10 data. The MWR also showed that most of
00:05:10 --> 00:05:13 IO's surface is remarkably smooth and made
00:05:13 --> 00:05:15 of very low density material, which fits a
00:05:15 --> 00:05:18 world that's constantly repaving itself with
00:05:18 --> 00:05:20 fresh volcanic deposits, burying its own
00:05:20 --> 00:05:22 craters almost as fast as they form.
00:05:23 --> 00:05:24 Avery: Now the study is in the Journal of
00:05:24 --> 00:05:27 Geophysical Research Planets, led by Shannon
00:05:27 --> 00:05:29 Brown at JPL. And NASA put it out on the
00:05:29 --> 00:05:32 22nd. But, Anna, uh, I think the really big
00:05:32 --> 00:05:35 deal here might not even be IO itself. It's
00:05:35 --> 00:05:36 the method.
00:05:36 --> 00:05:39 Anna: I completely agree. This is the first time
00:05:39 --> 00:05:41 anyone has read a subsurface temperature
00:05:41 --> 00:05:44 profile of a rocky body from orbit. And
00:05:44 --> 00:05:46 that technique doesn't care whether the World
00:05:46 --> 00:05:49 is fiery or frozen. Point it at an icy
00:05:49 --> 00:05:52 moon, Europa Enceladus, and in principle,
00:05:52 --> 00:05:54 you could sense the warmth of an ocean
00:05:54 --> 00:05:56 beneath the ice or work out how thick that
00:05:56 --> 00:05:57 ice actually is.
00:05:58 --> 00:06:00 Avery: Which is precisely the question those
00:06:00 --> 00:06:02 missions are built to answer. Europa Clipper
00:06:02 --> 00:06:03 is already on its way
00:06:03 --> 00:06:06 Anna: and it gets better and closer to home. Juno's
00:06:06 --> 00:06:09 principal investigator, Scott Bolton, pointed
00:06:09 --> 00:06:12 out that you could fly an MWR type instrument
00:06:12 --> 00:06:14 over a volcano here on Earth and read the
00:06:14 --> 00:06:17 same kind of subsurface temperature gradient.
00:06:17 --> 00:06:19 A whole new way to study our own volcanoes
00:06:19 --> 00:06:20 from the air.
00:06:20 --> 00:06:23 Avery: So an instrument built for Jupiter's clouds
00:06:23 --> 00:06:25 ends up potentially rewriting how we study
00:06:25 --> 00:06:27 volcanoes on Earth. That's the kind of
00:06:27 --> 00:06:29 accidental genius that makes me love this
00:06:29 --> 00:06:30 stuff.
00:06:30 --> 00:06:32 Anna: It's the story of exploration in miniature,
00:06:32 --> 00:06:35 isn't it? You build a tool for one job, you
00:06:35 --> 00:06:37 point it somewhere new and it hands you a
00:06:37 --> 00:06:40 capability nobody planned for. IO got its
00:06:40 --> 00:06:43 first ever subsurface reading and we got a
00:06:43 --> 00:06:45 new way to take the temperature of worlds.
00:06:45 --> 00:06:48 Avery: Ours included a fitting lead. And keep
00:06:48 --> 00:06:50 IO in your back of your mind, because Jupiter
00:06:50 --> 00:06:52 itself is going to come back around in our
00:06:52 --> 00:06:54 skywatch in a slightly surprising way.
00:06:55 --> 00:06:57 Anna: Ooh, a, uh, tease. Alright. From a moon
00:06:57 --> 00:07:00 on fire to something at the very edge of what
00:07:00 --> 00:07:01 we can see.
00:07:01 --> 00:07:03 Avery: Now onto story two.
00:07:03 --> 00:07:06 JWST's little red
00:07:06 --> 00:07:08 dots. So, Anna, set us up nicely to the
00:07:08 --> 00:07:11 deep early universe. One of the strangest
00:07:11 --> 00:07:13 things the James Webb's telescope has turned
00:07:13 --> 00:07:16 up since it started sending back data in 2022
00:07:16 --> 00:07:18 is a whole population of objects
00:07:18 --> 00:07:20 nicknamed little red dots.
00:07:21 --> 00:07:22 Anna: I love that they just called them what they
00:07:22 --> 00:07:23 look like.
00:07:23 --> 00:07:25 Avery: Astronomers are refreshingly literal.
00:07:25 --> 00:07:28 Sometimes they're exactly that. Tiny,
00:07:28 --> 00:07:31 intensely red, compact points of light.
00:07:31 --> 00:07:34 And they're ancient. They show up around 600
00:07:34 --> 00:07:36 million years after the Big Bang. And then
00:07:36 --> 00:07:39 here's the weird part. They seem to vanish by
00:07:39 --> 00:07:41 the time the universe is about a billion and
00:07:41 --> 00:07:44 a half years old. Nobody's been sure what
00:07:44 --> 00:07:46 they even are. Supermassive black holes
00:07:46 --> 00:07:49 wrapped in gas bursts of furious star
00:07:49 --> 00:07:51 formation. Something else entirely.
00:07:51 --> 00:07:53 Anna: And there's a new answer this week.
00:07:53 --> 00:07:56 Avery: A new idea, and it's a clever one. A team led
00:07:56 --> 00:07:58 by John Chisum at the University of Texas at
00:07:58 --> 00:08:01 Austin, published in the Astrophysical
00:08:01 --> 00:08:03 Journal Letters, suggests the little red dots
00:08:03 --> 00:08:06 might be globular clusters caught in the act
00:08:06 --> 00:08:07 of being born.
00:08:08 --> 00:08:10 Anna: Globular clusters, those dense, ancient
00:08:10 --> 00:08:13 balls of hundreds of thousands of stars that
00:08:13 --> 00:08:16 hang around the outskirts of galaxies like
00:08:16 --> 00:08:16 ours.
00:08:16 --> 00:08:19 Avery: Those exact things, around 150 of them,
00:08:19 --> 00:08:22 orbit the Milky Way. And their origin has
00:08:22 --> 00:08:25 been its own long standing mystery. So this
00:08:25 --> 00:08:28 paper does something elegant. It takes two
00:08:28 --> 00:08:30 puzzles. What are little red dots? And where
00:08:30 --> 00:08:33 do globular clusters come from? Ann proposes
00:08:33 --> 00:08:35 they're the same puzzle that the little red
00:08:35 --> 00:08:38 dots are simply what globular clusters look
00:08:38 --> 00:08:39 like while they were forming.
00:08:39 --> 00:08:41 Anna: Two birds, one stone.
00:08:41 --> 00:08:43 Avery: That's exactly the phrase the researchers
00:08:43 --> 00:08:46 reach for in the model. A, uh, young cluster
00:08:46 --> 00:08:49 of stars supplies the blue ultraviolet light.
00:08:49 --> 00:08:51 And a single short lived, absolutely
00:08:51 --> 00:08:54 colossal star at the center, a
00:08:54 --> 00:08:56 supermassive star tens of thousands of
00:08:56 --> 00:08:59 times the Sun's mass, supplies the red.
00:08:59 --> 00:09:02 And crucially, it predicts specific chemical
00:09:02 --> 00:09:05 fingerprints, unusual amounts of helium and
00:09:05 --> 00:09:08 nitrogen, the very oddities we already see in
00:09:08 --> 00:09:10 the stars of today's globular clusters.
00:09:11 --> 00:09:13 Anna: So the test is in the chemistry.
00:09:13 --> 00:09:16 Avery: The test is in the chemistry and the team is
00:09:16 --> 00:09:18 careful about it. Co author Mike Boylan
00:09:18 --> 00:09:21 Kolchin put it. Well, there's no single
00:09:21 --> 00:09:24 smoking gun yet. But this would explain a lot
00:09:24 --> 00:09:26 of surprising observations at once. They're
00:09:26 --> 00:09:29 calling it plausible and laying out ways to
00:09:29 --> 00:09:30 stress test it.
00:09:30 --> 00:09:33 Anna: There's a lovely framing. I saw that these
00:09:33 --> 00:09:35 might be, uh, cosmic dinosaurs that never
00:09:35 --> 00:09:37 actually went extinct.
00:09:37 --> 00:09:39 Avery: That's the one we used to think the
00:09:39 --> 00:09:42 dinosaurs simply vanished. Then we
00:09:42 --> 00:09:45 realized they became birds. The suggestion
00:09:45 --> 00:09:47 here is that the little red dots didn't
00:09:47 --> 00:09:49 disappear either. They grew up into the
00:09:49 --> 00:09:51 globular clusters. You can still point a
00:09:51 --> 00:09:54 backyard telescope at tonight. The strange
00:09:54 --> 00:09:57 early universe. And the familiar one might be
00:09:57 --> 00:09:58 far more connected than we thought.
00:09:59 --> 00:10:01 Anna: From the oldest starlight to possibly
00:10:01 --> 00:10:03 no starlight at all.
00:10:03 --> 00:10:05 Because the next one is all about listening.
00:10:06 --> 00:10:08 For more than 60 years, the Search for
00:10:08 --> 00:10:11 Extraterrestrial Intelligence, SETI has
00:10:11 --> 00:10:13 mostly listened in one narrow stretch of the
00:10:13 --> 00:10:15 radio dial, a band between about
00:10:15 --> 00:10:18 1.4 and 1.7 gigahertz
00:10:18 --> 00:10:20 that astronomers call the water hole.
00:10:21 --> 00:10:21 Avery: Why there?
00:10:21 --> 00:10:24 Anna: Two reasons. It's a naturally quiet part of
00:10:24 --> 00:10:26 the spectrum and it sits right between the
00:10:26 --> 00:10:29 frequencies given off by hydrogen and by
00:10:29 --> 00:10:31 hydroxyl, the two pieces that together make
00:10:31 --> 00:10:34 water. The romantic idea is that any water
00:10:34 --> 00:10:37 based civilization might recognize it as
00:10:37 --> 00:10:40 an obvious meeting place. A, ah, cosmic
00:10:40 --> 00:10:41 watering hole.
00:10:41 --> 00:10:43 Avery: Poetic, but maybe a touch assumption
00:10:43 --> 00:10:44 heavy.
00:10:44 --> 00:10:46 Anna: That's exactly the point a young researcher
00:10:46 --> 00:10:49 has just made. Louisa Mason, a PhD
00:10:49 --> 00:10:51 student at the University of Manchester,
00:10:52 --> 00:10:54 presented work at the Royal Astronomical
00:10:54 --> 00:10:57 Society's National Astronomy meeting, arguing
00:10:57 --> 00:10:59 we might be listening on the wrong channel
00:10:59 --> 00:11:02 entirely. And rather than ask for expensive
00:11:02 --> 00:11:05 new telescope time, she did something smart.
00:11:05 --> 00:11:07 She went digging in the archives.
00:11:07 --> 00:11:07 Avery: Old data.
00:11:08 --> 00:11:11 Anna: Old data from Alma, that enormous array of
00:11:11 --> 00:11:13 dishes up on the chajenant plateau In Chile,
00:11:13 --> 00:11:16 which observes at much higher millimeter and
00:11:16 --> 00:11:19 submillimeter frequencies that SETI has
00:11:19 --> 00:11:21 barely touched. She ran the first ever
00:11:21 --> 00:11:24 SETI search through archived ALMA
00:11:24 --> 00:11:27 observations, hunting for narrow artificial
00:11:27 --> 00:11:27 looking signals.
00:11:28 --> 00:11:30 Avery: Um, and did she find E.T.
00:11:30 --> 00:11:33 Anna: she did not. No technosignatures, which is
00:11:33 --> 00:11:36 the honest and entirely expected result from
00:11:36 --> 00:11:39 just four archived observations. But here's
00:11:39 --> 00:11:41 the finding that made me sit up when she
00:11:41 --> 00:11:43 properly modeled how many stars were sitting
00:11:43 --> 00:11:45 in the background of those observations.
00:11:45 --> 00:11:47 Stars caught in the frame. While ALMA was
00:11:47 --> 00:11:50 pointed at something else. The count jumped
00:11:50 --> 00:11:52 from a previous estimate of around
00:11:52 --> 00:11:55 288 stars
00:11:55 --> 00:11:56 to more than six million.
00:11:57 --> 00:12:00 Avery: Six million. Just from recounting what was
00:12:00 --> 00:12:01 already there.
00:12:01 --> 00:12:04 Anna: More than six million. She calls it
00:12:04 --> 00:12:07 stellar bycatch. All the stars you
00:12:07 --> 00:12:09 survey by accident every single time you
00:12:09 --> 00:12:12 point a big telescope anywhere. It
00:12:12 --> 00:12:14 means archives around the world may already
00:12:14 --> 00:12:17 hold a vastly larger SETI survey
00:12:17 --> 00:12:20 than anyone realized, hiding inside data
00:12:20 --> 00:12:21 gathered for complet completely different
00:12:21 --> 00:12:22 reasons.
00:12:22 --> 00:12:25 Avery: I love that you don't always need a bigger
00:12:25 --> 00:12:27 net. Sometimes you just need to count what
00:12:27 --> 00:12:28 you've already caught.
00:12:29 --> 00:12:31 Anna: Beautifully put. New frequencies and
00:12:31 --> 00:12:34 millions of free stars. Not a bad
00:12:34 --> 00:12:35 afternoon's work.
00:12:35 --> 00:12:38 And speaking of signals arriving, there's one
00:12:38 --> 00:12:40 headed for Earth right now.
00:12:40 --> 00:12:43 Avery: And this one's live unfolding as we record
00:12:43 --> 00:12:46 our own star has been rustless. There's an
00:12:46 --> 00:12:48 active region on the sun cataloged as region
00:12:48 --> 00:12:51 4494. And on the 26th
00:12:52 --> 00:12:54 it let off a moderate flare. An M M class
00:12:54 --> 00:12:57 flare. An M M3.2 to be exact.
00:12:57 --> 00:13:00 Anna: M class being middle of the road as
00:13:00 --> 00:13:01 flares go.
00:13:01 --> 00:13:04 Avery: Moderate, yes, below the big X class
00:13:04 --> 00:13:06 monsters, but nothing to sneeze at. And
00:13:06 --> 00:13:09 separately, a cloud of solar material. A, uh,
00:13:09 --> 00:13:11 coronal mass ejection launched back on the
00:13:11 --> 00:13:14 24th is due to give Earth a glancing
00:13:14 --> 00:13:16 blow right about now.
00:13:16 --> 00:13:19 Anna: A glancing blow. So not a direct
00:13:19 --> 00:13:19 hit.
00:13:20 --> 00:13:22 Avery: Not a direct hit, which is the good news. But
00:13:22 --> 00:13:25 even a side wipe can rattle our magnetic
00:13:25 --> 00:13:28 field. Forecasters are calling for G1,
00:13:29 --> 00:13:30 possibly nudging up to G2
00:13:31 --> 00:13:34 geomagnetic storm levels across the
00:13:34 --> 00:13:37 27th and 28th. And the fun part for
00:13:37 --> 00:13:39 us is what that does to the sky. Aurorae.
00:13:39 --> 00:13:41 Anna: Uh, aurorae.
00:13:41 --> 00:13:43 Avery: When that solar material meets the magnetic
00:13:43 --> 00:13:45 field, it funnels particles down over the
00:13:45 --> 00:13:48 poles and lights up the atmosphere. The
00:13:48 --> 00:13:50 southern lights, the Aurora Australis for our
00:13:50 --> 00:13:52 listeners down here. And the northern lights
00:13:52 --> 00:13:55 up top at, uh, G1 to G2, we're
00:13:55 --> 00:13:58 mostly talking higher latitudes. So
00:13:58 --> 00:14:00 Tasmania and the deep south of New Zealand
00:14:00 --> 00:14:03 have the better odds. Here up north, think
00:14:03 --> 00:14:05 Scotland, Scandinavia and the northern tier
00:14:05 --> 00:14:06 of the US and Canada.
00:14:07 --> 00:14:10 Anna: And I should say space weather moves fast.
00:14:10 --> 00:14:12 By the time you're hearing this, the numbers
00:14:12 --> 00:14:13 may well have shifted.
00:14:14 --> 00:14:16 Avery: Good caveat. So if you're keen, check the
00:14:16 --> 00:14:18 live alerts, the Space Weather Prediction
00:14:18 --> 00:14:21 center or the Bureau of Meteorology's Space
00:14:21 --> 00:14:23 Weather Service here in Australia for the
00:14:23 --> 00:14:25 current picture. But it's worth a glance at
00:14:25 --> 00:14:27 the southern horizon tonight because the sun
00:14:27 --> 00:14:29 may just have laid on a show.
00:14:29 --> 00:14:32 Anna: A perfect handover because it's time to look
00:14:32 --> 00:14:32 up.
00:14:33 --> 00:14:36 Skywatch. Though this is meteor week
00:14:36 --> 00:14:38 in theory, we've got a run of showers
00:14:38 --> 00:14:41 peaking over the next few nights. The July
00:14:41 --> 00:14:44 Gamma Draconids tonight, the Pisces
00:14:44 --> 00:14:47 Austrianids around the 28th and 29th. And
00:14:47 --> 00:14:49 then the big one for us, the Southern Delta
00:14:49 --> 00:14:52 Aquarids, building to their peak around the
00:14:52 --> 00:14:55 30th, alongside the alpha capricornids
00:14:55 --> 00:14:56 on the 30th and 31st.
00:14:57 --> 00:14:59 Avery: And in theory being the operative phrase,
00:15:00 --> 00:15:02 because there's a giant obstacle rising in
00:15:02 --> 00:15:03 the east.
00:15:03 --> 00:15:06 Anna: The Moon. The Full Buck Moon lands on the
00:15:06 --> 00:15:09 29th, and a nearly full moon all week
00:15:09 --> 00:15:12 is going to flood the sky with light and wash
00:15:12 --> 00:15:14 out most of these meteors, which tend to be
00:15:14 --> 00:15:16 on the faint side to begin with.
00:15:16 --> 00:15:18 Avery: So is it a write off?
00:15:18 --> 00:15:21 Anna: Not at all. You just have to be smart about
00:15:21 --> 00:15:24 it first. The Southern Delta Aquariids
00:15:24 --> 00:15:27 genuinely favor us. In the south, the
00:15:27 --> 00:15:29 radiant over near the star Skat in
00:15:29 --> 00:15:32 Aquarius climbs high overhead from southern
00:15:32 --> 00:15:35 latitudes. Which is exactly why this is so
00:15:35 --> 00:15:37 often the Southern hemisphere's best shower
00:15:37 --> 00:15:39 of the year. Though for our listeners in
00:15:39 --> 00:15:42 Australia and New Zealand, look after
00:15:42 --> 00:15:45 midnight into the pre dawn hours when that
00:15:45 --> 00:15:46 radiant is highest.
00:15:46 --> 00:15:48 Avery: And um, for the Northern hemisphere, for
00:15:48 --> 00:15:50 Anna: North America and other northern listeners,
00:15:50 --> 00:15:53 the radiant sits lower in the southern sky.
00:15:53 --> 00:15:56 But the southern United States, Mexico and
00:15:56 --> 00:15:59 Southern Europe still get a decent view. Same
00:15:59 --> 00:16:02 advice. The hours after midnight local time
00:16:02 --> 00:16:04 into the couple of hours before dawn are your
00:16:04 --> 00:16:06 best window. And face south.
00:16:07 --> 00:16:09 Avery: And here's the pro tip that beats the Moon.
00:16:09 --> 00:16:11 The Alpha Capricornids. They're not
00:16:11 --> 00:16:14 numerous, only a handful an hour. But they're
00:16:14 --> 00:16:16 famous for slow, bright, colorful
00:16:16 --> 00:16:19 fireballs. And a fireball doesn't care about
00:16:19 --> 00:16:22 moonlight. So even in a bright week, one
00:16:22 --> 00:16:25 brilliant, lazy Alpha Capricornid drifting
00:16:25 --> 00:16:27 across the sky is worth the wait. North or
00:16:27 --> 00:16:28 south?
00:16:28 --> 00:16:30 Anna: Lovely. And if the meteors do get washed out,
00:16:30 --> 00:16:33 there are planets to fall back on in the
00:16:33 --> 00:16:35 evening. Low in the west after sunset, Venus
00:16:35 --> 00:16:38 is blazing away, unmistakable. And climbing
00:16:38 --> 00:16:40 a little higher each night as it heads for
00:16:40 --> 00:16:42 its best evening showing in August.
00:16:42 --> 00:16:43 Avery: And, um, the morning sky.
00:16:43 --> 00:16:46 Anna: The morning belongs to Saturn. Golden well up
00:16:46 --> 00:16:48 in the pre dawn sky. And it actually paused
00:16:48 --> 00:16:50 in its motion against the background stars
00:16:50 --> 00:16:53 this week. Mars is climbing higher before
00:16:53 --> 00:16:56 dawn too. And if you've got a clear flat
00:16:56 --> 00:16:58 horizon, elusive Mercury is making a
00:16:58 --> 00:17:01 low pre dawn appearance in the last days of
00:17:01 --> 00:17:01 the month.
00:17:01 --> 00:17:03 Avery: And one that ties us right back to where we
00:17:03 --> 00:17:04 started. Jupiter.
00:17:04 --> 00:17:07 Anna: Yes, here's the lovely irony. We
00:17:07 --> 00:17:10 opened the show at IO, a moon of Jupiter. But
00:17:10 --> 00:17:13 Jupiter itself as just slipped behind the
00:17:13 --> 00:17:15 sun. It reaches solar conjunction on the
00:17:15 --> 00:17:18 29th, essentially lined up on the far side
00:17:18 --> 00:17:21 of our star. So the very planet whose moon
00:17:21 --> 00:17:24 we spent our whole lead story on is the one
00:17:24 --> 00:17:26 planet you can't actually see in the sky
00:17:26 --> 00:17:26 right now.
00:17:26 --> 00:17:29 Avery: The moon. We can study up close. The planet
00:17:29 --> 00:17:32 we've temporarily lost space has a sense of
00:17:32 --> 00:17:32 humor.
00:17:32 --> 00:17:34 Anna: It'll be back in the morning sky in late
00:17:34 --> 00:17:36 August. And one last one for our northern
00:17:36 --> 00:17:38 friends before we go. Look straight up after
00:17:38 --> 00:17:40 dark and you'll find the summer triangle.
00:17:40 --> 00:17:43 Vega, uh, Deneb, uh, and Altair riding high
00:17:43 --> 00:17:46 overhead, a reliable anchor on a moonlit
00:17:46 --> 00:17:46 night.
00:17:46 --> 00:17:48 Avery: North or south, there's always something up
00:17:48 --> 00:17:48 there.
00:17:48 --> 00:17:51 Anna: And that's our show for Tuesday, A first look
00:17:51 --> 00:17:53 beneath the skin of the solar system's most
00:17:53 --> 00:17:56 volcanic moon. Two cosmic mysteries that
00:17:56 --> 00:17:58 might be one. A fresh way to listen for
00:17:58 --> 00:18:01 company, and a burst of weather from our own
00:18:01 --> 00:18:01 star.
00:18:01 --> 00:18:03 Avery: If you enjoyed it, find. Follow Astronomy
00:18:03 --> 00:18:05 Daily wherever you get your podcasts and find
00:18:05 --> 00:18:08 our new website@astronomydaily,IO
00:18:08 --> 00:18:10 and on the socials strodaily
00:18:10 --> 00:18:12 pod. We're back tomorrow.
00:18:12 --> 00:18:14 Anna: Until then, from Avery and me, keep looking
00:18:14 --> 00:18:15 up.
00:18:15 --> 00:18:16 Avery: Clear skies.
00:18:28 --> 00:18:30 Sam. Hmm.