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Episode Summary In this episode of Astronomy Daily, Anna and Avery explore six major stories from the world of space and astronomy. Leading the show is a landmark result from the ALMA telescope: the first-ever measurement of semi-heavy water inside an interstellar object. The interstellar comet 3I/ATLAS contains up to 40 times more deuterium-rich water than Earth's oceans, revealing it formed in an ultracold environment very unlike our own solar system. The hosts then unpack the solution to a decades-long mystery: a massive binary star system near the galactic centre is responsible for the gas clouds feeding the Milky Way's supermassive black hole. Japan's MMX spacecraft — currently on the launch pad — is introduced, along with the exciting detail that its sample capsule will return Phobos material to Australian soil in 2031. Stellar archaeologists at ISTA have found fossilised magnetism on white dwarf stars, shedding light on the Sun's distant future. A thought-provoking segment examines the idea that any alien civilisation searching for intelligent life may already have detected us. And the episode closes with timely aurora and comet skywatching advice for Southern Hemisphere listeners. Story Sources & Links Segment 1 — 3I/ATLAS Deuterium Water Study: Nature Astronomy (April 24, 2026) — 'A Direct View of the Chemical Properties of Water from Another Planetary System: Water D/H in 3I/ATLAS' — Salazar Manzano, Paneque-Carreno et al. ALMA Observatory press release: almaobservatory.org. University of Michigan news: eurekalert.org Segment 2 — Milky Way Black Hole Feeder Stars: 'The gas streamer G1-2-3 in the Galactic Center' — Gillessen et al., Astronomy & Astrophysics (2026). ESO/MPE press release: phys.org Segment 3 — Japan MMX Phobos Mission: JAXA MMX mission page: mmx.jaxa.jp. Space.com coverage. Sample capsule landing: Woomera Prohibited Zone, South Australia. Segment 4 — Stellar Archaeologists / White Dwarf Fossil Magnetism: Institute of Science and Technology Austria (ISTA). Coverage: Space.com Segment 5 — Alien Technosignatures / SETI: Space.com feature. SETI Institute: seti.org Segment 6 — CME / Aurora / Comet: SpaceWeather.com. EarthSky sun news. NASA April 2026 skywatching guide (Comet C/2025 R3).
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00:00:00 --> 00:00:03 Anna: Welcome to Astronomy Daily. I'm Anna.
00:00:03 --> 00:00:05 Avery: And I'm Avery. It is Friday
00:00:05 --> 00:00:08 24th April, and we have got
00:00:08 --> 00:00:10 a genuinely remarkable show lined up for you
00:00:10 --> 00:00:11 today.
00:00:11 --> 00:00:13 Anna: We do, and I want to kick things off with
00:00:13 --> 00:00:15 something that had the whole team talking
00:00:15 --> 00:00:16 this morning.
00:00:16 --> 00:00:19 Scientists have just published the first ever
00:00:19 --> 00:00:22 chemical analysis of water inside an
00:00:22 --> 00:00:25 interstellar comet. And what they found is
00:00:25 --> 00:00:26 extraordinary.
00:00:26 --> 00:00:29 Avery: We're talking about our old friend three I
00:00:29 --> 00:00:32 ATLs, the interstellar visitor that
00:00:32 --> 00:00:34 swept through our solar system last year. And
00:00:34 --> 00:00:37 the verdict from astronomers. It came from a
00:00:37 --> 00:00:39 world that was much colder than ours.
00:00:40 --> 00:00:42 Anna: Much colder. Like almost
00:00:42 --> 00:00:45 incomprehensibly colder. We have that
00:00:45 --> 00:00:47 story, plus what's been feeding the
00:00:47 --> 00:00:50 supermassive black hole at the heart of our
00:00:50 --> 00:00:53 galaxy. That mystery may finally be
00:00:53 --> 00:00:53 solved.
00:00:53 --> 00:00:56 Avery: Japan has a spacecraft sitting on a launch
00:00:56 --> 00:00:59 pad right now ready to head to a tiny moon
00:00:59 --> 00:01:01 of Mars and bring a piece of it back to
00:01:01 --> 00:01:03 Earth. And tonight, Aurora watchers in
00:01:03 --> 00:01:06 Australia and New Zealand keep your eyes on
00:01:06 --> 00:01:06 the sky.
00:01:07 --> 00:01:09 Anna: All that and we're asking the big question,
00:01:09 --> 00:01:12 could aliens already know that we exist?
00:01:12 --> 00:01:15 The answer might actually be yes.
00:01:15 --> 00:01:17 Avery: It's a big one. Let's get into it.
00:01:17 --> 00:01:20 Anna: Our lead story today is a world first, and
00:01:20 --> 00:01:22 it involves the interstellar comet that
00:01:22 --> 00:01:25 captured everyone's imagination when it
00:01:25 --> 00:01:26 started swept through our solar system last
00:01:26 --> 00:01:27 year.
00:01:27 --> 00:01:30 Avery: Three I atls, the third
00:01:30 --> 00:01:33 interstellar object ever detected passing
00:01:33 --> 00:01:35 through our neck of the cosmic woods. And now
00:01:35 --> 00:01:38 scientists are telling us something truly jaw
00:01:38 --> 00:01:40 dropping about where it came from.
00:01:40 --> 00:01:42 Anna: A team led by PhD student Louis
00:01:42 --> 00:01:45 Salazar Manzano at the University of
00:01:45 --> 00:01:47 Michigan, working with colleagues at the ALMA
00:01:47 --> 00:01:50 UM telescope in Chile, has made the very
00:01:50 --> 00:01:53 first measurement of deuterated water. What's
00:01:53 --> 00:01:56 sometimes called sea? Semi heavy water inside
00:01:56 --> 00:01:57 an interstellar object.
00:01:57 --> 00:02:00 Avery: Okay, for anyone who slept through chemistry
00:02:00 --> 00:02:03 class, what exactly is deuterated water?
00:02:03 --> 00:02:06 Anna: Great question, though. Regular water,
00:02:06 --> 00:02:09 H2O has hydrogen atoms with just a
00:02:09 --> 00:02:11 proton at their core. But deuterium is a
00:02:11 --> 00:02:14 heavier form of hydrogen that has both a
00:02:14 --> 00:02:17 proton and a neutron. When you swap
00:02:17 --> 00:02:19 one of those regular hydrogen atoms for a
00:02:19 --> 00:02:21 deuterium atom, you. You get what scientists
00:02:21 --> 00:02:24 call HDO semi heavy water,
00:02:24 --> 00:02:26 or deuterated water.
00:02:26 --> 00:02:29 Avery: And the key thing is the ratio of heavy
00:02:29 --> 00:02:32 water to regular water in a comet tells you
00:02:32 --> 00:02:33 about the temperature of the environment
00:02:33 --> 00:02:35 where that comet originally formed.
00:02:36 --> 00:02:39 Anna: Exactly. Cold, low radiation
00:02:39 --> 00:02:41 environments produce more deuterium rich
00:02:41 --> 00:02:44 water. And three I atlas it's
00:02:44 --> 00:02:47 loaded with it. The Alma measurements show it
00:02:47 --> 00:02:49 contains around 30 times more semi
00:02:49 --> 00:02:52 heavy water than any comet in our own solar
00:02:52 --> 00:02:55 system and 40 times than Earth's.
00:02:55 --> 00:02:58 Avery: Oceans 40 times. That's
00:02:58 --> 00:02:59 not a small difference.
00:02:59 --> 00:03:02 Anna: It really isn't. And what that tells us is
00:03:02 --> 00:03:05 that 3i atlas formed in an environment that
00:03:05 --> 00:03:07 was utterly unlike the early solar system,
00:03:08 --> 00:03:11 likely somewhere extremely cold, well
00:03:11 --> 00:03:14 below minus 240 degrees Celsius,
00:03:14 --> 00:03:16 in the outer reachings of some distant
00:03:16 --> 00:03:18 planetary system, or possibly in a
00:03:18 --> 00:03:20 primordial interstellar cloud.
00:03:20 --> 00:03:23 Avery: And there is more intrigue here because some
00:03:23 --> 00:03:26 researchers think, uh, three I ATLs could
00:03:26 --> 00:03:28 be up to 10 or 12 billion years old,
00:03:29 --> 00:03:31 which would mean it formed before our sun
00:03:31 --> 00:03:32 even existed.
00:03:32 --> 00:03:35 Anna: Which makes it, in the words of one of the
00:03:35 --> 00:03:37 researchers, a preserved fragment of an
00:03:37 --> 00:03:40 ancient planetary system. A fossil from
00:03:40 --> 00:03:43 the early Milky Way grifting through our
00:03:43 --> 00:03:43 neighborhood.
00:03:43 --> 00:03:46 Avery: Harvard astronomer Avi Loeb has raised the
00:03:46 --> 00:03:48 characteristically eyebrow raising question
00:03:48 --> 00:03:51 about the abundance of deuterium, noting that
00:03:51 --> 00:03:54 deuterium is actually fusion fuel and
00:03:54 --> 00:03:57 wondering out loud whether that overabundance
00:03:57 --> 00:03:59 might be a technological signature. Although
00:03:59 --> 00:04:01 he admits that's highly speculative.
00:04:02 --> 00:04:05 Anna: Very speculative, but fun to think about.
00:04:05 --> 00:04:07 The paper is published today in the journal
00:04:07 --> 00:04:10 Nature Astronomy. And it also marks the first
00:04:10 --> 00:04:13 time any team has successfully performed this
00:04:13 --> 00:04:15 kind of chemical analysis on an object that
00:04:15 --> 00:04:17 originated beyond our solar system.
00:04:18 --> 00:04:20 Avery: Each interstellar comet, as one of the
00:04:20 --> 00:04:22 researchers put it, brings a little bit of
00:04:22 --> 00:04:24 its history, its fossils, from somewhere else
00:04:24 --> 00:04:27 in the galaxy. And with instruments like
00:04:27 --> 00:04:29 alma, we're starting to actually read those
00:04:29 --> 00:04:30 fossils.
00:04:30 --> 00:04:33 Anna: A landmark result. And they say this now
00:04:33 --> 00:04:35 opens the door to doing the same chemical
00:04:35 --> 00:04:37 fingerprinting on future interstellar
00:04:37 --> 00:04:40 visitors. So 3i Atlas
00:04:40 --> 00:04:43 may have set a new template for how we study
00:04:43 --> 00:04:44 objects from beyond.
00:04:44 --> 00:04:47 Avery: Okay, next up, a mystery that has puzzled
00:04:47 --> 00:04:50 astronomers for decades may finally have an
00:04:50 --> 00:04:52 answer. And it involves the 4 millionth solar
00:04:52 --> 00:04:54 mass black hole sitting at the very
00:04:54 --> 00:04:57 Anna: center of our galaxy, Sagittarius A,
00:04:58 --> 00:05:00 the sleeping giant at the heart of the Milky
00:05:00 --> 00:05:00 Way.
00:05:00 --> 00:05:02 Avery: For years, astronomers have been watching
00:05:02 --> 00:05:05 strange gas clouds drift towards it along
00:05:05 --> 00:05:08 almost identical paths. Gas clouds called
00:05:08 --> 00:05:11 G1, G2, and the newly discovered
00:05:11 --> 00:05:14 third cloud, informally known as G2T.
00:05:14 --> 00:05:16 And nobody could work out where they were
00:05:16 --> 00:05:18 coming from or why they were on such
00:05:18 --> 00:05:20 remarkably similar orbits.
00:05:20 --> 00:05:23 Anna: Until now. A team of researchers led
00:05:23 --> 00:05:25 by the Max Planck Institute for
00:05:25 --> 00:05:28 Extraterrestrial Physics, using the Very
00:05:28 --> 00:05:30 Large Telescope in Chile, has cracked it.
00:05:31 --> 00:05:33 And the answer is delightfully dramatic.
00:05:33 --> 00:05:34 Avery: Go on, then.
00:05:34 --> 00:05:37 Anna: Two massive stars locked in what the paper
00:05:37 --> 00:05:39 describes as a violent embrace. A
00:05:39 --> 00:05:42 binary STAR system called IRS
00:05:42 --> 00:05:45 16SW located near the
00:05:45 --> 00:05:48 galactic center, whose powerful stellar
00:05:48 --> 00:05:51 winds continuously shed enormous amounts of
00:05:51 --> 00:05:51 gas.
00:05:51 --> 00:05:54 Avery: And as IRS 16SW orbits
00:05:54 --> 00:05:57 Sagittarius A, each ejection of Gas
00:05:57 --> 00:05:59 gets flung out in a slightly different orbit,
00:05:59 --> 00:06:02 which explains why G1, G2, and
00:06:02 --> 00:06:05 G2T are on almost identical
00:06:05 --> 00:06:07 paths, but rotated a tiny bit relative to
00:06:07 --> 00:06:08 each other.
00:06:08 --> 00:06:10 Anna: Exactly. And crucially, the team's
00:06:10 --> 00:06:13 calculations show that the infall of just one
00:06:13 --> 00:06:16 such clump, roughly the mass of Earth
00:06:16 --> 00:06:19 every decade, provides enough material to
00:06:19 --> 00:06:22 sustain Sagittarius A's current level of
00:06:22 --> 00:06:22 activity.
00:06:22 --> 00:06:25 Avery: So it's not some exotic, mysterious process.
00:06:26 --> 00:06:28 It's just two stars in a wild gravitational
00:06:28 --> 00:06:31 dance, constantly shedding material that, uh,
00:06:31 --> 00:06:33 slowly trickles down into the black hole.
00:06:33 --> 00:06:35 Anna: It's a beautiful result because it connects
00:06:35 --> 00:06:37 three things that astronomers study.
00:06:38 --> 00:06:41 Stellar evolution, gas dynamics, and black
00:06:41 --> 00:06:44 hole feeding into one consistent
00:06:44 --> 00:06:47 picture. And it suggests that star formation
00:06:47 --> 00:06:50 and black hole growth may be intimately
00:06:50 --> 00:06:51 linked even in our own galaxy.
00:06:51 --> 00:06:54 Avery: And the discovery also rules out a previous
00:06:54 --> 00:06:56 theory that each of those gas clouds might be
00:06:56 --> 00:06:59 hiding a star at its core. Given that G1,
00:06:59 --> 00:07:01 G2, and G2t are all on
00:07:01 --> 00:07:04 practically identical orbits, the odds of
00:07:04 --> 00:07:07 three separate stars independently ending up
00:07:07 --> 00:07:08 on those paths are essentially zero.
00:07:09 --> 00:07:11 Anna: Right. They must share an origin. And
00:07:11 --> 00:07:14 IRS 16 SW is the
00:07:14 --> 00:07:17 most compelling explanation. The research is
00:07:17 --> 00:07:19 published in the journal Astronomy and
00:07:19 --> 00:07:20 Astrophysics.
00:07:20 --> 00:07:22 Avery: Before we move on to our next story today,
00:07:22 --> 00:07:24 just a quick reminder to Support our sponsor,
00:07:24 --> 00:07:26 NordVPN and do yourself a great big money
00:07:26 --> 00:07:29 saving favor. Get secure online for less.
00:07:29 --> 00:07:32 With the Service we use NordVPN, I
00:07:32 --> 00:07:34 can't recommend them enough. Check out our
00:07:34 --> 00:07:36 special listener deal by clicking on the link
00:07:36 --> 00:07:36 in the show Notes.
00:07:36 --> 00:07:39 Anna: Now, a mission story that we've been keeping
00:07:39 --> 00:07:41 an eye on for a while, and one that has a
00:07:41 --> 00:07:43 very special connection to our part of the
00:07:43 --> 00:07:44 world.
00:07:44 --> 00:07:47 Avery: Japan's Martian Moons exploration mission,
00:07:47 --> 00:07:50 mmx UM M has officially arrived at the
00:07:50 --> 00:07:53 Tanegashima Space center and is being
00:07:53 --> 00:07:56 prepared for launch later this year. We're
00:07:56 --> 00:07:59 talking November or December 2026.
00:07:59 --> 00:08:02 Anna: And the destination? Phobos, one of the
00:08:02 --> 00:08:04 two tiny, lumpy moons of Mars.
00:08:05 --> 00:08:07 MMX is going to fly to Phobos,
00:08:07 --> 00:08:10 land on it, drill into it, and bring back
00:08:10 --> 00:08:12 pieces of it to Earth.
00:08:12 --> 00:08:14 Avery: The first ever sample return from the Mars
00:08:14 --> 00:08:16 system. Which is pretty extraordinary when
00:08:16 --> 00:08:17 you think about it.
00:08:17 --> 00:08:20 Anna: It is. And this mission has had a rocky road,
00:08:20 --> 00:08:23 no pun intended. It was originally supposed
00:08:23 --> 00:08:26 to launch in 2024, but ran into problems
00:08:26 --> 00:08:29 with Japan's H3 rocket. There was also
00:08:29 --> 00:08:31 concern after a second H3 failure in
00:08:31 --> 00:08:34 December 2025. But that issue was
00:08:34 --> 00:08:37 isolated to a payload fairing problem, not
00:08:37 --> 00:08:39 the rocket itself, and the path was cleared
00:08:39 --> 00:08:41 for MMX to proceed.
00:08:41 --> 00:08:44 Avery: So what's the mission going to actually do
00:08:44 --> 00:08:45 once it gets there?
00:08:45 --> 00:08:48 Anna: Ella Max will arrive in orbit around Mars in
00:08:48 --> 00:08:51 2027 and spend time mapping both
00:08:51 --> 00:08:53 Phobos and the smaller moon Deimos.
00:08:53 --> 00:08:56 Then, in 2029, it will actually
00:08:56 --> 00:08:59 land on Phobos and collect about 10 grams
00:08:59 --> 00:09:02 of surface and subsurface material
00:09:02 --> 00:09:04 using two different sampling systems.
00:09:05 --> 00:09:07 Avery: 10 grams doesn't sound like much, but sample
00:09:07 --> 00:09:10 return missions have taught us that even tiny
00:09:10 --> 00:09:12 amounts of pristine material can be enorm
00:09:13 --> 00:09:16 scientifically valuable. Japan's Hayabusa2
00:09:16 --> 00:09:18 mission returned barely a teaspoon of
00:09:18 --> 00:09:20 material from the asteroid Ryugu, and
00:09:20 --> 00:09:23 scientists are still extracting discoveries
00:09:23 --> 00:09:23 from it.
00:09:23 --> 00:09:26 Anna: The big scientific question MMX hopes to
00:09:26 --> 00:09:29 answer is how did Phobos and
00:09:29 --> 00:09:31 Deimos actually form? Were they
00:09:31 --> 00:09:34 asteroids captured by Mars gravity from the
00:09:34 --> 00:09:36 outer solar system, which would mean they
00:09:36 --> 00:09:39 should be rich in water and organics, or are
00:09:39 --> 00:09:42 they debris from a, uh, giant impact on young
00:09:42 --> 00:09:44 Mars, in which case the heat would have
00:09:44 --> 00:09:45 driven off any water.
00:09:46 --> 00:09:48 Avery: And the answer has implications for
00:09:48 --> 00:09:50 understanding how the inner solar system
00:09:50 --> 00:09:52 formed and possibly for the origins of life
00:09:52 --> 00:09:53 on Earth.
00:09:54 --> 00:09:56 Anna: Now, here's the detail that I know will
00:09:56 --> 00:09:58 resonate with our Australian listeners, in
00:09:58 --> 00:10:01 particular, when NMX returns to Earth in
00:10:01 --> 00:10:03 2031 with its precious cargo.
00:10:04 --> 00:10:06 Avery: The sample return capsule lands in Australia,
00:10:07 --> 00:10:10 specifically the Woomera prohibited zone in
00:10:10 --> 00:10:10 South Australia.
00:10:11 --> 00:10:13 Anna: Though there's a direct connection for us
00:10:13 --> 00:10:16 Phobos material delivered to Australian
00:10:16 --> 00:10:19 soil, that's something to look forward to.
00:10:19 --> 00:10:22 Avery: MMX also carries the IDEX rover,
00:10:22 --> 00:10:24 built jointly by the German and French space
00:10:24 --> 00:10:26 agencies, which will actually drive on
00:10:26 --> 00:10:29 Phobos. Given that gravity on Phobos is
00:10:29 --> 00:10:32 about 1800 times weaker than on Earth,
00:10:32 --> 00:10:33 that'll be quite a drive.
00:10:34 --> 00:10:37 Anna: An audacious mission. It's on the pad. The
00:10:37 --> 00:10:38 clock is running.
00:10:38 --> 00:10:41 Avery: All right, I love this next story, partly
00:10:41 --> 00:10:43 because of the job title, Stellar
00:10:43 --> 00:10:45 archaeologists. That's what the researchers
00:10:45 --> 00:10:46 behind it are
00:10:46 --> 00:10:49 Anna: calling themselves, which is a fantastic job
00:10:49 --> 00:10:52 title. And what they found is genuinely
00:10:52 --> 00:10:54 illuminating, not just for understanding
00:10:54 --> 00:10:57 stars in general, but for understanding the
00:10:57 --> 00:10:58 future of our own sun.
00:10:59 --> 00:11:00 Avery: So what's the discovery?
00:11:01 --> 00:11:03 Anna: Scientists at the Institute of Science and
00:11:03 --> 00:11:05 Technology, Austria have found what they're
00:11:05 --> 00:11:08 calling fossilized magnetism on white dwarf
00:11:08 --> 00:11:11 stars. And they've used that to build a new
00:11:11 --> 00:11:13 model that explains how magnetic fields
00:11:13 --> 00:11:16 behave as a star evolves from a bloated
00:11:16 --> 00:11:19 red giant all the way through to a cold,
00:11:19 --> 00:11:20 dense white dwarf.
00:11:20 --> 00:11:23 Avery: For listeners who need the refresher, a white
00:11:23 --> 00:11:26 dwarf is what our sun will eventually become.
00:11:26 --> 00:11:29 In about 5 billion years, the sun will
00:11:29 --> 00:11:32 exhaust the hydrogen in its core, puff
00:11:32 --> 00:11:34 out into a Red giant, probably swallowing
00:11:34 --> 00:11:37 Mercury and Venus in the process, and then
00:11:37 --> 00:11:40 shed its outer layers, leaving behind a dense
00:11:40 --> 00:11:43 Earth sized remnant called a white dwarf.
00:11:43 --> 00:11:46 Anna: And what this research does is connect the
00:11:46 --> 00:11:48 magnetic field that we can detect at the core
00:11:48 --> 00:11:51 of a red giant using a technique called
00:11:51 --> 00:11:53 astroseismology, which is essentially
00:11:53 --> 00:11:56 starquakes, to the magnetic field that
00:11:56 --> 00:11:58 appears at the surface of a white dwarf
00:11:58 --> 00:12:00 billions of years later, doesn't disappear
00:12:00 --> 00:12:03 Avery: or reset, it's preserved. It travels with
00:12:03 --> 00:12:06 the star through its entire evolution from
00:12:06 --> 00:12:08 red giant to white dwarf, and then
00:12:08 --> 00:12:11 reemerges at the surface. Hence fossil
00:12:11 --> 00:12:12 magnetism.
00:12:12 --> 00:12:15 Anna: And interestingly, the team found that
00:12:15 --> 00:12:18 older white dwarfs tend to be more magnetic
00:12:18 --> 00:12:20 than younger ones, which fits neatly with the
00:12:20 --> 00:12:23 fossil field theory. As more of the star's
00:12:23 --> 00:12:26 interior becomes magnetized over time,
00:12:26 --> 00:12:29 the field gradually spreads to the surface.
00:12:30 --> 00:12:32 Avery: So what does this mean for us, for our Sun?
00:12:32 --> 00:12:35 Anna: Well, it deepens our understanding of how
00:12:35 --> 00:12:37 stars like the sun evolve in their final
00:12:37 --> 00:12:40 stages. Magnetic fields play a significant
00:12:41 --> 00:12:43 role in how a, uh, star's interior works and
00:12:43 --> 00:12:46 how long it lives. By understanding how
00:12:46 --> 00:12:49 those fields persist and transform,
00:12:49 --> 00:12:51 we get a much clearer picture of what the
00:12:51 --> 00:12:53 Sun's twilight years will
00:12:53 --> 00:12:56 Avery: actually look like, which is still 5 billion
00:12:56 --> 00:12:58 years away. So, uh, I'm not immediately
00:12:58 --> 00:12:58 worried.
00:12:59 --> 00:13:01 Anna: Probably not your most pressing concern
00:13:01 --> 00:13:04 today, no. But it's a beautiful piece of
00:13:04 --> 00:13:06 science, connecting observations of different
00:13:06 --> 00:13:09 stellar life stages across billions of years
00:13:09 --> 00:13:12 of cosmic time. Stellar archaeology,
00:13:12 --> 00:13:14 indeed, indeed.
00:13:14 --> 00:13:16 Avery: And I hope this helps answer some questions
00:13:16 --> 00:13:17 for our listeners.
00:13:17 --> 00:13:18 We do get a lot on this
00:13:18 --> 00:13:21 Anna: subject now, a story that I think is
00:13:21 --> 00:13:23 going to spark some very interesting
00:13:23 --> 00:13:26 conversations. And the premise is simple but,
00:13:26 --> 00:13:28 uh, profound. If there are intelligent
00:13:28 --> 00:13:31 civilizations out there looking for signs of
00:13:31 --> 00:13:34 life in the universe, they may already have
00:13:34 --> 00:13:34 found us.
00:13:35 --> 00:13:37 Avery: Which is either very exciting or
00:13:37 --> 00:13:40 mildly terrifying, depending on your point of
00:13:40 --> 00:13:40 view.
00:13:40 --> 00:13:43 Anna: Possibly both. The thinking goes like,
00:13:43 --> 00:13:46 when we search for signs of intelligent life,
00:13:46 --> 00:13:48 what do we look for? We look for
00:13:48 --> 00:13:50 technosignatures, evidence that a, uh,
00:13:50 --> 00:13:53 civilization has modified its environment in
00:13:53 --> 00:13:54 detectable ways.
00:13:55 --> 00:13:57 Avery: Radio signals, laser pulses, chemical
00:13:57 --> 00:14:00 signatures and atmospheres. Things that
00:14:00 --> 00:14:02 couldn't plausibly be produced by natural
00:14:02 --> 00:14:02 processes.
00:14:03 --> 00:14:06 Anna: And the key insight is Earth already
00:14:06 --> 00:14:09 has a lot of those. Our planet has been
00:14:09 --> 00:14:11 broadcasting radio waves into space for over
00:14:11 --> 00:14:14 a century. Those signals have already reached
00:14:14 --> 00:14:17 more than a thousand nearby stars,
00:14:17 --> 00:14:19 including Proxima, Centauri,
00:14:19 --> 00:14:22 Avery: Vega, uh, Barnard's Star. If there's
00:14:22 --> 00:14:24 anyone listening around those stars, they've
00:14:24 --> 00:14:26 potentially been receiving our broadcast for,
00:14:26 --> 00:14:27 for decades.
00:14:28 --> 00:14:30 Anna: And it's not just radio. Earth has
00:14:30 --> 00:14:33 enormous human made structures that might be
00:14:33 --> 00:14:35 visible to sufficiently Advanced telescopes,
00:14:36 --> 00:14:39 huge solar farms covering dozens of square
00:14:39 --> 00:14:41 kilometers. City lights visible from
00:14:41 --> 00:14:44 orbit. The chemical fingerprint of industrial
00:14:44 --> 00:14:46 activity in our atmosphere.
00:14:46 --> 00:14:49 Avery: So the question flips from are we searching
00:14:49 --> 00:14:52 for them to have they already found us?
00:14:53 --> 00:14:55 Anna: Right. And researchers studying this angle
00:14:55 --> 00:14:58 suggest that what we call technosignature
00:14:58 --> 00:15:01 detection from our end, the tools we'd use
00:15:01 --> 00:15:03 to find alien civilizations are
00:15:03 --> 00:15:06 exactly the same tools an alien civilization
00:15:06 --> 00:15:09 would use to find us. We're not hidden.
00:15:09 --> 00:15:12 Avery: There's something both humbling and thrilling
00:15:12 --> 00:15:14 about that. We've been sending out our
00:15:14 --> 00:15:16 calling card for a hundred years. Whether
00:15:16 --> 00:15:19 anyone's received it and decided to respond
00:15:19 --> 00:15:22 is, of course, the great unanswered
00:15:22 --> 00:15:22 question.
00:15:22 --> 00:15:25 Anna: The SETI Institute is actually working on
00:15:25 --> 00:15:27 updated protocols right now for what happens
00:15:27 --> 00:15:30 if we do receive a confirmed signal, a
00:15:30 --> 00:15:33 declaration of principles that would govern
00:15:33 --> 00:15:35 how scientists announce the discovery and
00:15:35 --> 00:15:38 how humanity responds. That's being
00:15:38 --> 00:15:41 finalized at a major international conference
00:15:41 --> 00:15:41 later this year.
00:15:42 --> 00:15:45 Avery: So the scientific community is quietly,
00:15:45 --> 00:15:47 methodically getting ready, which I find
00:15:47 --> 00:15:48 rather reassuring.
00:15:49 --> 00:15:52 Anna: Me, too. The universe is a big place.
00:15:52 --> 00:15:54 The question of whether we're alone in it is
00:15:54 --> 00:15:57 one of the oldest and most profound that
00:15:57 --> 00:15:59 humanity has ever asked. And the answer,
00:15:59 --> 00:16:02 one way or another, could come from someone
00:16:02 --> 00:16:03 finding us first.
00:16:04 --> 00:16:07 Avery: And finally today, a story for the sky
00:16:07 --> 00:16:09 watchers among you. And if you're in
00:16:09 --> 00:16:11 Australia or New Zealand, listen up, because
00:16:11 --> 00:16:13 there's something potentially beautiful on
00:16:13 --> 00:16:14 offer tonight.
00:16:14 --> 00:16:17 Anna: A coronal mass ejection, a CME from an
00:16:17 --> 00:16:20 eruption on the sun earlier this week is
00:16:20 --> 00:16:22 delivering a glancing blow to Earth right
00:16:22 --> 00:16:24 Now, today, on the 24th of April.
00:16:25 --> 00:16:28 Avery: To give a bit of context, a few days ago, two
00:16:28 --> 00:16:30 filaments on the sun erupted simultaneously
00:16:30 --> 00:16:33 in opposite directions. A pretty dramatic
00:16:33 --> 00:16:36 solar display. One of those eruptions sent a
00:16:36 --> 00:16:38 wave of charged solar material in our
00:16:38 --> 00:16:39 direction.
00:16:39 --> 00:16:42 Anna: It's only a glancing blow, not a direct hit.
00:16:43 --> 00:16:45 But combined with fast solar wind from a
00:16:45 --> 00:16:47 coronal hole that's been rattling Earth's
00:16:47 --> 00:16:49 magnetic field for several days now,
00:16:50 --> 00:16:52 conditions are elevated. We could see
00:16:52 --> 00:16:55 G1 minor geomagnetic storm
00:16:55 --> 00:16:57 levels. That's a kp index of 5.
00:16:58 --> 00:17:01 Avery: And, um, G1 conditions can push auroras
00:17:01 --> 00:17:04 to lower latitudes than usual. So if you're
00:17:04 --> 00:17:06 at a higher latitude in the southern
00:17:06 --> 00:17:08 hemisphere, southern parts of Australia,
00:17:08 --> 00:17:11 South Island, New Zealand, Tasmania,
00:17:11 --> 00:17:13 and you've got clear skies tonight. It's
00:17:13 --> 00:17:15 worth getting away from city lights and
00:17:15 --> 00:17:16 looking south.
00:17:17 --> 00:17:20 Anna: There are no guarantees with auroras. They're
00:17:20 --> 00:17:22 unpredictable by nature, but the conditions
00:17:22 --> 00:17:25 are more favorable than average. Check the
00:17:25 --> 00:17:28 Bureau of Meteorology's Space Weather Alerts
00:17:28 --> 00:17:31 or thespaceweather.com website for
00:17:31 --> 00:17:33 the latest KP Index readings throughout the
00:17:33 --> 00:17:33 evening.
00:17:34 --> 00:17:36 Avery: And even if the aurora doesn't materialize,
00:17:36 --> 00:17:39 there's a bonus in the southern sky right
00:17:39 --> 00:17:40 now. Comet C
00:17:41 --> 00:17:44 2025? S, uh, three Pan Starrs is
00:17:44 --> 00:17:46 approaching its closest point to Earth on
00:17:46 --> 00:17:49 April 27, just three days away.
00:17:49 --> 00:17:52 It's estimated to reach around magnitude 7
00:17:52 --> 00:17:55 or 8, which means binoculars or a
00:17:55 --> 00:17:57 small telescope should show it in the evening
00:17:57 --> 00:18:00 sky in early May for Southern Hemisphere
00:18:00 --> 00:18:00 observers.
00:18:01 --> 00:18:03 Anna: So eyes to the south tonight. Aurora
00:18:03 --> 00:18:05 conditions and a, uh, comment on approach.
00:18:06 --> 00:18:08 Not a bad Friday evening, all things
00:18:08 --> 00:18:08 considered.
00:18:09 --> 00:18:10 Avery: Not bad at all.
00:18:10 --> 00:18:12 Anna: And that brings us to the end of today's
00:18:12 --> 00:18:15 astronomy Daily Season 5, Episode
00:18:15 --> 00:18:16 92.
00:18:17 --> 00:18:19 Avery: What a show. An interstellar
00:18:19 --> 00:18:22 comet carrying water from a billion year old
00:18:22 --> 00:18:25 frozen world. The secret of what's feeding
00:18:25 --> 00:18:28 the Milky Way's most famous black hole,
00:18:28 --> 00:18:31 Japan's audacious mission to Mars
00:18:31 --> 00:18:32 Moon with the return
00:18:32 --> 00:18:34 Anna: capsule landing in Australia,
00:18:35 --> 00:18:38 stellar archaeologists decoding the future of
00:18:38 --> 00:18:41 our sun, the sobering and exciting
00:18:41 --> 00:18:43 possibility that aliens already know we
00:18:43 --> 00:18:46 exist, and a, uh, solar storm making a run
00:18:46 --> 00:18:48 at our magnetosphere as we speak.
00:18:48 --> 00:18:51 Avery: If you enjoyed the episode, please leave us a
00:18:51 --> 00:18:53 review wherever you listen. It makes a huge
00:18:53 --> 00:18:56 difference for an independent show like ours.
00:18:56 --> 00:18:59 Anna: Find us on X, Facebook, TikTok,
00:18:59 --> 00:19:01 YouTubeMusic Rumble and Instagram
00:19:02 --> 00:19:04 Strodaily Podcast and visit
00:19:04 --> 00:19:07 astronomydaily.IO for show notes,
00:19:07 --> 00:19:09 transcripts and links to all the research we
00:19:09 --> 00:19:12 covered today from me, Avery and from me
00:19:12 --> 00:19:15 Anna. Clear skies, Curious
00:19:15 --> 00:19:15 minds.
00:19:29 --> 00:19:37 Avery: Sam
00:19:37 --> 00:19:37 mhm.