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00:00:00 --> 00:00:02 Anna: Hello and welcome to Astronomy
00:00:02 --> 00:00:04 Daily. I'm Anna.
00:00:04 --> 00:00:07 Avery: And I'm avery. It's Tuesday the 7th of
00:00:07 --> 00:00:10 July, 2026, and we've got a properly
00:00:10 --> 00:00:11 eclectic mix for you today.
00:00:11 --> 00:00:14 Anna: We're starting close to home, very close
00:00:14 --> 00:00:17 to home, with a beach in Queensland and some
00:00:17 --> 00:00:20 rather mysterious silver balls.
00:00:20 --> 00:00:23 Avery: Then it's out to an asteroid, out to an
00:00:23 --> 00:00:25 interstellar comet, uh, out to a planet
00:00:25 --> 00:00:28 40 light years away, out to a
00:00:28 --> 00:00:31 merger of six galaxies 12 billion years
00:00:31 --> 00:00:34 in the past, and finally right out to
00:00:34 --> 00:00:36 the edge of the solar system itself.
00:00:36 --> 00:00:39 Anna: A proper grand tour. Let's get into it,
00:00:39 --> 00:00:42 and let's start with a story that reads more
00:00:42 --> 00:00:44 like a mystery novel than a science bulletin.
00:00:45 --> 00:00:47 Over the weekend, six large metallic
00:00:47 --> 00:00:50 spheres washed up on Forest beach near
00:00:50 --> 00:00:52 Townsville in North Queensland.
00:00:52 --> 00:00:54 Avery: And naturally, the Internet had some
00:00:54 --> 00:00:57 theories. But the real explanation is
00:00:57 --> 00:00:59 almost as interesting. The Queensland Fire
00:00:59 --> 00:01:02 Department cordoned off a 50 meter
00:01:02 --> 00:01:05 exclusion zone, and crews in hazmat
00:01:05 --> 00:01:07 gear carefully secured the objects into
00:01:07 --> 00:01:08 drums.
00:01:08 --> 00:01:10 Anna: Because these things can be genuinely
00:01:10 --> 00:01:13 hazardous. Space archaeologist Associate
00:01:13 --> 00:01:15 Professor Alice Gorman from Flinders
00:01:15 --> 00:01:18 University had a look at the footage and said
00:01:18 --> 00:01:20 they're consistent with pressurized fuel
00:01:20 --> 00:01:22 vessels likely made of titanium
00:01:22 --> 00:01:25 alloys. And titanium has an extremely
00:01:25 --> 00:01:28 high melting point, which is exactly why
00:01:28 --> 00:01:30 these survive RE entry when so much else
00:01:30 --> 00:01:31 burns up.
00:01:32 --> 00:01:34 Avery: They're sometimes nicknamed spaceballs, and
00:01:34 --> 00:01:36 Gorman notes that they can show up years
00:01:36 --> 00:01:38 after the launch that produced them. There
00:01:38 --> 00:01:40 was no scorching on these ones, which
00:01:40 --> 00:01:42 suggests it came from a rocket stage that
00:01:42 --> 00:01:44 fell away early rather than from a spacecraft
00:01:44 --> 00:01:46 that burned up on final RE entry.
00:01:46 --> 00:01:49 Anna: On Sunday night, the Australian Space Agency
00:01:49 --> 00:01:51 confirmed it's working with Queensland
00:01:51 --> 00:01:53 authorities and the Emergency Management
00:01:54 --> 00:01:56 Agency and said in a statement that the
00:01:56 --> 00:01:59 objects are, quote, consistent with debris
00:01:59 --> 00:02:01 from a foreign rocket body that recently re
00:02:01 --> 00:02:03 entered the atmosphere from orbit.
00:02:03 --> 00:02:05 Avery: They haven't officially named a launch yet,
00:02:05 --> 00:02:07 but there are a couple of candidates worth
00:02:07 --> 00:02:10 watching. China launched the Long March 6th
00:02:10 --> 00:02:12 and the Long March 8A over that same weekend.
00:02:13 --> 00:02:15 Nothing confirmed, but the timing lines up.
00:02:15 --> 00:02:18 Anna: It's a great reminder of just how much
00:02:18 --> 00:02:20 hardware is coming back down to Earth these
00:02:20 --> 00:02:23 days. More launches than ever means more
00:02:23 --> 00:02:25 RE entries than ever. And Australia's
00:02:25 --> 00:02:28 coastline, being enormous and facing a lot of
00:02:28 --> 00:02:31 open ocean, catches more than its fair share.
00:02:31 --> 00:02:33 Avery: If you're on the Queensland coast and you
00:02:33 --> 00:02:35 spot something like this, please don't touch
00:02:35 --> 00:02:37 it. Uh, call it in. These vessels can still
00:02:37 --> 00:02:39 contain leftover propellants like hydrazine,
00:02:39 --> 00:02:41 which is nasty stuff.
00:02:41 --> 00:02:44 Anna: Great advice. We'll keep an eye on this one
00:02:44 --> 00:02:46 and let you know if the source gets confirmed
00:02:46 --> 00:02:49 from debris coming down to a, uh, spacecraft
00:02:49 --> 00:02:52 going up close and personal with an asteroid
00:02:52 --> 00:02:54 62 million miles away.
00:02:54 --> 00:02:57 Avery: This is JAXA's Hayabusa 2, the same probe
00:02:57 --> 00:02:59 that brought samples of asteroid Ryugu back
00:02:59 --> 00:03:02 to Australia's own umara Desert in 2020.
00:03:02 --> 00:03:04 It's been out on an extended mission ever
00:03:04 --> 00:03:07 since, and on Sunday it completed its first
00:03:07 --> 00:03:09 asteroid encounter. Of that extended mission,
00:03:09 --> 00:03:10 a flyby of
00:03:10 --> 00:03:13 Anna: asteroid Torifune, and flyby
00:03:13 --> 00:03:16 undersells it a bit. Hayabusa2 came within
00:03:16 --> 00:03:18 about 800 meters of Tori Fune,
00:03:18 --> 00:03:21 traveling at something like 18
00:03:21 --> 00:03:24 kilometers an hour. JAXA has described it as
00:03:24 --> 00:03:27 a deliberately risky operation designed
00:03:27 --> 00:03:29 specifically to test high speed, high
00:03:29 --> 00:03:32 precision navigation technology that could
00:03:32 --> 00:03:34 one day deflect a hazardous asteroid.
00:03:34 --> 00:03:37 Avery: Torifune is a two lobed object, a bit like a
00:03:37 --> 00:03:40 peanut or a snowman, about 450 meters
00:03:40 --> 00:03:43 across. The spinning once every five hours.
00:03:43 --> 00:03:45 The pictures that have come back taken by the
00:03:45 --> 00:03:47 optical navigation camera and the thermal
00:03:47 --> 00:03:50 infrared imager, show rocks and boulders
00:03:50 --> 00:03:53 scattered across both lobes. Yuya Mimasu,
00:03:53 --> 00:03:56 who heads the Hayabusa 2 Extended Mission
00:03:56 --> 00:03:58 Team, told a press conference he was
00:03:58 --> 00:04:01 genuinely shocked by how good the image was
00:04:01 --> 00:04:03 given. It was captured in a fleeting moment
00:04:03 --> 00:04:06 during a high speed pass. The infrared
00:04:06 --> 00:04:09 images are just as valuable. They reveal
00:04:09 --> 00:04:12 cooler shadowed regions and warmer
00:04:12 --> 00:04:15 sunlit patches, which tell scientists about
00:04:15 --> 00:04:17 the surface texture and thermal behavior of
00:04:17 --> 00:04:18 the rock.
00:04:18 --> 00:04:21 Anna: Hayabusa2's next stop is even more
00:04:21 --> 00:04:23 ambitious asteroid 1998
00:04:24 --> 00:04:27 KY26, just 11 meters across,
00:04:27 --> 00:04:29 potentially the smallest asteroid ever
00:04:29 --> 00:04:32 visited by a spacecraft. That encounter isn't
00:04:32 --> 00:04:35 due until 2031, so Torifune was
00:04:35 --> 00:04:36 very much the warm up act.
00:04:36 --> 00:04:39 Avery: A warm up act 62 million miles from
00:04:39 --> 00:04:42 home. Not bad for a spacecraft that's been
00:04:42 --> 00:04:43 flying for almost 12 years.
00:04:44 --> 00:04:47 Anna: Sticking with old travelers, let's check in
00:04:47 --> 00:04:49 on three I ATLAS, the interstellar
00:04:49 --> 00:04:52 comet that's been fascinating astronomers
00:04:52 --> 00:04:53 since last July.
00:04:53 --> 00:04:56 Avery: New research out this week, led by Cyriel
00:04:56 --> 00:04:59 Opadam at the University of Edinburgh, used
00:04:59 --> 00:05:02 the European Southern Observatory's Very
00:05:02 --> 00:05:05 Large Telescope to study the comet's
00:05:05 --> 00:05:07 chemical fingerprint in detail. And it's
00:05:07 --> 00:05:10 given us our best clue yet about where
00:05:10 --> 00:05:13 3i Atlas actually came from.
00:05:13 --> 00:05:15 Anna: The short version this comet almost
00:05:15 --> 00:05:18 certainly formed in the outer reaches of a
00:05:18 --> 00:05:20 star system built around a star far
00:05:20 --> 00:05:23 older than our Sun. Combined with earlier
00:05:23 --> 00:05:26 work on hydrogen and carbon isotopes,
00:05:26 --> 00:05:29 some estimates now put the comet's age at
00:05:29 --> 00:05:31 somewhere between 3 and 12 billion
00:05:31 --> 00:05:34 years, which, if it holds up, would make
00:05:34 --> 00:05:37 3i atlas one of the oldest objects
00:05:37 --> 00:05:39 ever directly studied by humanity.
00:05:40 --> 00:05:42 Avery: Opiton put it beautifully she said
00:05:42 --> 00:05:45 interstellar comets are basically fossils
00:05:45 --> 00:05:47 from planetary formation, but from a system
00:05:47 --> 00:05:50 very far away that we're lucky enough to
00:05:50 --> 00:05:51 study up close for once.
00:05:52 --> 00:05:55 Anna: 3i Atlas is only the third confirmed
00:05:55 --> 00:05:57 interstellar object after Oumuamua
00:05:57 --> 00:06:00 in 2017 and Borisov in
00:06:00 --> 00:06:03 2019. And it's already fading as it
00:06:03 --> 00:06:05 heads back out of the solar system for good.
00:06:06 --> 00:06:09 The VLT team says these observations are
00:06:09 --> 00:06:11 nearing their end simply because the comet is
00:06:11 --> 00:06:14 getting too faint to study, which
00:06:14 --> 00:06:16 Avery: makes the timing of this result rather
00:06:16 --> 00:06:18 poignant. One of our last really detailed
00:06:18 --> 00:06:21 looks at 3i Atlas, and it turns out to be one
00:06:21 --> 00:06:24 of the most revealing. And with the Vera
00:06:24 --> 00:06:26 Rubin Observatory now fully operational,
00:06:27 --> 00:06:29 scientists reckon we could be entering what
00:06:29 --> 00:06:31 they're calling the golden age of
00:06:31 --> 00:06:33 interstellar object discovery.
00:06:33 --> 00:06:35 Anna: Every new one a fresh surprise, by the sound
00:06:35 --> 00:06:36 of it.
00:06:36 --> 00:06:38 Avery: Now, uh, for a discovery that even NASA
00:06:38 --> 00:06:40 didn't think was possible when this
00:06:40 --> 00:06:41 spacecraft launched.
00:06:41 --> 00:06:43 Anna: This is TESS, the Transiting
00:06:43 --> 00:06:46 Exoplanet Survey Satellite. Since
00:06:46 --> 00:06:49 2018, its entire job has been
00:06:49 --> 00:06:51 watching for the tiny dimming of starlight
00:06:51 --> 00:06:54 when a planet crosses in front of its star.
00:06:54 --> 00:06:57 That's given us hundreds of confirmed worlds.
00:06:57 --> 00:06:59 But this week, in a paper in the
00:06:59 --> 00:07:02 Astrophysical Journal Letters, a team reports
00:07:02 --> 00:07:04 that TESS has found a planet using a
00:07:04 --> 00:07:07 completely different method, gravitational
00:07:07 --> 00:07:08 microlensing.
00:07:09 --> 00:07:11 Avery: Microlensing relies on general relativity.
00:07:11 --> 00:07:14 When one star passes almost exactly in front
00:07:14 --> 00:07:17 of a more distant background star, its
00:07:17 --> 00:07:19 gravity bends and briefly magnifies that, uh,
00:07:19 --> 00:07:22 background star's light. If the foreground
00:07:22 --> 00:07:24 star has a planet, that planet leaves its own
00:07:24 --> 00:07:26 tiny ripple in the brightening.
00:07:26 --> 00:07:29 Anna: The planet in question is called Gaia
00:07:29 --> 00:07:32 23 Bra B, first hinted at
00:07:32 --> 00:07:34 back in 2023 by the European Space
00:07:34 --> 00:07:37 Agency's Gaia mission, which spotted the
00:07:37 --> 00:07:39 stellar brightening but didn't have enough
00:07:39 --> 00:07:41 data to confirm a planet. PES
00:07:41 --> 00:07:44 archived observations from that same event
00:07:44 --> 00:07:46 turned out to hold the missing piece.
00:07:46 --> 00:07:49 Avery: It's a super Jupiter, about 1.6
00:07:49 --> 00:07:52 times Jupiter's mass, orbiting an orange
00:07:52 --> 00:07:54 dwarf star some 40 light years away,
00:07:55 --> 00:07:57 vastly further than the planet's TESS usually
00:07:57 --> 00:08:00 finds within about 150 light years.
00:08:01 --> 00:08:03 Anna: University of New Mexico's Diana Dragomir,
00:08:03 --> 00:08:06 who worked on the discovery, said plainly
00:08:06 --> 00:08:09 that nobody expected TESS to ever be
00:08:09 --> 00:08:11 capable of finding this kind of planet. And
00:08:11 --> 00:08:14 because microlensing events are one offs,
00:08:14 --> 00:08:16 they happen once and never repeat. This
00:08:16 --> 00:08:19 really was a needle hiding in eight years of
00:08:19 --> 00:08:20 haystack data.
00:08:21 --> 00:08:23 Avery: A team member, Mallory Harris, had a great
00:08:23 --> 00:08:26 line about it. She said microlensing will
00:08:26 --> 00:08:28 probably find the first Earth analog, and
00:08:28 --> 00:08:30 then we'll just have to wave at it as it
00:08:30 --> 00:08:32 drifts by, because we'll never see it again.
00:08:32 --> 00:08:35 Anna: Bittersweet, but also a lovely preview
00:08:35 --> 00:08:38 of what NASA's upcoming Nancy Grace Roman
00:08:38 --> 00:08:40 Space Telescope will do at scale. It's
00:08:40 --> 00:08:43 expected to find around a thousand planets
00:08:43 --> 00:08:46 this way, from one planet 40 light
00:08:46 --> 00:08:48 years away to something on a truly different
00:08:48 --> 00:08:49 scale altogether.
00:08:50 --> 00:08:52 Avery: A new paper led by ZL Wen of the Chinese
00:08:52 --> 00:08:55 Academy of Sciences describes what
00:08:55 --> 00:08:57 astronomers are calling an extremely rare
00:08:57 --> 00:09:00 galaxy mega merger six massive
00:09:00 --> 00:09:02 galaxies caught in the act of merging into
00:09:02 --> 00:09:05 one roughly 12 billion years ago.
00:09:05 --> 00:09:08 Anna: Using the mild Boke and Blanco
00:09:08 --> 00:09:10 telescopes, combined with earlier James Webb
00:09:10 --> 00:09:13 and radio interferometry data, the team
00:09:13 --> 00:09:15 reconstructed what was originally thought to
00:09:15 --> 00:09:18 be a single distant galaxy hosting an active
00:09:18 --> 00:09:21 black hole. Instead, it turned out to be a
00:09:21 --> 00:09:24 protocluster, a gravitationally bound clump
00:09:24 --> 00:09:27 of galaxies in the very earliest stage of
00:09:27 --> 00:09:29 building what's called a brightest cluster
00:09:29 --> 00:09:30 galaxy.
00:09:30 --> 00:09:32 Avery: None of these six are lightweights either.
00:09:32 --> 00:09:35 Four are already individually massive, and
00:09:35 --> 00:09:38 together they're packing hundreds of billions
00:09:38 --> 00:09:40 of solar masses of stars into a region
00:09:40 --> 00:09:43 smaller than the Milky Way. Their combined
00:09:43 --> 00:09:45 star formation rate is somewhere between 70
00:09:45 --> 00:09:48 and 160 solar masses a year.
00:09:48 --> 00:09:50 Compare that to the Milky Way's current rate
00:09:50 --> 00:09:52 of fewer than 10.
00:09:52 --> 00:09:54 Anna: Based on how fast the galaxies are moving
00:09:54 --> 00:09:57 relative to each other. The team estimates
00:09:57 --> 00:09:59 the whole merger will wrap up within a few
00:09:59 --> 00:10:02 billion years, producing one enormous,
00:10:02 --> 00:10:04 ultra luminous galaxy at the heart of a young
00:10:04 --> 00:10:05 cluster.
00:10:05 --> 00:10:07 Avery: It's also a nice test case for the
00:10:07 --> 00:10:09 relationship between black holes and their
00:10:09 --> 00:10:12 host galaxies. The young central black hole
00:10:12 --> 00:10:14 in this system is growing right alongside its
00:10:14 --> 00:10:16 six merging hosts, which should help refine
00:10:16 --> 00:10:19 our models of how that black hole to galaxy
00:10:19 --> 00:10:21 relationship actually gets built in the
00:10:21 --> 00:10:24 Anna: early universe 12 billion years ago, and
00:10:24 --> 00:10:27 we're only piecing it together now. Astronomy
00:10:27 --> 00:10:28 really does run on a different clock.
00:10:28 --> 00:10:31 Avery: And to finish, let's go all the way out to
00:10:31 --> 00:10:34 the true edge of the solar system, courtesy
00:10:34 --> 00:10:36 of NASA's New Horizons spacecraft.
00:10:36 --> 00:10:38 Anna: New Horizons is currently about
00:10:39 --> 00:10:41 66 astronomical units from the sun,
00:10:42 --> 00:10:44 more than 66 times the Earth's sun
00:10:44 --> 00:10:47 distance, and it's still carrying a working
00:10:47 --> 00:10:50 instrument called swap, the Solar Wind
00:10:50 --> 00:10:53 Around Pluto detector. A new study
00:10:53 --> 00:10:56 led by Dr. Heather Elliott at the Southwest
00:10:56 --> 00:10:59 Research Institute has used SWAP to track
00:10:59 --> 00:11:02 exactly how the solar wind slows down
00:11:02 --> 00:11:04 as it heads toward interstellar space.
00:11:05 --> 00:11:08 Avery: The solar wind starts out supersonic, around
00:11:08 --> 00:11:10 a million miles an hour, but as it travels
00:11:10 --> 00:11:13 outward, it runs into incoming neutral gas
00:11:13 --> 00:11:16 drifting in from interstellar space. That
00:11:16 --> 00:11:19 gas gets ionized, gets picked up by the solar
00:11:19 --> 00:11:21 wind, and effectively acts as a drag
00:11:22 --> 00:11:23 slowing the whole flow
00:11:23 --> 00:11:26 Anna: down, Elliot's team found. The
00:11:26 --> 00:11:28 slowdown steepens the further out you go.
00:11:29 --> 00:11:31 By around 58 astronomical units,
00:11:31 --> 00:11:34 the wind is measured at somewhere between 13
00:11:34 --> 00:11:37 and 15% slower than it is near
00:11:37 --> 00:11:40 Earth. Earlier data between 30
00:11:40 --> 00:11:43 and 43 AU had only shown a, uh,
00:11:43 --> 00:11:45 5 to 10% dip, so this
00:11:45 --> 00:11:48 confirms the drag really compounds with
00:11:48 --> 00:11:48 distance.
00:11:49 --> 00:11:51 Avery: Why does this matter? Beyond pure curiosity,
00:11:52 --> 00:11:53 because the shape and strength of this
00:11:53 --> 00:11:56 boundary the helioschere controls how many
00:11:56 --> 00:11:59 galactic cosmic rays make it through to
00:11:59 --> 00:12:01 threaten astronauts on long missions to the
00:12:01 --> 00:12:04 Moon or Mars. Better maps of the boundary
00:12:04 --> 00:12:06 mean better radiation forecast for future
00:12:06 --> 00:12:06 crews.
00:12:06 --> 00:12:09 Anna: New Horizons is expected to reach the actual
00:12:09 --> 00:12:12 termination shock, where the wind drops below
00:12:12 --> 00:12:15 the local speed of sound somewhere between
00:12:15 --> 00:12:18 2029 and 2040. Depending on
00:12:18 --> 00:12:20 how the models settle, it would only be the
00:12:20 --> 00:12:22 third spacecraft in history to make that
00:12:22 --> 00:12:25 crossing, after Voyager 1 and Voyager
00:12:25 --> 00:12:26 2.
00:12:26 --> 00:12:29 Avery: Dr. Alan Stern, the mission's principal
00:12:29 --> 00:12:31 investigator, put it nicely. New
00:12:31 --> 00:12:34 Horizons remains the only active spacecraft
00:12:34 --> 00:12:37 out there in the outer heliosphere, quietly
00:12:37 --> 00:12:39 building on everything the Voyagers found
00:12:39 --> 00:12:40 decades ago.
00:12:40 --> 00:12:43 Anna: A fitting note to end on From a beach in
00:12:43 --> 00:12:45 Queensland to the true edge of the Sun's
00:12:45 --> 00:12:46 influence.
00:12:46 --> 00:12:49 Avery: That's a wrap on today's edition of Astronomy
00:12:49 --> 00:12:52 Daily beach mysteries, asteroid
00:12:52 --> 00:12:55 close calls, ancient comets, hidden
00:12:55 --> 00:12:58 exoplanets, a 12 billion year old
00:12:58 --> 00:13:01 mega merger, and the edge of the solar system
00:13:01 --> 00:13:01 itself.
00:13:02 --> 00:13:04 Anna: If you enjoyed today's episode, please hit
00:13:04 --> 00:13:06 subscribe wherever you're listening and leave
00:13:06 --> 00:13:09 us a review. It genuinely helps new listeners
00:13:09 --> 00:13:09 find the show.
00:13:10 --> 00:13:12 Avery: And here's today's did you know? For ya,
00:13:13 --> 00:13:15 Hayabusa2's flyby of Tory fun
00:13:15 --> 00:13:18 happened at a distance of under a kilometer.
00:13:18 --> 00:13:20 At 18 kilometers an hour,
00:13:21 --> 00:13:23 that's roughly the same speed the
00:13:23 --> 00:13:25 International Space Station orbits the Earth.
00:13:25 --> 00:13:26 Anna: I'm Anna.
00:13:26 --> 00:13:29 Avery: And I'm Avery. We'll see you next time on
00:13:29 --> 00:13:30 Astronomy Daily.
00:13:33 --> 00:13:34 Mhm.
00:13:42 --> 00:13:42 Anna: The story.