Interstellar Comet From a Frozen Ancient World + Black Hole Mystery SOLVED

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Anna: Welcome to Astronomy Daily. I'm Anna.

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Avery: And I'm Avery. It is Friday

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24th April, and we have got

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a genuinely remarkable show lined up for you

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today.

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Anna: We do, and I want to kick things off with

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something that had the whole team talking

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this morning.

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Scientists have just published the first ever

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chemical analysis of water inside an

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interstellar comet. And what they found is

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extraordinary.

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Avery: We're talking about our old friend three I

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ATLs, the interstellar visitor that

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swept through our solar system last year. And

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the verdict from astronomers. It came from a

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world that was much colder than ours.

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Anna: Much colder. Like almost

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incomprehensibly colder. We have that

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story, plus what's been feeding the

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supermassive black hole at the heart of our

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galaxy. That mystery may finally be

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solved.

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Avery: Japan has a spacecraft sitting on a launch

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pad right now ready to head to a tiny moon

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of Mars and bring a piece of it back to

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Earth. And tonight, Aurora watchers in

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Australia and New Zealand keep your eyes on

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the sky.

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Anna: All that and we're asking the big question,

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could aliens already know that we exist?

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The answer might actually be yes.

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Avery: It's a big one. Let's get into it.

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Anna: Our lead story today is a world first, and

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it involves the interstellar comet that

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captured everyone's imagination when it

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started swept through our solar system last

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year.

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Avery: Three I atls, the third

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interstellar object ever detected passing

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through our neck of the cosmic woods. And now

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scientists are telling us something truly jaw

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dropping about where it came from.

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Anna: A team led by PhD student Louis

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Salazar Manzano at the University of

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Michigan, working with colleagues at the ALMA

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UM telescope in Chile, has made the very

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first measurement of deuterated water. What's

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sometimes called sea? Semi heavy water inside

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an interstellar object.

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Avery: Okay, for anyone who slept through chemistry

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class, what exactly is deuterated water?

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Anna: Great question, though. Regular water,

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H2O has hydrogen atoms with just a

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proton at their core. But deuterium is a

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heavier form of hydrogen that has both a

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proton and a neutron. When you swap

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one of those regular hydrogen atoms for a

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deuterium atom, you. You get what scientists

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call HDO semi heavy water,

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or deuterated water.

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Avery: And the key thing is the ratio of heavy

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water to regular water in a comet tells you

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about the temperature of the environment

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where that comet originally formed.

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Anna: Exactly. Cold, low radiation

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environments produce more deuterium rich

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water. And three I atlas it's

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loaded with it. The Alma measurements show it

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contains around 30 times more semi

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heavy water than any comet in our own solar

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system and 40 times than Earth's.

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Avery: Oceans 40 times. That's

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not a small difference.

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Anna: It really isn't. And what that tells us is

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that 3i atlas formed in an environment that

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was utterly unlike the early solar system,

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likely somewhere extremely cold, well

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below minus 240 degrees Celsius,

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in the outer reachings of some distant

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planetary system, or possibly in a

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primordial interstellar cloud.

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Avery: And there is more intrigue here because some

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researchers think, uh, three I ATLs could

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be up to 10 or 12 billion years old,

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which would mean it formed before our sun

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even existed.

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Anna: Which makes it, in the words of one of the

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researchers, a preserved fragment of an

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ancient planetary system. A fossil from

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the early Milky Way grifting through our

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neighborhood.

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Avery: Harvard astronomer Avi Loeb has raised the

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characteristically eyebrow raising question

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about the abundance of deuterium, noting that

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deuterium is actually fusion fuel and

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wondering out loud whether that overabundance

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might be a technological signature. Although

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he admits that's highly speculative.

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Anna: Very speculative, but fun to think about.

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The paper is published today in the journal

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Nature Astronomy. And it also marks the first

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time any team has successfully performed this

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kind of chemical analysis on an object that

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originated beyond our solar system.

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Avery: Each interstellar comet, as one of the

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researchers put it, brings a little bit of

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its history, its fossils, from somewhere else

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in the galaxy. And with instruments like

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alma, we're starting to actually read those

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fossils.

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Anna: A landmark result. And they say this now

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opens the door to doing the same chemical

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fingerprinting on future interstellar

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visitors. So 3i Atlas

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may have set a new template for how we study

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objects from beyond.

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Avery: Okay, next up, a mystery that has puzzled

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astronomers for decades may finally have an

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answer. And it involves the 4 millionth solar

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mass black hole sitting at the very

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Anna: center of our galaxy, Sagittarius A,

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the sleeping giant at the heart of the Milky

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Way.

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Avery: For years, astronomers have been watching

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strange gas clouds drift towards it along

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almost identical paths. Gas clouds called

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G1, G2, and the newly discovered

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third cloud, informally known as G2T.

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And nobody could work out where they were

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coming from or why they were on such

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remarkably similar orbits.

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Anna: Until now. A team of researchers led

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by the Max Planck Institute for

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Extraterrestrial Physics, using the Very

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Large Telescope in Chile, has cracked it.

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And the answer is delightfully dramatic.

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Avery: Go on, then.

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Anna: Two massive stars locked in what the paper

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describes as a violent embrace. A

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binary STAR system called IRS

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16SW located near the

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galactic center, whose powerful stellar

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winds continuously shed enormous amounts of

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gas.

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Avery: And as IRS 16SW orbits

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Sagittarius A, each ejection of Gas

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gets flung out in a slightly different orbit,

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which explains why G1, G2, and

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G2T are on almost identical

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paths, but rotated a tiny bit relative to

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each other.

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Anna: Exactly. And crucially, the team's

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calculations show that the infall of just one

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such clump, roughly the mass of Earth

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every decade, provides enough material to

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sustain Sagittarius A's current level of

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activity.

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Avery: So it's not some exotic, mysterious process.

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It's just two stars in a wild gravitational

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dance, constantly shedding material that, uh,

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slowly trickles down into the black hole.

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Anna: It's a beautiful result because it connects

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three things that astronomers study.

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Stellar evolution, gas dynamics, and black

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hole feeding into one consistent

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picture. And it suggests that star formation

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and black hole growth may be intimately

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linked even in our own galaxy.

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Avery: And the discovery also rules out a previous

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theory that each of those gas clouds might be

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hiding a star at its core. Given that G1,

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G2, and G2t are all on

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practically identical orbits, the odds of

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three separate stars independently ending up

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on those paths are essentially zero.

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Anna: Right. They must share an origin. And

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IRS 16 SW is the

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most compelling explanation. The research is

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published in the journal Astronomy and

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Astrophysics.

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Avery: Before we move on to our next story today,

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just a quick reminder to Support our sponsor,

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special listener deal by clicking on the link

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in the show Notes.

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Anna: Now, a mission story that we've been keeping

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an eye on for a while, and one that has a

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very special connection to our part of the

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world.

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Avery: Japan's Martian Moons exploration mission,

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mmx UM M has officially arrived at the

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Tanegashima Space center and is being

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prepared for launch later this year. We're

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talking November or December 2026.

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Anna: And the destination? Phobos, one of the

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two tiny, lumpy moons of Mars.

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MMX is going to fly to Phobos,

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land on it, drill into it, and bring back

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pieces of it to Earth.

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Avery: The first ever sample return from the Mars

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system. Which is pretty extraordinary when

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you think about it.

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Anna: It is. And this mission has had a rocky road,

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no pun intended. It was originally supposed

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to launch in 2024, but ran into problems

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with Japan's H3 rocket. There was also

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concern after a second H3 failure in

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December 2025. But that issue was

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isolated to a payload fairing problem, not

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the rocket itself, and the path was cleared

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for MMX to proceed.

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Avery: So what's the mission going to actually do

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once it gets there?

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Anna: Ella Max will arrive in orbit around Mars in

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2027 and spend time mapping both

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Phobos and the smaller moon Deimos.

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Then, in 2029, it will actually

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land on Phobos and collect about 10 grams

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of surface and subsurface material

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using two different sampling systems.

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Avery: 10 grams doesn't sound like much, but sample

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return missions have taught us that even tiny

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amounts of pristine material can be enorm

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scientifically valuable. Japan's Hayabusa2

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mission returned barely a teaspoon of

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material from the asteroid Ryugu, and

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scientists are still extracting discoveries

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from it.

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Anna: The big scientific question MMX hopes to

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answer is how did Phobos and

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Deimos actually form? Were they

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asteroids captured by Mars gravity from the

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outer solar system, which would mean they

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should be rich in water and organics, or are

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they debris from a, uh, giant impact on young

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Mars, in which case the heat would have

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driven off any water.

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Avery: And the answer has implications for

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understanding how the inner solar system

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formed and possibly for the origins of life

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on Earth.

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Anna: Now, here's the detail that I know will

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resonate with our Australian listeners, in

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particular, when NMX returns to Earth in

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2031 with its precious cargo.

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Avery: The sample return capsule lands in Australia,

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specifically the Woomera prohibited zone in

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South Australia.

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Anna: Though there's a direct connection for us

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Phobos material delivered to Australian

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soil, that's something to look forward to.

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Avery: MMX also carries the IDEX rover,

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built jointly by the German and French space

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agencies, which will actually drive on

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Phobos. Given that gravity on Phobos is

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about 1800 times weaker than on Earth,

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that'll be quite a drive.

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Anna: An audacious mission. It's on the pad. The

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clock is running.

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Avery: All right, I love this next story, partly

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because of the job title, Stellar

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archaeologists. That's what the researchers

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behind it are

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Anna: calling themselves, which is a fantastic job

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title. And what they found is genuinely

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illuminating, not just for understanding

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stars in general, but for understanding the

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future of our own sun.

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Avery: So what's the discovery?

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Anna: Scientists at the Institute of Science and

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Technology, Austria have found what they're

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calling fossilized magnetism on white dwarf

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stars. And they've used that to build a new

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model that explains how magnetic fields

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behave as a star evolves from a bloated

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red giant all the way through to a cold,

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dense white dwarf.

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Avery: For listeners who need the refresher, a white

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dwarf is what our sun will eventually become.

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In about 5 billion years, the sun will

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exhaust the hydrogen in its core, puff

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out into a Red giant, probably swallowing

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Mercury and Venus in the process, and then

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shed its outer layers, leaving behind a dense

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Earth sized remnant called a white dwarf.

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Anna: And what this research does is connect the

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magnetic field that we can detect at the core

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of a red giant using a technique called

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astroseismology, which is essentially

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starquakes, to the magnetic field that

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appears at the surface of a white dwarf

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billions of years later, doesn't disappear

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Avery: or reset, it's preserved. It travels with

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the star through its entire evolution from

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red giant to white dwarf, and then

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reemerges at the surface. Hence fossil

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magnetism.

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Anna: And interestingly, the team found that

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older white dwarfs tend to be more magnetic

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than younger ones, which fits neatly with the

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fossil field theory. As more of the star's

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interior becomes magnetized over time,

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the field gradually spreads to the surface.

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Avery: So what does this mean for us, for our Sun?

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Anna: Well, it deepens our understanding of how

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stars like the sun evolve in their final

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stages. Magnetic fields play a significant

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role in how a, uh, star's interior works and

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how long it lives. By understanding how

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those fields persist and transform,

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we get a much clearer picture of what the

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Sun's twilight years will

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Avery: actually look like, which is still 5 billion

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years away. So, uh, I'm not immediately

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worried.

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Anna: Probably not your most pressing concern

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today, no. But it's a beautiful piece of

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science, connecting observations of different

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stellar life stages across billions of years

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of cosmic time. Stellar archaeology,

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indeed, indeed.

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Avery: And I hope this helps answer some questions

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for our listeners.

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We do get a lot on this

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Anna: subject now, a story that I think is

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going to spark some very interesting

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conversations. And the premise is simple but,

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uh, profound. If there are intelligent

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civilizations out there looking for signs of

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life in the universe, they may already have

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found us.

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Avery: Which is either very exciting or

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mildly terrifying, depending on your point of

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view.

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Anna: Possibly both. The thinking goes like,

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when we search for signs of intelligent life,

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what do we look for? We look for

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technosignatures, evidence that a, uh,

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civilization has modified its environment in

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detectable ways.

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Avery: Radio signals, laser pulses, chemical

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signatures and atmospheres. Things that

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couldn't plausibly be produced by natural

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processes.

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Anna: And the key insight is Earth already

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has a lot of those. Our planet has been

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broadcasting radio waves into space for over

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a century. Those signals have already reached

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more than a thousand nearby stars,

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including Proxima, Centauri,

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Avery: Vega, uh, Barnard's Star. If there's

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anyone listening around those stars, they've

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potentially been receiving our broadcast for,

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for decades.

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Anna: And it's not just radio. Earth has

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enormous human made structures that might be

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visible to sufficiently Advanced telescopes,

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huge solar farms covering dozens of square

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kilometers. City lights visible from

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orbit. The chemical fingerprint of industrial

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activity in our atmosphere.

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Avery: So the question flips from are we searching

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for them to have they already found us?

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Anna: Right. And researchers studying this angle

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suggest that what we call technosignature

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detection from our end, the tools we'd use

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to find alien civilizations are

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exactly the same tools an alien civilization

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would use to find us. We're not hidden.

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Avery: There's something both humbling and thrilling

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about that. We've been sending out our

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calling card for a hundred years. Whether

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anyone's received it and decided to respond

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is, of course, the great unanswered

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question.

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Anna: The SETI Institute is actually working on

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updated protocols right now for what happens

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if we do receive a confirmed signal, a

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declaration of principles that would govern

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how scientists announce the discovery and

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how humanity responds. That's being

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finalized at a major international conference

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later this year.

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Avery: So the scientific community is quietly,

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methodically getting ready, which I find

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rather reassuring.

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Anna: Me, too. The universe is a big place.

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The question of whether we're alone in it is

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one of the oldest and most profound that

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humanity has ever asked. And the answer,

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one way or another, could come from someone

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finding us first.

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Avery: And finally today, a story for the sky

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watchers among you. And if you're in

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Australia or New Zealand, listen up, because

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there's something potentially beautiful on

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offer tonight.

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Anna: A coronal mass ejection, a CME from an

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eruption on the sun earlier this week is

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delivering a glancing blow to Earth right

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Now, today, on the 24th of April.

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Avery: To give a bit of context, a few days ago, two

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filaments on the sun erupted simultaneously

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in opposite directions. A pretty dramatic

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solar display. One of those eruptions sent a

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wave of charged solar material in our

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direction.

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Anna: It's only a glancing blow, not a direct hit.

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But combined with fast solar wind from a

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coronal hole that's been rattling Earth's

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magnetic field for several days now,

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conditions are elevated. We could see

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G1 minor geomagnetic storm

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levels. That's a kp index of 5.

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Avery: And, um, G1 conditions can push auroras

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to lower latitudes than usual. So if you're

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at a higher latitude in the southern

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hemisphere, southern parts of Australia,

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South Island, New Zealand, Tasmania,

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and you've got clear skies tonight. It's

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worth getting away from city lights and

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looking south.

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Anna: There are no guarantees with auroras. They're

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unpredictable by nature, but the conditions

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are more favorable than average. Check the

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Bureau of Meteorology's Space Weather Alerts

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or thespaceweather.com website for

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the latest KP Index readings throughout the

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evening.

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Avery: And even if the aurora doesn't materialize,

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there's a bonus in the southern sky right

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now. Comet C

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2025? S, uh, three Pan Starrs is

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approaching its closest point to Earth on

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April 27, just three days away.

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It's estimated to reach around magnitude 7

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or 8, which means binoculars or a

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small telescope should show it in the evening

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sky in early May for Southern Hemisphere

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observers.

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Anna: So eyes to the south tonight. Aurora

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conditions and a, uh, comment on approach.

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Not a bad Friday evening, all things

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considered.

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Avery: Not bad at all.

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Anna: And that brings us to the end of today's

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astronomy Daily Season 5, Episode

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92.

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Avery: What a show. An interstellar

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comet carrying water from a billion year old

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frozen world. The secret of what's feeding

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the Milky Way's most famous black hole,

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00:18:28.480 --> 00:18:31.280
Japan's audacious mission to Mars

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Moon with the return

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Anna: capsule landing in Australia,

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stellar archaeologists decoding the future of

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our sun, the sobering and exciting

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possibility that aliens already know we

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exist, and a, uh, solar storm making a run

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at our magnetosphere as we speak.

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Avery: If you enjoyed the episode, please leave us a

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review wherever you listen. It makes a huge

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00:18:53.860 --> 00:18:56.140
difference for an independent show like ours.

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Anna: Find us on X, Facebook, TikTok,

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00:18:59.420 --> 00:19:01.580
YouTubeMusic Rumble and Instagram

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00:19:02.060 --> 00:19:04.180
Strodaily Podcast and visit

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astronomydaily.IO for show notes,

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transcripts and links to all the research we

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covered today from me, Avery and from me

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Anna. Clear skies, Curious

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minds.

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Avery: Sam

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mhm.