Beach Mystery, Asteroid Close Encounter, and the Cosmic Dance of Ancient Comets

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Anna: Hello and welcome to Astronomy

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Daily. I'm Anna.

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Avery: And I'm avery. It's Tuesday the 7th of

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July, 2026, and we've got a properly

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eclectic mix for you today.

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Anna: We're starting close to home, very close

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to home, with a beach in Queensland and some

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rather mysterious silver balls.

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Avery: Then it's out to an asteroid, out to an

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interstellar comet, uh, out to a planet

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40,000 light years away, out to a

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merger of six galaxies 12 billion years

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in the past, and finally right out to

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the edge of the solar system itself.

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Anna: A proper grand tour. Let's get into it,

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and let's start with a story that reads more

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like a mystery novel than a science bulletin.

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Over the weekend, six large metallic

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spheres washed up on Forest beach near

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Townsville in North Queensland.

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Avery: And naturally, the Internet had some

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theories. But the real explanation is

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almost as interesting. The Queensland Fire

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Department cordoned off a 50 meter

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exclusion zone, and crews in hazmat

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gear carefully secured the objects into

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drums.

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Anna: Because these things can be genuinely

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hazardous. Space archaeologist Associate

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Professor Alice Gorman from Flinders

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University had a look at the footage and said

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they're consistent with pressurized fuel

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vessels likely made of titanium

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alloys. And titanium has an extremely

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high melting point, which is exactly why

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these survive RE entry when so much else

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burns up.

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Avery: They're sometimes nicknamed spaceballs, and

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Gorman notes that they can show up years

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after the launch that produced them. There

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was no scorching on these ones, which

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suggests it came from a rocket stage that

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fell away early rather than from a spacecraft

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that burned up on final RE entry.

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Anna: On Sunday night, the Australian Space Agency

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confirmed it's working with Queensland

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authorities and the Emergency Management

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Agency and said in a statement that the

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objects are, quote, consistent with debris

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from a foreign rocket body that recently re

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entered the atmosphere from orbit.

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Avery: They haven't officially named a launch yet,

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but there are a couple of candidates worth

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watching. China launched the Long March 6th

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and the Long March 8A over that same weekend.

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Nothing confirmed, but the timing lines up.

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Anna: It's a great reminder of just how much

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hardware is coming back down to Earth these

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days. More launches than ever means more

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RE entries than ever. And Australia's

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coastline, being enormous and facing a lot of

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open ocean, catches more than its fair share.

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Avery: If you're on the Queensland coast and you

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spot something like this, please don't touch

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it. Uh, call it in. These vessels can still

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contain leftover propellants like hydrazine,

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which is nasty stuff.

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Anna: Great advice. We'll keep an eye on this one

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and let you know if the source gets confirmed

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from debris coming down to a, uh, spacecraft

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going up close and personal with an asteroid

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62 million miles away.

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Avery: This is JAXA's Hayabusa 2, the same probe

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that brought samples of asteroid Ryugu back

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to Australia's own umara Desert in 2020.

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It's been out on an extended mission ever

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since, and on Sunday it completed its first

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asteroid encounter. Of that extended mission,

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a flyby of

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Anna: asteroid Torifune, and flyby

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undersells it a bit. Hayabusa2 came within

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about 800 meters of Tori Fune,

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traveling at something like 18,000

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kilometers an hour. JAXA has described it as

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a deliberately risky operation designed

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specifically to test high speed, high

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precision navigation technology that could

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one day deflect a hazardous asteroid.

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Avery: Torifune is a two lobed object, a bit like a

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peanut or a snowman, about 450 meters

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across. The spinning once every five hours.

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The pictures that have come back taken by the

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optical navigation camera and the thermal

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infrared imager, show rocks and boulders

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scattered across both lobes. Yuya Mimasu,

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who heads the Hayabusa 2 Extended Mission

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Team, told a press conference he was

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genuinely shocked by how good the image was

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given. It was captured in a fleeting moment

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during a high speed pass. The infrared

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images are just as valuable. They reveal

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cooler shadowed regions and warmer

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sunlit patches, which tell scientists about

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the surface texture and thermal behavior of

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the rock.

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Anna: Hayabusa2's next stop is even more

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ambitious asteroid 1998

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KY26, just 11 meters across,

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potentially the smallest asteroid ever

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visited by a spacecraft. That encounter isn't

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due until 2031, so Torifune was

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very much the warm up act.

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Avery: A warm up act 62 million miles from

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home. Not bad for a spacecraft that's been

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flying for almost 12 years.

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Anna: Sticking with old travelers, let's check in

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on three I ATLAS, the interstellar

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comet that's been fascinating astronomers

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since last July.

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Avery: New research out this week, led by Cyriel

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Opadam at the University of Edinburgh, used

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the European Southern Observatory's Very

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Large Telescope to study the comet's

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chemical fingerprint in detail. And it's

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given us our best clue yet about where

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3i Atlas actually came from.

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Anna: The short version this comet almost

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certainly formed in the outer reaches of a

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star system built around a star far

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older than our Sun. Combined with earlier

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work on hydrogen and carbon isotopes,

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some estimates now put the comet's age at

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somewhere between 3 and 12 billion

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years, which, if it holds up, would make

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3i atlas one of the oldest objects

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ever directly studied by humanity.

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Avery: Opiton put it beautifully she said

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interstellar comets are basically fossils

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from planetary formation, but from a system

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very far away that we're lucky enough to

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study up close for once.

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Anna: 3i Atlas is only the third confirmed

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interstellar object after Oumuamua

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in 2017 and Borisov in

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2019. And it's already fading as it

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heads back out of the solar system for good.

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The VLT team says these observations are

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nearing their end simply because the comet is

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getting too faint to study, which

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Avery: makes the timing of this result rather

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poignant. One of our last really detailed

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looks at 3i Atlas, and it turns out to be one

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of the most revealing. And with the Vera

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Rubin Observatory now fully operational,

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scientists reckon we could be entering what

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they're calling the golden age of

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interstellar object discovery.

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Anna: Every new one a fresh surprise, by the sound

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of it.

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Avery: Now, uh, for a discovery that even NASA

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didn't think was possible when this

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spacecraft launched.

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Anna: This is TESS, the Transiting

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Exoplanet Survey Satellite. Since

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2018, its entire job has been

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watching for the tiny dimming of starlight

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when a planet crosses in front of its star.

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That's given us hundreds of confirmed worlds.

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But this week, in a paper in the

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Astrophysical Journal Letters, a team reports

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that TESS has found a planet using a

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completely different method, gravitational

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microlensing.

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Avery: Microlensing relies on general relativity.

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When one star passes almost exactly in front

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of a more distant background star, its

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gravity bends and briefly magnifies that, uh,

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background star's light. If the foreground

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star has a planet, that planet leaves its own

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tiny ripple in the brightening.

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Anna: The planet in question is called Gaia

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23 Bra B, first hinted at

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back in 2023 by the European Space

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Agency's Gaia mission, which spotted the

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stellar brightening but didn't have enough

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data to confirm a planet. PES

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archived observations from that same event

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turned out to hold the missing piece.

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Avery: It's a super Jupiter, about 1.6

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times Jupiter's mass, orbiting an orange

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dwarf star some 40,000 light years away,

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vastly further than the planet's TESS usually

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finds within about 150 light years.

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Anna: University of New Mexico's Diana Dragomir,

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who worked on the discovery, said plainly

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that nobody expected TESS to ever be

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capable of finding this kind of planet. And

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because microlensing events are one offs,

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they happen once and never repeat. This

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really was a needle hiding in eight years of

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haystack data.

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Avery: A team member, Mallory Harris, had a great

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line about it. She said microlensing will

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probably find the first Earth analog, and

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then we'll just have to wave at it as it

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drifts by, because we'll never see it again.

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Anna: Bittersweet, but also a lovely preview

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of what NASA's upcoming Nancy Grace Roman

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Space Telescope will do at scale. It's

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expected to find around a thousand planets

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this way, from one planet 40,000 light

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years away to something on a truly different

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scale altogether.

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Avery: A new paper led by ZL Wen of the Chinese

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Academy of Sciences describes what

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astronomers are calling an extremely rare

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galaxy mega merger six massive

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galaxies caught in the act of merging into

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one roughly 12 billion years ago.

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Anna: Using the mild Boke and Blanco

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telescopes, combined with earlier James Webb

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and radio interferometry data, the team

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reconstructed what was originally thought to

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be a single distant galaxy hosting an active

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black hole. Instead, it turned out to be a

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protocluster, a gravitationally bound clump

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of galaxies in the very earliest stage of

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building what's called a brightest cluster

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galaxy.

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Avery: None of these six are lightweights either.

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Four are already individually massive, and

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together they're packing hundreds of billions

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of solar masses of stars into a region

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smaller than the Milky Way. Their combined

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star formation rate is somewhere between 70

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and 160 solar masses a year.

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Compare that to the Milky Way's current rate

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of fewer than 10.

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Anna: Based on how fast the galaxies are moving

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relative to each other. The team estimates

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the whole merger will wrap up within a few

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billion years, producing one enormous,

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ultra luminous galaxy at the heart of a young

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cluster.

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Avery: It's also a nice test case for the

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relationship between black holes and their

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host galaxies. The young central black hole

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in this system is growing right alongside its

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six merging hosts, which should help refine

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our models of how that black hole to galaxy

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relationship actually gets built in the

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Anna: early universe 12 billion years ago, and

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we're only piecing it together now. Astronomy

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really does run on a different clock.

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Avery: And to finish, let's go all the way out to

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the true edge of the solar system, courtesy

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of NASA's New Horizons spacecraft.

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Anna: New Horizons is currently about

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66 astronomical units from the sun,

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more than 66 times the Earth's sun

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distance, and it's still carrying a working

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instrument called swap, the Solar Wind

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Around Pluto detector. A new study

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led by Dr. Heather Elliott at the Southwest

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Research Institute has used SWAP to track

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exactly how the solar wind slows down

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as it heads toward interstellar space.

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Avery: The solar wind starts out supersonic, around

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a million miles an hour, but as it travels

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outward, it runs into incoming neutral gas

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drifting in from interstellar space. That

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gas gets ionized, gets picked up by the solar

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wind, and effectively acts as a drag

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slowing the whole flow

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Anna: down, Elliot's team found. The

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slowdown steepens the further out you go.

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By around 58 astronomical units,

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the wind is measured at somewhere between 13

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and 15% slower than it is near

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Earth. Earlier data between 30

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and 43 AU had only shown a, uh,

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5 to 10% dip, so this

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confirms the drag really compounds with

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distance.

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Avery: Why does this matter? Beyond pure curiosity,

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because the shape and strength of this

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boundary the helioschere controls how many

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galactic cosmic rays make it through to

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threaten astronauts on long missions to the

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Moon or Mars. Better maps of the boundary

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mean better radiation forecast for future

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crews.

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Anna: New Horizons is expected to reach the actual

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termination shock, where the wind drops below

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the local speed of sound somewhere between

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2029 and 2040. Depending on

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how the models settle, it would only be the

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third spacecraft in history to make that

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crossing, after Voyager 1 and Voyager

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2.

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Avery: Dr. Alan Stern, the mission's principal

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investigator, put it nicely. New

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Horizons remains the only active spacecraft

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out there in the outer heliosphere, quietly

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building on everything the Voyagers found

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decades ago.

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Anna: A fitting note to end on From a beach in

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Queensland to the true edge of the Sun's

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influence.

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Avery: That's a wrap on today's edition of Astronomy

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Daily beach mysteries, asteroid

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close calls, ancient comets, hidden

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exoplanets, a 12 billion year old

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mega merger, and the edge of the solar system

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itself.

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Anna: If you enjoyed today's episode, please hit

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subscribe wherever you're listening and leave

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us a review. It genuinely helps new listeners

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find the show.

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Avery: And here's today's did you know? For ya,

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Hayabusa2's flyby of Tory fun

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happened at a distance of under a kilometer.

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At 18,000 kilometers an hour,

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that's roughly the same speed the

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International Space Station orbits the Earth.

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Anna: I'm Anna.

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Avery: And I'm Avery. We'll see you next time on

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Astronomy Daily.

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Mhm.

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Anna: The story.