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

Anna: Hello and welcome to Astronomy

Daily. I'm Anna.

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

July, 2026, and we've got a properly

eclectic mix for you today.

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

to home, with a beach in Queensland and some

rather mysterious silver balls.

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

interstellar comet, uh, out to a planet

40,000 light years away, out to a

merger of six galaxies 12 billion years

in the past, and finally right out to

the edge of the solar system itself.

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

and let's start with a story that reads more

like a mystery novel than a science bulletin.

Over the weekend, six large metallic

spheres washed up on Forest beach near

Townsville in North Queensland.

Avery: And naturally, the Internet had some

theories. But the real explanation is

almost as interesting. The Queensland Fire

Department cordoned off a 50 meter

exclusion zone, and crews in hazmat

gear carefully secured the objects into

drums.

Anna: Because these things can be genuinely

hazardous. Space archaeologist Associate

Professor Alice Gorman from Flinders

University had a look at the footage and said

they're consistent with pressurized fuel

vessels likely made of titanium

alloys. And titanium has an extremely

high melting point, which is exactly why

these survive RE entry when so much else

burns up.

Avery: They're sometimes nicknamed spaceballs, and

Gorman notes that they can show up years

after the launch that produced them. There

was no scorching on these ones, which

suggests it came from a rocket stage that

fell away early rather than from a spacecraft

that burned up on final RE entry.

Anna: On Sunday night, the Australian Space Agency

confirmed it's working with Queensland

authorities and the Emergency Management

Agency and said in a statement that the

objects are, quote, consistent with debris

from a foreign rocket body that recently re

entered the atmosphere from orbit.

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

but there are a couple of candidates worth

watching. China launched the Long March 6th

and the Long March 8A over that same weekend.

Nothing confirmed, but the timing lines up.

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

hardware is coming back down to Earth these

days. More launches than ever means more

RE entries than ever. And Australia's

coastline, being enormous and facing a lot of

open ocean, catches more than its fair share.

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

spot something like this, please don't touch

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

contain leftover propellants like hydrazine,

which is nasty stuff.

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

and let you know if the source gets confirmed

from debris coming down to a, uh, spacecraft

going up close and personal with an asteroid

62 million miles away.

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

that brought samples of asteroid Ryugu back

to Australia's own umara Desert in 2020.

It's been out on an extended mission ever

since, and on Sunday it completed its first

asteroid encounter. Of that extended mission,

a flyby of

Anna: asteroid Torifune, and flyby

undersells it a bit. Hayabusa2 came within

about 800 meters of Tori Fune,

traveling at something like 18,000

kilometers an hour. JAXA has described it as

a deliberately risky operation designed

specifically to test high speed, high

precision navigation technology that could

one day deflect a hazardous asteroid.

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

peanut or a snowman, about 450 meters

across. The spinning once every five hours.

The pictures that have come back taken by the

optical navigation camera and the thermal

infrared imager, show rocks and boulders

scattered across both lobes. Yuya Mimasu,

who heads the Hayabusa 2 Extended Mission

Team, told a press conference he was

genuinely shocked by how good the image was

given. It was captured in a fleeting moment

during a high speed pass. The infrared

images are just as valuable. They reveal

cooler shadowed regions and warmer

sunlit patches, which tell scientists about

the surface texture and thermal behavior of

the rock.

Anna: Hayabusa2's next stop is even more

ambitious asteroid 1998

KY26, just 11 meters across,

potentially the smallest asteroid ever

visited by a spacecraft. That encounter isn't

due until 2031, so Torifune was

very much the warm up act.

Avery: A warm up act 62 million miles from

home. Not bad for a spacecraft that's been

flying for almost 12 years.

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

on three I ATLAS, the interstellar

comet that's been fascinating astronomers

since last July.

Avery: New research out this week, led by Cyriel

Opadam at the University of Edinburgh, used

the European Southern Observatory's Very

Large Telescope to study the comet's

chemical fingerprint in detail. And it's

given us our best clue yet about where

3i Atlas actually came from.

Anna: The short version this comet almost

certainly formed in the outer reaches of a

star system built around a star far

older than our Sun. Combined with earlier

work on hydrogen and carbon isotopes,

some estimates now put the comet's age at

somewhere between 3 and 12 billion

years, which, if it holds up, would make

3i atlas one of the oldest objects

ever directly studied by humanity.

Avery: Opiton put it beautifully she said

interstellar comets are basically fossils

from planetary formation, but from a system

very far away that we're lucky enough to

study up close for once.

Anna: 3i Atlas is only the third confirmed

interstellar object after Oumuamua

in 2017 and Borisov in

2019. And it's already fading as it

heads back out of the solar system for good.

The VLT team says these observations are

nearing their end simply because the comet is

getting too faint to study, which

Avery: makes the timing of this result rather

poignant. One of our last really detailed

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

of the most revealing. And with the Vera

Rubin Observatory now fully operational,

scientists reckon we could be entering what

they're calling the golden age of

interstellar object discovery.

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

of it.

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

didn't think was possible when this

spacecraft launched.

Anna: This is TESS, the Transiting

Exoplanet Survey Satellite. Since

2018, its entire job has been

watching for the tiny dimming of starlight

when a planet crosses in front of its star.

That's given us hundreds of confirmed worlds.

But this week, in a paper in the

Astrophysical Journal Letters, a team reports

that TESS has found a planet using a

completely different method, gravitational

microlensing.

Avery: Microlensing relies on general relativity.

When one star passes almost exactly in front

of a more distant background star, its

gravity bends and briefly magnifies that, uh,

background star's light. If the foreground

star has a planet, that planet leaves its own

tiny ripple in the brightening.

Anna: The planet in question is called Gaia

23 Bra B, first hinted at

back in 2023 by the European Space

Agency's Gaia mission, which spotted the

stellar brightening but didn't have enough

data to confirm a planet. PES

archived observations from that same event

turned out to hold the missing piece.

Avery: It's a super Jupiter, about 1.6

times Jupiter's mass, orbiting an orange

dwarf star some 40,000 light years away,

vastly further than the planet's TESS usually

finds within about 150 light years.

Anna: University of New Mexico's Diana Dragomir,

who worked on the discovery, said plainly

that nobody expected TESS to ever be

capable of finding this kind of planet. And

because microlensing events are one offs,

they happen once and never repeat. This

really was a needle hiding in eight years of

haystack data.

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

line about it. She said microlensing will

probably find the first Earth analog, and

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

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

Anna: Bittersweet, but also a lovely preview

of what NASA's upcoming Nancy Grace Roman

Space Telescope will do at scale. It's

expected to find around a thousand planets

this way, from one planet 40,000 light

years away to something on a truly different

scale altogether.

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

Academy of Sciences describes what

astronomers are calling an extremely rare

galaxy mega merger six massive

galaxies caught in the act of merging into

one roughly 12 billion years ago.

Anna: Using the mild Boke and Blanco

telescopes, combined with earlier James Webb

and radio interferometry data, the team

reconstructed what was originally thought to

be a single distant galaxy hosting an active

black hole. Instead, it turned out to be a

protocluster, a gravitationally bound clump

of galaxies in the very earliest stage of

building what's called a brightest cluster

galaxy.

Avery: None of these six are lightweights either.

Four are already individually massive, and

together they're packing hundreds of billions

of solar masses of stars into a region

smaller than the Milky Way. Their combined

star formation rate is somewhere between 70

and 160 solar masses a year.

Compare that to the Milky Way's current rate

of fewer than 10.

Anna: Based on how fast the galaxies are moving

relative to each other. The team estimates

the whole merger will wrap up within a few

billion years, producing one enormous,

ultra luminous galaxy at the heart of a young

cluster.

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

relationship between black holes and their

host galaxies. The young central black hole

in this system is growing right alongside its

six merging hosts, which should help refine

our models of how that black hole to galaxy

relationship actually gets built in the

Anna: early universe 12 billion years ago, and

we're only piecing it together now. Astronomy

really does run on a different clock.

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

the true edge of the solar system, courtesy

of NASA's New Horizons spacecraft.

Anna: New Horizons is currently about

66 astronomical units from the sun,

more than 66 times the Earth's sun

distance, and it's still carrying a working

instrument called swap, the Solar Wind

Around Pluto detector. A new study

led by Dr. Heather Elliott at the Southwest

Research Institute has used SWAP to track

exactly how the solar wind slows down

as it heads toward interstellar space.

Avery: The solar wind starts out supersonic, around

a million miles an hour, but as it travels

outward, it runs into incoming neutral gas

drifting in from interstellar space. That

gas gets ionized, gets picked up by the solar

wind, and effectively acts as a drag

slowing the whole flow

Anna: down, Elliot's team found. The

slowdown steepens the further out you go.

By around 58 astronomical units,

the wind is measured at somewhere between 13

and 15% slower than it is near

Earth. Earlier data between 30

and 43 AU had only shown a, uh,

5 to 10% dip, so this

confirms the drag really compounds with

distance.

Avery: Why does this matter? Beyond pure curiosity,

because the shape and strength of this

boundary the helioschere controls how many

galactic cosmic rays make it through to

threaten astronauts on long missions to the

Moon or Mars. Better maps of the boundary

mean better radiation forecast for future

crews.

Anna: New Horizons is expected to reach the actual

termination shock, where the wind drops below

the local speed of sound somewhere between

2029 and 2040. Depending on

how the models settle, it would only be the

third spacecraft in history to make that

crossing, after Voyager 1 and Voyager

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

investigator, put it nicely. New

Horizons remains the only active spacecraft

out there in the outer heliosphere, quietly

building on everything the Voyagers found

decades ago.

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

Queensland to the true edge of the Sun's

influence.

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

Daily beach mysteries, asteroid

close calls, ancient comets, hidden

exoplanets, a 12 billion year old

mega merger, and the edge of the solar system

itself.

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

subscribe wherever you're listening and leave

us a review. It genuinely helps new listeners

find the show.

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

Hayabusa2's flyby of Tory fun

happened at a distance of under a kilometer.

At 18,000 kilometers an hour,

that's roughly the same speed the

International Space Station orbits the Earth.

Anna: I'm Anna.

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

Astronomy Daily.

Mhm.

Anna: The story.

In this episode