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How Impact Craters Could Have Reversed Venus’s Rotation—The Surprising Science · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Anna: From the farthest reaches of the galaxy to
0:02
the red dust of Mars. You're tuned in to
0:05
Astronomy Daily, your daily briefing on, um,
0:08
the universe. I'm Anna.
0:10
Avery: And I'm Avery. Today on the show, an
0:12
interstellar comet has just revealed it's
0:15
older than our sun by billions of years.
0:18
Perseverance scores its most impressive
0:20
organic detection yet on Mars. And
0:22
Europe's dark matter detective turns its gaze
0:25
to the heart of our own galaxy and delivers
0:28
the most stunning portrait ever made.
0:30
Anna: We've also got a controversial plan to dump
0:33
the world's largest space station into the
0:35
Pacific Ocean, raising some very pointed
0:38
questions. Plus, an asteroid that killed the
0:41
dinosaurs may have kept underground life
0:44
burning for 8 million years. And
0:46
astronomers have just found that a, uh,
0:48
famous nebula has a long lost twin
0:51
sibling.
0:52
Avery: It's Thursday, the 26th of June,
0:55
2026, and this is Astronomy
0:57
Daily.
0:58
Anna: We start today with one of the most
1:00
remarkable findings in the short but
1:02
extraordinary history of interstellar
1:05
astronomy. The comet known as 3i
1:08
Atlas, which swept through our solar system
1:11
last year and captured the imagination of
1:13
scientists worldwide, has now revealed
1:16
something almost impossible to wrap your head
1:18
around. This comet is older than our Sun.
1:22
Avery: Much older, potentially. Two new papers
1:25
published in the journal Nature this week,
1:27
using data from NASA's James Webb Space
1:29
Telescope, report that 3i
1:32
Atlas carries a chemical fingerprint unlike
1:35
anything found in our own solar system. And
1:38
that fingerprint points to an origin between
1:40
10 and 12 billion years ago.
1:43
Anna: To put that in perspective, our sun is about
1:45
4 1/2 billion years old. So this
1:48
comet may have been drifting through the
1:50
galaxy for more than twice the lifetime of
1:52
our entire Sol solar system before it
1:55
happened to pass through our neighborhood.
1:57
Avery: The key evidence comes from isotopes,
1:59
specifically the ratio of two forms of carbon
2:02
and a type of water molecule called semi
2:05
heavy water, in which some of the hydrogen
2:08
atoms carry an extra neutron.
2:10
Astronomers using Webb's near infrared
2:13
Spectroscope found that 3i Atlas
2:16
has far less carbon 13 relative to
2:19
carbon 12 than anything in our solar system.
2:22
And carbon 13 builds up in the universe over
2:24
time as successive generations of stars are
2:27
born, live, and explode. Less carbon
2:30
13 means an older origin, one from
2:33
a time before many stars had even had the
2:36
chance to die.
2:37
Anna: The semi heavy water signature is equally
2:40
telling. That kind of water tends to form in
2:42
high radiation environments, cold,
2:45
massive star forming regions that were far
2:48
more common in the early universe. And taken
2:50
together, the Webb team concludes this comet
2:53
formed during what astronomers call cosmic
2:56
noon, when star formation across the universe
2:59
was at its absolute peak.
3:01
Avery: Lead researcher Martin Cordiner of NASA's
3:04
Goddard Space Flight center described it as a
3:06
unique opportunity to study an ancient object
3:09
from the distant galaxy, probably predating
3:12
our sun and solar system. His words. On
3:15
one hand, we get direct insight into that
3:17
distant time and place, and on the other, we
3:20
learned something about how our own solar
3:23
system may be.
3:24
Anna: A companion study from the European Southern
3:27
Observatory's Very Large Telescope found
3:30
complementary evidence in the comet's carbon
3:32
and nitrogen isotope ratios, further
3:35
cementing the picture of an ancient, cold,
3:37
alien origin. 3i
3:40
Atlas, it seems, is a genuine relic from
3:42
another era of the universe
3:44
Avery: entirely, and it's on its way out. The
3:47
comet is now departing our solar system,
3:50
never to return. But the data it's left
3:52
behind will be studied for years, perhaps
3:55
decades.
3:56
Anna: We stay in the realm of ancient chemistry,
3:59
but this time a little closer to home, just
4:02
40 to 250 million km
4:05
away, depending on where Mars and Earth
4:07
happen to be in their orbits. NASA's
4:10
Perseverance rover has just delivered what
4:12
scientists are calling the most robust
4:15
organic detection made in Jezero Crater.
4:18
A new study published in Science Advances
4:21
reports that the rover's SHERLOCK instrument,
4:24
a laser based spectrometer on the end of the
4:27
robotic arm, has detected complex
4:29
macromolecular carbon in two mudstone
4:32
rocks at a site called Bright angel in an
4:35
ancient river valley called Neretva
4:38
Vallis.
4:39
Avery: The paper's own summary describes it as, and
4:41
I'm quoting, the most robust organic
4:44
detection in Jezero Crater. That thus far
4:47
and the only detection of macromolecular
4:49
carbon on a natural rock surface on Mars.
4:53
That's macromolecular, meaning large,
4:55
complex carbon based molecules, the kind that
4:58
on Earth are associated with biology. But we
5:01
need to be careful here.
5:03
Anna: Absolutely. The researchers are very clear
5:06
that detecting organic carbon on Mars
5:08
does not mean life. The SHERLOCK instrument
5:11
cannot distinguish between carbon produced by
5:14
biology and carbon produced by geology
5:17
or delivered by meteorites. What it can
5:20
do is show that the chemical ingredients were
5:22
there, and in this case, they were there in
5:25
abundance. Hundreds of individual
5:27
detections across just two rocks.
5:30
Avery: What makes this particularly compelling is
5:33
the location these mudstones are at. Bright
5:36
angel connected to Naret Va Vallis, the
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ancient river channel that fed Jezero
5:40
Crater's western delta billions of years ago.
5:43
This was a water rich environment, exactly
5:46
the kind of place where on Earth you would
5:49
expect to find microbial sheltering in
5:51
sediment.
5:52
Anna: One of the two rocks examined is the now
5:54
famous Chayava Falls, the very rock
5:57
that caused such excitement last year with
6:00
its distinctive leopard spot markings.
6:02
Finding complex macromolecular carbon in
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it adds yet another Intriguing layer to the
6:08
mystery. The other rock showed organic
6:11
carbon associated with carbonate and sulfate
6:14
minerals, both of which can be connected to
6:16
biological processes.
6:19
Avery: The researchers also note this is the first
6:21
detection of this type of complex carbon in a
6:24
mudstone on Mars outside of Gale Crater,
6:26
where the Curiosity rover operates more than
6:29
three and a half thousand kilometers away.
6:32
That suggests the conditions that allowed
6:34
organics to form and survive may have been
6:37
widespread across Mars, not just in one
6:39
localized area.
6:41
Anna: The samples Perseverance has collected are
6:43
still sealed in its sample tubes, waiting for
6:46
a future Mars sample return mission to bring
6:49
them back to Earth. When they arrive in a
6:51
laboratory, scientists will be able to run
6:54
tests orders of magnitude more
6:56
sophisticated than anything a rover
6:59
instrument can perform. That's when the real
7:01
detective work begins.
7:03
Avery: Microlensing works by detecting the tiny
7:05
brightening of a background star when a
7:08
foreground star and any orbiting planets pass
7:10
in front of it. Acting as a gravitational
7:13
lens. It's a powerful technique for finding
7:16
cold, distant planets that are otherwise
7:18
invisible. And to do it, you need an
7:20
incredibly crowded starfield, which, as it
7:23
turns out, is exactly what the galactic bulge
7:26
provides.
7:27
Anna: The Euclid Image already contains
7:29
51 known planetary systems.
7:32
Scientists expect it will also help confirm
7:34
and measure the masses of around 60
7:37
previously detected but poorly characterized
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exoplanets. And when Roman comes online
7:43
and begins repeatedly monitoring the same
7:45
field, the two data sets together will give
7:48
us the most complete picture yet. Yet of how
7:51
many planets exist throughout the galaxy.
7:54
Avery: For Australian and Southern Hemisphere
7:56
listeners, you're in an ideal position to see
7:58
the galactic center in the night sky. Right
8:00
now, it's high in the winter sky in the
8:03
constellation Sagittarius. And under dark
8:05
skies, away from city lights, you can see the
8:08
glow of the bulge. With your naked eye,
8:10
you're looking at the very region Euclid just
8:12
photographed.
8:14
Now, a story about endings and the
8:16
complications that come with them. The
8:18
International Space Station has been
8:20
continuously inhabited for more than 24
8:23
years. It's hosted astronauts from 22
8:25
countries, conducted thousands of
8:27
experiments, and served as humanity's
8:30
permanent foothold in low Earth orbit. But
8:32
its time is running out, and NASA's plan for
8:35
how to retire it is now under scrutiny from
8:38
some unexpected quarters.
8:39
Anna: The plan, in brief, is
8:42
starting in 2028, the ISS will
8:45
begin a, uh, gradual orbital lowering.
8:48
In mid-2029, NASA will launch
8:51
a SpaceX built in deorbit
8:53
vehicle and attach it to the station.
8:56
That vehicle, fitted with 46
8:59
Draco thrusters, will then push the
9:01
entire structure out of orbit in a
9:04
controlled re entry, targeting a
9:06
splashdown in the remote South Pacific,
9:09
near a location called Point Nemo.
9:12
Avery: Point Nemo is the most isolated spot on the
9:15
planet, more than 2,600 km
9:18
from the nearest land. It's already known as
9:21
a spacecraft cemetery. Russia's Mir station
9:24
ended its days there, along with hundreds of
9:26
other spacecraft. NASA chose it precisely
9:29
because it minimizes the risk to any human
9:31
population. But a leading ocean conservation
9:34
organization says that calculation misses
9:37
something important.
9:38
Anna: The Ocean foundation based in Washington
9:41
D.C. says the deorbit plan, and
9:44
I'm quoting, raises serious concerns for
9:47
ocean health that the space community has not
9:50
adequately grappled with. The organization's
9:53
president Mark Spalding, says there is a
9:55
quote, troubling structural gap in
9:58
international law that the ISS de orbit
10:01
throws into sharp relief.
10:03
Avery: The legal gap he's referring to is this.
10:06
The 1972 Space Liability
10:08
Convention requires that if a country's space
10:11
debris falls on another nation's territory or
10:13
damages another nation's property, the
10:16
launching country must pay compensation.
10:19
But international waters and the ocean floor
10:21
beneath them, um, are not a nation's
10:23
territory. There's no equivalent protection
10:26
for the deep sea.
10:27
Anna: And this isn't a small amount of debris.
10:30
The ISS weighs roughly
10:32
450,000 kilograms.
10:35
While much of the structure will burn up
10:37
during re entry, denser heat resistant
10:40
components, including pressurized modules,
10:43
structural beams and hardware are expected
10:46
to survive and reach the seafloor. The
10:48
exact quantity and composition of what will
10:51
sink is, according to critics,
10:54
insufficiently studied.
10:55
Avery: The concerns have now drawn the attention of
10:58
the U.S. government Accountability Office,
11:00
which has issued a report highlighting the
11:02
issues. The Ocean foundation is calling for
11:05
NASA to conduct a full environmental impact
11:07
assessment before proceeding with the re
11:09
entry, currently planned for around 2030 to
11:12
2031. There's still time, but not
11:15
unlimited time to address these questions.
11:18
Anna: It's a fascinating tension. The very
11:20
success of the ISS program, the
11:23
sheer scale of the structure humanity built
11:26
up there is now what makes disposing of
11:29
it so complicated. And this case,
11:31
as legal experts have noted, is likely to
11:34
set precedents for how we handle the growing
11:37
number of much larger orbital platforms
11:40
expected in the coming decades.
11:42
Moving on to our next story. Today,
11:45
66 million years ago, a 10
11:48
kilometer wide asteroid slammed into
11:51
what is now the Yucatan Peninsula of
11:54
Mexico with a force equivalent to
11:57
billions of nuclear weapons. The
12:00
impact triggered Megatsunami, a uh,
12:03
global firestorm and a years long
12:05
impact winter that blotted out the sun
12:08
and wiped out roughly three quarters of
12:11
all species on Earth, including
12:14
every non avian dinosaur. It
12:17
is the most studied extinction event in
12:20
history.
12:21
Avery: But new research from the University of
12:22
Glasgow has uncovered a remarkable footnote
12:25
to that catastrophe. While the surface of the
12:27
Earth was plunged into darkness and death
12:30
underground in the shattered rocks beneath
12:32
the crater, life may have found a way,
12:35
and not just briefly. The new study suggests
12:38
it found the way for 8 million years.
12:40
Anna: The Chicxulub crater, the scar left by
12:43
that asteroid is buried beneath layers of
12:46
sediment and ocean in the Gulf of Mexico.
12:49
But it still spans nearly 200
12:51
km in diameter. When the asteroid
12:54
hit, the immense heat it generated
12:57
fractured the bedrock and superheated water
13:00
trapped in the rock, creating a vast
13:02
hydrothermal system beneath the crater.
13:05
A network of hot water flowing through
13:08
porous shattered rock.
13:10
Avery: Hydrothermal systems like this are well known
13:12
on Earth at, uh, mid ocean ridges and
13:15
volcanic vents. They host entire ecosystems
13:18
of organisms that live completely
13:20
independently of sunlight. Bacteria,
13:22
tube worms, crabs, and more, all
13:25
powered by chemical energy from the Earth's
13:27
interior. The question for scientists has
13:30
always been, how long did Chicxulub's version
13:33
of this system survive?
13:34
Anna: Previous estimates based on computer models
13:37
from the early 2000s suggested about 2
13:40
million years. The new study, led by Dr. Ann
13:43
Marie Pickerskill of the Scottish
13:45
University's Environmental Research center,
13:47
used advanced argon. Argon dating of
13:50
potassium rich feldspar crystals collected
13:52
during a 2016 drilling expedition to the
13:55
crater's peak ring. The result? The
13:58
system remained active for at least 8 million
14:01
years, four times longer than anyone had
14:03
previously estimated, and the longest impact
14:06
generated hydrothermal system ever
14:09
documented.
14:10
Avery: To be clear, this doesn't mean complex life
14:12
was thriving underground while the dinosaurs
14:15
went extinct. Above, we're talking about
14:17
microbial life, bacteria and other
14:19
microorganisms sheltering in the warm,
14:22
chemically rich porous rock, shielded from
14:24
the radiation and temperature extremes at the
14:27
surface. But even that is extraordinary,
14:30
and the
14:30
Anna: implications extend beyond Earth.
14:33
Mars has endured countless asteroid impacts
14:36
over its history and may have once had liquid
14:38
water. If the same dynamics applied there,
14:41
and there's no reason to think they wouldn't
14:43
then. Even as Mars became cold and dry on the
14:46
surface, underground hydrothermal systems
14:48
could have kept microbial life viable for
14:50
millions of years. The Chicxulub finding
14:53
makes that possibility more credible than
14:55
ever.
14:56
Avery: We close today with a story that's part
14:58
astronomy, part cosmic detective work.
15:01
And we'll admit it a little bit poetic.
15:04
Somewhere between 4,000 and 5,000 light years
15:07
away, in the constellation Gemini, there's a
15:10
supernova remnant called
15:12
IC443.
15:14
Astronomers gave it a more evocative nickname
15:17
long ago, the Jellyfish Nebula, for its
15:20
billowing tentacle like filaments of glowing
15:22
gas.
15:23
Anna: It's one of the most photographed nebulae in
15:26
the sky, a favorite of astrophotographers the
15:29
world over. Its soft, wispy tendrils of
15:32
light are, uh, the expanding shockwave from a
15:34
star that died in a spectacular explosion
15:37
somewhere between 3,000 and 30,000 years ago.
15:40
It's beautiful. It's well studied, and
15:42
astronomers thought they knew it well.
15:44
Avery: But new research has revealed that the
15:46
Jellyfish Nebula has been hiding something.
15:49
Lurking right there in the bright glare of
15:51
the Jellyfish itself, Barely visible against
15:54
it, is a second supernova remnant connected
15:56
to IC443 by a bright
15:59
filament of gas. Astrophysicists are
16:02
calling this the first. First confirmed pair
16:04
of sibling supernova remnants ever
16:06
identified.
16:07
Anna: Two massive stars, born from the same cloud
16:10
of gas and dust, lived out their lives in
16:13
relative proximity, and then both died in
16:16
supernovae, leaving behind these two glowing,
16:19
expanding shells of debris. The fact that
16:21
their remnants are still connected by that
16:23
filament of gas tells us the two explosions
16:26
happened close enough in space and time to
16:29
interact with one another.
16:30
Avery: What makes the discovery particularly
16:32
striking is not just what was found, but
16:35
where it was hiding. The second remnant had
16:37
been there all along, but the Jellyfish
16:39
Nebula's own brightness had been obscuring
16:42
it, like trying to see a faint star right
16:44
next to the Full Moon. It took careful
16:47
analysis to disentangle the two structures
16:49
and recognize the second for what it was.
16:52
Anna: It's a reminder that even some of the most
16:54
familiar objects in the sky can still
16:56
surprise us. That even after decades of
16:59
observation, the universe has a habit of
17:01
tucking secrets away in plain sight,
17:04
waiting for us to look a little more
17:06
carefully.
17:07
Avery: And for observers in Australia and New
17:09
Zealand, the Jellyfish Nebula is in Gemini,
17:11
which sits low on the northern horizon in
17:14
winter evenings. While the nebula itself
17:16
requires a telescope, it's a wonderful target
17:19
for astrophotographers. And now, when you
17:22
photograph it, you can tell people you're
17:24
looking at two nebulae for the price of one.
17:26
Anna: And that's our universe for today. An
17:29
ancient interstellar traveler, older than the
17:32
Sun. The strongest hint yet that Mars once
17:35
had the chemistry for life. The most detailed
17:38
portrait ever made of our galaxy's crowded
17:40
heart. The ISS's complicated
17:43
farewell. A crater that kept life burning
17:46
Underground for 8 million years, and a, uh,
17:49
nebula that turned out to be twins.
17:51
Avery: The universe keeps delivering. Make sure you
17:53
subscribe so you never miss an episode.
17:55
Anna: And subscribe.
17:55
Avery: And if today's show sparked something for
17:57
you, leave us a review. It genuinely helps
17:59
the show reach more
18:00
Anna: listeners, find us at astronomydaily
18:03
IO Follow us Astrodaily Pod on
18:06
all your socials, and we'll see you right
18:08
back here tomorrow.
18:09
Avery: Until then, keep looking up.