Speaker 1: Okay, let's just dive right in. Imagine a high speed train. Okay,
but this train, well, it's maybe up to five point
six kilometers wide, and it's made of ancient ice from
another star system, and it's currently tearing through our solar
system at fifty eight kilometers per second.
Speaker 2: Yeah, that speed is it's staggering. That's the situation that's
got scientists all over the world scrambling pointing basically every
telescope they can at it.
Speaker 1: We are tracking this incredibly rare visitor right from way
outside our stellar neighborhood.
Speaker 2: Exactly, and the scientific mobilization to understand it has been
well unprecedented. This is only the third one like it
we've ever confirmed. Wow, and it's forcing us to, you know,
rewrite the book on how comets work. Almost in real time.
Speaker 1: We're talking about three ils. It's sort of burst onto
the scene back in July twenty twenty five, first spotted
by the ATLS survey, that's.
Speaker 2: The Asteroid Terrestrial Impact Last Alert System. Their job is
scanning the sky for potential threats, but they found this instead.
Speaker 1: And here is where it gets really wild, especially for
anyone trying to keep up the sheer amount of scientific
information about this thing has just exploited that.
Speaker 2: Speed of discovery is really key here. When it was
first spotted, maybe four research papers something like that. Right now,
just a few months later, we're looking at nearly seventy papers,
seventy covering everything from what it's made of to well
some pretty out there ideas.
Speaker 1: Like alien origins, which we'll definitely get to.
Speaker 2: Yeah, it's this incredibly dynamic, almost frantic race against time
because we know we don't have long before it heads
back out into deep space.
Speaker 1: So our mission today for you listening is to try
and cut through all that noise, synthesize everything we know,
everything you need to know about this elusive visitor before
it gets closest to the sun.
Speaker 2: Consider this your deep dive, the shortcut to getting up
to speed on this interstellar anomaly.
Speaker 1: Okay, so let's set the stage, as you said, Third
interstellar object three I. We had Uhamua back in twenty seventeen,
which was weird in its right, totally weird, and then
Comet Borisov in twenty nineteen.
Speaker 2: Right, which looked more like a typical comment but still
from another star.
Speaker 1: And this one three IAT lists. The parameters are just
mind bending. That speed fifty eight kilometers a second, that's
what like one hundred and thirty thousand miles an hour roughly.
Speaker 2: Yeah, and the age estimate astronomers think this thing is
incredibly ancient, somewhere between three and eleven billion.
Speaker 1: Years old, eleven billion years.
Speaker 2: It's potentially been traveling since the very early days of
star formation in the universe, a leftover from way back.
Speaker 1: Then, three maybe eleven billion years, drifting through space just
to zip through our little solar system for a few months.
I mean, the perspective on that is just hard to grasp,
it really is. Okay, let's start decoding this thing section.
Speaker 2: One, right, and we have to start with the urgency.
That incredible speed dictates the speed of the science. You know,
that jump from just a handful of papers to nearly
seventy Yeah, that really highlights what armors call a target of.
Speaker 1: Opportunity, meaning drop everything else.
Speaker 2: Exactly, drop everything, because if you wait, if you stick
to normal scheduling, the object's gone. The data is lost forever.
Speaker 1: And when you say drop everything, we're talking about interrupting
carefully planned observations on the biggest, most in demand telescopes
on and off the planet. Like getting time on Hubble.
Speaker 2: Oh, it's notoriously difficult. You write proposals years in advance.
You're competing with thousands of other scientists for just a
few hours of observation time.
Speaker 1: It's like the Mount Everest of telescope.
Speaker 2: Time pretty much. But Hubble and other major facilities they
have specific time set aside for these kinds of emergencies,
for targets that are unique, scientifically, crucial and fleeting.
Speaker 1: And three ISO made the cut.
Speaker 2: Oh, absolutely, it was deemed worthy of basically skipping the
entire queue. That level of response that tells you just
how important the scientific community thinks understanding this object is
getting a sample, even remotely of material from another star system.
That's huge.
Speaker 1: Hubble delivered almost immediately, didn't it. It got an image
back on July twenty first, the object was still pretty
far out then.
Speaker 2: Yeah, four hundred and forty six million kilometers from Earth,
still way out there.
Speaker 1: I saw that image, and what's cool is you can
actually see this speed. The background stars aren't pinpricks.
Speaker 2: They're streaks, right, little lines of light.
Speaker 1: Exactly because the telescope had to lock onto this fast
moving comet and track it across the sky during the exposure,
the stars trailed in the background. It's a visual confirmation
of just how quickly it's moving.
Speaker 2: And even visually it was already looking interesting. The comma
the dust cloud around the nucleus have this really distinctive
tear drop shape. But the absolutely critical finding from Hubble
the game changer was the size.
Speaker 1: Ah right, Because the first estimates were bigger, much bigger. Yeah.
Speaker 2: Those initial sort of back of the envelope calculations were
based purely on how bright the object looked overall. They
assumed most of that light was reflected off the solid nucleus,
the icy.
Speaker 1: Core, which is u usually the standard starting point.
Speaker 2: I guess it is, but it's a problem if the
object is really active, like this one clearly was, if
it's spewing out a lot of gas and dust, and then.
Speaker 1: That cloud reflects sunlight too, making the whole thing look brighter.
Speaker 2: Precisely, most of the light you're seeing isn't from the
nucleus itself, it's reflected off that huge enveloping dust cloud,
the coma. So once the Hubble team carefully subtracted the
light contribution from that massive coma.
Speaker 1: The estimated size of the actual solid bed. The nucleus
had to shrink dramatically.
Speaker 2: We went from those early guesses that it might be
you know, ten kilometers wide, maybe even bigger.
Speaker 1: Which would be a monster comet.
Speaker 2: A very significant object, yes, down to a much more
refined estimate. The nucleus diameter is somewhere between four hundred
and forty meters, so less than half a kilometer and
maybe five point six kilometers at the absolute upper end.
Speaker 1: Okay, that's a massive reduction, and that changes the whole conversation,
doesn't it, especially around how rare it is, and as
you mentioned those alien.
Speaker 2: Theories, it completely reframes the statistical arguments. Ok A smaller
object is much more likely to be just a natural
piece of interstellar debris wandering by. We'll definitely circle back
to that whole controversy.
Speaker 1: But this smaller size, this intense activity, it points towards
needing to understand its composition, right, what's actually in.
Speaker 2: This thing exactly? And that's where the James Web Space
Telescope came in. JWST, the Infrared Powerhouse.
Speaker 1: Web took a look on August six, used its Near
Infrared Spectrograph NIRSpec. That's the instrument you want for sniffing
out molecules, especially icy ones.
Speaker 2: That's right. A study led by astrochemist doctor Martin Cordner.
Near infrared light is perfect because different molecules, different ices,
absorb and emit infrared light at very specific wavelengths. It's
like a chemical fingerprint.
Speaker 1: So what did web find in that early look composition wise?
Speaker 2: Well, first, it confirmed the coma was complex. The gas
and dust weren't coming off smoothly uniformly. It showed complex
morphology suggesting uneven heating or different materials exposed on the
like patches.
Speaker 1: Of different stuff boiling off at different rates.
Speaker 2: Sort of Yeah. And crucially, at that distance, still quite
far from the sun, it found that carbon monoxide CO
and carbon dioxide CO two were sublimating, turning directly from
ice to gas much more readily than water.
Speaker 1: Ice was okay, So CO and CO two are more
volatile than water. They turn into gas at colder temperatures,
much more volatile.
Speaker 2: Yes, this tells us that these ices CO and CO
two must be near the surface of the nucleus, maybe
mixed in the pop layers. There are the first things
to boil off as the comet feels even the faintest
warmth from the approaching sun. Water ice needs things to
get significantly warmer.
Speaker 1: But web also spotted something physically weird, didn't it Something
about the dust?
Speaker 2: Ah? Yes, the sunword dust anomaly. This was unexpected. Normally,
you know, a comet's tail points away from the sun.
Speaker 1: Right pushed by sunlight pressure in the solar wind, like
a wind sock exactly.
Speaker 2: But the Jawst observations and others found a surprising amount
of dust, a significant amount appearing to emanate towards the
sun on the sunward side of the nucleus.
Speaker 1: Okay, that sounds wrong, Like the wind sock is pointing
into the wind. How does that work?
Speaker 2: It required some pretty sophisticated modeling to figure out it's
not actually defying physics, thankfully. The leading hypothesis involves a
couple of things. First, remember that intense outgassing of CO
and CO two we just talked about.
Speaker 1: Yeah, the hypervolatils boiling off.
Speaker 2: That escaping gas, especially the CO two, could be acting
like little rocket engines, blasting dust grains off the nuclear
surface with considerable force in all directions, not just away
from the sun.
Speaker 1: Okay, so the initial launch isn't just passive exactly.
Speaker 2: And then second, as these dust grains travel away from
the nucleus, they might be fragmenting, breaking into smaller pieces.
How would they fragment could be collisions, could be the
solar radiation itself breaking down fragile structures, But smaller fragments
scatter sunlight much more efficiently, so you get this halo effect,
and the increased reflection from these fragmented grains, especially on
the sunward side where the sunlight is hitting them directly,
creates the appearance of more dust coming off in that direction.
Speaker 1: Ah, So it's partly an optical illusion caused by the
dust breaking up and reflecting more light back at us,
combined with the forceful.
Speaker 2: Ejection that seems to be the best explanation. It's in
fact really exacerbated by how incredibly active this object is,
how much gas is powering this process.
Speaker 1: It paints a picture of a really volatile, maybe even
structurally weak object, doesn't it already showing signs of stress
way out there?
Speaker 2: Absolutely fragile and hyperactive seem to be the key takeaways
early on.
Speaker 1: Okay, let's talk more about that activity search, because it
wasn't just web that noticed something unusual let's bring in tests.
Speaker 2: Right, the Transiting Exoplanet Survey satellite tests.
Speaker 1: Now Tess's day job is hunting for planets around other stars.
It stares at huge patches of sky looking for the
tiny dips in starlight when a planet passes in front
of its star. How does an exo planet hut and have?
Speaker 2: Studying a comet tests is a fantastic example of getting
more science out of a mission than originally planned. Because
it stares at these wide feels for long periods, about
a month at a time.
Speaker 1: It just happened to be looking in the right place
at the right time exactly.
Speaker 2: Is High precision cameras actually captured three i allis between
May seventh and June second, well before the official discovery
in July by the ground based ATLA survey.
Speaker 1: Wow, So it gave us prediscovery data like fighting old
security footage of an event.
Speaker 2: Precisely, it's like a time machine for the comet's early behavior.
And that backward look provided by tests led to probably
the biggest surprise so far, the brightest paradix.
Speaker 1: The brightness paradox. Okay, with the paradox, well, a.
Speaker 2: Team of researchers Feinstein Nunin Seligman among them, used this
test data to measure the object's brightness its visual magnitude
during that May June period. Now, during that test observation window,
the object was getting closer to the Sun. It moved
inwards by about zero point nine astronomical units, So.
Speaker 1: The distance from the Earth to the Sun closer. That's
a significant move inwards.
Speaker 2: It is, and basic physics tells you as it gets closer,
it intercepts more sunlight, gets warmer, and should get brighter
as more ice supplements.
Speaker 1: Makes sense, So what was the expected brightness increase?
Speaker 2: Based on how typical solar system comments behave They calculated
that its flux, the total energy it received and reflected,
should have increased by a factor of about one point
five over that period. That would make its visual magnitude
around twenty point five by the end of the observation. Remember,
lower magnitude numbers mean brighter objects.
Speaker 1: Okay, so expect one point five times brighter magnitude twenty
point five. That's the baseline. What did tests actually see.
Speaker 2: The reality was stunning. Its magnitude didn't just reach twenty
point five, It surged all the way to nineteen point
two eight.
Speaker 1: Well, wait, nineteen point two eight is much brighter than.
Speaker 2: Twenty point five, significantly brighter. That brightness corresponds to a
flux increase, not by a factor of one point five,
but by a factor of five, five times brighter than
expect just from getting closer to the sun.
Speaker 1: Five times. Okay, that's not subtle. What causes that kind
of explosive brightening. It wasn't like a single outburst, right,
It was a sustained increase.
Speaker 2: It seemed to be sustained over that period. Yeah, it
implies the amount of material boiling off, the amount of
dust and gas being produced was far far higher than
you'd expect from just water, ice, or even CO and
CO two at that distance.
Speaker 1: So when you combine that extreme brightness increase from tests
with the smaller nucleus size we got from Hubble, what's
the conclusion? How can a small object be so incredibly
active so far out?
Speaker 2: It leads directly to what's being called the hypervolatile hypothesis.
Speaker 1: Hypervolatile meaning stuff even more volatile than CO two.
Speaker 2: Exactly, if you have a relatively small nucleus, maybe only
a few kilometers wide at most, generating five times the
expected activity, it must be releasing materials that need almost
no heat to turn into gas. The analysis suggested this
object might have already been significantly active when it was
still six Au away from the Sun.
Speaker 1: Six au. That's near Jupiter's orbit way out there.
Speaker 2: For context, water ice really only starts sublimating in earnest
around three au, maybe four Au. For some comets, even
CO two needs things to warm up a bit more
than they are at six AU.
Speaker 1: So to be active way out at six AU, you
need something with an incredibly low boiling.
Speaker 2: Point, precisely things like solid nitrogen N two or maybe
even solid hydrogen H two, though hydrogen is trickier. These
are called exotic or hypervolatile aces. They're very common in
the coldest, outermost regions of stellar systems, like our Kuiper
Belt or Ort cloud.
Speaker 1: So the thinking is three ietulusts formed in a similar
super cold region around its parent star, preserving these hypervolatiles.
Speaker 2: That's the implication. It's chemically distinct. It's been kept in
a pristine deep freeze for billions of years, loaded with
this incredibly sensitive material, and then as soon as it
felt even the faint warmth of our sun boom, it
just exploded. Into activity.
Speaker 1: So tests didn't just give as a time machine. It
gave us a fundamental clue about the chemistry just by
measuring brightness. That's amazing, it really is.
Speaker 2: And test data also helped tackle another puzzle, the rotation.
Speaker 1: Puzzle, how fast is it spinning?
Speaker 2: Exactly? By analyzing the light curve how the object's brightness
varies over time as different sides of rotate into view,
you can figure out its rotation period and get clues
about its shape and stability.
Speaker 1: Right like with Umamua, its light curve was quite extreme,
suggesting that weird elongated shape.
Speaker 2: Yeah, Umua's light curve was relatively clean, though dramatic. Three
I Atlas initially was the opposite. The test light curve
data was quite noisy, very messy.
Speaker 1: What does a noisy light curve suggest?
Speaker 2: It could mean a highly irregular shape, or maybe it's
not spinning smoothly, perhaps it's tumbling end over end. It
made it really hard to pick out a clear repeating
pattern at first, so tricky to pin down the spin.
Speaker 1: Very tricky. With test alone, they did find some tentative
hints possible signals suggesting periods around twenty nine hours and
maybe sixteen hours, but it wasn't definitive from that data set.
Speaker 2: That's where you need the big guns on the ground, right,
dedicated observations exactly.
Speaker 1: You need specialized ground based telescopes capable of taking very rapid,
frequent measurements, high cadence observations to really nail down the rotation.
And they did follow up observations confirm the shorter period,
the sixteen hour one. Yes, the sixteen hour spin period
seems to be the correct one.
Speaker 2: And knowing that rotation is vital, why does it tell
us more than just how fast it's turning?
Speaker 1: It can Yeah, a relatively fast rotation period for an
object potentially made of loosely bound ice and rock could
put significant stress on its structure. It might make it
more prone to flying apart, especially as it gets closer
to the sun and the outgassing ramps up. It adds
to that picture of fragility. Okay, so we have this
picture emerging small nucleus ancient incredibly hyperactive due to exotic ices,
possibly fragile spinning every sixteen hours. Let's get deeper into
the actual chemistry. Now, what specific molecules have we detected?
Speaker 2: Right? This springs us to section three chemical fingerprints and
some really strange physical properties. And for the chemical finger fronts,
the Gemini South telescope in Chile played a crucial role.
Speaker 1: Gemini South up high in the Andes great seeing.
Speaker 2: Conditions there fantastic site. On August twenty seventh, they used
their multi object spectrograph GMOs to get not just images
but also spectra of the coma.
Speaker 1: And tail and visually did it confirm the activitiy? Oh?
Speaker 2: Yeah. By late August the tail was clearly visible, stretching
about eleven hundred and twentieth of a degree across the
sky in their images, a clear visual confirmation of that
massive activity surge. The test data hinted at earlier, but.
Speaker 1: The real prize was the spectrum the chemical breakdown absolutely.
Speaker 2: The analysis led by Binyang found a very clear emission
signature in the CN.
Speaker 1: Band CN that's cyanide.
Speaker 2: Cyanide, yes, a molecule made of one carbon and one
nitrogen atom. Detecting CN emission is pretty standard for commets.
It's a common molecule, but actually confirming it in an
interstellar object is critical verification.
Speaker 1: How does a chunk of ice end up releasing cyanide gas?
It sounds vaguely sinister.
Speaker 2: Huh, it does, but it's a natural process. The nucleus
ice likely contains frozen hydrogen cyanide HCN. It's a simple molecule,
very common in interstellar space and protoplanetary discs.
Speaker 1: Okay, So HTN is frozen inside.
Speaker 2: Then what as the comet nears the sun. The water
ice starts sublimating, turning to gas. This gas flow carries
the frozen HTN along with it, away from the nucleus
surface into the coma. Once the HCN molecule is out
in the coma, floating free, it gets zapped by ultraviolet sunlight.
That solar radiation has enough energy to break the bond
between the hydrogen and the cyanode group.
Speaker 1: So sunlight breaks apart the HCN, leaving the CN.
Speaker 2: Exactly and that free CN molecule then gets energized by
sunlight and emits light at very specific wavelengths, creating that
characteristic spectral signature that Gemini detected.
Speaker 1: And does when you detect CN tell you anything it does.
Speaker 2: That CN signature typically becomes strong when a comet gets
within about two point five to three AU from the Sun.
That's the distance where water sublimation really kicks in strongly
enough to release sufficient HCN. And that distance range fits
perfectly with where three Ilus was located in late August
when Gemini observe.
Speaker 1: It, so it's like a location marker based on chemistry.
Did they figure out how much cyanide was coming on?
Speaker 2: They did. They measured the production rate at about eight
hundred six tillion cyanide molecules per second.
Speaker 1: Six tillion. That's a lot of zero.
Speaker 2: It's eight followed by twenty three zeros, an absolutely mind
boggling number in everyday terms.
Speaker 1: But how does that compare to say, comets from our
own solar system? Is that a lot or a little
for a commet?
Speaker 2: Interestingly compared to many of the brighter commets we see
originating from our ort cloud or Kuiper belt, that CN
production rate actually puts three Ilus on the lower end
of the scale loor end.
Speaker 1: But we just said it was hyperactive and five times
brighter than expected. How can it be both hyperactive and
a low producer of cyanide?
Speaker 2: That's the key, right It points back to that small
hypervolatile nucleus. It might be inc credibly efficient at releasing
gas because of those exotic ices near the surface, leading
to the high brightness and activity. But maybe the overall
abundance of specific molecules like hcn within the nucleus isn't
exceptionally high compared to some giant orc cloud comment.
Speaker 1: Okay, that makes sense, high efficiency, maybe not huge.
Speaker 2: Reserves, which leads directly to another critical classification they made
carbon chain depletion.
Speaker 1: Carbon chain depletion. What does that mean?
Speaker 2: Scientists look at the ratio of different carbon bearing molecules. Specifically,
they measured the amount of di carbon, which is C
two two carbon atoms bonded together, relative to the amount
of cyanide cn C.
Speaker 1: Two versus cn What does that ratio tell you?
Speaker 2: Di carbon C two is thought to form from the
breakdown of more complex, longer carbon chain molecules frozen in
the nucleus ice. So a higher C two to cn
ratio suggests the comet formed in an environment richer in
these complex organic precursors.
Speaker 1: And three I. At last, what was its ratio?
Speaker 2: It was classified as one of the most carbon chained
pla pleated commets ever observed. Its C two cn ratio
is less than point zero nine.
Speaker 1: Less than point zero nine C two molecules for every
CN molecule, so very little.
Speaker 2: C two extremely little. In simpler terms, it's severely lacking
in the stuff that breaks down to form C two.
It seems chemically quite primitive or formed under very specific conditions.
Speaker 1: What kind of conditions lead to that being carbon chain depleted?
Speaker 2: It suggests the place where three I at lass originally
formed around its parent star was probably unique. Maybe it
formed at extremely low temperatures, so cold that these more
complex carbon chains simply couldn't condense effectively.
Speaker 1: Onto the ice greens, or maybe something else.
Speaker 2: Another possibility is that it formed in a region heavily
shielded from the ultraviolet radiation of its host star. Usually
UV radiation helps process simpler molecules into more complex ones
over time. If it was shielded, that processing wouldn't happen
as much.
Speaker 1: And didn't comet Borisov, the previous interstellar comet, also show
this intriguingly.
Speaker 2: Yes, Boresov was all so found to be carbon chain depleted,
though maybe not quite as severely as three IE lists.
It's starting to hint at a potential pattern for interstellar
Comment two for.
Speaker 1: Two suggests it might be common for these interstellar visitors,
but well, a sample size of two is still tiny exactly.
Speaker 2: We need more visitors, But it's a fascinating clue about
the chemical environments in the outer reaches of other star systems.
It might be telling us that the conditions needed to
build up complex carbon chemistry are less common out there.
Or maybe these depleted objects are just the ones most
easily ejected in this chemistry.
Speaker 1: This lack of complex binding agents maybe ties back to
that fragility you mentioned.
Speaker 2: It absolutely could. There was a great quote from astronomer
Karen Meach describing objects like this. She said, they are
really very fragile, dirty snowballs.
Speaker 1: Ragile, dirty snowballs. I like that.
Speaker 2: It's a perfect description, and it's a stark warning. If
this hyperactive, chemically simple, potentially loosely bound ice ball gets
hit with too much thermal stress as it whips around
the sun.
Speaker 1: It could just cintegrate.
Speaker 2: It could break apart, and if that happens, you'd suddenly
expose huge amounts of fresh ice from the interior, stuff
that hasn't seen sunlight in billions of years. That would
cause a massive sudden surge and outcasting a spectacular flare up.
The whole astronomical community is kind of holding its breath,
watching to see if it holds together through perihelium.
Speaker 1: Okay, beyond the chemistry, there was another technique used something
really specialized to probe its physical structure.
Speaker 2: Yes, polarimetry. This was only the second time polarimetry had
ever been successfully used on an interstellar object, after boris
off polarimetry.
Speaker 1: Okay, break that down. What are we measuring.
Speaker 2: It's complex, but basically, sunlight is unpolarized. The light waves
vibrate in all directions. When that sunlight hits the dust
grains in the comet's coma and scatters towards our telescopes,
the light becomes partially polarized. The way it's polarized, the direction,
and the amount depends critically on the physical properties of
the dust grains it's scattered off.
Speaker 1: Soasuring the polarization of the light you can figure out
stuff about.
Speaker 2: The dust exactly. It tells you things you can't easily
get from just brightness or standard spectroscopy, things like the
average size of the dust grains, their shape, whether they're
smooth or fluffy, their composition, to some extent, the structure
of the regolith on the nuclear surface. If you could
measure that directly and even the overall shape of the coma, so.
Speaker 1: A powerful tool for understanding the physical nature of the dust.
What did the polarimetry team led by Zuri Gray find
four three ils?
Speaker 2: They announced their findings on September fifth, and it was
another major anomaly. They found that three I atlass exhibits
an exceptionally deep and narrow negative polarization branch.
Speaker 1: Okay, deep narrow negative polarization. Let's unpack negative polarization right.
Speaker 2: When light scatters, imagine a plane defined by the Sun,
the comet, and the observer US on Earth. That's the
scattering plane. If the scattered light tends to vibrate perpendicular
to this plane, we call that positive polarization. That's more
typical for many asteroids and some comets, and negative polarization
means the light preferentially vibrates parallel to the scattering plane.
It usually happens at certain viewing angles. But the depth
and narrowness of this negative branch for three idealas was extreme.
Speaker 1: How extreme? What does it mean physically?
Speaker 2: It means this specific light scattering behavior has never been
seen before, not in any comet, not in any asteroid ever.
Observed within our own solar system. Nothing quite matches it
never wow.
Speaker 1: Okay, So what does that imply about the dust.
Speaker 2: This deep and negative polarization strongly suggests the dust grains
are structurally very complex. They're likely not simple compact spheres
or chunks like typical silicate dust. They might be highly porous,
extremely irregular, fluffy aggregates think microscopic snowflakes or fractal structures.
It's a physical fingerprint indicating the dust formed in a
very different environment or from different materials than typical solar
system bodies.
Speaker 1: So if positive polarization is like light bouncing off relatively
smooth pebbles, negative polarization is like light getting trapped and
bouncing around inside incredibly intricate, fluffy dust bunnies.
Speaker 2: That's a really good analogy.
Speaker 1: Yeah.
Speaker 2: It fundamentally sets three Ilis apart, and importantly, it also
sets it apart from comet Borisov.
Speaker 1: Worsov didn't show that.
Speaker 2: Now Borisov showed positive polarization more similar, though not identical,
to comments in our solar system. This confirms that three
Iolis and Borsov, despite both being interstellar visitors, likely came
from different types of environments or are fundamentally different types
of objects. Three ils might represent a whole new class
of small planetary body based on this unique light scattering signature.
Speaker 1: Its dust is just alien, physically different.
Speaker 2: Alien in the truest sense, originating elsewhere and having measurably
different physical properties.
Speaker 1: And yet amidst all this incredibly high tech analysis from
Hubble web Gemini, there was this other anomaly that popped
up thanks to amateurs, the green hue.
Speaker 2: Yes, this was a wonderful example of pro am collaboration
and just kenops. In early September, there was a lunar eclipse,
which meant dark.
Speaker 1: Skies, perfect comet watching condition.
Speaker 2: Exactly, and experienced amateur astronomers Michael Jaeger and Jeral Raymond
were taking long exposure photos from Namibia and they noticed
this beautiful, distinct green glow around three iAtlas.
Speaker 1: A green comet. That's pretty classic, right. We know why
comets sometimes turn green, we do.
Speaker 2: The green color is typically caused by the fluorescence of
diatomic carbon C two, that molecule we discussed earlier. When
C two molecules released from the nucleus get energized by sunlight,
they glow green.
Speaker 1: Okay, so amateur sea green sciences green means C two.
Well that's the problem.
Speaker 2: The problem is the conflict with the spectroscopy. Remember the
Gemini results showed three aat liss is extremely carbon chain depleted.
It produces very very little C two compared to cn ah.
Speaker 1: So the chemical analysis says hardly any C two, but
the photos say glowing green, which means C two. That
doesn't add up.
Speaker 2: It's a direct conflict in the data, presenting a fascinating
little mystery. Right now, there are a couple of possibility. Okay,
look what one is That C two production has suddenly
rapidly ramped up in the short time between the Gemini
spectroscopy run in late August and the amateur observations in
early September. Maybe the increasing heat finally started breaking down
whatever parent molecules produce ce two more efficiently, so.
Speaker 1: The chemistry changed quickly.
Speaker 2: It's possible comets can change activity levels rapidly. The other
possibility is, well, maybe there's another explanation for the green
hue in this specific object. Maybe some other molecule or
dust property is causing a green glow under these conditions,
something we haven't seen before. Because this object's composition is
so unique.
Speaker 1: So either rabid chemical evolution or completely new source of
green in comets. That's a great little cliffhanger for future research.
Speaker 2: It really is. It perfectly illustrates how dynamic this whole
field is. Right now, we're getting conflicting data points in
near real time.
Speaker 1: Okay, this feels like a good point to pivot to
the inevitable controversy that seems to follow these in interstellar
objects around section four, the alien hypothesis.
Speaker 2: Ah yes, and that inevitably brings us to astrophysicist Avi Lobe.
Speaker 1: Lobe is a prominent Harvard astrophysicist, well respected but also
known for pushing boundaries, sometimes controversially, especially regarding interstellar objects
and the search for extraterrestrial intelligence.
Speaker 2: He definitely makes headlines. His initial argument concerning three il
as emerged back in July, shortly after discovery, and it
was critically based on those early much larger size.
Speaker 1: Estimates ten kilometer estimates exactly low.
Speaker 2: Ebb argued, from a statistical standpoint, based on our best
understanding of how much stuff rocks, ice should be floating
between the stars, the probability of a natural object as
large as ten kilometers wandering into our solar system during
our observational lifetime was extremely low.
Speaker 1: So he was saying, finding something this big naturally is
so unlikely, we should question if it is natural.
Speaker 2: That was the core of his initial challenge. He basically
set up a dichotomy. Either our models of interstellar object
density are fundamentally wrong by a huge margin, or this
object isn't just a random piece of rock and ice,
and the alternative you propose was the controversial alternative alien technologer.
Just days after his initial statistical argument, he co authored
a follow up paper. The title was pretty direct, is
the interstellar object three I eight less? Alien technology?
Speaker 1: Can't get much clearer than that? Do they elaborate on
what kind of tech?
Speaker 2: They explored possibilities referencing concepts like the dark forest resolution
to the Fermi paradox.
Speaker 1: Right, the Fermi paradox being if aliens are common, where
are they? And the dark forest idea.
Speaker 2: Is it's a somewhat chilling idea that the universe might
be like a dark forest full of hunters in prey.
Advanced civilizations might stay silent and hidden like prey to
avoid attracting attention from potential cosmic predators. Broadcasting your existence
is too risky.
Speaker 1: So Low and his co authors suggested three I eight
less could be some kind of hidden pro maybe deliberately
targeting our system or just passing through silently.
Speaker 2: They explored that possibility, Yes, maybe using a gravitational assist
to fly by maneuver. Importantly, they did include a caveat
in the paper, stating the exploration was partly for educational
purposes and quote fun to pursue, irrespective of its likely validity.
Speaker 1: Fun to pursue. Oh okay, But science isn't just about
fund speculation. It's about data. And this is where the
scientific rebuttal came in. Strong, wasn't it?
Speaker 2: Absolutely? The most immediate and critical flaw pointed out by
many in the community was Love's continued reliance on that
outdated larger ten kilometer size.
Speaker 1: Estimate, even after Hubble had refined it.
Speaker 2: Yes, by the time the alien technology paper was circulating,
the Hubble observations had already drastically reduced the maximum possible
size down to five point six kilometers and likely much smaller, and.
Speaker 1: A smaller object is statistically much.
Speaker 2: More compt Exactly the entire premise of his statistical improbability
argument essentially collapse apsed once you plugged in the best available,
observationally constrained size data. Science demands you use the most current,
most credible data, and the argument as presented failed that
fundamental test.
Speaker 1: So the community's reaction was basically correct the input data
and the need for an exotic explanation evaporates.
Speaker 2: That was the core of the scientific rebuttal on the
size front. And then there was the orbital mechanics.
Speaker 1: Argument, right because some of Lobe's hypotheses, especially for Umu Mua,
previously involved needing some kind of non gravitational acceleration like
a push from engines or a solar fail to explain
its trajectory. Did that come up here?
Speaker 2: It did indirectly, but geoscientist akm asenal Hawk published a
detailed rebuttal focusing specifically on the trajectory of three I Atlas.
He argued very compellingly that the object's path, including its
flybys of Venus, Mars, and Jupiter, could be perfectly well
explained by natural cometary dynamics alone.
Speaker 1: Meaning the push it gets from gas and dust escaping
that outgassing.
Speaker 2: Force precisely show that the observed trajectory did not require
any kind of artificial, non gravitational push or engineered maneuver.
The subtle deviations from a purely gravitational path were entirely
consistent with the kind of outgassing forces we expect from
a hyperactive commet like this one. No need to invoke
alien engines.
Speaker 1: So natural physics works just fine to explain where it's going.
Speaker 2: That's the strong consensus view. While three iotlis is undeniably weird,
its composition, its activity, its polarization are all highly unusual,
its motion seems to follow the known laws of commentary
physics quite well. The lesson really is caution against jumping
to extraordinary conclusions, however fun they might be. Before all
the natural explanations based on the best data have been
thoroughly exhausted.
Speaker 1: A good reminder for all science. Really. Okay, So where
did that leave us now? As this fascinating, ancient, hyperactive, fragile,
maybe green, definitely weird object heads towards the Sun, what's
the final act?
Speaker 2: Well, the next major milestone is perihelion, its approach to
the Sun that happens on October THIRTYEF.
Speaker 1: How close does it get?
Speaker 2: It'll pass about one point four au from the Sun,
so a bit further out than Earth's orbit, closer than
Mars's orbit. That's when the heating will be most.
Speaker 1: Intense primetime for activity.
Speaker 2: But there's a catch, isn't there?
Speaker 1: Unfortunately yes, right around perihelion and for a period afterwards,
the comet will be too close to the Sun in
our sky to observe safely from Earth or with space
telescopes like Hubble and Web. It gets lost in the
Sun's glare, so just when it's likely most active, we
can't really watch it closely.
Speaker 2: For that peak period. Mostly No, it's frustrating timing. It
essentially dips behind the Sun from our perspective, cutting off
detailed observation until it emerges from the glare sometime in
early December.
Speaker 1: But astronomers are obviously not giving up. The race isn't over.
What's planned for when it reappears in December.
Speaker 2: Oh, the observation campaigns are already lined up. It's going
to be intensive. NASA's solar observing missions like SOHO and
maybe even Mavin at Mars might catch glimpses of its activity.
Closer to the Sun, and the other Comming Sphere X
mission could contribute.
Speaker 1: To and the big ground and space telescopes.
Speaker 2: Absolutely Renewed observation time has already been allocated on Hubble,
on James Webb and on the Gemini Observatory. Once it's
safely observable again in December, they'll be hitting it hard,
tracking how its activity changes as it moves away from
the Sun and starts to cool down again. We'll have
several months of prime observation as it recedes back towards
interstellar space.
Speaker 1: That post perihelium phase sounds crucial. So as we wait
for it to round the Sun and come back into view,
what are the big questions left hanging? What should you,
our listener be pondering?
Speaker 2: Yeah, there are some great ones. First, the chemistry as
it cools down after perihelium. Will those hypervolatiles the nitrogen
or whatever it is continue to dominate or did the
intense heating near the Sun finally bake off those surface
layers and trigger a massive release of good old water
ice from deeper inside. Watching the chemical signature change as
it receives will tell us a lot about its layered structure.
Speaker 1: And then there's the elephant in the room. Will it survive.
Speaker 2: That's the big one, the fragility factor. Did it hold
together through the thermal and gravitational stresses of perihelium or
did it break apart? As Karen Meach warned, If it
did fragment, we might see a spectacular brightening event as
it emerges from the Sun's glare as all that fresh
interior ice gets exposed, or we might see multiple fainter
fragments instead of one object. Its physical state post perihelium
is a huge question mark, and the.
Speaker 1: Ultimate question, I suppose is the origin always.
Speaker 2: Can we refine our understanding of where it came from
by continuing to study its unique chemical fingerprint, that extreme
carbon depletion, and its bizarre physical properties, especially that unique
negative polarization signature. Can we maybe start to narrow down
the type of star system it might have originated in.
Every weird data point is another clue, another coordinate helping
us trace this ancient wanderer back to its home among
the stars.
Speaker 1: That deep negative polarization, the light scattering that we've ever
seen before in our own systems, comets or asteroids. That
really feels like the most profound physical clue we have
right now.
Speaker 2: Doesn't it it's arguably the most unique physical characteristic. Yes,
because it's not just weird. It actually links three iatlists
to something else, something within our own solar system, but
far far out.
Speaker 1: What's the link?
Speaker 2: That specific pattern of deep, narrow negative polarization, while unique
among typical comets and asteroids, bears a striking resemblance to
the polarization measured from some of the most distant mysterial
objects in our own solar system, the Transneptunian objects or
t and os, and the centaurs that orbit out beyond
Neptune in the frigid outer darkness.
Speaker 1: Wait, so it's dust physically behaves like the dust from
the most remote objects in our solar system, even though
it came from another star entirely.
Speaker 2: That's the profound connection the polarimetry suggests. It implies a
potential shared heritage, not of the same parent star, but
perhaps the same kind of formation environment.
Speaker 1: Meaning things formed in the absolute coldest, most remote, maybe
most radiation shielded outskirts of stellar systems, whether ours or
another one billions of years ago, might end up with
physically similar dust structures.
Speaker 2: That's the provocative thought, isn't it that this subtle physical property.
The way light scatters off microscopic dust grains might be
telling us something fundamental about the conditions and the most
remote nurseries where icy bodies form regardless of which star
they orbit. Three eye Loss isn't just a visitor. It's
like a physical sample delivered to our doorstep from the
dark frozen fringes of another stellar system, formed billions of
years ago. Ponder what that similarity implies about the commonality,
or perhaps the specific conditions required for forming these kinds
of icy bodies across the entire galaxy.