Was the interstellar visitor oumuamua natural or artificial?

Daniel and Jorge talk about the claims that 'Oumuamua might have been alien space junk.

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:08):
Hey, Daniel, you like having visitors.

Speaker 2 (00:10):
I like having visitors at my university and visitors at home. Sure,
I like people.

Speaker 1 (00:16):
You like people. How about aliens?

Speaker 2 (00:19):
I would love if aliens send us a message or
an object or came to visit. They're welcome to have
dinner at my house.

Speaker 1 (00:26):
What about the university?

Speaker 2 (00:27):
If aliens came, I would be a superstar at the university.

Speaker 1 (00:30):
Wait, you would be the star or the aliens would
be the star. I think the aliens would probably grab
the headlines more than than the receiving professor.

Speaker 2 (00:40):
Yeah, probably, and we'd have lots of great questions for them.

Speaker 1 (00:43):
But then, what would you feed them for dinner if
they came to your house?

Speaker 2 (00:46):
Probably some engineers.

Speaker 1 (00:47):
Ouch. Wait, you would do the cooking. That's pretty dark, man.

Speaker 2 (00:50):
I would do a lot for alien answers.

Speaker 1 (00:52):
Yeah, boy, remind me never to go visit your house.

Speaker 2 (00:58):
You never know if you're coming for dinner or if
you are dinner.

Speaker 1 (01:01):
Definitely not staying for dinner. Hi am Rhem, a cartoonist
and the author of Oliver's Great Big Universe.

Speaker 2 (01:22):
Oh I'm Daniel. I'm a particle physicist and a professor
at UC Irvine, and I would love to get my
hands on anything alien, ideas, objects.

Speaker 1 (01:31):
Visitors, anything alien that sounds little and not safe for work,
Like you would put your hands on any part of alien.

Speaker 2 (01:38):
I think any part of alien would be safe for work.
You know, it's all in the interest of science.

Speaker 1 (01:42):
I guess. I guess it depends on what kind of
work or you are.

Speaker 2 (01:47):
If you are looking into unravel the mysteries of the cosmos,
then yeah, it's all up for grabs.

Speaker 1 (01:52):
I see, you might not do like pat some bags
or something, shake some hands or tentacles perhaps.

Speaker 2 (01:57):
You know, there's a lot of people on campus here
who literally get their hands a lot dirtier than I
ever do.

Speaker 1 (02:02):
I'm pretty sure everybody in the world gets their hands
dirty than a physicist. I mean, I guess you do
get chalk dust on your hands kind of, or dry
eras or dust on your fingers.

Speaker 2 (02:14):
We once had to unbox one thousand computers that all
arrived from Dell the same day and set them all up.
But I'm not sure what kind of dirt we got
on our hands that day.

Speaker 1 (02:23):
Yeah, yeah, it doesn't sound like a working class dust there.
But anyways, welcome to our podcast. Daniel and Jorge explain
the Universe, a production of iHeartRadio, in which we.

Speaker 2 (02:32):
Treat the entire universe as safe for work. We think
everything about the universe is beautiful and wonderful, nothing should
be censored, and all of its secrets should be revealed
to us. We would love to unravel them for ourselves,
but we'd also love to get some tips from aliens
about what's going on out there in deep space.

Speaker 1 (02:51):
That's right. It is a beautiful universe, and we are
all visitors in it, at least for the time that
we are in this universe. So we like to give
you a little bit of a tour of what we
know and what we found out about all the cool
spots and all of the great places to see in
this great cosmos.

Speaker 2 (03:06):
And most of the things we know about the cosmos
come from seeing, come from receiving photons from outer edges
of the galaxy or from other galaxies, from using that
to build a mental model in our minds of how
the universe is built. But sometimes we also get stuff
from other parts of the universe. We get tiny little
protons that might have flowed from other parts of the galaxy.

(03:27):
We get dust from all over. Sometimes we might even
get rocks and other stuff.

Speaker 1 (03:33):
Yeah. Well, although small rocks are okay to get here
on Earth right from the deaths of space, big rocks
are a problem.

Speaker 2 (03:39):
It depends a little bit on how they arrive. If
they fly by and let us study them, then that's
all right. But yeah, if they impact in the Pacific
and cause a mile high tsunami, then yes, that's a problem.

Speaker 3 (03:49):
Mmmm.

Speaker 1 (03:50):
You like like day visitors, not like overnight visitors.

Speaker 2 (03:55):
I mean, hey, come into orbit, right, then we can
study you for years. That'd be awesome.

Speaker 1 (04:00):
Is that possible? It could like a rock come and
suddenly we get a new moon.

Speaker 2 (04:03):
Absolutely. As we talked about on our episode about how
moons are formed, some moons in the Solar System were
captured as they flew by. So it's certainly possible for
us to catch some weird object from another Solar system
and have it become pout of ours, an adopted planet
or moon.

Speaker 1 (04:19):
Well, it's like a visitor that never leaves.

Speaker 2 (04:21):
It becomes part of our family.

Speaker 1 (04:23):
Man, We don't discriminate, But could it crash it into
our moon? Like, if we catch it, could it maybe
run into our current moon? That would be a problem, right.

Speaker 2 (04:30):
That would be a problem. If it like disintegrated the
Moon and that to breathe and rain down on the
surface of the Earth. Yeah, you seemed to be in
kind of a cataclysmic mood today. I mean, mostly we're
just looking at this stuff and learning about the universe.

Speaker 1 (04:42):
Well, you know, apparently if I go visit you, I
might end up as dinner. So I gotta, you know,
think of the worst case scenario. Apparently in this podcast,
I gotta watch out.

Speaker 2 (04:51):
You do got to pay attention. That's true.

Speaker 1 (04:53):
But it is a wonderful universe to visit and to
live in, and to study and to explore. And as
Daniel said, sometimes we get visitors from the far reaches
of space, and recently we got an extra special, an
extra rare kind of visitor.

Speaker 2 (05:08):
That's right. In twenty seventeen, a strange rock came through
the Solar system. We called it oh Muama. It was
a big surprise to everyone and an exceptional opportunity to
learn something about the rest of the galaxy, to actually
look at a chunk from another solar system.

Speaker 1 (05:25):
Wait, I feel like you're maybe prebiasing this a little bit.
How do we know it was a rock? Do we
know it was a rock?

Speaker 2 (05:31):
I guess I'm not speaking technically When I say a rock,
I just mean a chunk of something, a chunk of stuff. Yes,
it was a thing, how about that?

Speaker 1 (05:39):
And it has maybe one of the coolest names in astronomy,
oh Muhama. What's the origin of that name?

Speaker 2 (05:45):
Daniel? That's right. It was discovered by a telescope in Hawaii,
and so they called it oh Muama, which means messenger
from Afar in one of the Hawaiian languages.

Speaker 1 (05:55):
WHOA. It's like email, space email, or like space ups driver.

Speaker 2 (06:01):
Does your email come in at twenty seven kilometers per second?

Speaker 1 (06:04):
I think it comes a little faster than that, doesn't it? Helene?
Takes me to read it though, that's a different question.

Speaker 2 (06:09):
That's right. And we talked about this object shortly after
it arrived, and all the controversy had stirred up because
there were some weird things about this object. It was
weirdly shaped, it was sort of glittering in a strange way.
It was a surprise that we even saw it. And
since then even more controversy has been stirred up.

Speaker 1 (06:25):
Yeah, there's a big controversy about its origins and whether
or not it's natural.

Speaker 2 (06:30):
Is it to.

Speaker 1 (06:30):
On the podcast, we'll be tackling the question, was the
interstellar visitor oh muamua natural or artificial?

Speaker 4 (06:42):
Band And by artificial we mean alien. Oh I thought
you just meant like not organic, like not good to eat. Yeah,
like it has esper tame or something.

Speaker 2 (06:54):
Yeah, you got to cut down on your artificial space
junk man. It's not good for your diet.

Speaker 5 (06:59):
Yeah.

Speaker 2 (06:59):
Yeah, come to my house. We serve you purely organic engineers.

Speaker 1 (07:03):
Oh my goodness, your house again. You seem to be
making that joke a little too much.

Speaker 2 (07:11):
But this is a really fun question because getting a
chunk of stuff from another Solar system is a way
to see what's out there. Right, It's like a core
sample of the rest of the universe, something we very
rarely get to see because we're on this little island
of the Solar System, this little patch of land that
we've been able to explore with our probes.

Speaker 1 (07:28):
Well, it might be a core sample of perhaps alien
technology or something.

Speaker 3 (07:32):
Right.

Speaker 1 (07:32):
That is the big question about OHM. Was it natural?
Is it like just a rock that's naturally floating out
there in space, or could it be some sort of
device or spaceship or something made by an alien civilization.

Speaker 2 (07:45):
That's the big question. And when this thing came to
the Solar system, a bunch of astronomers looked at it
and studied it and debated it, of course, and one
astronomer in particular has made a lot of hay about it,
Avi Lob But professor at Harvard wrote a book called
Extraterrestrial The First Sign of Intelligent Life whoa This of
course made a big splash and was a best seller

(08:06):
and got a lot of people talking. The sort of
mainstream community in astronomer didn't take it very seriously, and
Professor Loepe has complained somewhat that his arguments have not
been addressed by sort of mainstream astronomy.

Speaker 1 (08:17):
You mean, he claimed that the omuma was a sign
that there are aliens out there, and now he's saying
that the people aren't taking him seriously.

Speaker 2 (08:25):
Yeah, that's exactly right.

Speaker 1 (08:27):
Well, as usual, we were wondering how many of our
listeners out there had heard of Omuama and had thought
about whether it was natural or artificial.

Speaker 2 (08:34):
So I'm actually visiting UC Riverside this week, so I
took the opportunity to walk around campus here at Usey
Riverside and ask people if they had heard of omuamua
and if they thought it was natural or artificial.

Speaker 1 (08:45):
So think about it for a second. Have you heard
of omuama before? And do you think it could be
a sign of aliens? Here's what people had to say.

Speaker 2 (08:53):
All right, So do you think omuamua was natural or artificial?

Speaker 3 (08:57):
Natural?

Speaker 2 (08:58):
Why is that? Have you heard of the object, oh,
Mua mua, the interstellar commet They came through the solar
system five years ago?

Speaker 3 (09:07):
No?

Speaker 2 (09:07):
No, okay? Great? Do you have an opinion about whether
it was a natural object like a comment from another
solar system or an artificial object like an alien craft?

Speaker 1 (09:16):
Maybe natural?

Speaker 2 (09:17):
Maybe?

Speaker 3 (09:18):
Natural?

Speaker 2 (09:18):
Okay, great? I never heard about it, this object that
came through Russell Solar System. All right, great? Do you
think it's more likely to be a natural object or
alien space junk?

Speaker 5 (09:33):
More like a natural object?

Speaker 2 (09:35):
Natural object? Because there's no evidence now.

Speaker 1 (09:37):
We found an alien right right, so.

Speaker 5 (09:41):
It's more like a natural object.

Speaker 2 (09:43):
How did you do an opinion?

Speaker 5 (09:45):
Yeah?

Speaker 1 (09:45):
More or less the same natural objects.

Speaker 3 (09:47):
It was more likely absolutely natural objects.

Speaker 1 (09:51):
All right. First of all, I'm not a lot of
name recognition, it seems, at least not in Riverside.

Speaker 2 (09:55):
I was even walking around the physics department at the
Riverside hoping to get people who thought about this stuff.

Speaker 1 (10:01):
Maybe you weren't pronouncing it right, Probably not.

Speaker 2 (10:04):
Yeah, you were.

Speaker 1 (10:05):
Attaching it to a dinner invitation, which is a problem
now that you have a reputation.

Speaker 2 (10:10):
I'm standing away from the engineering buildings on every campus
from now on.

Speaker 1 (10:13):
Yeah, it sounds like the engeneers just stay away from you.
But yeah, a not a lot of recognition. Although some
people had heard of it and they seem to think
it's natural.

Speaker 2 (10:21):
They do seem to think it's natural. I mean, it's
a fascinating object and there are some things about it
that are weird that can teach us about what's out
there in the universe. I think the evidence for it
being actually alien is quite a reach. That kind of
thing you might put in a best selling book that
you want to sell a lot of copies of, but
not something that would really stand up to peer review.
I see.

Speaker 1 (10:41):
I mean, if a physics professor writes a book about aliens,
that's obviously just a big money grab, right.

Speaker 2 (10:49):
I think it depends on the claims you put in
that book. And so on the episode today, we wanted
to dig deep into what's going on with Omua Mua.
Is it natural? Is it artificial? What do we know
about it? What can we say?

Speaker 1 (11:01):
Well, let's dig into it, then, Daniel, what is this
object and when was it first spotted?

Speaker 2 (11:05):
So it's definitely from another solar system. We spotted it
first on October eighteenth, twenty seventeen by the pan Star's telescope.
This is a really awesome telescope. It's in Hawaii. It's
actually two of them. Each of them are almost two
meters in diameter, and they're on the summit of Haleyakela
on the island of Maui, and their job is basically
to look for stuff that might hit the Earth. They're

(11:28):
taking pictures of the night sky all the time and
they're looking for changes, looking for stuff that's moving. It's
part of this search for Near Earth objects to see
whether there are things out there that are moving that
might of course hit the Earth.

Speaker 1 (11:39):
Well, it's pretty cool. It's like a WatchGuard almost for
the entire planet. It's a full time it's doing that
full time.

Speaker 2 (11:45):
It's doing that full time. It's pretty awesome. This is
sort of a newer effort by NASK. It really was
kicked off after comet shoemaker Levy in the nineties when
we saw, wow, things in the Solar system really can
impact comments and cause huge fireballs. We got to put
some more money on this. So in the last twenty
or thirty years, NASA and some international partners have really
dedicated some resources to looking for near Earth objects. And

(12:07):
they see a lot of them, and they've cataloged all
the big ones, and we know mostly what's out there,
but sometimes they see something strange. And in twenty seventeen
they saw this object moving in a way that they
could tell it was not coming from inside of our
Solar system.

Speaker 1 (12:21):
Interesting, so just out there looking at this night sky
all the time and it records if something changes. Now,
how did they know that it was coming from outside
the Solar.

Speaker 2 (12:31):
System because of where he was coming from. It entered
from above the plane of the Solar system. The whole
Solar system is basically flat. Everything's orbiting in a plane
that's determined by the north south pole of the Sun.
But this thing was sort of coming in from above
the plane from the direction of the constellation Lira, and
passed really close to the Sun, actually within the orbit
of Mercury, and then out the other side.

Speaker 1 (12:51):
I guess the question is, you know, if you look
at the night sky and you see a streak, it's
kind of hard to tell in three D where it
is or where it's going, or you know exactly what direction,
just because you're getting just to the view of it.
How did they figure out where in the Solar system
it was going?

Speaker 2 (13:06):
You can reconstruct its three D trajectory. First of all,
we have two of these cameras who have a slightly
binocular view. But then also as it gets brighter and dimmer,
you can figure out sort of its radial velocity, and
they can measure its velocity across our view just by
seeing how the points of light are moving, So they
can end up with a three D trajectory and then
backtrack and say where could this thing have come from
in order to give us this path?

Speaker 1 (13:26):
Now, I think you said that they saw a streak,
not just a little point flying through space.

Speaker 2 (13:30):
Yeah, most of the stuff in the Solar system is moving,
and it's moving fast, but it's not moving that fast.
So on this camera it usually just registers as a
pixel like light from the Sun hits it bounces off
and it comes into the telescope in Hawaii and it
makes a bright pixel and we say, okay, there's something there.
But this was moving so fast twenty six kilometers per
second relative to our solar system that actually made a streak.

(13:52):
It was like multiple pixels across whoa.

Speaker 1 (13:55):
And so, and I guess they didn't just see it once.
They could track this thing, right.

Speaker 2 (13:59):
They could track this thing exactly, But by the time
they saw it, it was already on its way out
of the Solar system. Like it made its closest approach
to the Sun and then came closer and closer to
the Earth, And by the time we saw it on
the Earth, it was already sort of like on its
way out of the Solar system. So then we could
just sort of like watch it from behind as it left,
and then it got dimmer and dimmer and dimmer. So
we only had a few weeks to gather data about

(14:20):
this thing. Whoa wa, wait, wait, why didn't we see
it before we saw it when it came close to
the Earth, And that's the easiest time to see it.
Before that, it was either like coming from the Sun,
which makes it impossible to see it, or it was
too dark.

Speaker 1 (14:32):
The object itself was too dark because I guess it
wasn't glowing by itself. It was just reflecting light exactly.

Speaker 2 (14:38):
You need to be sort of lucky with the arrangement
of the Sun and the object and the Earth to
even see these things, right, because you need light from
the Sun to hit it and then bounce off and
hit the Earth. As you say, it's not glowing. It
doesn't have fusion. It's just a big chunk of stuff.
It has to reflect light to us from the Sun
and lots of spots on its trajectory to be basically invisible.

Speaker 1 (14:56):
Well, scientists noticed some weird things about it that make
them think that, hmm, if this thing is natural or
of alien origin. So let's stick into what those odd
things about it were and talk about whether it is
a message from aliens. But first let's take a quick break,

(15:22):
all right, we're talking about visitors to our solar system.
In twenty seventeen, we got one that we seemed a
little fishy.

Speaker 2 (15:31):
Called it definitely was a lot of fun to look
at and to think about, all right.

Speaker 1 (15:35):
So we saw this in our telescopes looking for asteroids
out there in space, and there was something a little
bit different about its trajectory seemed to be coming definitely
from outside the Solar system, and scientists think at least
the time they thought or are they considered the possibility
that it might be from an alien civilization or something.
What were some of the things that made people think, hmm,

(15:56):
this isn't maybe just an asteroid.

Speaker 2 (15:58):
So first of all, it seemed to have a weird shape,
like a lot of the asteroids in our solar system
are mostly spherical, like they're round ish. This thing either
was really really long and thin. A lot of the
artistic depictions of it draw it sort of like a cigar,
or it was sort of flat, like a pancake. So
that's thing number one that makes it kind of weird.

Speaker 1 (16:16):
But could we actually see its shape or isn't it
so far away? Could you basically just see a dot?

Speaker 2 (16:21):
Yeah, we can't see its shape directly, you're right, but
we could deduce its shape by how it's spinning and
how its brightness changes. So it's not a sphere. Then
as it spins, you might reflect more or less light
off the larger or smaller surfaces that it's presenting, So
they have to deduce its shape from how it's spinning,
which is why we're not sure if it's a cigar
or a pancake. We just know it's not very spherical.

Speaker 1 (16:43):
Wait, so if it was spherical, then we just looked
like a constant dot of light in the sky, right.
But this wasn't a constant dot of light.

Speaker 2 (16:51):
It was not a constant dot of light. Exactly what
was it? The light varied really dramatically, like by factors
of ten, so which made them think that maybe it
was really long and thin, and sometimes you were seeing
the long side of it, and sometimes it was really
narrow and you were just reflecting light off the tip.
But definitely was not a sphere because otherwise, as you say,
it would give you a constant signal.

Speaker 1 (17:10):
So it was like blinking or just kind of fading
in and out.

Speaker 2 (17:13):
It was more fading in and out, never totally disappear.
If you look at the light curve, you see it
varies over a very wide range.

Speaker 1 (17:19):
In what timescale, like every hour, every second.

Speaker 2 (17:22):
More like hours exactly. We only have a few weeks
of data of this thing. But it was spinning pretty fast.
I think it was also tumbling, like it wasn't only
spinning along one axis, it was like spinning in two
different ways at the same time.

Speaker 1 (17:34):
But at least we think it was spinning, right, We
don't actually know because you just see a pixel of light, right.

Speaker 2 (17:39):
Yeah, exactly, this is all reconstruction. But there was a
bunch of stuff about it which seemed kind of weird.
There was the shape that was how it moved. It
seemed to move in a way that wasn't just gravity.
Seemed like it got a little boost as it was
leaving the Solar System, which made people think like, ooh,
maybe it's an alien spaceship, or maybe it's a light
sale or these things that like gathers folk tons from

(18:00):
stars to pick up acceleration. So that was Avi Lobe's
suggestion that this might be a discarded alien light sale
that fell through our Solar system.

Speaker 1 (18:10):
And it's also kind of rare to get stuff from
that direction, right, like we don't get a lot of
comments or asteroids from our asteroid build.

Speaker 2 (18:18):
Well, we don't know how rare it is, right. We
sort of turned on this eyeball to the universe fairly recently,
and seeing one sort of new either means that we're very,
very lucky, or it means that there may be more
common than initial calculations suggest it could be that space
is filled with chunks little bits from other solar systems,
and it's not that unusual to see one.

Speaker 1 (18:38):
All right. There were some weird things about it that
made people wonder about this, but one professor in particular
sort of seemed to have gone all in on it.

Speaker 2 (18:46):
That's right. Jason Wright, a professor at Penn State, wrote
a detailed blog post responding point by point to all
the claims made in Avi Lobe's book. And I thought
it would be a good idea to chat with him
about all these ideas and what he thought Omama might
actually have been.

Speaker 1 (19:02):
Okay, So then, just to be clear, you spoke to
Jason Wright, who's arguing against the book written by Lobe,
who argued that om Oma was of not just extra
terrestrial origin, which it is because it's not from Earth,
but that it's a sign of intelligent life.

Speaker 2 (19:17):
Yeah, that's right. Loeb is making some pretty outlandish claims
in his book, and he's also complaining that nobody's taking
him seriously. So Jason Wright decided to take it seriously
and address all the claims and say what we know
and what we don't know. And of course nobody knows
for sure what this thing was, but we should be
careful about the claims we make.

Speaker 1 (19:34):
All right, Well, here's Daniel's interview with Professor Jason Wright.

Speaker 2 (19:39):
Great so that it's my pleasure to introduce to the
podcast Professor Jason Wright. He's professor of astronomy and astrophysics
at Penn State. He's a member of the Center for
Exo Planet's and Habitable Worlds, and amazingly, he's the director
of the Penn State Extraterrestrial Intelligence Center, which sounds like
a lot of fun. Jason, Welcome to the podcast.

Speaker 5 (20:00):
Thanks good to be here.

Speaker 2 (20:01):
As director of the Extraterrestrial Intelligence Center, do you get
first access to the alien bodies to interrogate them and
ask them questions?

Speaker 3 (20:08):
No, no, thank goodness. That's that's definitely outside the purview
of what we do here at the Pace SETI Center.
So yeah, I can't have no information on that.

Speaker 5 (20:17):
Score for you.

Speaker 2 (20:18):
All right, Well, I do want to ask you questions
about things you're actually an expert in, and I was
very excited to talk to you because this blog post
you wrote where you did a point by point analysis
of the claims made in Avulobe's book about the possible
extraterrestrial or alien nature of O Muamua. So I'd love
to ask you first to briefly run down what are
the evidence for the anomalies what a sort of five

(20:40):
categories he lays out, and then dig into them with you.

Speaker 3 (20:43):
Yeah, so, Omuma, you know, it was definitely interstellar, We
know that for sure, and it was definitely very strange.
But when we say it's strange, what we mean is
we kind of had a sense for roughly what comments
look like in general, and we thought when we saw
one come from interstellar space, it would more or less
look like the comets that orbit the Sun. And the

(21:04):
main reason is that the comets that orbit the Sun,
that come from the Ork Cloud very far out, they're
basically in interstellar space. There's not a big difference between
the space and the Ork Cloud and between the stars,
and so we didn't expect it to be so different
from typical comets.

Speaker 5 (21:19):
There's a big.

Speaker 3 (21:19):
Caveat with that, though, which is that O Muhamuha was
extremely small, and we don't generally detect comets that's small
in the Solar System just because being so small, they
reflect hardly any light and they're very hard to see.
We have very few examples of any objects in the
Solar System that small orbiting the Sun, which means we

(21:39):
don't actually have a basis to compare to. So when
we say it's strange, it's really strange compared to expectations,
not necessarily strange with respect to ordinary comets in the
Solar System of that size. So the first thing that
was really strange about it is that its brightness varied
a lot, and that has been interpreted to mean that

(22:02):
it must not be round, which is perfectly reasonable for
something of that size. You have to be quite large,
like a large asteroid, to be round. But it was
really extreme. I mean, the brightness variations indicated that the
axis ratios had to be something like five to one,
or maybe even as high as ten to one, and
the shape was kind of unclear. We say this because

(22:24):
if it were just that part of the surface was
dark and part of it was highly reflective, that can
only change the brightness so much as it rotates, and
the brightness variations are highly irregular, so that suggests it's
either like flat like a pancake, or long like a cigar,
and that it's tumbling doing this kind of uncontrolled rotation,
and sometimes we see the thin end of a muamua

(22:47):
and that's what it's hardly reflecting, and the light towards us,
and that's when it gets very dark.

Speaker 2 (22:51):
So when you say brightness, you're not talking about this
thing glowing obviously, right, it's reflecting light from the sun.

Speaker 5 (22:56):
That's right. All objects are going to reflect light from
the sun.

Speaker 3 (22:59):
And if it's shaped like a pancake and as it's tumbling,
then when we see the whole pancake sort of face on,
then it's reflecting a lot more sunlight and it'll appear bright.
But then if we see it edge on, we'll hardly
see any sunlight reflective. We can try to infer the shape,
but it's a really inexact science. It's an unconstrained problem,
and so it's possible it's something like a ten to

(23:22):
one long cigar, like in a lot of the imagery
you might have seen online. There was an artist's picture
of it being almost needlelike, but I think most planetary
scientists think it's probably more like a flat pancake, maybe
six times wider than it is thick. If it were
shaped like a round rock than a sphere, then as
the sphere spins, we always see the same size. So

(23:42):
the only way that the brightness would vary is if
part of it was reflective and part of it was not.
Now that's normal. Things have dark areas and bright areas
on them, But we would see it change in exactly
the same pattern every rotation. And there's only so much
variation that you can get from from that sort of
a surface brightness changing. When you see this kind of

(24:05):
very irregular, very strong brightness variations, that's most naturally explained by.

Speaker 5 (24:10):
A strain shape.

Speaker 2 (24:11):
So imagine you had like a piece of charcoal and
half of it was dipped in white paint, so you know,
if you illuminated it, it looked like black and white, but
it's perfectly spherical and it's spinning. You're saying that we
would see a regular variation in the brightness. We would
see it bright and dark and bright and dark.

Speaker 3 (24:27):
Right, you see almost a sinus soidal variation. And only
if you happen to be at that special orientation that
you got it completely white or completely black once a
rotation would those brightness variations be.

Speaker 5 (24:40):
You know, ten to one or something extremely strong.

Speaker 2 (24:43):
And so you're saying that what we saw were huge
variations in the brightness, and the pattern was kind of irregular,
meaning that we're not like seeing the same side of
it over and over. Is that what you mean by tumbling?
That is what I mean by tumbling.

Speaker 3 (24:54):
So when something just spins, then every single rotation it
comes back to the same area, like the earth spinning
or something like that. But if you take an a
regularly shaped object, and the classic example here is something
like a chalk border eraser or a white border eraser,
if you try to spin it lengthwise, you'll find it
won't uniformly spin.

Speaker 5 (25:16):
It'll start doing this very strange.

Speaker 3 (25:17):
Irregular, almost kind of random flipping in the air in
all these different directions, and that's called tumbling. And when
that happens, you do not see this regular brightness variation.
And so Omuamua is definitely tumbling. And what that means
is it's very hard to model because it's almost a
random variation, and that's why it's so frustratingly difficult to
figure out what its actual shape is.

Speaker 2 (25:38):
So does tumbling just means spinning on more than one
axis at the same time.

Speaker 5 (25:43):
That's right, that's a good way of thinking about it.

Speaker 3 (25:45):
Basically, the axis of rotation sort of changes with respect
to the shape of the object, and it's not regular.
This object is so small and so far away that
it's just a point of light, and so everything.

Speaker 5 (25:58):
About it we have to infer. From that light.

Speaker 3 (26:00):
We can watch it change its brightness and so try
and figure out what shapes would do that. We can
also look at how bright it is at different wavelengths,
and that helps us infer what the surface might be
made of based on what light gets reflective and what
light gets absorbed.

Speaker 2 (26:15):
So we're looking at a single pixel in a telescope
and just watching it get darker and brighter, and from
that we have this crazy artist impression with all these
like crags and knooks and all these vinkles on it.

Speaker 5 (26:25):
That's exactly right.

Speaker 2 (26:28):
Crazy.

Speaker 5 (26:30):
It really helps to imagine yourself there.

Speaker 3 (26:32):
It really helps give you physical intuition for what's going on,
and so I think it's a really valuable exercise for
us to imagine what these things might look like. But
we always have to bring with that the caveat that
we have filled in way more details than we actually know,
and sometimes that can be frustrating when communicating to the public.
Trying to convey we are sure about this, but these
other details I'm showing you are just complete fiction and

(26:54):
could easily be wrong, like the crags right, the little
shapes on that long black cigar shape.

Speaker 2 (26:59):
Especially in exo planet science, I feel like they're often
showing us essentially fantasy data. You know, this is what
an artist thinks this planet looks like, when really the
image we have is a single pixel.

Speaker 3 (27:10):
Every planet around another star we've ever detected, We've only gotten,
you know, information from just just a point. Sometimes that
point is just the star and we can infer it's there,
and in a few cases we can actually image the planet,
but by that we just mean we see the star
in one part of the image and this little dot
that's the planet in another part of the image. Exoplanets
have a really special place in the imagination of, you know,

(27:33):
of the world, because unlike you know, a nebula or
a supernova or a gamma ray burst, a planet feels
like a place you know, that we could in principle visit,
and in science fiction where you know, we do go
and visit. And so the reason people are interested is
it's like, what would it be like if you were there.
You want to imagine what it's like if you were there.
It's one of the things that made planetary exploration so

(27:56):
compelling when we started to visit Venus and Mars and
Jupiter and Saturn, is that we actually send robots there
and we will even say we've been to Jupiter. Right, Okay,
we have not been to Jupiter, but we've got great
pictures that make us feel like we've been to Jupiter.
And so that's why you get these like NASA Exoplanet
Travel Bureau posters right where they're like advertising come to

(28:17):
this planet and they you know, all the cool stuff
and these very retro style those are really popular and
those are really fun for that reason, and it makes
exoplanets a lot of fun to study.

Speaker 2 (28:26):
All right, but we're not selling Omuamua as a tourist destination.
We wanted to understand the shape of it because we
had sort of a deeper question, right, which was like,
is this thing weird or unusual? And so you were
saying that the initial idea was that it was long
and thin, sort of like ten times longer than it
is thin. But now we have another idea that maybe
it's flat, like a pancake. How can both of those

(28:48):
be consistent with the light variation?

Speaker 5 (28:49):
Right?

Speaker 3 (28:50):
And I think that's because it's tumbling, and so we
don't actually know what its orientation was because it's kind
of this random orientation and the data are really sparse,
you know. We don't get to point the Hubble Space
telescope at it constantly and follow its brightness all the time.

Speaker 5 (29:05):
Only the largest telescopes.

Speaker 3 (29:07):
Because it was so small it could make accurate brightness
measurements on the ground, you can only do it during
the day, and you know when you're allowed to use
the telescope. So you end up with this very sparse
data set where you only know it's brightness, you know,
for a few times. Maybe you get a bunch of
measurements over the course of a couple of days, and
then nothing for a month, And so you're trying to
infer the shape from very limited information, and it just

(29:30):
turns out there are multiple different shapes that plausibly could
do that depending on exactly how it's tumbling, which is random.

Speaker 5 (29:36):
It can't be.

Speaker 2 (29:36):
Predicted, And so then the shape is important to this
larger question of like what is it? Because the argument
is made that like long thin things are weird and
unusual and therefore might be alien. Is that the idea.

Speaker 3 (29:49):
So Abby's point was that if you look at the
the most extreme models that fit the data, some of
them said the access ratio is ten to one to one,
and you know, we could also fit it with something
only five to one to one, and.

Speaker 5 (30:03):
We could also fit it with pancakes.

Speaker 3 (30:04):
But that was like the strangest and most extreme value
that people published as a possibility, and he really grabbed
onto that, and he argued that that's far beyond the
access ratio that we see in any object in the
Solar system, and so that automatically puts it in this
you know, that looks unnatural, that looks weird, that's something
else kind of category. And so that's when all these

(30:26):
caveats come in. This is a very small object. We
have very few examples of such small objects. But interestingly,
the objects in the Solar system that do have extreme
access ratio it's like five to five to one or something,
are also among the very smallest things in the solar system.
So it's very possible that very small objects often have
these kinds of access ratio. And you know, it's not

(30:48):
like we can't you know, come up with reasons why
that might be. If you take a bar of soap,
and you know, a bar of soap sitting there in
your shower, every time you take a shower, the soap
loses so and it kind of loses soap from all sides.
It doesn't just become a smaller, you know, rectangular prism
with every shower. It becomes flatter and flatter and thinner

(31:09):
and thinner until it's just like, you know, this little wafer.
And so whenever you erode something evenly on all sides,
that's sort of naturally what happens. If you start kind of,
you know, pancake shaped, you'll end up extremely pancake shaped.
So if this object is made of ices of some sort,
some very you know, cold stuff like like water ice

(31:32):
or carbon dioxide ice or nitogen ice or something like that,
then as that ice sublimates away, it would be very
natural for it to end.

Speaker 5 (31:39):
Up having an access ratio like that. That makes sense.

Speaker 3 (31:43):
That could be what's going on, But we have access
to so few objects of this size that it's just
a story.

Speaker 5 (31:49):
But it's plausible, it makes sense.

Speaker 3 (31:51):
The strangest thing about it is probably its orbit so
we caught it pretty late in the game. It had
already come in from interstellar space. It whipped around the Sun.
It was on its way out when it was discovered.
It happened to come very close to Earth then, and
then as it left the Solar System, because it was
the first time we'd seen such an object, it was
tracked pretty carefully by the Hubble Space telescope and other

(32:13):
telescopes on Earth.

Speaker 5 (32:14):
And as we tracked its orbit, it did not.

Speaker 3 (32:17):
Follow the orbit you would expect from just Newtonian gravity,
the orbits that the planets follow around the Sun. It
seemed to be getting some sort of a push away
from the Sun that made it slow down less than
you would think on its way out. So that's called
a non gravitational acceleration. It's not usually seen in large

(32:38):
objects like planets, because what could push a planet around
other than gravity.

Speaker 5 (32:42):
Comets, on the other.

Speaker 3 (32:43):
Hand, tend to have this a lot, and that's because
as they get close to the Sun, the ices on
their surfaces melt. They come off in these big jets,
and then from the rocket effect of that gas escaping
the surface of the comet, the comet will react and
move the other way. And so comets sort of propel
themselves by all of that gas coming off of their surface.

Speaker 2 (33:03):
So, just so that I understand, you're saying, if you
dropped like an innert rock, rock that didn't have any rockets,
wasn't the spaceship had no way to apply a force.
We could predict very precisely how it would move in
the sun the gravitational field.

Speaker 3 (33:15):
If it's a big enough rock that other things can't
push it around, that's right, it's going to follow a
very well defined curve. If you take an astronomy class,
you know it's got to be a circle and ellipse
or a problem or hyperbole.

Speaker 5 (33:27):
These are the conic sections.

Speaker 3 (33:28):
They are the solutions to Newton's equations for two objects
that are gravitationally attracted to each other.

Speaker 2 (33:34):
And so one way to find out if something is
an alien ship, for example, is to see is it
moving under thrust? Basically, is it firing. Some engines like
the Space Shuttle or our ships don't obviously move just
in gravitational orbits.

Speaker 5 (33:47):
Right, right, there's.

Speaker 3 (33:48):
Actually two reasons you would expect an artificial object to
do this. Interestingly, one of the first claims of an
alien spaceship in the Solar System was under very very
similar reasoning. It was by Joseph Schklovsky, who was a
Soviet astronomer who co wrote a book with Carl Sagan

(34:09):
on Life in the Universe, and in that book he
described the difficulties in getting the orbit of Phobos, the
moon of Mars, which people were trying to predict where
the moon would be and it just wouldn't be where
it was supposed to be, and trying to figure out
what the problem was. Now, the problem was probably just
bad data at the time. It was a very faint
object to see back then. But one possibility Shklovsky pointed

(34:32):
out was that it was hollow. Now, why would being
hollow mean it doesn't follow a normal lunar orbit. The
reason is that the Sun's radiation actually carries with it
a little bit of momentum. When the solar photons hit you,
they're kind of gently nudging you away from the Sun. Now,
this is an incredibly weak effect, you'll never notice just
standing there. But if you have a light enough object

(34:53):
like a pebble orbiting the Sun, this actually matters, and
it will make that pebble's orbit around the Sun a
little different than you'd otherwise expect, and so Schklovsky's suggestion
was that despite being very large, many kilometers across that
Phobos was actually hollow, and so that photon pressure from
the Sun was enough because it hardly weighed anything because

(35:14):
it wasn't solid rock to alter its orbit. This didn't
really go anywhere. I think in the end they figured
out it really is just a rock. But it was
an early example of this, and so the same thing
could be happening.

Speaker 5 (35:26):
AVI argues to omu.

Speaker 3 (35:27):
Wa Mua that if it's actually not a big lump
of rock, but it's very thin, or it's hollow or
something like that, then the pressure from the solar photons
will push it away from the Sun much the way
that we saw it getting pushed away from the Sun.
So the argument was, you know, it could be a
comment and that's what we're seeing, or AVI says it

(35:49):
could be highly reflective and hardly weigh anything, and that would.

Speaker 2 (35:52):
Do it too, basically if it's an alien light sale right.

Speaker 3 (35:56):
So AVI works on a project called Breakthrough Starshot, and
the idea idea is to build spacecraft that can travel
interstellar distances to actually go and visit a nearby star system.
And the method that breakthrough Starshot proposes is to build
a light sail. So you have a very small spacecraft
and you attach it to a highly reflective sail, and

(36:17):
then you shoot a powerful laser at the sale, and
that powerful laser will then, through radiation pressure, accelerate it
to extremely high speeds if it's low enough mass. So
his suggestion was that this might be the method that
aliens around the galaxy use to propel their spacecraft. And
then once you get going, you know, those sales, perhaps

(36:38):
they get discarded or perhaps something hits them and they
fall off. But his argument is that the galaxy could
be littered with the detritus.

Speaker 5 (36:45):
Of all of these launches.

Speaker 3 (36:48):
And if that's the case, then we might expect now
and then one of these sales to come, you know,
through the solar system, and you'll be able to tell
it to sale because when light hits it, it pushes it
very easily. It has a very large surface area or
its mass, and you know it was designed so that
photons could push it around.

Speaker 2 (37:05):
And then wouldn't you be able to predict very specifically
how that would move through our solar system? Like it
should get a bigger push when it's closer to the Sun,
a smaller push when it is further away. Did OMMA
follow that kind of trajectory?

Speaker 3 (37:17):
Again, we only caught it on the way out, not
on the way in, so we don't have the complete
orbit for OMU, But from what we could tell, the
acceleration it felt, the non gravitational acceleration was entirely away
from the Sun. So that is consistent with solar photons
pushing on it. It's also consistent with a comment. Now,
there was just a little while ago a study that

(37:40):
looked at what if you had a sale, what, you know,
would it really all be just pushing away from the sun.
So we don't know, you know, how a sale would fold,
what it would be made of, you know what degrees
of freedom it has, what its shape would be, you know,
alien solar sales.

Speaker 5 (37:56):
Who knows. So they just started with.

Speaker 3 (37:58):
A simple toy model to see, you know, roughly what
we might expect. So they just said, okay, it's a
rigid sheet. Let's just take a rigid sheet, let it
get pushed by sunlight, throw it to the sun and
see what happens to it. Oh, and they made it tumble.
They didn't have it always present the same face to
the sun because we know Oua was tumbling. And what
they found was that most of the time the sheet

(38:21):
is not directly pointed at the Sun, which means when
the light reflects off of it, the push is not
directly away from the Sun, but off to the side
at some angle depending on how it's oriented. And so
as it flutters, as it tumbles, the push it receives
from the Sun will keep changing directions, but it will
often be lateral. It's not entirely away. And they found

(38:42):
that for their model anyway, that was inconsistent with the
orbit of omu Wa Mua. And so you can't rule
out any possible solar sail or whatnot. But they said,
if it's really thin and tumbling and it's radiation pressure,
you probably would have seen lateral acceleration. So it's probably
not a light sale.

Speaker 2 (38:57):
So what have zigzagged more if it was a light.

Speaker 5 (38:59):
Sail something like that.

Speaker 3 (39:01):
I don't know the details about whether it would have
a preferential direction to the side. It probably depends on
exactly how it's being pushed. Now, Avi's big argument for
why it needed to be radiation pressure, and not commentary outgassing.
Is that a Muhamua never showed a coma. Most comments
when they get close to the sun, they start evaporating
their ices and that forms a cloud that reflects a

(39:24):
lot of sunlight and they get bright and then some
of that cloud goes off the back and that's their tail.
Muhamoua never showed evidence of a coma. In addition, we
looked carefully to see if we could detect any gases
around it, and the Spitzer space telescope couldn't find any,
and so to AVI, this is pretty conclusive that it's
not a comet, that it was not outgassing, and it

(39:45):
must have been reflection. And if it's reflection, it must
have been low mass, which means it must be artificial. Now,
a lot of planetary scientists subjected to this. It could
be made of a strange kind of ice. After all,
this is an interstellar comet. It's the first one we've seen.
Who knows, you know, what common out there. So my
colleague Steve Dash has proposed that it is made of
nitrogen ice.

Speaker 5 (40:05):
We know nitrogen ice exists. The surface of Pluto has
big regions. That's just nitrogen ice.

Speaker 3 (40:11):
And here I mean if you get you know, the
area breathing cold enough, you know, first you'll get the
liquid nitrogen. And then if you get that liquid nitrogen
much much colder, it'll turn solid. And that's what I'm
talking about. This is so cold that it's solid nitrogen ice.
And that actually fits the data very well.

Speaker 5 (40:28):
If it's a chunk of nitrogen ice.

Speaker 2 (40:30):
So we're talking about a chunk of nitrogen ice coming
through the Solar system, and then the Sun is heating
it up and the nitrogen boils off, and that's effectively
like a little rocket. So the comet is getting non
gravitational acceleration because it's pushing out all those nitrogen atoms,
and that's effectively how a rocket works. So it's like
a natural rocket on the back of a comet. That's

(40:50):
what you're saying.

Speaker 3 (40:50):
That's exactly right, and that's how all commets work. The
question was, with this apparent comet, why didn't we see
all of this dust and gas around it? And so
the answer needs to be it's a very clean commet.
It doesn't have a lot of dust to blow off,
and the gas must be something we didn't look for,
like nitrogen there's another suggestion that it might be hydrogenized,

(41:11):
which would.

Speaker 5 (41:12):
Be pretty exotic. We don't know that hydrogen ized can
even exist in space, but it's.

Speaker 3 (41:16):
A possibility, and that might also fit the data pretty well.
So these are kind of out there explanations. We haven't
seen something like that in the Solar System, or at
least we haven't obviously seen something like that in the
Solar system.

Speaker 5 (41:28):
There are so called dark comets.

Speaker 3 (41:30):
These are clearly commets that're clearly outgassing, because we see
these non gravitational accelerations, but they don't have comi, they
don't have tails, and it's hard to find the gas
around them, and so it could just be that these
dark comets weren't really recognized as being important and interesting
and characteristic of the first thing we'd have.

Speaker 5 (41:50):
Come through the Solar system.

Speaker 2 (41:52):
So you're saying that there are other examples in our
Solar system of non gravitational acceleration without obvious outgassing with
no tail kind of thing. We've seen it before.

Speaker 3 (42:01):
Yes, yes, we've discovered many more of them recently. I
think Omumua has spurred a lot of interest in them.
But yes, there are examples like that.

Speaker 2 (42:23):
That's sort of. My other question is one line of
argument you're making is this thing is small and weird,
and it might just seem weird because we haven't seen
the small stuff in our solar system, and so when
we compare it to the big stuff, it seems weird.
But then why did we see omuumu If the small
stuff in our solar system is hard for us to see,
why did we even see Omuamua.

Speaker 3 (42:44):
Well, one thing, it's very hard to see very small objects,
so it's not surprising it took a long time to
find something that small. Secondly, it's got to get very
close to Earth. Things orbiting the Sun sort of have
preferential orbits. There are certain places we find them, and
they tend not to come very close to Earth because
anything that comes close to Earth will feel Earth's gravity
and get perturbed, and then it won't be in that

(43:06):
orbit anymore. And after five billion years, you know, all
those things will have been cleared out. So you need
something on a strange, temporary orbit. It's not gonna last long.
That comes by, gets deflected by the Earth and it's gone.
So interstellar objects don't care about that. They just go
where they go. If they get perturbed. They get perturbed
because you know they're not going to be around for
long anyway, it doesn't matter. So it's not that surprising

(43:29):
that we don't see these very small objects super close
to Earth if they're orbiting the Sun. But I think
the real answer is just they're hard to find. You've
got to get incredibly lucky, and for the reason I
just said, you're more likely to get lucky apparently with
these interstellar.

Speaker 2 (43:42):
Ones and for a Mumu. There's a detail that I
never understood which released specifically to that, which is that
we only saw it after it was moving away from us.
Why didn't we see it when it was closer to us?
Isn't that when it would have been easiest.

Speaker 5 (43:53):
No, No, we did see it when it was closest
to the Earth, or not long after. It was closest
to the Earth in and out of the Soul system
has to do with where it was with respect to
the Sun. So as it approached the Sun, it was
pretty far away from Earth. I don't remember the exact orbit.
It may have even been in the same direction as
the Sun from Earth's perspective, in which case you.

Speaker 3 (44:12):
Have no hope to see it during the day, and
it was only on its way out that it was
both close to the Earth and visible at night. And
then we got very lucky with its discovery in the
pan Star's survey.

Speaker 2 (44:24):
So its closest approach to the Sun was before it
came by the Earth, which is when we spotted it.
So one lesson from Omulamua might be, hey, there's a
bunch of interesting tiny stuff in our solar system. We
should understand it better so that when tiny stuff from
other solar systems comes through we have more context. Is
that the message?

Speaker 5 (44:42):
I think that's very important. I think all of this discussion.

Speaker 3 (44:45):
On Amula Mua has really made these objects perhaps seem
more interesting and spurred a lot of interest in them,
because it doesn't seem right that the very first interstellar
object we see would be something that has no analogs
in our own soul system. And we're very interested in
these interstellar objects because we have very few examples of

(45:06):
material that's not from our own solar system, and principle,
these things probably formed when the planets in other stellar
systems were forming, and those are hard to study because
they're very far away. But if little, you know, bits
of stuff gets flung out of those and comes here
to Earth and just you know, sort of lands in
our lap.

Speaker 5 (45:25):
That's a great way to study these other systems.

Speaker 3 (45:27):
Not that we can tell exactly which system it came from,
but you know, in principle, just in general, to see
what other fragments of planets from other sellar systems might
be like is super interesting.

Speaker 2 (45:38):
So another topic that people mentioned a lot when Omumua
was discovered was that it seems surprising that we found
one so quickly. As soon as we turned on this telescope,
very shortly afterwards, we found this weird object objects which
people expected to be very very rare. I remember reading
this argument that for us to see one so quickly,
basically every star in the Milky Way would have to

(45:58):
have and eject like ten to the fifteen objects during
its lifetime for us to so quickly see one. What's
the understanding now is now do we understand that while
really stars are creating lots of these stellar debris and
flinging around the Solar System.

Speaker 3 (46:12):
So first of all, we didn't detect a Mua MUAs
as soon as possible. The Pan star survey has been
going on for over ten years. It's just very hard
to detect something this small. You have to really get
lucky that you just happen to catch it when.

Speaker 5 (46:24):
It's close to Earth.

Speaker 3 (46:25):
So it's not that we found when as soon as
we started looking. Rather, when people calculated how many of
these things they expected there to be in the galaxy,
it was thought that these surveys wouldn't get lucky enough
to see one.

Speaker 5 (46:38):
But remember these guesses are based on our.

Speaker 3 (46:42):
Understanding of planet formation, for which we've never had a
physical sample. A lot of these models are, you know,
just trying to understand what's going on inside of these
proto planetsary nebula where you can't really see what's going.

Speaker 5 (46:53):
On, especially objects of this size.

Speaker 3 (46:56):
Those estimates really strongly depend on how many things there
are at different sizes. So generally you know there's gonna
be a lot of big rocks orbiting a star, and
then more medium rocks, and then lots and lots of
little tiny ones, And the total number of rocks strongly
depends on how sort of steep that relationship is. So
for every one rock that's a kilometer across, how many

(47:19):
are one hundred meters across? Is it is ten times
as many? Is it twenty times as many, is it
two hundred times as many? And so on all the
way down to the size of omumamua, And that's really unknown.
We just don't know how many little objects there should be.
So the you know, the number that get ejected for
star required for us to have seen one is a
little on the high end of what we expected, but

(47:43):
it's not completely outrageous. And that number also depends on
how reflective and shiny they are. This object seems to
be extremely reflective, like it's pure ice. That makes the
smaller ones much easier to detect than those previous estimates
would have guessed.

Speaker 2 (48:00):
So even just by getting one or two objects, we
can infer something about the broader population of zillions and
zillions of objects.

Speaker 3 (48:07):
That's really fascinating, right, Yeah, in order for us to
have seen one by now, there must have been a lot,
and I.

Speaker 5 (48:11):
Should point out we now have two.

Speaker 3 (48:13):
There's also common borisofv So shortly after a muhama, a
second comment, interstellar comment was discovered, and it actually looks
a lot like we.

Speaker 5 (48:21):
Expected Intersteller comments to look.

Speaker 3 (48:23):
So I don't know whether that makes a muamoa weirder
or more ordinary. It kind of goes both ways. It
means that, yes, it's not weird that we found a muhama.
We found Borisov too. On the other hand, Borisoft doesn't
look like a muhama. So there's at least two different
kinds of these comments.

Speaker 2 (48:37):
Apparently, and in the context of the question of like
is this a natural object or an alien object? It's
not implausible. You're saying that there could be enormous numbers
of these bits and pieces of other Solar systems floating around,
rainy down on us occasionally.

Speaker 5 (48:52):
It's in fact quite expected.

Speaker 3 (48:54):
Like we know that the planet formation process kicks out
the building blocks, planets, little asteroids, little commets. We know
that that happens, and we still see that in the
Solar System because Jupiter knocked a lot of these things
during planet formation out of the Solar System. We know
that because some small fraction of those things that kicked
out of the Solar System didn't quite make it. They

(49:16):
got far from the Sun, they slowed down, slow down
from the Sun's gravity, and the Sun just barely held
on to them. And now they orbit the Sun in
the Orc cloud and occasionally come and visit us as
long period commets, and so you know, you can tell
from the number of comets that come in how many
didn't get fully ejected, and from that try to extrapolate
to how many must have successfully been ejected.

Speaker 5 (49:36):
And it's a lot.

Speaker 2 (49:37):
But in comparison for us to see, for example, a
piece of alien junk, it would mean that the galaxy
has to be like overflowing with alien junk, right, Like
if we're seeing a light sale, that would suggest that
there are like ten to the fifteen alien junk light
sales out there as well.

Speaker 3 (49:52):
So Audi's hypothesis is that it is very common to
launch large numbers of spacecraft with light sails, and that
the galaxy is just filled with the litter from all
of these space launches all the time. So yeah, you
have to imagine sort of a pangalactic technology that's sending
ships from star to star.

Speaker 5 (50:13):
All the time.

Speaker 2 (50:13):
Wow, well, that is a large hypothesis to consider. Let's
also talk about the velocity of this object. I understand
that it had a sort of unusual or unexpected speed
as it entered the Solar System, right.

Speaker 3 (50:25):
So there's a big caveat which is that we don't
know how it entered the Solar System, because that depends
on the amount of non gravitational acceleration that it experienced,
and it depends on how much mass it lost. So
under the ice models, I think we favor most it
lost something like ninety percent of its mass as it

(50:48):
warmed up and got near the Sun, which means it
experienced a lot of non gravitational acceleration before we even
saw it. But we don't really know how much that.

Speaker 2 (50:57):
Big error bars on there, So it could have been
a huge bar of soap as it approached the Solar
system and then we just saw a little sliver after
it got melted by the Sun.

Speaker 5 (51:05):
That's exactly right. That could very easily be what happened.

Speaker 3 (51:08):
And with big uncertainties like that, it's hard to extrapolate
backwards and get.

Speaker 5 (51:14):
An accurate reading on how it came in.

Speaker 3 (51:16):
Now, if we do our best and say, you know,
where did it probably come from, then the direction it
came from is kind of interesting. It's basically exactly the
direction the Sun is headed through the galaxy, and the
speed it came in at is basically exactly the speed
of the Sun through the galaxy, which means it was

(51:37):
basically from the galaxy's perspective.

Speaker 5 (51:39):
Sitting still, it wasn't moving at all. We ran into it,
and that's very.

Speaker 3 (51:45):
Interesting, and so some people have tried to hypothesize what
that could mean. We suspect that this thing was kicked
out of a young stellar system when its planets were forming,
So a new star that had been born, say millions
of years ago or something like that, and stars form
out of clouds of gas, and clouds of gas typically

(52:07):
are kind of stationary in the galaxy. So everything orbits
the galaxy. And if you just sort of look at
the velocity on average of all this stuff orbiting, that's
what I mean by standing still. That's what we call
the local standard of rest, and that's the orbit you
would just expect stuff to take.

Speaker 5 (52:22):
If it hadn't been pushed around gravitationally by things. So
gas tends to be in that kind of an orbit.

Speaker 3 (52:28):
The stars it forms tend to be in that kind
of orbit, and this stuff that gets ejected from those
young stars tend to be in that kind of an orbit.
The Sun is over four.

Speaker 5 (52:37):
Billion years old.

Speaker 3 (52:38):
In those four and a half billion years, it's had
close encounters with stars, It's gone by giant molecular clouds.
It's gotten perturbed and bumped around, and now its orbit
is kind of wonky. It kind of bobs up and
down and in and out, and it has this velocity,
and it's that velocity that we saw reflected back at
us from Omuamua. So the story that makes sense, but

(52:59):
again big Aerbars, is that a nearby cloud of gas
formed a star millions of years ago in this special
velocity frame, you know, in this kind of orbit around
the galaxy, that star kicked out o'muamua. Omua has very
low velocity with respect to that star because it just
barely escaped and then whacked the sun came.

Speaker 5 (53:19):
And plowed right into it. So it all kind of
hangs together.

Speaker 2 (53:22):
And this sort of more sensationalist view is that it's
like a buoy. It's some sort of like it's at
rest with respects of the galaxy to serve as like
a navigational beacon or something.

Speaker 3 (53:33):
Right, And so Aby sees this special velocity and says,
what are the odds that it would have that velocity?
And we're like, well, you know, pretty good if it's
a young object, because that's the velocity young objects has
it's never mind, lots of things going different velocities, why
would it be special. So then he dreams up a
reason why aliens might want to put an object in

(53:53):
that particular reference frame, and so he suggested it was
like a booi, that it sits there for some purpose
at that velocity. And then I guess the sun came
along and knocked it out, and now it's, you know,
headed off in some other direction. I mean, I guess
I don't know why they would do that. It also
doesn't seem consistent with it being a light sale. If
it's just a discarded light sale, that's not a booi,
that's just a piece of litter. Or maybe the thing

(54:14):
that got launched was a booi, and it's I don't
really understand anyway. You know, you can always dream up
some reason aliens might make something have a particular character,
but I'm not sure for Omua Mua. We have one
story that explains all of these characters.

Speaker 2 (54:29):
So then to wrap up, Omumu is definitely an interesting object, right.
It had a sort of unusual shape, maybe some unusual reflectivity.
Fascinating acceleration tells us something maybe about the population of
these things in our Solar System and in other solar systems,
the velocity of stuff. But all in all, what is
your best hypothesis? Is it that it's some chunk of

(54:50):
nitrogen or hydrogen ice that the Sun basically plowed into.

Speaker 3 (54:54):
Yeah, So with the caveat that I'm not a planetary scientist,
like I got into this because people were asking me,
as the director of the Penn State Extraterrestrial Intelligence Center,
what I thought of claims that it might be a spacecraft.
And so in addressing those claims, you know, I had
to learn from the planetary science community.

Speaker 5 (55:12):
What was weird about it, what wasn't weird about it?

Speaker 3 (55:15):
And so, you know, I worked with two planetary scientists,
Sean Raymond and Steve Desh, who taught me a lot
about these things and about what we do and don't
know about Omuamua, And we thought about all of the.

Speaker 5 (55:26):
Different suggestions that have been made.

Speaker 3 (55:29):
So I basically reflect what they, as experts, tell me
sounds most reasonable, and that is that it's a chunk
of ice, that it's a comet that has some weird
kind of ice, and that's really interesting. Steve's preferred hypothesis
is that it's nitrogen ice, and he's worked really hard
to show that that fits all the data very well
and is a plausible substance other people like hydrogen. And

(55:49):
you know, there also might be ideas that just we
haven't come up with yet. It could be that when
we finally get a close look at one of these things,
we're surprised. You know.

Speaker 5 (55:56):
Oh, of course, that's why Omumama looked like that.

Speaker 2 (55:59):
Tell you talk about the sort of role of these
crazy hypotheses in science. You know, Amy makes a lot
of noise about being like Galileo. You know that his
ideas aren't being taken seriously, et cetera. Tell me, do
you think it's useful for us to entertain these crazy ideas?
What do you think about is the comments he's made
in public about this versus the comments he's made in
sort of more academic settings.

Speaker 3 (56:21):
I think it's really important that we constantly challenge conventional wisdom,
especially in areas where we have very little data, like
small small objects around the Sun or interstellar comments. And
I think it's very easy for us to feel like
we've got everything figured out and then be blind when
data showing us that we're wrong comes along.

Speaker 5 (56:41):
And rejecting it.

Speaker 3 (56:42):
It's like, oh, well, that's that's an extraordinary hypothesis that
we could have been wrong.

Speaker 2 (56:46):
You know.

Speaker 5 (56:46):
But for the.

Speaker 3 (56:47):
Most part, I think scientists are really eager to be
the one that makes that big surprising discovery. We tend
to be very open minded about this stuff. And you know,
when this started coming through, science fiction had already primed
us to think it might be an alien spacecraft. You know,
there's this story by Arthur Clark Rendezvous with Rama, and
on Twitter. As soon as it, you know, was announced,

(57:08):
we were joking like, oh, we've got to name it Rama.
Maybe it's an alien spacecraft. Like, you know, this idea
was out there. These kinds of challenges to our conventional
thinking are important, and I think in general they are
appreciated by most scientists, provided you know, the level of
certainty that's being conveyed here is appropriate. You know, have

(57:29):
we considered this, have we ruled it out? Could it
be this is kind of weird?

Speaker 5 (57:32):
Wouldn't that be cool? You know, as long as.

Speaker 3 (57:35):
You're acknowledging the weight of evidence that it's not from
prior experience, I think it's fine. Where I think Avi
rankles a lot of people is by you know, claiming that,
you know, his ideas are being shot down, you know,
just because they're radical, and not because of the certainty.

Speaker 5 (57:53):
He's conveying to the public and how likely it is.

Speaker 3 (57:55):
I mean, he wrote wrote a whole book that you know,
it hedges a little, it's little meally mouthed, but it's
basically making the argument that it must.

Speaker 5 (58:03):
Be an alien spacecraft.

Speaker 3 (58:05):
And he makes statements in the media that you know,
it really needs to be artificial, when that's not true
at all. And that's when people really start getting you know,
upset with a lot of obvious behavior. And then you know,
when he comes back and says, we're just being closed
minded and we're just this is just professional jealousy of
all the attention he's getting.

Speaker 2 (58:26):
You know, that gets old really fast, right, You wrote
in your essay quote Loeb's work is unambiguously counterproductive, alienating
the community working on these problems and misinforming the public
about the state of the field. And as somebody who
works both in academia trying to understand the sort of
the cutting edge knowledge and interfacing with the public, I'm

(58:47):
definitely sensitive to this question of like how we present
our work to the public with all of its nuances
and caveats, and how that reflects the work being done
sort of at the cutting edge. It's important to get
that balance, right, I agree with.

Speaker 3 (58:58):
You, Yeah, And you know, to be clear, the problem
isn't that he suggested it's an alien spacecraft, right, That's
not counterproductive. That's fun, that's interesting. We should be wondering,
just like Shrowsky did, if there we might be able
to find alien spacecraft in the Solar System, that'd be
very cool. So or at least we can show there
aren't any. And you know, that's something people have studied

(59:18):
and talked about and you know, is very appropriate. It's
the you know, my objection is to the level of
certainty that he projects on the fact that this is
one to the public, but also the way that he
dismisses expertise of people who have studied this stuff their
whole careers and gets angry at them for contradicting him,
and just tells people that they're wrong and closed minded

(59:39):
and they don't know what they're talking about, even though they,
you know, are the ones that have degrees in the
field and have studied it for.

Speaker 5 (59:45):
Decades, you know, And he's just coming into it for the.

Speaker 2 (59:48):
First time, right, And of course every scientist would love
if he was right, if we did discover aliens or
a piece of alien junk, we'd all be jumping for joy.
Something else you wrote in your essay quote, there is
little joy for debunking claims in science. I think resonated
with me also, because, yeah, we would love to make
this discovery, but of course we got to be cautious

(01:00:08):
and we got to be careful extraordinary claims and extraordinary evidence.
As we've always said, yeah.

Speaker 3 (01:00:13):
That's right, and it really is no fun debunking claim
In the early days of planet discovery, when I was
a graduate student, there were lots you know, every time
you found a planet, it was on the front page
of the New York Times, and so there was a
lot of incentive to fool yourself into thinking that some
signal that you detected was a planet around another star.
And so there were a lot of planes made that

(01:00:34):
were clearly right, a lot that you know, a little iffy, and.

Speaker 5 (01:00:37):
Some that were just wishful thinking, unfortunately on the part
of the astronomers that made them.

Speaker 3 (01:00:41):
And we were always torn, like do we stop the
work we're doing finding these new planets to go and
debunk this other claim and kind of clean up the
masks and say no, no, that one turned out not
to be right, because you know that's no fun. No
one likes being the party pooper. You know that person
isn't going to like you very much after you've done
something like that. But also, we have better things to do, right,

(01:01:03):
You have cool new planets to go find, and you
only have so much time, and so it is frustrating,
and you know it needs to be done. When claims
reach a certain level of attention that you know someone
needs to come in and sort of spell out, actually,
you know what we really think about it.

Speaker 2 (01:01:17):
Well, thank you very much for taking the time to
go through all these points and give us an understanding
of what sort of the cutting edge science is on
these questions. And thank you very much for talking to
us today. Very helpful and a lot of fun to
learn about this. What do you think the future holds
for this field? Do you think we'll see more of
these things come into our solar system and learn more
about the sort of small dark objects in our own

(01:01:38):
solar system and the rest of the galaxy.

Speaker 5 (01:01:40):
Yeah, I really do.

Speaker 3 (01:01:41):
The Reuben observatory is coming online in just a few years,
and it's going to perform this gigantic survey. It's going
to image the entire southern sky every three days basically,
and it will have so much light collecting power and
it will survey so much of the sky at once
that it will probably find things like oh Muamo almost

(01:02:03):
every year. And that means we'll have a lot of
these to study, and we'll be able to catch some
of them on the way into the Solar System and
see how much mass they lose. We'll be able to
see how many of them look like oh Muhamoa, you know,
and try and you know, learn about their characteristics more generally.
They're even plans, which I just find amazing and wonderful,
to launch spacecraft to go catch one of them. Now

(01:02:26):
they're moving too fast to actually just straight up catch,
but you could launch something that sort of lurks in
the Solar System and when an opportune one comes on
that it could intercept, could fly in the way and
intercept it and get close up pictures and maybe even
get a sample.

Speaker 2 (01:02:40):
Wow, that would be awesome. And I do still, of course,
have some hope that maybe one of them is a
piece of alien space junk, and that would be an
incredible discovery.

Speaker 5 (01:02:48):
That would be pretty cool that I'd be very excited
about that.

Speaker 2 (01:02:51):
All right, Well, thanks again very much for coming on
the program today.

Speaker 5 (01:02:54):
My pleasure. Thanks for having me.

Speaker 1 (01:02:56):
All Right, that was a great interview. It's kind of
interesting that Jason's job it is also to look for
extraterrestrial life.

Speaker 2 (01:03:02):
Yeah, he's not only interested in this stuff, and like
many of us, he wants to discover aliens. Right, Nobody
is out there debunking obvious claims because we don't want
to believe in aliens. We all want to believe it.
It would be the discovery of the millennium of history.
But we also don't want to mislead the general public
about something that was most likely just a chunk of ice.

Speaker 1 (01:03:22):
And so in general, Jason thinks that it could all
be explained, all of the weird things about Omuama have
a more non alien explanation.

Speaker 2 (01:03:32):
Yeah, Jason thinks that this is actually teaching us something
about solar systems, that Omama may not be that unusual,
and that there might be these chunks of ice out
there in other solar systems and in ours. One of
the big points in the book is that this thing
looks different from the things in our solar system. But
Jason points out that we're not great at seeing these
things even in our solar systems. So it might be

(01:03:52):
that there's a whole hidden ocean of these chunks of
ice out there in our own or cloud we just
didn't know about them, And so maybe Omumua's not that unusual.
It's just sort of telling us something about the world
out there and our own backyard.

Speaker 1 (01:04:05):
Have we seen anything like it since it's been now
five years.

Speaker 2 (01:04:09):
Well, we have seen another interstellar object two Iborisov also
came through our solar system a couple of years later,
and people have started looking for Oma like objects in
our solar system and they've seen a few. They've seen
some dark comets, these things that have non gravitational acceleration
without displaying any sort of tail or coma. So I
think it really has cracked open the door for us

(01:04:30):
understanding our own solar system a bit better.

Speaker 1 (01:04:33):
Or maybe the aliens are just sending us a bunch
of messages, or maybe we're a popular tourist destination.

Speaker 2 (01:04:38):
Or maybe we're just a dumping ground for alien junk.

Speaker 1 (01:04:41):
No, but the junk left, didn't it.

Speaker 2 (01:04:43):
That's true. Yeah, maybe we're just a byway for alien
junk towards the galactic dump.

Speaker 1 (01:04:48):
Well, I guess that would still be a pretty interesting
discovery Alien junk mail.

Speaker 2 (01:04:52):
That would be awesome and I look forward to the day. Aliens.
Please do send us your.

Speaker 1 (01:04:56):
Junk all right, Well, we hope you enjoyed that. Thanks
for joining us, see you next time.

Speaker 2 (01:05:09):
Thanks for listening, and remember that Daniel and Jorge Explain
the Universe is a production of iHeartRadio. For more podcasts
from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever
you listen to your favorite shows.