February 11, 2026 • 35 mins
NASA is sending astronauts back to the moon. But why? What deep mysteries still hide on the far side of the moon? Jorge jumps over the moon to find out.
See omnystudio.com/listener for privacy information.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
Hey, please take a second and leave us a review
on Apple Podcasts, Spotify, or wherever you listen to the podcast.
Thanks a lot. Hey, Welcome to Science Stuff, the production
of iHeartRadio. I'm poor, Hey Champ, and today we are
going to the Moon. You might think you know the moon,
(00:22):
but actually it is full of scientific mysteries. We're going
to be talking about where the moon came from, what
it's made out of, and what it can tell us
about how life started on Earth. So get ready to
go over the moon as we tackle the unanswered questions
about our mysterious moon enjoying. Hey everyone, Today we're talking
(00:49):
to doctor Matt Siegler. Doctor Ziegler is a planetary scientist
at the University of Hawaii who works on several missions
for NASA and the European Space Agency, including did You
Are the miss mission to put astronauts back on the Moon.
He's going to answer three questions for us. Number one,
where did the moon come from? As it turns out,
(01:10):
it's really unusual for us to have such a big moon.
Number two, why does the moon always faces the same way?
Wasn't always the case? And number three, why are we
going back to the moon? It turns out scientists have
identified a deep mystery about the Moon that might have
huge implications for space travel and our search for extraterrest
(01:34):
deal life. So here's my conversation with doctor Matt Siegler. Well,
thank you doctor Siegler for joining us again.
Speaker 2 (01:42):
Okay, welcome.
Speaker 1 (01:44):
The last time we talked it was New Year's and
we talked about how the Earth goes around the Sun.
And now we're getting close to the lunar New Year,
so I thought it would be interesting to talk about
the moon.
Speaker 2 (01:54):
Okay, that's actually my specialties. That's great to talk about
something that I know.
Speaker 1 (02:01):
Are you saying you're a lunatic?
Speaker 2 (02:03):
Yes, yeah, we're proud to call ourselves lunatics.
Speaker 1 (02:08):
Well, in what ways is our moon unusual in the
Solar System?
Speaker 2 (02:12):
Okay? Well, the weirdest thing about our moon is how
big it is compared to Earth. There are a couple
of moons out there, some of Saturn's moons and a
couple of Jupiter's moons that are about the size of
our moon or even a little bigger. But those planets
are huge, right, you could fit I think it's thirteen
hundred earths inside of Jupiter, right, Wow, huh. And so
(02:36):
their biggest moon is a very small moon compared to
the size of its body, meaning.
Speaker 1 (02:41):
Like if Jupiter had a moon that's proportionately the same
size as our moon, it would be like the size
of Saturn or something.
Speaker 2 (02:47):
Yeah, it would be like the size of Neptune at least.
So yeah, And the only other planet that, if you
want to call it a planet that has a similar
is Pluto.
Speaker 3 (02:56):
Right.
Speaker 1 (02:56):
Oh, no, no, we don't talk about Pluto in this podcast.
Speaker 2 (02:59):
You don't talk about about plu.
Speaker 1 (03:00):
We don't know.
Speaker 2 (03:03):
Pluto has a moon that's about a tenth of its
size or something like that.
Speaker 1 (03:08):
But plut itself is very small, smaller than us, right,
smaller than our moon kind of.
Speaker 2 (03:12):
Yeah, Pluto is around it could fit inside the continental US.
So it's a pretty small body.
Speaker 1 (03:18):
Okay, Oh, that's a very polite way to say it.
It's a small body. Yes, yes, small body.
Speaker 2 (03:24):
So that's the weirdest thing about our moon is how
big it is compared to us.
Speaker 1 (03:30):
So that's the first mystery about the moon. Why is
it so big? None of the other planets have a
moon this big.
Speaker 3 (03:38):
Why is that?
Speaker 1 (03:39):
Well, as it turns out, Charles Darwin's Sun George Darwin
had a theory about that.
Speaker 2 (03:46):
So that's actually a funny part of the history is
our moon is relatively large. It's about the size of
the Pacific Ocean basin, and so Charles Darwin's son, I
believe George Darwin first theorized that the Moon might have
been created from the Earth by being spit out of
the Pacific Ocean basin, and the Pacific Ocean was the
hole left behind. So that's a good way to remember
(04:09):
the size of the Moon is roughly the size of
the Pacific Ocean, because that was one of the first thoughts, Well, well,
we have a hole here on Earth that's about the
size of the moon.
Speaker 1 (04:19):
Yeah, maybe that's came It was like a giant pimple
that just popped off the Earth. That was the theory, yes, yes,
or the Darwin giant pimple theory. Yeah, George Darwin didn't
quite get thinks is right as this famous dad Charles Darwin,
or did he?
Speaker 2 (04:39):
Now we kind of think it's crazy, but really how
we think the moon formed now was not all that different.
It's just that that spitting out happened in a big
event when something the size of Mars or so collided
into the early Earth and caused that event where material
got spit out and formed the moon.
Speaker 1 (05:00):
That's a wild theory, Like we have a moon that's
like gray white, but we think it happened because some
giant mini planet crashed into the original Earth.
Speaker 2 (05:10):
Yeah, so that's the idea is the original early Solar
system was full of things that were flying all around,
and some of them collided into each other, and the
debris of that collision formed something kind of like a
ring of Saturn around the Earth. Right, it was a ring,
and then that coalesced together and became the Moon.
Speaker 1 (05:27):
So like our Earth is a mix of those two
original planets, and the Moon is a mix of those
two original planets.
Speaker 2 (05:32):
Exactly.
Speaker 1 (05:34):
Yes, scientists think the way the moon form was that
a planet the size of Mars crashed into a pre
Earth planet about four and a half billion years ago,
and then the debris from that crash clumped together and
formed the Moon. But here's a big question, how do
we know that? What makes us think that's how the
(05:55):
Moon formed. Well, it turns out this idea started when
we first walked on the Moon.
Speaker 2 (06:02):
And this explains basically what we found when the Apollo
samples were returned in the nineteen sixties and seventies. Huh,
was that a lot of the isotopes of atoms were
incredibly similar between the Earth and the Moon.
Speaker 1 (06:18):
What do you mean isotopes?
Speaker 2 (06:19):
So normally an atom will have the same number of
protons and neutrons, and so an isotope is one that
has different numbers of neutrons.
Speaker 1 (06:28):
Okay than the normal one I see. And so it's
where for the isotopes on Earth to match the ones
on the Moon.
Speaker 2 (06:35):
Yeah, So that turns out to be one of the
key identifiers of where something formed in the early Solar
System is it's the isotopes of its different atoms, and
particularly good one is oxygen.
Speaker 1 (06:49):
It turns out you can tell exactly where in the
Solar System a piece of rock comes from by its isotopes.
Like a piece of rock has more of one kind
of oxygen or carbon, you can tell it came from
close to the Sun, or near Jupiter, or way out
at the edges of the Solar system.
Speaker 2 (07:09):
So we think the whole Solar System essentially was a
big cloud of gas and dust that was leftover from
some other star that exploded, right, huh, And that cloud
kind of collust around the early Sun, and then when
that Sun turned on, you know, very early in the
Solar system four point six billion years ago, it heated
that cloud and basically boiled off different isotope ratios as
(07:33):
you went different distance from the Sun. And then when
the planets formed, out of those different isotopic ratios as
a function of distance away from the Sun, they seem
to have checked those isotopes permanently after that.
Speaker 1 (07:47):
Interesting, it's like the rocks have a tag that says
where in the Solar System formed.
Speaker 2 (07:53):
Yeah, so when we see a meteorite that we have
identified has come from Mars or a meteorite from the
Asteroid belt, these will have different oxygen isotope ratios than
the Earth. But the Moon has almost the same as
the Earth, like too incredible precision, such that the only
(08:17):
way that we can explain it was that they essentially
formed together as a single body. Okay, and so the
Earth and the Moon are incredibly similar, and it could
be that it's just kind of telling us they formed
at the exact same distance from the Sun. But the
precision in which they match seems to only be explained
if they really formed together in this idea of the
(08:39):
giant impact or simple.
Speaker 1 (08:44):
I see the match is too good. It's just too
identical to the Earth.
Speaker 2 (08:47):
Yeah, Like these are identical twins, you know, they had
to be born from the same mother.
Speaker 1 (08:53):
I see the DNA says their siblings, same mother, same father.
Speaker 2 (08:56):
Okay, And so there were lots of theory going around,
and as far as I understand it, there was some
international meeting about this in the early nineteen eighties and
there was a lot of debate, and then out came
the giant impact as the winner, and it's kind of
been the standard since then.
Speaker 1 (09:13):
Interesting. So it's not like we have some smoking gun
that says that this is what happened, or that there
was a camera or somebody saw this happened. It's like, well,
we can't think of anything else, and this is the
only thing that we have left.
Speaker 2 (09:25):
Yeah, and everything that we find out knew about the
Moon seems to fit with the theory of the giant impact.
Like what like one of the things we found out
was from seismometers on the Moon. We've been able to
figure out that the Moon has a fairly small iron core, right,
and the Earth actually has a really big iron core
for its size. And so where did this extra iron
(09:49):
on the Earth come from and the lack of iron
on the Moon come from. Well, it may have been
that you had this big impact and then more the
iron went into the big object than into the small
on it.
Speaker 3 (10:01):
Oh.
Speaker 1 (10:01):
I see, what do you think the junior Darwin would
feel now that you've disproven his theory and not lived
up to the greatness of the Darwin name.
Speaker 2 (10:12):
I don't know. I think scientists by nature like to
know the truth or the facts about the matter, and
if an idea that we clung to turns out to
be wrong, we should kind of give it up.
Speaker 3 (10:24):
Yeah.
Speaker 2 (10:24):
So I think that was a strong philosophy of science
then and it still is today.
Speaker 1 (10:29):
Nice all right, when we come back, we're going to
tackle the second big mystery about the moon, which is
why is the Moon always facing us the same way?
In case you haven't noticed, every time you look at
the Moon, no matter where you are on the planet
or what time of the month or year, it is,
the features on the Moon always look the same, even
(10:50):
though it's spinning around the Earth. How can it be
that it's training at just the right rate for it
to always look the same to us?
Speaker 3 (10:59):
We'll answer that.
Speaker 1 (10:59):
Question and more after the break.
Speaker 3 (11:02):
We'll be right back. Hey, we'll come back.
Speaker 1 (11:15):
We're answering questions about the moon, and so far we've
talked about where the moon came from four and a
half billion years ago and how scientists figured out what happened.
Now we're going to answer another big question about the moon,
which is why is the Moon always facing us the
same way? If you think about it, the Earth is
going around the Sun, but the Earth doesn't always face
(11:38):
the same way to the Sun. If you were standing
on the surface of the Sun, the Earth would look
like it's spinning and it would look different every time
you see it. But you can't say that about the Moon.
The features of the Moon always look the same to us.
The only people in history that have gotten in a
different view of the Moon are the Apollo astronauts that
(12:00):
went there back in the nineteen sixties. Well, the reason
that the Moon always looks the same to us, according
to Professor Matt Ziegler, has to do with the fact
that the Moon isn't round. Okay, next question, Matt, why
is the Moon always facing the same way to us?
Speaker 2 (12:18):
Okay, So the moon is what we call tidally locked
which essentially means one side is always facing us.
Speaker 1 (12:26):
Right. Is that another characteristic of science.
Speaker 2 (12:30):
If you don't know, we give it a fancy name
and basically says this is all we know about it. Yeah.
So a lot of moons in the Solar System are
also tidally.
Speaker 1 (12:41):
Locked, not just our moon.
Speaker 2 (12:43):
Like Jupiter's moons gets large. Four moons are all tidally locked.
So one face of Io is always facing Jupiter, one
face of Europa is always facing Jupiter.
Speaker 1 (12:54):
Whow, we're not alone. Our moon is not the only one.
The moon is what scientists call tidally locked, which basically
means it's always facing us the same way. But there
is a reason why this happens, and it has to
do with how gooey the Earth and the Moon are.
Speaker 2 (13:16):
This happens essentially because of how gooey an object is.
Speaker 3 (13:21):
Uh huh.
Speaker 2 (13:22):
So if something's spinning and it's gooey inside, it can
dissipate energy.
Speaker 1 (13:27):
Okay, meaning like if you were spinning a water balloon.
Speaker 2 (13:30):
Yeah. Or a good analogy is if you're spinning a
hard boiled egg versus a normal egg. Right, the hard
boiled egg will spin and spin and spin, right, but
the non heart boiled egg will slow itself down pretty
quickly because that ah, yeah, that goo inside is kind
of churning around and dissipating energy of that spin.
Speaker 1 (13:51):
I see, if I spin a raw egg in space,
it'll eventually slow down because the liquid inside is losing energy.
Speaker 2 (13:57):
Yeah, And so something akin to this happens inside of
a body like the Moon that initially early on at
least had a large liquid inside of it, right.
Speaker 1 (14:07):
Oh. It initially the Moon was gooey, oh yeah, because
it was formed from the giant impact right, which was
really hot and made a lot of things melt. What
doctor Ziegler is saying is that when the Moon formed,
it was probably spinning really fast, but the inside of
it was gooey. It was melted rock or lava. It
(14:29):
was still hot from one the huge collision that formed
the Moon happened, and that melted inside made the Moon
stop spinning.
Speaker 3 (14:37):
It's sort of like.
Speaker 1 (14:38):
If you take a regular plastic water bottle and you
try to toss it up into the air so that
it spins, it'll eventually stop spinning in mid air, and
that's because the water inside.
Speaker 3 (14:48):
Of it slashes around.
Speaker 1 (14:50):
Well, the same thing happened to the Moon, and actually
it's also happening to the Earth.
Speaker 2 (14:57):
And the Moon is doing this today to the Earth. Actually,
and so the Earth is actually slowing down. Right, Our
day is twenty four hours now. It used to be
twenty two hours, and earlier on in the Earth's history
it was as short as four hours. So we think
when the Earth and Moon formed that the Earth day
(15:18):
was about four hours long.
Speaker 1 (15:20):
Really, yeah, we were spinning that fast.
Speaker 2 (15:23):
Yeah, and then the Moon has caused us to slow
down that we're now at twenty four hours a day.
What maybe in a billion years will be at twenty
five hours a day or something like that. Right.
Speaker 1 (15:35):
Oh, so the reason the day feels this long is because.
Speaker 3 (15:38):
Of the moon.
Speaker 2 (15:39):
Yeah, it's the moon's fault.
Speaker 1 (15:40):
You had a long day, Blame the moon. Howl of
the moon.
Speaker 2 (15:43):
Yeah, but if your day was too short, if it
went by too fast, then think the moon.
Speaker 1 (15:49):
Right, Oh yeah, that's right, that's right.
Speaker 2 (15:50):
So the same way that the Earth day is slowly
getting longer because the Earth is slowing its spin, the
Moon went through something similar. It's just because the Moon
is a lot smaller, it happened a lot faster. Basically.
Speaker 1 (16:03):
Okay, maybe take me back, So we had this big crash,
A lot of stuff went out there into space eventually
formed the moon. The moon had a squishy inside, meaning
like it was lava inside.
Speaker 2 (16:14):
Right basically, right, Yeah, basically it's magma if it's not erupted.
Speaker 1 (16:19):
Not the whole other episode. It was magma or lava
melted rock. It was melted rock, and it was spinning
super fast.
Speaker 3 (16:26):
Yeah.
Speaker 2 (16:26):
So we had a fast spinning Earth and a fast
spinning Moon, and basically them tugging on each other slowed
each other down. Okay, So if I was a live
bike there and on Earth, I would die because I
couldn't breathe and standing on lava. But if I could
somehow be there, my day would be four hours long,
and I would see the moon like basically spinning in place.
(16:47):
The Moon would look different every time I looked at it. Yeah,
you would see the far side of the moon back then.
Speaker 1 (16:53):
Oh okay, And over time we slowed down and the
moon slowed down to the point where now it's always
looking at us the same way. Yes, So is it
just luck that we just happened to be alive at
a time when it's spinning. It just the right time
for it to be always looking at it, or is
it stuck there?
Speaker 2 (17:10):
I wouldn't say it's that lucky, because we think it's
stuck very quickly, like in potentially a few thousand years
to less than a million years, Like the moon slowed
itself down very quickly. So the moon'spent tidally locked for
most of Earth's history, really, and then it got stuck there. Yeah,
and then it's been stuck there. And it's a little
(17:32):
arbitrary which side ended up stuck facing the Earth. And
that's still a debate of why the near side of
the Moon is the near side.
Speaker 1 (17:41):
Okay, you might be wondering, if the Moon went from
spinning really fast to slowing down, why did it stop.
It's still going around to Earth, so why didn't the
Moon suddenly start spinning in place the other way? Well,
according to doctor Siegler, it all has to do with
the shape of the moon.
Speaker 2 (18:00):
The Moon isn't a perfect sphere. It's kind of egg
shaped itself or what rugby ball shaped or whatever you
want to call it. Yeah, just slightly.
Speaker 1 (18:09):
Yes, the Moon is not perfectly round. You might have
heard that the Earth is not perfectly round either. It's
a little wider around the middle or the equator. That's
because the Earth is spinning, and so it bulges out, but.
Speaker 2 (18:23):
The Moon isn't round.
Speaker 1 (18:24):
In a different way and for a different reason, the
Moon doesn't bulge out, it's actually stretched out. It looks
slightly closer to a rugby ball or an American football
ball with one of the pointy ends pointing at the Earth.
And the reason it's that shape isn't because it's spinning,
but because the Earth is pulling on it. As the
(18:46):
Moon goes in orbit around the Earth, the Earth's gravity
pulls on the Moon to keep it in that orbit,
and that causes the Moon to get stretched. And I
think I came up with a good analogy for tidal logging,
which is that sort of like if you're in a
merry go round and someone's at the edge and they're
about to fall off, like you grabbed their hand to
(19:07):
keep them in the merry go round, and so the
centropgal force is pulling them out, but I'm holding their
hand pulling them in, and so that causes them to stretch, right.
Speaker 2 (19:17):
Okay, Yeah, that would be a good description of it.
Speaker 1 (19:20):
Yeah, okay, And so that's what causes the Moon to
look sort of like a football shape pointing at us.
Speaker 2 (19:26):
Yeah, and at some point in the Moon's history it
became solid enough, it cooled off enough that it froze
in a football shape at that time.
Speaker 1 (19:36):
Okay, so here's what scientists think happened. There was a
pre Earth planet somewhere close to our current orbit. He
got smashed by another planet about the size of Mars.
Some of the debris stayed in place and became the Earth,
and some of the debris floated out in space and
became the Moon. This new Moon was an orbit around
(19:57):
the new Earth, but it was gooey and melted on
the inside. That made it stop spinning in place. And
because it was being pulled around in an orbit around
the Earth, it stretched out a little to be closer
to the shape of a football pointed back at the Earth.
Then it cooled off and it got stuck in that shape.
And once it got stuck in that shape, it became
(20:17):
tidally locked, with one end of the football always pointing.
Speaker 3 (20:20):
At the Earth.
Speaker 1 (20:22):
Wait, wait, wait, wait, I think what you're saying is
that just because of the particular history of when the
Moon cooled is the reason we're always seeing the same side.
Because if it had stay squisher longer. Maybe the moon
would be rounder now, less football.
Speaker 2 (20:36):
Shape, maybe, but I think it would still become tidally
locked eventually.
Speaker 3 (20:40):
Yeah. Okay, that's good.
Speaker 2 (20:42):
That's a good thought. I have to think about that
one more than live on the air.
Speaker 1 (20:48):
Am I gonna get my name in a paper?
Speaker 2 (20:50):
Now? The cham.
Speaker 1 (20:54):
The cham procrastinating hot football theory of moon tidal walking. Yes,
rolls off the tongue exactly.
Speaker 3 (21:03):
Okay.
Speaker 1 (21:04):
There are a couple of interesting things about this scenario.
The first is that the arrangement of having something football
shape pointing at you in orbit is stable, meaning that
if the football, for some reason tilton starts to point
in a different direction, the physics of the orbit will
make it snap back. Remember the analogy of keeping someone
(21:25):
from falling off a merry go round if they start
to twist or turn, the fact that you're grabbing their
hand and pulling on them towards the center of the
merry go round means to'll go back to the same position.
And that is why the moon is always facing us
the same way. We're basically looking at one of the
pointy ends of the football shaped moon. It's part of
(21:46):
the moon that we never see that's the other pointy
end of the football. Oh I see. So, like if
I took the moon right now and I flipped it
one to eighty degrees, we would be looking at the
different side of the moon, but it would stay locked
to that side of the moon. Yes, Oh, fascinating. Somebody
should do that, man.
Speaker 2 (22:06):
Yeah, if they were like a giant impact or someone
crashed a really really big rocket into the Moon, that
they were enough to unlock it, you could have imagined
that it would lock again in that other way.
Speaker 1 (22:17):
Like I'm tired of seeing this side of the moon, Like,
I'm done with it, Let's see the other side. Somebody's
give it a little push and it'll lock back to
the other side exactly. Yeah.
Speaker 3 (22:27):
Okay.
Speaker 1 (22:27):
You might be wondering, why would I want to look
at the other side of the moon? Is it really
that different? Well, it turns out that it is different,
and scientists don't really know why.
Speaker 2 (22:38):
But there are all these weird things we've learned about
the moon. Now, is that the crust on the far
side of the moon is a lot thicker than the
crust on the near side of the moon. Whoa, and
like the near side of the moon has all the
lava flows right far side has none of that? What?
And so why did the near side of the moon
and the far side of the moon end up so different?
(22:58):
And is that because of the tidal locking or is
it a cause of why we tidally locked with this face?
Speaker 1 (23:05):
Did it tidally lock because one side is different than
the other? Or is one side different than the other
because it's going around the Earth always facing the same way.
Speaker 2 (23:14):
Yeah, And there are different ideas about what caused that difference.
That the Moon might have had a giant impact of
its own that created the difference originally, or that just
imagine you tidally locked when you're still really close to
the Earth and the Earth is still a molten ball
of lava, but it really heats one side more than
(23:35):
the other. Yeah, and that could cause a difference. So
there are a number of theories out there of how
that would cause the near side on the far side
to be different in the way they are.
Speaker 1 (23:47):
In other words, we sort of know why the moon
is always facing us the same way, but we don't
know why it's this side of the Moon that's facing us.
It could have been random, or there could be more things,
but the moon and its history that we don't know about. Okay,
when we come back, we're going to tackle the last
mystery of the Moon, and it's a big one. It's
(24:10):
a secret that could determine the future of space travel
and it could help us understand the reason why there's
life on Earth. So stay with us.
Speaker 3 (24:21):
We'll be right back.
Speaker 1 (24:32):
Hey, welcome back. We're not going to tackle the big
open questions about the Moon. It turns out there's a
lot we don't know about the Moon, including a question
that might have huge implications for the future of space
travel and what we know about how life started on Earth.
Here's doctor Matt Ziegler, a planetary scientist involved in the
(24:53):
New Artemis mission stake astronauts back to the Moon. Okay, Matt,
what don't we know about the Moon? What are some
of the biggest mysteries we're trying to figure out right now?
Speaker 2 (25:06):
Oh? Yeah, that depends on which subdiscipline of lunar science
you're in.
Speaker 1 (25:11):
I think, really, what flavor of lunatic are you? So?
Speaker 2 (25:16):
One thing we don't know about is what's on the
interior of the Moon.
Speaker 1 (25:19):
We don't know.
Speaker 2 (25:20):
Yeah, we have lots of pictures of the surface of
the Moon. We know that sometimes stuff came up from
the surface of the moon, But we want to figure
out what's going on inside of the moon and how.
Speaker 1 (25:30):
Wait wait before in the episode, you told me that
we know how much iron is inside the moon.
Speaker 2 (25:35):
Yeah, we know kind of basic things that like, the
moon has these different layers and they're about this big.
And we know that because in the nineteen seventies we
had seismometers around the moon that we're recording moonquakes.
Speaker 3 (25:49):
Uh huh.
Speaker 2 (25:49):
And so from listening to a moonquake, you can tell
kind of how thick the different layers are, what the
density of the interior is, but you don't really know
the composition entirely. You're kind of guessing based on density.
And so one of the ways you can figure out
the composition is by measuring how much heat is coming out.
Speaker 1 (26:09):
Yes, it turns out we don't know exactly what the
inside of the Moon is made out of. So one
project doctor Siger is working on is to take the
moon's temperature. There are radioactive elements inside the Moon that
are giving off heat, and so by burying thermometers all
over the moon, you could reconstruct what all those radioactive
(26:29):
elements are.
Speaker 2 (26:32):
And just this last year about a year ago now,
we had the first geothermal heat flow probe since then
land on the Moon with one of these missions that's
kind of leading up to Artemis.
Speaker 1 (26:44):
Basically, we put a thermometer on the Moon.
Speaker 2 (26:46):
Yeah, we drilled the thermometer about a meter down below
the nerve. And if we do this in enough locations
around the Moon, we can start to put together this
picture of how the heat producing elements are different around
the whole Moon.
Speaker 1 (27:00):
Okay, And so the mystery is what exactly's in there?
What could be inside the moon?
Speaker 2 (27:04):
Yeah? Is the material in the Moon the same or
different than the material deep inside of Earth? Right? And
that gets back to this idea did the Moon form
from the Earth?
Speaker 1 (27:14):
Right?
Speaker 2 (27:14):
We know that these oxygen isotopes and sauch are telling
us that the Moon and the Earth seemed to form together,
but the composition of the deep interior is going to
be another data point telling us did they form from
the same spot?
Speaker 1 (27:26):
I see, what if you find that the inside of
the Moon is made out of cheese.
Speaker 2 (27:31):
Well then then we better go there and mind the cheese.
It's hard milking cows. And I don't know, I think
it still might be cheaper to get cheese from cows
on the Earth.
Speaker 1 (27:45):
But I don't know, but it's moon cheese. You can
charge your premium, Yes, exactly.
Speaker 3 (27:52):
Okay. The last mystery.
Speaker 1 (27:53):
Doctor Seeger brought up about the Moon is a pretty
interesting one. It's tied to the new Artemis missions that
you might have seen in the news, where we're bringing
astronauts back to the Moon and what they find could
revolutionize the future of space travel.
Speaker 2 (28:10):
I would say. Another big mystery and one of the
big motivators of the Artemis program coming up to the
Moon and the whole international exploration of the Moon is
is their ice at the poles of the Moon.
Speaker 1 (28:23):
Oh, we don't know.
Speaker 2 (28:24):
No, So we have craters, and because the Moon has
a very low tilt, a crater near the pole will
literally be a place where the sun don't shine.
Speaker 1 (28:33):
Right, I see, it's the moon hole. The moon hill
is where the sun don't shine. Yes, yes, it turns
out there might be places on the Moon with water
on it. At the north and south poles of the Moon,
there are craters so deep that they never get hit
by light from the sun, and because they never feel
the heat of the sun, they are super cold, which
(28:53):
means they could be full of ice.
Speaker 2 (28:56):
And so these places on the surface of the Moon,
because get no direct sunlight, actually can be colder than
like the surface of Pluto. Whoa, And so any water
molecules that land there, you know, maybe a comet hit
the Moon, or maybe an asteroid that had like water
in its rock materials hit the Moon. Ah, that water
should stick at the poles.
Speaker 1 (29:19):
That's right, there could be huge lakes of ice inside
of craters in the North and South poles of the Moon.
You might have heard on a previous episode of this
podcast or somewhere else that scientists think most of the
water that we have here on Earth actually came from
asteroids or comets that flew here from the far edges
of the Solar System. In other words, most of the
(29:40):
water that you drink that makes up your body could
be important. Well, the same thing probably happened on the Moon.
Must have also been hit with comets and asteroids full
of water, except that on the Moon, because there's no atmosphere,
most of that water probably evaporated into space when it
got hit by sunlight, except potentially in the craters on
(30:02):
the north and South poles of the Moon.
Speaker 3 (30:05):
And if there's water.
Speaker 1 (30:06):
There, it could have a big impact onto things. The
first is space traveling, and we're hoping that that ice
is there, both because we want, you know, astronauts to
drink martinis on the Moon and could generally stay alive
and hydrated.
Speaker 2 (30:23):
Yes, and hydrated, and also that if you saw the
Space Shuttle ever launch, it had a big cloud coming out.
What that was was mostly steam. Right, So water is
rocket fuel.
Speaker 1 (30:35):
You could make rocket fuel out of water. Yeah, that's right.
You can turn water into rocket fuel. It's a process
called electrolysis where you separate the H two O into
H and oh, and once you have oxygen gas and
hydrogen gas, it can burn those to push rockets further
out into space.
Speaker 2 (30:55):
So basically, if we can find enough ice on the Moon,
the Moon also becomes a fueling station for our exploration
of the universe. Right, that's wow. That's another exciting thing
about it.
Speaker 1 (31:09):
And the other exciting thing about finding water on the
Moon is that if there is water there in deep craters,
it would be sort of an untouched record how water
came to our solar system neighborhood billions of years ago.
Speaker 2 (31:23):
It's kind of like flypaper and it essentially should record
the delivery of this water to the Moon.
Speaker 1 (31:30):
It might tell us like, yes, we did get water
from asteroids or comets.
Speaker 2 (31:35):
Yeah, and tell us you know where the sources of
our water came from. Yeah, And this is really important
for understanding the big pictures of like, well, could there
be life somewhere else out there? Right, because now we're
finding all these other solar systems. And did the same
thing that caused water to somehow come from outside the
(31:55):
outer Solar System to Earth? Is that a common process
that happens in every solar system or is it a
weird thing that only happened in our Solar system?
Speaker 3 (32:05):
Yeah?
Speaker 2 (32:05):
That you would have a planet that's warm enough to
live on because we're close but also wet.
Speaker 1 (32:11):
We want to know more about why Earth has water
because water is the key ingredient in life.
Speaker 2 (32:17):
Yes, and the Moon holds a record of water that
the Earth does not.
Speaker 1 (32:23):
You're making the Moon seem like a really good tourist stop,
Like it might have fuel for you to go to
other parts of the universe. It might have some good
history so you can read while you're there. Yeah, and
it might have some cheese inside also for your snacks. Exactly.
Speaker 2 (32:38):
Yeah, So in a thousand years, the Moon might be
the wall drugs. You'll see signs for a thousand miles
before you get to the name.
Speaker 1 (32:48):
It might be the BUCkies of space.
Speaker 2 (32:50):
Yes, the moon is, but we've only got one.
Speaker 1 (32:53):
Well, the buggies are really hard to find too, aren't they.
Speaker 2 (32:56):
Yeah?
Speaker 1 (32:56):
Yeah, all right, last question, Matt. When you step out
in a warm Hawaiian night you see the full moon,
what are you thinking that?
Speaker 2 (33:07):
Well, just last night, I think we're out and I
saw the moon with my kids, and I said, you know,
in a couple of weeks, there's going to be people
behind that thing, right, And that thought alone is pretty
neat and exciting. Yeah, that there will be people there,
and maybe you know, in a few years it will
(33:27):
be all of us, right, a lot of us going
going to this gas station in the sky. Yeah, And
it's just neat to look at the Moon and knowing
about some of this history, of all the processes that
happened on the Moon, from the delivery of ice to
volcanoes on the surface of the Moon. There's a lot
of exciting stuff that you can imagine going on up there,
(33:47):
and you can imagine it differently on the moon because
you can see it. You know, I see Jupiter in
the night sky, and I can imagine what's going on
in that dot maybe. But the Moon is somehow this
thing that we all can relate to because it's still something.
We can see it from the Earth.
Speaker 1 (34:04):
And it is a part of the Earth, right.
Speaker 2 (34:06):
Yeah, it appears to be part of the Earth and
part of our formation of the Earth. And we're part
of the Earth, right We're made of the material from
the Earth too, So the moon is.
Speaker 3 (34:18):
Our brother, all right.
Speaker 1 (34:22):
So to recap scientists think our moon came from the
random collision of two small planets. The moon is always
facing us the same way because it's shaped a little
like an American football. We're not one hundred percent sure
what's inside of it. It could still be cheese. And
the moon might in the future serve as a gas
station for our exploration of the cosmos. So if all of
(34:46):
that doesn't turn you into a lunatic, I don't know
what will. Thanks for joining us. See you next time
you've been listening to science stuff. Production of Heart Radio
written and produced by me or Hey Cham, edited by
Rose Seguda, Executive producer Jerry Rowland, and audio engineer and
(35:07):
mixer Kasey Pegram, and you can follow me on social media.
Just search for PhD Comics and the name of your
favorite platform. Be sure to subscribe to sign stuff on
the iHeartRadio app, Apple Podcasts or wherever you get your podcasts,
and please tell your friends we'll be back next Wednesday
with another episode.
Hey, please take a second and leave us a review
on Apple Podcasts, Spotify, or wherever you listen to the podcast.
Thanks a lot. Hey, Welcome to Science Stuff, the production
of iHeartRadio. I'm poor, Hey Champ, and today we are
going to the Moon. You might think you know the moon,
(00:22):
but actually it is full of scientific mysteries. We're going
to be talking about where the moon came from, what
it's made out of, and what it can tell us
about how life started on Earth. So get ready to
go over the moon as we tackle the unanswered questions
about our mysterious moon enjoying. Hey everyone, Today we're talking
(00:49):
to doctor Matt Siegler. Doctor Ziegler is a planetary scientist
at the University of Hawaii who works on several missions
for NASA and the European Space Agency, including did You
Are the miss mission to put astronauts back on the Moon.
He's going to answer three questions for us. Number one,
where did the moon come from? As it turns out,
(01:10):
it's really unusual for us to have such a big moon.
Number two, why does the moon always faces the same way?
Wasn't always the case? And number three, why are we
going back to the moon? It turns out scientists have
identified a deep mystery about the Moon that might have
huge implications for space travel and our search for extraterrest
(01:34):
deal life. So here's my conversation with doctor Matt Siegler. Well,
thank you doctor Siegler for joining us again.
Speaker 2 (01:42):
Okay, welcome.
Speaker 1 (01:44):
The last time we talked it was New Year's and
we talked about how the Earth goes around the Sun.
And now we're getting close to the lunar New Year,
so I thought it would be interesting to talk about
the moon.
Speaker 2 (01:54):
Okay, that's actually my specialties. That's great to talk about
something that I know.
Speaker 1 (02:01):
Are you saying you're a lunatic?
Speaker 2 (02:03):
Yes, yeah, we're proud to call ourselves lunatics.
Speaker 1 (02:08):
Well, in what ways is our moon unusual in the
Solar System?
Speaker 2 (02:12):
Okay? Well, the weirdest thing about our moon is how
big it is compared to Earth. There are a couple
of moons out there, some of Saturn's moons and a
couple of Jupiter's moons that are about the size of
our moon or even a little bigger. But those planets
are huge, right, you could fit I think it's thirteen
hundred earths inside of Jupiter, right, Wow, huh. And so
(02:36):
their biggest moon is a very small moon compared to
the size of its body, meaning.
Speaker 1 (02:41):
Like if Jupiter had a moon that's proportionately the same
size as our moon, it would be like the size
of Saturn or something.
Speaker 2 (02:47):
Yeah, it would be like the size of Neptune at least.
So yeah, And the only other planet that, if you
want to call it a planet that has a similar
is Pluto.
Speaker 3 (02:56):
Right.
Speaker 1 (02:56):
Oh, no, no, we don't talk about Pluto in this podcast.
Speaker 2 (02:59):
You don't talk about about plu.
Speaker 1 (03:00):
We don't know.
Speaker 2 (03:03):
Pluto has a moon that's about a tenth of its
size or something like that.
Speaker 1 (03:08):
But plut itself is very small, smaller than us, right,
smaller than our moon kind of.
Speaker 2 (03:12):
Yeah, Pluto is around it could fit inside the continental US.
So it's a pretty small body.
Speaker 1 (03:18):
Okay, Oh, that's a very polite way to say it.
It's a small body. Yes, yes, small body.
Speaker 2 (03:24):
So that's the weirdest thing about our moon is how
big it is compared to us.
Speaker 1 (03:30):
So that's the first mystery about the moon. Why is
it so big? None of the other planets have a
moon this big.
Speaker 3 (03:38):
Why is that?
Speaker 1 (03:39):
Well, as it turns out, Charles Darwin's Sun George Darwin
had a theory about that.
Speaker 2 (03:46):
So that's actually a funny part of the history is
our moon is relatively large. It's about the size of
the Pacific Ocean basin, and so Charles Darwin's son, I
believe George Darwin first theorized that the Moon might have
been created from the Earth by being spit out of
the Pacific Ocean basin, and the Pacific Ocean was the
hole left behind. So that's a good way to remember
(04:09):
the size of the Moon is roughly the size of
the Pacific Ocean, because that was one of the first thoughts, Well, well,
we have a hole here on Earth that's about the
size of the moon.
Speaker 1 (04:19):
Yeah, maybe that's came It was like a giant pimple
that just popped off the Earth. That was the theory, yes, yes,
or the Darwin giant pimple theory. Yeah, George Darwin didn't
quite get thinks is right as this famous dad Charles Darwin,
or did he?
Speaker 2 (04:39):
Now we kind of think it's crazy, but really how
we think the moon formed now was not all that different.
It's just that that spitting out happened in a big
event when something the size of Mars or so collided
into the early Earth and caused that event where material
got spit out and formed the moon.
Speaker 1 (05:00):
That's a wild theory, Like we have a moon that's
like gray white, but we think it happened because some
giant mini planet crashed into the original Earth.
Speaker 2 (05:10):
Yeah, so that's the idea is the original early Solar
system was full of things that were flying all around,
and some of them collided into each other, and the
debris of that collision formed something kind of like a
ring of Saturn around the Earth. Right, it was a ring,
and then that coalesced together and became the Moon.
Speaker 1 (05:27):
So like our Earth is a mix of those two
original planets, and the Moon is a mix of those
two original planets.
Speaker 2 (05:32):
Exactly.
Speaker 1 (05:34):
Yes, scientists think the way the moon form was that
a planet the size of Mars crashed into a pre
Earth planet about four and a half billion years ago,
and then the debris from that crash clumped together and
formed the Moon. But here's a big question, how do
we know that? What makes us think that's how the
(05:55):
Moon formed. Well, it turns out this idea started when
we first walked on the Moon.
Speaker 2 (06:02):
And this explains basically what we found when the Apollo
samples were returned in the nineteen sixties and seventies. Huh,
was that a lot of the isotopes of atoms were
incredibly similar between the Earth and the Moon.
Speaker 1 (06:18):
What do you mean isotopes?
Speaker 2 (06:19):
So normally an atom will have the same number of
protons and neutrons, and so an isotope is one that
has different numbers of neutrons.
Speaker 1 (06:28):
Okay than the normal one I see. And so it's
where for the isotopes on Earth to match the ones
on the Moon.
Speaker 2 (06:35):
Yeah, So that turns out to be one of the
key identifiers of where something formed in the early Solar
System is it's the isotopes of its different atoms, and
particularly good one is oxygen.
Speaker 1 (06:49):
It turns out you can tell exactly where in the
Solar System a piece of rock comes from by its isotopes.
Like a piece of rock has more of one kind
of oxygen or carbon, you can tell it came from
close to the Sun, or near Jupiter, or way out
at the edges of the Solar system.
Speaker 2 (07:09):
So we think the whole Solar System essentially was a
big cloud of gas and dust that was leftover from
some other star that exploded, right, huh, And that cloud
kind of collust around the early Sun, and then when
that Sun turned on, you know, very early in the
Solar system four point six billion years ago, it heated
that cloud and basically boiled off different isotope ratios as
(07:33):
you went different distance from the Sun. And then when
the planets formed, out of those different isotopic ratios as
a function of distance away from the Sun, they seem
to have checked those isotopes permanently after that.
Speaker 1 (07:47):
Interesting, it's like the rocks have a tag that says
where in the Solar System formed.
Speaker 2 (07:53):
Yeah, so when we see a meteorite that we have
identified has come from Mars or a meteorite from the
Asteroid belt, these will have different oxygen isotope ratios than
the Earth. But the Moon has almost the same as
the Earth, like too incredible precision, such that the only
(08:17):
way that we can explain it was that they essentially
formed together as a single body. Okay, and so the
Earth and the Moon are incredibly similar, and it could
be that it's just kind of telling us they formed
at the exact same distance from the Sun. But the
precision in which they match seems to only be explained
if they really formed together in this idea of the
(08:39):
giant impact or simple.
Speaker 1 (08:44):
I see the match is too good. It's just too
identical to the Earth.
Speaker 2 (08:47):
Yeah, Like these are identical twins, you know, they had
to be born from the same mother.
Speaker 1 (08:53):
I see the DNA says their siblings, same mother, same father.
Speaker 2 (08:56):
Okay, And so there were lots of theory going around,
and as far as I understand it, there was some
international meeting about this in the early nineteen eighties and
there was a lot of debate, and then out came
the giant impact as the winner, and it's kind of
been the standard since then.
Speaker 1 (09:13):
Interesting. So it's not like we have some smoking gun
that says that this is what happened, or that there
was a camera or somebody saw this happened. It's like, well,
we can't think of anything else, and this is the
only thing that we have left.
Speaker 2 (09:25):
Yeah, and everything that we find out knew about the
Moon seems to fit with the theory of the giant impact.
Like what like one of the things we found out
was from seismometers on the Moon. We've been able to
figure out that the Moon has a fairly small iron core, right,
and the Earth actually has a really big iron core
for its size. And so where did this extra iron
(09:49):
on the Earth come from and the lack of iron
on the Moon come from. Well, it may have been
that you had this big impact and then more the
iron went into the big object than into the small
on it.
Speaker 3 (10:01):
Oh.
Speaker 1 (10:01):
I see, what do you think the junior Darwin would
feel now that you've disproven his theory and not lived
up to the greatness of the Darwin name.
Speaker 2 (10:12):
I don't know. I think scientists by nature like to
know the truth or the facts about the matter, and
if an idea that we clung to turns out to
be wrong, we should kind of give it up.
Speaker 3 (10:24):
Yeah.
Speaker 2 (10:24):
So I think that was a strong philosophy of science
then and it still is today.
Speaker 1 (10:29):
Nice all right, when we come back, we're going to
tackle the second big mystery about the moon, which is
why is the Moon always facing us the same way?
In case you haven't noticed, every time you look at
the Moon, no matter where you are on the planet
or what time of the month or year, it is,
the features on the Moon always look the same, even
(10:50):
though it's spinning around the Earth. How can it be
that it's training at just the right rate for it
to always look the same to us?
Speaker 3 (10:59):
We'll answer that.
Speaker 1 (10:59):
Question and more after the break.
Speaker 3 (11:02):
We'll be right back. Hey, we'll come back.
Speaker 1 (11:15):
We're answering questions about the moon, and so far we've
talked about where the moon came from four and a
half billion years ago and how scientists figured out what happened.
Now we're going to answer another big question about the moon,
which is why is the Moon always facing us the
same way? If you think about it, the Earth is
going around the Sun, but the Earth doesn't always face
(11:38):
the same way to the Sun. If you were standing
on the surface of the Sun, the Earth would look
like it's spinning and it would look different every time
you see it. But you can't say that about the Moon.
The features of the Moon always look the same to us.
The only people in history that have gotten in a
different view of the Moon are the Apollo astronauts that
(12:00):
went there back in the nineteen sixties. Well, the reason
that the Moon always looks the same to us, according
to Professor Matt Ziegler, has to do with the fact
that the Moon isn't round. Okay, next question, Matt, why
is the Moon always facing the same way to us?
Speaker 2 (12:18):
Okay, So the moon is what we call tidally locked
which essentially means one side is always facing us.
Speaker 1 (12:26):
Right. Is that another characteristic of science.
Speaker 2 (12:30):
If you don't know, we give it a fancy name
and basically says this is all we know about it. Yeah.
So a lot of moons in the Solar System are
also tidally.
Speaker 1 (12:41):
Locked, not just our moon.
Speaker 2 (12:43):
Like Jupiter's moons gets large. Four moons are all tidally locked.
So one face of Io is always facing Jupiter, one
face of Europa is always facing Jupiter.
Speaker 1 (12:54):
Whow, we're not alone. Our moon is not the only one.
The moon is what scientists call tidally locked, which basically
means it's always facing us the same way. But there
is a reason why this happens, and it has to
do with how gooey the Earth and the Moon are.
Speaker 2 (13:16):
This happens essentially because of how gooey an object is.
Speaker 3 (13:21):
Uh huh.
Speaker 2 (13:22):
So if something's spinning and it's gooey inside, it can
dissipate energy.
Speaker 1 (13:27):
Okay, meaning like if you were spinning a water balloon.
Speaker 2 (13:30):
Yeah. Or a good analogy is if you're spinning a
hard boiled egg versus a normal egg. Right, the hard
boiled egg will spin and spin and spin, right, but
the non heart boiled egg will slow itself down pretty
quickly because that ah, yeah, that goo inside is kind
of churning around and dissipating energy of that spin.
Speaker 1 (13:51):
I see, if I spin a raw egg in space,
it'll eventually slow down because the liquid inside is losing energy.
Speaker 2 (13:57):
Yeah, And so something akin to this happens inside of
a body like the Moon that initially early on at
least had a large liquid inside of it, right.
Speaker 1 (14:07):
Oh. It initially the Moon was gooey, oh yeah, because
it was formed from the giant impact right, which was
really hot and made a lot of things melt. What
doctor Ziegler is saying is that when the Moon formed,
it was probably spinning really fast, but the inside of
it was gooey. It was melted rock or lava. It
(14:29):
was still hot from one the huge collision that formed
the Moon happened, and that melted inside made the Moon
stop spinning.
Speaker 3 (14:37):
It's sort of like.
Speaker 1 (14:38):
If you take a regular plastic water bottle and you
try to toss it up into the air so that
it spins, it'll eventually stop spinning in mid air, and
that's because the water inside.
Speaker 3 (14:48):
Of it slashes around.
Speaker 1 (14:50):
Well, the same thing happened to the Moon, and actually
it's also happening to the Earth.
Speaker 2 (14:57):
And the Moon is doing this today to the Earth. Actually,
and so the Earth is actually slowing down. Right, Our
day is twenty four hours now. It used to be
twenty two hours, and earlier on in the Earth's history
it was as short as four hours. So we think
when the Earth and Moon formed that the Earth day
(15:18):
was about four hours long.
Speaker 1 (15:20):
Really, yeah, we were spinning that fast.
Speaker 2 (15:23):
Yeah, and then the Moon has caused us to slow
down that we're now at twenty four hours a day.
What maybe in a billion years will be at twenty
five hours a day or something like that. Right.
Speaker 1 (15:35):
Oh, so the reason the day feels this long is because.
Speaker 3 (15:38):
Of the moon.
Speaker 2 (15:39):
Yeah, it's the moon's fault.
Speaker 1 (15:40):
You had a long day, Blame the moon. Howl of
the moon.
Speaker 2 (15:43):
Yeah, but if your day was too short, if it
went by too fast, then think the moon.
Speaker 1 (15:49):
Right, Oh yeah, that's right, that's right.
Speaker 2 (15:50):
So the same way that the Earth day is slowly
getting longer because the Earth is slowing its spin, the
Moon went through something similar. It's just because the Moon
is a lot smaller, it happened a lot faster. Basically.
Speaker 1 (16:03):
Okay, maybe take me back, So we had this big crash,
A lot of stuff went out there into space eventually
formed the moon. The moon had a squishy inside, meaning
like it was lava inside.
Speaker 2 (16:14):
Right basically, right, Yeah, basically it's magma if it's not erupted.
Speaker 1 (16:19):
Not the whole other episode. It was magma or lava
melted rock. It was melted rock, and it was spinning
super fast.
Speaker 3 (16:26):
Yeah.
Speaker 2 (16:26):
So we had a fast spinning Earth and a fast
spinning Moon, and basically them tugging on each other slowed
each other down. Okay, So if I was a live
bike there and on Earth, I would die because I
couldn't breathe and standing on lava. But if I could
somehow be there, my day would be four hours long,
and I would see the moon like basically spinning in place.
(16:47):
The Moon would look different every time I looked at it. Yeah,
you would see the far side of the moon back then.
Speaker 1 (16:53):
Oh okay, And over time we slowed down and the
moon slowed down to the point where now it's always
looking at us the same way. Yes, So is it
just luck that we just happened to be alive at
a time when it's spinning. It just the right time
for it to be always looking at it, or is
it stuck there?
Speaker 2 (17:10):
I wouldn't say it's that lucky, because we think it's
stuck very quickly, like in potentially a few thousand years
to less than a million years, Like the moon slowed
itself down very quickly. So the moon'spent tidally locked for
most of Earth's history, really, and then it got stuck there. Yeah,
and then it's been stuck there. And it's a little
(17:32):
arbitrary which side ended up stuck facing the Earth. And
that's still a debate of why the near side of
the Moon is the near side.
Speaker 1 (17:41):
Okay, you might be wondering, if the Moon went from
spinning really fast to slowing down, why did it stop.
It's still going around to Earth, so why didn't the
Moon suddenly start spinning in place the other way? Well,
according to doctor Siegler, it all has to do with
the shape of the moon.
Speaker 2 (18:00):
The Moon isn't a perfect sphere. It's kind of egg
shaped itself or what rugby ball shaped or whatever you
want to call it. Yeah, just slightly.
Speaker 1 (18:09):
Yes, the Moon is not perfectly round. You might have
heard that the Earth is not perfectly round either. It's
a little wider around the middle or the equator. That's
because the Earth is spinning, and so it bulges out, but.
Speaker 2 (18:23):
The Moon isn't round.
Speaker 1 (18:24):
In a different way and for a different reason, the
Moon doesn't bulge out, it's actually stretched out. It looks
slightly closer to a rugby ball or an American football
ball with one of the pointy ends pointing at the Earth.
And the reason it's that shape isn't because it's spinning,
but because the Earth is pulling on it. As the
(18:46):
Moon goes in orbit around the Earth, the Earth's gravity
pulls on the Moon to keep it in that orbit,
and that causes the Moon to get stretched. And I
think I came up with a good analogy for tidal logging,
which is that sort of like if you're in a
merry go round and someone's at the edge and they're
about to fall off, like you grabbed their hand to
(19:07):
keep them in the merry go round, and so the
centropgal force is pulling them out, but I'm holding their
hand pulling them in, and so that causes them to stretch, right.
Speaker 2 (19:17):
Okay, Yeah, that would be a good description of it.
Speaker 1 (19:20):
Yeah, okay, And so that's what causes the Moon to
look sort of like a football shape pointing at us.
Speaker 2 (19:26):
Yeah, and at some point in the Moon's history it
became solid enough, it cooled off enough that it froze
in a football shape at that time.
Speaker 1 (19:36):
Okay, so here's what scientists think happened. There was a
pre Earth planet somewhere close to our current orbit. He
got smashed by another planet about the size of Mars.
Some of the debris stayed in place and became the Earth,
and some of the debris floated out in space and
became the Moon. This new Moon was an orbit around
(19:57):
the new Earth, but it was gooey and melted on
the inside. That made it stop spinning in place. And
because it was being pulled around in an orbit around
the Earth, it stretched out a little to be closer
to the shape of a football pointed back at the Earth.
Then it cooled off and it got stuck in that shape.
And once it got stuck in that shape, it became
(20:17):
tidally locked, with one end of the football always pointing.
Speaker 3 (20:20):
At the Earth.
Speaker 1 (20:22):
Wait, wait, wait, wait, I think what you're saying is
that just because of the particular history of when the
Moon cooled is the reason we're always seeing the same side.
Because if it had stay squisher longer. Maybe the moon
would be rounder now, less football.
Speaker 2 (20:36):
Shape, maybe, but I think it would still become tidally
locked eventually.
Speaker 3 (20:40):
Yeah. Okay, that's good.
Speaker 2 (20:42):
That's a good thought. I have to think about that
one more than live on the air.
Speaker 1 (20:48):
Am I gonna get my name in a paper?
Speaker 2 (20:50):
Now? The cham.
Speaker 1 (20:54):
The cham procrastinating hot football theory of moon tidal walking. Yes,
rolls off the tongue exactly.
Speaker 3 (21:03):
Okay.
Speaker 1 (21:04):
There are a couple of interesting things about this scenario.
The first is that the arrangement of having something football
shape pointing at you in orbit is stable, meaning that
if the football, for some reason tilton starts to point
in a different direction, the physics of the orbit will
make it snap back. Remember the analogy of keeping someone
(21:25):
from falling off a merry go round if they start
to twist or turn, the fact that you're grabbing their
hand and pulling on them towards the center of the
merry go round means to'll go back to the same position.
And that is why the moon is always facing us
the same way. We're basically looking at one of the
pointy ends of the football shaped moon. It's part of
(21:46):
the moon that we never see that's the other pointy
end of the football. Oh I see. So, like if
I took the moon right now and I flipped it
one to eighty degrees, we would be looking at the
different side of the moon, but it would stay locked
to that side of the moon. Yes, Oh, fascinating. Somebody
should do that, man.
Speaker 2 (22:06):
Yeah, if they were like a giant impact or someone
crashed a really really big rocket into the Moon, that
they were enough to unlock it, you could have imagined
that it would lock again in that other way.
Speaker 1 (22:17):
Like I'm tired of seeing this side of the moon, Like,
I'm done with it, Let's see the other side. Somebody's
give it a little push and it'll lock back to
the other side exactly. Yeah.
Speaker 3 (22:27):
Okay.
Speaker 1 (22:27):
You might be wondering, why would I want to look
at the other side of the moon? Is it really
that different? Well, it turns out that it is different,
and scientists don't really know why.
Speaker 2 (22:38):
But there are all these weird things we've learned about
the moon. Now, is that the crust on the far
side of the moon is a lot thicker than the
crust on the near side of the moon. Whoa, and
like the near side of the moon has all the
lava flows right far side has none of that? What?
And so why did the near side of the moon
and the far side of the moon end up so different?
(22:58):
And is that because of the tidal locking or is
it a cause of why we tidally locked with this face?
Speaker 1 (23:05):
Did it tidally lock because one side is different than
the other? Or is one side different than the other
because it's going around the Earth always facing the same way.
Speaker 2 (23:14):
Yeah, And there are different ideas about what caused that difference.
That the Moon might have had a giant impact of
its own that created the difference originally, or that just
imagine you tidally locked when you're still really close to
the Earth and the Earth is still a molten ball
of lava, but it really heats one side more than
(23:35):
the other. Yeah, and that could cause a difference. So
there are a number of theories out there of how
that would cause the near side on the far side
to be different in the way they are.
Speaker 1 (23:47):
In other words, we sort of know why the moon
is always facing us the same way, but we don't
know why it's this side of the Moon that's facing us.
It could have been random, or there could be more things,
but the moon and its history that we don't know about. Okay,
when we come back, we're going to tackle the last
mystery of the Moon, and it's a big one. It's
(24:10):
a secret that could determine the future of space travel
and it could help us understand the reason why there's
life on Earth. So stay with us.
Speaker 3 (24:21):
We'll be right back.
Speaker 1 (24:32):
Hey, welcome back. We're not going to tackle the big
open questions about the Moon. It turns out there's a
lot we don't know about the Moon, including a question
that might have huge implications for the future of space
travel and what we know about how life started on Earth.
Here's doctor Matt Ziegler, a planetary scientist involved in the
(24:53):
New Artemis mission stake astronauts back to the Moon. Okay, Matt,
what don't we know about the Moon? What are some
of the biggest mysteries we're trying to figure out right now?
Speaker 2 (25:06):
Oh? Yeah, that depends on which subdiscipline of lunar science
you're in.
Speaker 1 (25:11):
I think, really, what flavor of lunatic are you? So?
Speaker 2 (25:16):
One thing we don't know about is what's on the
interior of the Moon.
Speaker 1 (25:19):
We don't know.
Speaker 2 (25:20):
Yeah, we have lots of pictures of the surface of
the Moon. We know that sometimes stuff came up from
the surface of the moon, But we want to figure
out what's going on inside of the moon and how.
Speaker 1 (25:30):
Wait wait before in the episode, you told me that
we know how much iron is inside the moon.
Speaker 2 (25:35):
Yeah, we know kind of basic things that like, the
moon has these different layers and they're about this big.
And we know that because in the nineteen seventies we
had seismometers around the moon that we're recording moonquakes.
Speaker 3 (25:49):
Uh huh.
Speaker 2 (25:49):
And so from listening to a moonquake, you can tell
kind of how thick the different layers are, what the
density of the interior is, but you don't really know
the composition entirely. You're kind of guessing based on density.
And so one of the ways you can figure out
the composition is by measuring how much heat is coming out.
Speaker 1 (26:09):
Yes, it turns out we don't know exactly what the
inside of the Moon is made out of. So one
project doctor Siger is working on is to take the
moon's temperature. There are radioactive elements inside the Moon that
are giving off heat, and so by burying thermometers all
over the moon, you could reconstruct what all those radioactive
(26:29):
elements are.
Speaker 2 (26:32):
And just this last year about a year ago now,
we had the first geothermal heat flow probe since then
land on the Moon with one of these missions that's
kind of leading up to Artemis.
Speaker 1 (26:44):
Basically, we put a thermometer on the Moon.
Speaker 2 (26:46):
Yeah, we drilled the thermometer about a meter down below
the nerve. And if we do this in enough locations
around the Moon, we can start to put together this
picture of how the heat producing elements are different around
the whole Moon.
Speaker 1 (27:00):
Okay, And so the mystery is what exactly's in there?
What could be inside the moon?
Speaker 2 (27:04):
Yeah? Is the material in the Moon the same or
different than the material deep inside of Earth? Right? And
that gets back to this idea did the Moon form
from the Earth?
Speaker 1 (27:14):
Right?
Speaker 2 (27:14):
We know that these oxygen isotopes and sauch are telling
us that the Moon and the Earth seemed to form together,
but the composition of the deep interior is going to
be another data point telling us did they form from
the same spot?
Speaker 1 (27:26):
I see, what if you find that the inside of
the Moon is made out of cheese.
Speaker 2 (27:31):
Well then then we better go there and mind the cheese.
It's hard milking cows. And I don't know, I think
it still might be cheaper to get cheese from cows
on the Earth.
Speaker 1 (27:45):
But I don't know, but it's moon cheese. You can
charge your premium, Yes, exactly.
Speaker 3 (27:52):
Okay. The last mystery.
Speaker 1 (27:53):
Doctor Seeger brought up about the Moon is a pretty
interesting one. It's tied to the new Artemis missions that
you might have seen in the news, where we're bringing
astronauts back to the Moon and what they find could
revolutionize the future of space travel.
Speaker 2 (28:10):
I would say. Another big mystery and one of the
big motivators of the Artemis program coming up to the
Moon and the whole international exploration of the Moon is
is their ice at the poles of the Moon.
Speaker 1 (28:23):
Oh, we don't know.
Speaker 2 (28:24):
No, So we have craters, and because the Moon has
a very low tilt, a crater near the pole will
literally be a place where the sun don't shine.
Speaker 1 (28:33):
Right, I see, it's the moon hole. The moon hill
is where the sun don't shine. Yes, yes, it turns
out there might be places on the Moon with water
on it. At the north and south poles of the Moon,
there are craters so deep that they never get hit
by light from the sun, and because they never feel
the heat of the sun, they are super cold, which
(28:53):
means they could be full of ice.
Speaker 2 (28:56):
And so these places on the surface of the Moon,
because get no direct sunlight, actually can be colder than
like the surface of Pluto. Whoa, And so any water
molecules that land there, you know, maybe a comet hit
the Moon, or maybe an asteroid that had like water
in its rock materials hit the Moon. Ah, that water
should stick at the poles.
Speaker 1 (29:19):
That's right, there could be huge lakes of ice inside
of craters in the North and South poles of the Moon.
You might have heard on a previous episode of this
podcast or somewhere else that scientists think most of the
water that we have here on Earth actually came from
asteroids or comets that flew here from the far edges
of the Solar System. In other words, most of the
(29:40):
water that you drink that makes up your body could
be important. Well, the same thing probably happened on the Moon.
Must have also been hit with comets and asteroids full
of water, except that on the Moon, because there's no atmosphere,
most of that water probably evaporated into space when it
got hit by sunlight, except potentially in the craters on
(30:02):
the north and South poles of the Moon.
Speaker 3 (30:05):
And if there's water.
Speaker 1 (30:06):
There, it could have a big impact onto things. The
first is space traveling, and we're hoping that that ice
is there, both because we want, you know, astronauts to
drink martinis on the Moon and could generally stay alive
and hydrated.
Speaker 2 (30:23):
Yes, and hydrated, and also that if you saw the
Space Shuttle ever launch, it had a big cloud coming out.
What that was was mostly steam. Right, So water is
rocket fuel.
Speaker 1 (30:35):
You could make rocket fuel out of water. Yeah, that's right.
You can turn water into rocket fuel. It's a process
called electrolysis where you separate the H two O into
H and oh, and once you have oxygen gas and
hydrogen gas, it can burn those to push rockets further
out into space.
Speaker 2 (30:55):
So basically, if we can find enough ice on the Moon,
the Moon also becomes a fueling station for our exploration
of the universe. Right, that's wow. That's another exciting thing
about it.
Speaker 1 (31:09):
And the other exciting thing about finding water on the
Moon is that if there is water there in deep craters,
it would be sort of an untouched record how water
came to our solar system neighborhood billions of years ago.
Speaker 2 (31:23):
It's kind of like flypaper and it essentially should record
the delivery of this water to the Moon.
Speaker 1 (31:30):
It might tell us like, yes, we did get water
from asteroids or comets.
Speaker 2 (31:35):
Yeah, and tell us you know where the sources of
our water came from. Yeah, And this is really important
for understanding the big pictures of like, well, could there
be life somewhere else out there? Right, because now we're
finding all these other solar systems. And did the same
thing that caused water to somehow come from outside the
(31:55):
outer Solar System to Earth? Is that a common process
that happens in every solar system or is it a
weird thing that only happened in our Solar system?
Speaker 3 (32:05):
Yeah?
Speaker 2 (32:05):
That you would have a planet that's warm enough to
live on because we're close but also wet.
Speaker 1 (32:11):
We want to know more about why Earth has water
because water is the key ingredient in life.
Speaker 2 (32:17):
Yes, and the Moon holds a record of water that
the Earth does not.
Speaker 1 (32:23):
You're making the Moon seem like a really good tourist stop,
Like it might have fuel for you to go to
other parts of the universe. It might have some good
history so you can read while you're there. Yeah, and
it might have some cheese inside also for your snacks. Exactly.
Speaker 2 (32:38):
Yeah, So in a thousand years, the Moon might be
the wall drugs. You'll see signs for a thousand miles
before you get to the name.
Speaker 1 (32:48):
It might be the BUCkies of space.
Speaker 2 (32:50):
Yes, the moon is, but we've only got one.
Speaker 1 (32:53):
Well, the buggies are really hard to find too, aren't they.
Speaker 2 (32:56):
Yeah?
Speaker 1 (32:56):
Yeah, all right, last question, Matt. When you step out
in a warm Hawaiian night you see the full moon,
what are you thinking that?
Speaker 2 (33:07):
Well, just last night, I think we're out and I
saw the moon with my kids, and I said, you know,
in a couple of weeks, there's going to be people
behind that thing, right, And that thought alone is pretty
neat and exciting. Yeah, that there will be people there,
and maybe you know, in a few years it will
(33:27):
be all of us, right, a lot of us going
going to this gas station in the sky. Yeah, And
it's just neat to look at the Moon and knowing
about some of this history, of all the processes that
happened on the Moon, from the delivery of ice to
volcanoes on the surface of the Moon. There's a lot
of exciting stuff that you can imagine going on up there,
(33:47):
and you can imagine it differently on the moon because
you can see it. You know, I see Jupiter in
the night sky, and I can imagine what's going on
in that dot maybe. But the Moon is somehow this
thing that we all can relate to because it's still something.
We can see it from the Earth.
Speaker 1 (34:04):
And it is a part of the Earth, right.
Speaker 2 (34:06):
Yeah, it appears to be part of the Earth and
part of our formation of the Earth. And we're part
of the Earth, right We're made of the material from
the Earth too, So the moon is.
Speaker 3 (34:18):
Our brother, all right.
Speaker 1 (34:22):
So to recap scientists think our moon came from the
random collision of two small planets. The moon is always
facing us the same way because it's shaped a little
like an American football. We're not one hundred percent sure
what's inside of it. It could still be cheese. And
the moon might in the future serve as a gas
station for our exploration of the cosmos. So if all of
(34:46):
that doesn't turn you into a lunatic, I don't know
what will. Thanks for joining us. See you next time
you've been listening to science stuff. Production of Heart Radio
written and produced by me or Hey Cham, edited by
Rose Seguda, Executive producer Jerry Rowland, and audio engineer and
(35:07):
mixer Kasey Pegram, and you can follow me on social media.
Just search for PhD Comics and the name of your
favorite platform. Be sure to subscribe to sign stuff on
the iHeartRadio app, Apple Podcasts or wherever you get your podcasts,
and please tell your friends we'll be back next Wednesday
with another episode.
Popular Podcasts
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
Betrayal Season 5
Saskia Inwood woke up one morning, knowing her life would never be the same. The night before, she learned the unimaginable – that the husband she knew in the light of day was a different person after dark. This season unpacks Saskia’s discovery of her husband’s secret life and her fight to bring him to justice. Along the way, we expose a crime that is just coming to light. This is also a story about the myth of the “perfect victim:” who gets believed, who gets doubted, and why. We follow Saskia as she works to reclaim her body, her voice, and her life. If you would like to reach out to the Betrayal Team, email us at betrayalpod@gmail.com. Follow us on Instagram @betrayalpod and @glasspodcasts. Please join our Substack for additional exclusive content, curated book recommendations, and community discussions. Sign up FREE by clicking this link Beyond Betrayal Substack. Join our community dedicated to truth, resilience, and healing. Your voice matters! Be a part of our Betrayal journey on Substack.
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com