Hey smart people, Joe here.
This is our planet.
And this is the moon.
And this is how far apart they ACTUALLY are, to scale.
You might not know this, but compared to other moons in our solar system, our moon is weird.
It’s 1/80th of Earth’s mass, which may not sound like a lot, but it’s ridiculously
big compared to the size of the planet it orbits.
For comparison, Saturn’s largest moon Titan is this big compared to our moon, but less
than 1/4000th of its host planet’s mass!
So how the heck did this chubby little nugget–the moon we call THE MOON–form?
The answer to that question is locked inside a vault at NASA’s Johnson Space Center,
right down the road in Houston, Texas.
And I recently paid them a visit and in the process got closer to the moon than I ever
Joe: Does anybody have the combination to this thing?
Joe: This looks like a vault.
Ryan: It turns out it is a vault.
Joe: knew that> Ryan: So this is a US Federal Reserve Bank
vault from 1978 Joe: Really?
That's pretty cool.
Joe: What's inside is worth more than money Ryan: There is no price on what's inside this.
70% of the moon rocks on earth are inside this vault.
Joe: 70% of the moon rocks are in there.
That is very important room.
Joe: Can we, can we go in?
Ryan: We can.
You wanna open the door?
I want to open the door.
That door weighs more than 4000 kilograms.
And behind it are more than 300 kilograms of rocks brought back to Earth by astronauts
on six of the Apollo missions.
Back in the 1960s, even though scientists had figured out enough science to put people
on the moon, they still didn’t know how it had formed.
The rocks we brought back were the key to unlocking this centuries-long mystery.
Some scientists, like Charles Darwin’s son George, had thought maybe the Earth once spun
so fast that a chunk ripped off.
Others thought the moon formed elsewhere in the solar system and was captured by Earth’s
Most of these original theories sound pretty loony.
Incidentally, the words “loony” or “lunacy” come from the old idea that the moon made
people temporarily insane.
But then in 1969, during the very first moonwalk,
one astronaut made a lucky decision that gave scientists the hint they’d been waiting
In July 1969 NASA blasted three men to the moon aboard Apollo 11, and on July 20th Neil
Armstrong and Buzz Aldrin touched down in the Sea of Tranquility.
They took some small steps, a few giant leaps, and a lot of pictures.
And then, at the last minute, right before they launched back to Earth, this happened:
Joe: These come from Apollo 11 right?
This was the last sample collected on Apollo 11, as Neil Armstrong's outside the LEM, the
lunar excursion module, getting ready to seal up the rock box.
He looked inside and thought it looks kind of empty.
And so what he decided to do is just shovel four shovels fulls of dirt into the, uh, the
rock box and then sealed it up.
And it turned out being this sample, and it was the largest single sample of brought back
from Apollo 11.
And that became a really important sample because as people looked through it, they
found little fragments of white rock and they're like, oh, it's anorthosite.
Why would there be anorthosite on the moon?
On the moon!
Wait, why is that weird?
You know what?
To understand why this scoop of soil was such a big deal, we need to back this story up
a little bit.
… in Florence, Italy, where a guy named Galileo Galilei had taken a new invention
called a Perspicillum and aimed it at the moon.
Today, we call that invention a telescope.
Across the terminator, the line of light and shadow stretching across the partial moon,
Galileo saw it had areas of high and low terrain.
He thought that, like on Earth, the darker, low-lying areas were seas, so he called them
Apollo 11 touched down in one of these, the “Sea of Tranquility”.
The moon’s highlands, on the other hand, were lighter in color, like this spot where
Apollo 16 landed.
And many of the shadowy shapes Galileo saw we later realized were impact craters.
All of this together told us that the moon was really, really old, and it had gotten
its butt kicked for a really long time.
After billions of years of impacts with space rocks the outer 5 to 15 meters of the moon’s
surface had been ground up into fine-grained stuff called “regolith”.
And that’s the sandy stuff Neil Armstrong scooped up.
Back on Earth, scientists painstakingly counted 1,676 individual grains of regolith in Neil’s
shovelful, and in that they found 84 specks of white stuff that they didn’t expect to
This sent NASA scientists on a Sherlock Holmes-style hunt for an explanation.
For that white anorthosite to get to the Sea of Tranquility, it must have been blasted
there by a giant impact, like a meteorite, from hundreds of km away in the moon’s highlands,
those lighter areas.
And if the highlands–which cover most of the moon–were anorthosite, that meant most
of the moon was covered in that white rock… elementary.
Ryan: To make anorthosite the main rock from the moon, be this white anorthosite, you need
to have a global ocean of magma that covers the entire moon, that's hundreds if not thousands
of kilometers thick.
Let’s have a little rock talk.
From studying Earth we know anorthosite forms in a very special way.
It’s an igneous rock, meaning it forms from cooling lava or magma.
As magma cools and crystallizes, anorthosite floats to the top, because it’s lighter
and less dense than other stuff in the magma.
Like how as ice solidifies out of liquid water, it floats because it’s less dense.
So for the moon’s surface to be covered in this white stuff, the moon must have melted
at some point.
Like, the whole thing.
A moon that was all magma.
But now scientists had a different mystery to solve: How the heck do you melt a moon?
Ryan: And then a guy named John Wood came up with this crazy idea that the moon formed
through a giant impact, all based on these millimeter sized fragments from one spot in
And everyone's like, “naw!”
This is called the giant impact hypothesis.
Earth gets smacked by another planet-sized thing, the giant, melted cloud of debris condenses
into our moon, creating a thousand-km-thick ocean of magma.
That’s a pretty loony story too, but none of those other older theories about the moon’s
formation could explain ALL of its weirdness, like why the moon’s core is so small and
so light compared to Earth’s core, or why the moon has slowly been moving farther away
from Earth for billions of years, or why the Earth and moon are made of the same elements
and atomic isotopes.
The giant impact theory could explain all of these, but to convince people that something
collided with the Earth 4 and a half billion years ago and created a magmoon… scientists
needed a little more evidence.
Ryan: This is what we call the Genesis Rock.
15415 it was collected on the Apollo 15 mission and the Apollo 15 site was selected in part
to find this rock.
When they got it back and they did the studies on it.
This was the rock that allowed scientists to unlock how the moon formed.
A body the size of Mars slammed into the Earth just after the Earth formed.
A ring of debris formed around the Earth, sort of like Saturn's rings, unlike Saturn's
rings that all collected into our moon.
So all the individual pieces collided together and formed our moon.
So every impact that brought the different pieces together, kinetic energy, It produced
heat and so you melted the outer hundreds and probably thousand kilometers.
There's an ocean of magma thousand kilometers deep.
So now you've got this giant of magma, lava.
And as it cools, things start to crystallize and the heavy minerals would sink out and
the light minerals would float.
And it turns out this white mineral plagioclase is less dense and it floated to the surface.
So you have rock bergs floating in an ocean of magma and eventually you have nothing but
rock bergs and the entire surface is covered with this anorthosite.
And then you have billions of years of impacts and things get smashed and moved around.
But this is the original piece.
It showed us how things formed.
Anorthosites like the Genesis Rock turn out to be the oldest rocks on the moon.
They date from the earliest age of the solar system, from the time when Earth and the other
planets were just forming, and thanks to us putting a few humans on the moon to collect
rocks, scientists were finally able to write the story of how the moon was created.
And that story is a pretty violent one.
But I think behind this story, there’s something maybe even more significant.
The journey to the moon wasn’t all about science at first, it began as a race between
the US and the Soviet Union to build technology, and to prove their military supremacy to each
other and the world.
But moon rocks helped change that.
We began to see space as a place for science that the whole world could use, and by the
end of the Apollo era, we weren’t just sending Air Force rocket jockeys up there, we were
And I think that changed NASA’s mission forever.
The last man on the moon, Gene Cernan, summed this idea up beautifully just before humans
left the lunar surface for the last time.
Despite their old age, we’re still learning new things from the moon rocks.
The history of the moon isn’t wrapped up just yet.
Maybe we’ll go back one day and science that chubby nugget a little bit more.
This has been absolutely incredible.
I, my mind has been blown not only about like the history of the moon, but just how amazing
is the science that NASA been doing.
Thank you so much for letting us in here.
Thanks for the awesome outfit.
Um, so do I get like, take a sample?
Oh, yeah, no, no.
Even tho I didn’t get to keep a moon rock.This
was an incredible video to make, I feel really lucky that I got to share this with you.
And you can keep your brain on the moon a little longer, because some of our friends
just put out videos from the NASA moon rock vault too.
So head over to Smarter Every Day and Objectivity where Destin and Brady have some more cool
Apollo moon rock science for you.
I’ll put links to those down in the description, or just check out the end of this video and
you can find links there.