[Music]
♪ What the heck is that? ♪♪
[Music fades]
Hi everyone – I’m Noah Petro,
the Project Scientist of NASA's Lunar Reconnaissance Orbiter Spacecraft
which has been at the Moon for over a decade now,
sending back a treasure-trove of data, including some spectacular images.
Inevitably, whenever NASA publishes a photo
or releases a video of ours showing the lunar landscape,
we get emails, tweets, and online posts from viewers
asking for us to further explain some of the weird looking visuals they are seeing.
So today, we’re going to look at these strange and mysterious looking features on the Moon
to answer the question: What the heck is that?
So let's launch into this!
In our video "Apollo 13 Views of the Moon" –
many viewers wondered about this strange looking circle with dark lines.
So what the heck is that?
Well, for starters, this is not the remnants of an ancient lake,
and apologies to the sci-fi crowd,
it’s not a secret Moon base with runways for spacecraft.
This is a geological feature known as Komarov Crater.
It’s 80 kilometers wide, and it’s on the far side of the Moon,
on the edge of Mare Moscoviense.
The floor is covered with a network of rilles that make it look like Sun-dried mud.
And it’s a great example of a floor-fractured crater, or FFC.
So what made Komarov look like that?
The leading idea among scientists is that FFCs are like
volcanoes that didn't quite reach the surface.
An impactor hits the Moon, forming the crater.
And underneath the crater floor, the impact creates a zone of broken rock,
called a breccia lens.
Magma from deeper inside the Moon rises into the cracks in the breccia lens,
but something stops it from getting all the way to the surface.
So, it spreads out under the crater floor, forming what’s called a sill.
The magma and hot gasses in the sill push on the crater floor from below,
causing it to bulge and fracture like the top of a cake in the oven.
The cracks you see are known as graben.
[Release the graben!]
Using data from Lunar Reconnaissance Orbiter,
scientists have cataloged over a hundred floor-fractured craters just like Komarov.
They are fascinating works of nature from billions of years ago.
[Billions!]
An image from the Apollo 11 mission has gotten a lot of attention over the years.
Here you see a pair of craters known as Messier and Messier A.
But they don’t look like the more typical round craters you see on the Moon.
LRO has taken even more high definition shots of these two sights, showing us incredible detail.
These oval shapes and areas of ejected rock do look like they could belong in Star Wars
as the crash site of the Millennium Falcon.
And actually, the way you might imagine a scene like that happening,
with an object slamming and then skipping across the surface
is what took place here - except with an asteroid.
You see, at very low angels, an incoming asteroid can actually become decapitated,
with the top part splitting off at impact
and either escaping back into space or skipping to form a second crater.
Think of it like skipping a stone across the water.
Both laboratory impact experiments and computer modeling
have demonstrated the physical affects of the oblique impact
of a large asteroid on the Moon. And LRO's data helps prove
the formation of these unusual features.
[LRO!]
Scattered across the lunar surface are these long winding features –
which many viewers have correctly assumed are channels.
On the Moon, these are called rilles.
There is a prominent one here on the Aristarchus plateau.
And if you were comparing to visuals on the Earth –
you might be tempted to think about long river canyons,
flowing in long, sweeping meanders –
like the mighty Mississippi pouring out into the Gulf of Mexico.
And if that’s what you’re thinking –
erase it from your memory, because it’s wrong.
Now to be fair, when these channels were observed on the Moon for the first time,
there was an immediate thought that water may have carved these features.
But, once we got actual samples from the Moon,
combined with additional spacecraft data and studies over the years,
we’ve come to understand that there was never flowing water on the Moon.
So what could carve these sweeping features?
If you said flowing liquid hot magma after it erupted onto the Moon's surface -
you’d be correct!
[Winner!]
When lava flows across the surface, it erodes the crust,
and slowly flows as it bends and turns, forming these beautiful channels.
We have a great view of this in our Rima Prinz visualization.
Here you see a long channel where lava once flowed
from the Vera volcanic depression.
Eruptions of lava fountains formed a lake of lava 300 meters deep
and carved a lava channel one-hundred times deeper than anything found on Earth.
These types of feature were so compelling
that the Apollo 15 mission went and explored one in 1971,
known as the Hadley rille.
Future explorers may visit others, but they should leave their fishing rods at home.
This visual is one of our most popular. This is a picture of Tycho crater,
and the famous central peak boulder, which is about 400 feet wide.
That’s longer than a football field.
How in the world did that wind up there?
Well I have no idea!
["Oh, daggum-it!"]
We’re going to fly now into a spot on the near side to look at this weird feature,
which has long defied an easy explanation.
It’s known as Reiner Gamma.
Those squiggles and swirls sure are bizarre.
A combination of computer modeling and data gathered
from numerous recent lunar missions, including Lunar Reconnaissance Orbiter,
now sheds light on the origin of these unusual surface decorations –
which we call lunar swirls.
Now think of it this way -
You’ve probably been told that when you go outside to put on your sunscreen.
Well, these beautiful swirls are constant reminders
that the Moon is no different from you and me.
Except that it’s a Moon, and we’re humans.
These swirls are examples of what happens when the Moon applies SPF three million.
The Moon is constantly bombarded by radiation from the Sun and galaxy,
as well as micro-meteorites that sand-blast the surface.
These swirls, however, show what happens
when the radiation is blocked from reaching the surface.
Data suggests that small magnetic anomalies block radiation from reaching the surface,
and therefore prevent the Moon from getting sunburned in these areas,
which keep them as bright as they appear to be.
So, the next time you put on sunblock to go lounge outside,
think of the Moon and how it gets baked in the Sun just like you and me.
[Aaaaaaah!]
Thanks for watching today.
Hopefully this video taught you more about the Moon,
and that you aren’t left thinking, “What the heck was that?”
I’m Noah Petro, signing off.