The lunar reconnaissance orbiter has been exploring the surface of the moon since 2009,
mapping and imaging the surface of the moon like never before.
It orbits about 50-200km above the moon’s surface as there is no atmosphere to slow
it down, meaning it can really see the surface in exquisite detail with its powerful camera,
the LROC.
Due to the moon’s close proximity to us, the amount of data it is able to send each
day far surpasses missions like the Mars Reconnaissance Orbiter, the Juno mission around Jupiter,
and the New Horizons mission that passed Pluto.
In fact, it can send back an astonishing 155 gigabytes per day, or 55 terabytes per year!
So, in a similar vein to my Mars series, I want to explore the surface of our Moon and
explain the images you will be looking at.
I’m Alex McColgan and you’re watching Astrum, and in this video we will explore
the tallest mountains found on the Moon!
The LRO, unlike the MRO, has a special ability to be able to take photos from an angle as
well as from a top down perspective.
This means we are able to view the mountains of the moon as if from the cockpit of a plane,
which gives us a better sense of height and scale.
Although, our sense of scale is already seriously messed up, as on Earth we have visual clues
to help us judge how high or wide something is.
For instance, we can tell the background here must be tens of kilometres away, because the
atmosphere makes the mountains quite hazy.
Also, we can see the town, some trees, all of which help us know roughly how big something
is that we are looking at.
But on the moon we don’t have any of that, no trees, no atmosphere, no towns.
Just looking at this image, how big would you say this mountain is?
How wide is the foreground in this image?
It would be fun to see your guesses in the comments.
As it happens, the foreground of this image is about 15 kilometres across, and the foreground
mountain is nearly 7km tall!
These two peaks at the back are a massive 200km away, and are roughly 4,500m tall.
Surprisingly, these peaks aren’t named like they probably would be if they were on Earth
at that size.
The best way to kind of get a sense of scale for these images is to use this amazing tool
NASA have released called Quickmap, where you can see the moon under various filters,
including a topographical map.
Here’s the mountain in the foreground of the image, and here is the background peaks.
You’ll also notice that these peaks are found around the rim of a crater.
Pretty much all of the mountains we will look at today can be found either on the rims or
centre of craters, including these ones found in the famous Copernicus crater.
When craters form, we all tend to think of the circle they
create, but big craters often have uplift in the centre.
Surprisingly enough, this is not due to a water drop impacting a pool of water effect,
or elastic rebound, where the centre shoots up again after impact.
This only happens with material with elastic strength trying to return to its original
shape.
Rather, craters have uplift in the centre due to the surface material attempting to
revert to a gravitational equilibrium.
Copernicus crater can easily be seen on the surface of the moon by an amateur telescope,
and as a result is one of the moon’s most viewed features from the ground.
These mountains in the centre look impressive, but they only rise about 1000m above the crater
floor.
Zooming out a bit, and you will see how dwarfed they are by the surrounding crater walls,
reaching 4000m above the crater floor.
Here’s the crater from another angle, and one thing
you will notice is that the basin of this crater is lumpy, but comparatively flat.
This is because after the massive impact that caused this 100km wide crater, the floor was
lava which eventually solidified.
Moving on to a new location on the moon, we come to the Apennine Mountains, an impressive
range of 3-5km high mountains found at the rim of one of the biggest impact craters in
the whole solar system, the Imbrium Basin, or Mare Imbrium.
These mountains look interesting next to this mare, or a solidified lava plain, and this
rille, kind of like a gorge found on the moon.
But apart from being a very interesting view, there’s something else special about this
place.
It is in fact where the Apollo 15 mission landed in 1971, which means there is also
a ground perspective to these mountains.
Here is the lunar module with these same mountains in the background.
From here it looks like they are so close, but remember our perception of things is skewed!
These actually rise about 5km high from the plain the camera is on, higher than the Himalayan
front above the Nepalese and Indian plains on Earth.
Astronauts also investigated the rille using their lunar rover.
This rille actually drops down 380m!
Rille’s on the Moon are a bit of a mystery as it isn’t clear why they are there.
One leading theory is that they are the exposed or collapsed magma tunnels under the surface
of the moon back when it was more geologically active.
From the perspective of the LRO, the tracks left by the rover can still be seen today,
as there is no wind on the moon to cover the tracks up with dust.
So even though the Apollo mission happened about 40 years before this photo was taken,
the remains can still be seen in pristine detail.
It wouldn’t be right to talk about some of the highest points on the moon without
talking about the highest point!
Sadly, it doesn’t look too impressive as it has a really shallow gradient – only
3 degrees.
It’s near the biggest impact crater on the whole moon, the Aitken Basin, which likely
formed 4 billion years ago.
As you can see, this crater is huge, and would have created a lot of ejecta.
This ejecta piled up all around the crater, including what is now known as the highest
point on the moon.
The basin was likely caused by a low-velocity impact with an object 200km in diameter, and
it would have been at a sharp angle as the ejecta was flung mainly in one direction.
Interestingly, the lowest point on the moon is not so far away from the highest point!
The lowest point, found at the bottom of a crater within the basin is -9106m, and the
highest point is taller than Everest, at 10,786m!
A just a side note for those of you that are curious, these heights come from comparing
the average radius of the moon with the elevation of the point.
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Thanks for watching!
The moon, although monochrome, really is a treat as it’s the only other celestial body
where humans have set foot, which means that there is still a ton to talk about!
If you want to see more like this, don’t forget to subscribe, and if you want to support
the channel, I have a Patreon page!
Donated $5 or more to have your name added to this list!
All the best!
And see you next time.