#barrier cliffs

It’s Complicated

So, in astronomy, to find out the gravity of a distant planet, all we really need is… for that planet to have a moon. :D That is, we can observe the distance and orbital period of the moon around its planet, and then, using the laws of celestial mechanics, we can determine the planet’s mass and, consequently, its gravity. Simple, right?

Now, guess what our beloved show kindly tells us about all of this…? That’s right! Absolutely! Nothing! >:D

We don’t know the altitude Aerrow flew at in the “Stratosphere” episode, nor the time it took him to complete an orbit, and we can only judge the size of Atmos by very indirect clues. But what are these more substantial reasons we can be so sure of?!

The answer to that question is the Barrier Cliffs.

How High Can Mountains Be?

Now, let’s look closely at the screenshot again. Piper kindly informs us that they were at an altitude of 20 leagues in the stratosphere at that moment. And it doesn’t really matter what a league is right now. Let’s just imagine it means 20 kilometers. That’s already a pretty significant stratosphere on Earth. Now, even without calculations, let’s consider: it seems like the height of these mountains is roughly the same as the altitude where Condor is currently located. That is, definitely more than 10 kilometers high.

Now let’s compare this to Earth’s mountains: who can tell me the highest mountain on Earth? Well, it’s Mauna Kea in Hawaii! A whopping 10.2 kilometers from its base on the ocean floor, making it 1.3 kilometers taller than Everest. Who knew?! >:D

Essentially, on Earth, this is close to the limit. Theoretically, it could reach 12 kilometers, but that becomes difficult. However, for Olympus Mons on Mars, this is far from the limit! It stands at a full 22 kilometers high! And it’s not just the tallest mountain on Mars, but the tallest mountain in the solar system!

Since the fact that the Barrier Cliffs are very high is presented as a given, this is the more substantial reason to assume that the gravity on Atmos might be similar to Mars’s - that is, about 2.5 times weaker than on Earth. Indirectly, this also suggests that Atmos might be roughly the same size as Mars, but we have to consider the possibility that Atmos could have a low density, which could ultimately make it larger. Also, those in the know have surely noticed that purely from an astronomical perspective, all of this raises a lot of questions, such as why Atmos hasn’t lost its atmosphere yet. But that, as they say, is a whole other story.