Today, I decided I’d figure out exactly HOW BIG it is. In like, actual numbers.



Let’s start by figuring out the composition of Alternia and its moons:

Seeing as Alternia has solid ground, is able to sustain life, AND has liquid water, we can assume that it’s made of mainly of rock (a “terrestrial”, or rock-based planet, as opposed to a “jovian”, or gas-based planet) and that it is located in the inner solar system (otherwise it would be covered in ice rather than desert, as one can see from the location of Midnight City in the intermission:)

This information, along with the fact that most Alternian life is nocturnal due to the days on Alternia being too hot for life forms to be active, all point to Alternia being in the inner solar system.

So, this is the information that we have so far:

ALTERNIA

Composition: Terrestrial (Rocky)

Location: Inner Solar System

Now that we have the composition, we can find the approximate size of the planet

The easiest way to do this is by looking at its moons. Particularly, its pink moon.

Alternia’s pink moon is ideal because of the smaller moon that orbits it.

As you can see, the smaller moon is round. This means that the moon is big enough to be round, which is no easy feat in astronomy. Because it is orbiting a moon, which itself orbits a larger body, it’s safe to assume that this “moonlet” is quite small. While it can be seen from Alternia, which would mean that it is big enough to be seen from Alternia, these pictures show that the Pink Moon’s orbital path is quite close to the actual planet:

This means that even a small moonlet would be easily visible from the surface of Alternia, due to the incredibly close proximity of the Pink Moon. As such, I will be assuming that it’s the smallest possible size that a round moon can be.

According to this source, an ice-based moon would be 400km in diameter and a rocky moon would be 600km in diameter. Because we figured out earlier that Alternia is in the inner solar system and therefore an ice-based moon would be affected by the heat, and would likely display a tail similar to that of a comet. Since the moon does not display a tail, it’s pretty safe to assume that the moonlet is rocky.

Therefore, the smallest possible size for the moonlet to be is about 600km (372.82 miles) in diameter.

Next, we can use this image to figure out the size of the Pink Moon:

Since we know the approximate size of the moonlet, we can use it to get the approximate size of the pink moon itself.

As we can see from this diagram, the moon is a little under 12.5 moonlets long.

To get an exact measurement, I measured the size of the cut off circle:

The entire circle, from the scale that I measured at, is 4.7cm tall (along the red line)



The pink moon itself ends directly above the white line. So, from the scale that I measured at, the part of the circle inside of the moon is 2.2cm tall.

This means that 2.2/4.7cm of that last circle is inside the moon.

Using *shudders* math, we can deduce that 46.8% of that circle is inside the moon. This means that the blue line measures 0.468 times 600km, or 280.85km(174.51 miles).

This means that the entire Pink Moon is (12*600)+280.85km in diameter, or 7,480.85km(4,648.38 miles) in diameter.

So here’s what we know so far:

>Alternia is a terrestrial planet, with terrestrial moons

>Its Pink Moon follows a very tight orbital path, which means that the exterior view of Alternia should give an accurate measurement of the planet by using the Pink Moon for scale.

>The Pink Moonlet is approximately 600km(372.82 miles) in diameter

>The Pink Moon is approximately 7,480.85km(4,648.38 miles) in diameter (That’s over half the diameter of Earth!)

Next, we’re going to use this information to find out the size of Alternia. We can do this by using this picture:

Which we’ve seen three times already.

As we figured out before, the Pink Moon follows a very close orbital path to Alternia, and goes AROUND the planet from this vantage point and not in front of or behind it. This means that the moon is probably not distorted from this point of view.

This time around, the Pink Moon’s size will be represented by a yellow circle:

Using this method, we get this line of reference:

Once again, the circles do not fit perfectly. The planet cuts off right above the white line. By zooming in and measuring within the same frame, I got these measurements:

The part inside of Alternia measures 2.0cm while the entire circle measures 5.4cm from the scale that I took the measurements at.

This means that 2.0/5.4 percent, or 37% of the circle is inside of Alternia.

So, the measurement of the part of this circle that is inside of Alternia is 0.37 times 7,480.85km, or 2,770.69km.

So, the size of the diameter of Alternia is 7 Pink Moons Plus 2,770.69, which is represented by the equation ([7*7,480.85]+2,770.69)

Solution to this equation:

(7*7,480.85)+2,770.69 = 52,365.95+2,770.69 = 55,136.64km

Therefore, Alternia is approximately 55,136.64km(34,260.32 miles) in diameter.

This means that Alternia is, at the very least, 4.3 times the size of Earth

This makes Alternia, a life-supporting, terrestrial planet, only slightly smaller than SATURN, which is the second-largest planet in our solar system.

And that’s at its smallest possible size. It’s highly likely that the moonlet is the same size as Earth’s moon, seeing as it’s just a painted-over image of our moon and is not big enough to have a moonlet of its own.

If this were the case, Alternia would be 319,222.93km(198,355.93 miles) in diameter, making it 4.6 times bigger than Jupiter and 50.1 times bigger than Earth.