The Orbit of the Moon

[:1]Here is something odd. And it's not the fact that the moon ALWAYS appears in the west, just like the sun is always drawn in the west, no matter what daytime it is.

The moon does not always appear same size on the screen. That means that his distance to Tyria is not a constant.



The large moon is seen from Riverside Province, the smaller one from Naphui, the Third from Vehtendi Valley. The moon can also be seen from Master Togo's bonus mission. He will also appear roughly medium sized.

If the size of the moon depended on ones position on the globe, then it would not appear smallest in Elona, but in Cantha. Since it is not that way, the distance between Tyria and the Moon has to vary.

That means his orbit is not circular but elliptic. If we assume that the moon's closest position to the planet is seen in Riverside, that means that the moon is eight times further away when the ellipses is at its furthest point (Vehtendi Valley?)

Next issue: If the moon appears always in the same spot, yet its size varies then that can mean only one thing.

** It takes the moon the same time to revolve around Tryira as Tyria takes to revolve around itself. But then the moon would not appear to have different sizes!!!!!

The solution is a rotating elliptical orbit of the moon! The moon is on an ellipses around Tyria, this ellipses has not a fixed focal point, instead it is rotating. Much like this graphic:



Rotating elliptical orbits are not uncommon in nature, most binary stars have them. If Tyria's moon has it, then it is most likely because it got caught by the gravity of the planet while passing by. In nature one can observe that often with black holes and binary stars close to each other. One is caught in the orbit of the other and starts its elliptical orbit while trying to break free, hence the rotation of the ellipses. Only problem: Since some energy is put into the rotation of the ellipses, the orbit itself degrades over time. Hence the black holes collide, the binary stars crash into each other, and the moon will come down on Tyria. That's right, global catastrophe coming up in Tyria. Why do we know that? Because the moon is not always the same size!

The whole synchronized rotation thing on the other hand does not have to be true. The results would be the same anyway. And that concludes my odd lore of the day.|||Pff. Every sage knows that the moon is the illegitimate love child of Lyssa and Grenth. It's size grows and shrinks based on whichever parent he favors more at the moment.

Heh, just kidding of course. Some nice math calculations you have there, but my point was that in a fantasy world, the moon's orbit isn't necessarily something dictated by science. Many fantasy settings hold the moon (and sun) to be divine beings in their own right, and it's entirely possible the moon is a sentient entity with its own patterns of movements. (The changes it displays during Halloween is possible proof of that too.)|||Yes, in World of warcraft there are moons that are seen as gods 2.

cant it be that Tyria is Flat then?

No, a dude stated that is was round..

maybe the Moon doesnt rotate around tyria but is stuck to it on one place and rotates with it.|||Physics, other than magic, appear to work normally in Tyria. We have weapons (bows are a good example) that work in a predictable manner. The moon also has not entered greatly into the mythology of the world (which considering most cultures' obsession with heavenly bodies is strange). This makes me think that the inhabitants of Tyria are aware of the moon's behavior and regard it as natural phenomenon rather than as a god or goddess. We do know that they observe the stars. We can be visited by celestial animals, I get an impression perhaps of magical spheres with the celestial creatures (check out the orbs at Nahpui) with maybe the moon inhabiting one of those or completely outside?

Hmm. I have no conclusions.

So ok, I have argued myself from physics to magical spheres.|||Quote:








The moon can also be seen from Master Togo's bonus mission. He will also appear roughly medium sized.




A character can see the moon in the Shattered Ravines as well. I'm not sure how it compares in size to your existing pictures, however.

I'd also be interested to know why there are different faces for the moon. The Vehtendi Valley moon does not look like the other two. The face shown in Shattered Ravines matches two of the three pictures given.

I'm not an astrophysicist, but I'm curious about your conclusion on rotating elliptical orbits. In the real world, the moon apparently changes size due to its proximity to the horizon:


Quote:








The Moon appears larger when close to the horizon. This is a purely psychological effect (see Moon illusion).




(source)

So I'd be curious about the sizes pictured and the horizon proximity for each -- in which case I'd suspect that the elliptical orbit isn't the correct reasoning.|||Quote:








A character can see the moon in the Shattered Ravines as well. I'm not sure how it compares in size to your existing pictures, however.

I'd also be interested to know why there are different faces for the moon. The Vehtendi Valley moon does not look like the other two. The face shown in Shattered Ravines matches two of the three pictures given.

I'm not an astrophysicist, but I'm curious about your conclusion on rotating elliptical orbits. In the real world, the moon apparently changes size due to its proximity to the horizon:

(source)

So I'd be curious about the sizes pictured and the horizon proximity for each -- in which case I'd suspect that the elliptical orbit isn't the correct reasoning.






Engine

From an engine perspective the sun and the moon are always drawn in the same place. At least the center is always in the same place. No matter if it is bright daylight or dusk, the sun has the same height relative to the horizon and is exactly to the west. If the position is the same and the size differs then it is not an illusion. The moon really moves further away.

Real Life

The Earth's moon does not perfectly face earth with the same side. We actually see 59% percent of its surface. It tilts a bit to the left and right. Still the moon takes the same time to rotate around itself as it takes for the Moon to rotate around the Earth. The result is that we only see one side. If the moon did not rotate, the people in Japan would actually see the other side of the moon. You can try that at home with two balls. mark one with a spot. If you want the spot to be visible from the ground of your second planet at all times then the marked ball has to rotate around itself while rotating around "the planet" in order for the spot to remain visible. Our Moon is too big to be an object caught in our gravity, it crashed into us, or Earth predecessor during the formation of the solar system to be exact. It orbits the Earth very long now which results in the fact that it always faces the same side towards us while slowly stopping the Earth's rotation. The moon's orbit is 5% off being a perfect circle.

Tyria

We see different faces of the Tyrian moon, meaning that it is rotating faster than our Earth's moon. It might not rotate at all, but we can't prove that without EXTENSIVE positional data, so from a few screens we can only prove and assume that it rotates. Moons do not have to rotate in synch with a planet although they tend to after a few billion years.

The orbit seems highly elliptical which most likely is the result of the moon getting trapped in the gravity of Tyria while passing by. For that to happen the gravity of Tyria would not be enough. Riverside (ok, all other pictures as well) proves the moon to be huge, so we are talking planets twice the size of Jupiter to catch such giant moons. Luckily magic provides enough room for speculation and enough force to trap it. Once trapped, the moon could remain on its elliptical orbit. A powerful person stopping the moon from crashing into Tyria and magically pushing it into a relatively stable orbit is our best bet. (If it is the Death Star with its own propulsion it would also make sense) As I said, since the mass of Tyria would be too small to attract that moon into this specific orbit, magic is the only alternative. In reality a moon that size would have crashed into Tyrai or passed by, with no scenario of getting captured.



I took some software rendering orbiting masses and found this relatively stable orbit explaining the huge difference in distance. Again, I can only stress the fact that this would be possible with the Earth and a small satellite and never with Tyria and an object the size of its moon. Btw, we are looking at the North Pole from the top in this picture.



An orbit like that would mean that the moon has not been here for billions of years (like our moon), but it has been caught in Tyria's gravity fairly recently. How recently cannot be determined as we do not know exact orbit times and their degradation. (500 years, 500.000.000 take a guess) At such an orbit it would actually make perfect sense that we rarely get to see the same side of the moon twice.

Personally, I think it's the same picture only zoomed and rotated every time, but even that would make no difference. Only one rotational axis more, no biggie.|||How could something so simple and beautiful like the Moon be ravaged by science in such manner?

Why can't we keep things simple?|||Science is quite elegant and beautiful, too, really; all it takes is perspective.|||The face on that smallest screen of the moon looks like the same face to me, but turned almost upside down, and that is perfectly possible, without indicating a faster speed of the moon's rotation.|||The moon not always appearing same side up means only one additional axis the moon rotates around. it has nothing to do with its orbit. The size is determined by its distance due to its orbit. If it tilts then because it is rotating (while orbiting Tyria)