Distance to the Sun/Moon

*sun is interchangeable for moon for purposes of this thread*

I am not too sure about my math on this one so I thought i would post it in the forums and see if anyone catches something thats a miss. This entire speculation is based on the current amount of sims and then max and min angles of the moon. According to this the moon is furthest away when directly over head and closest just before setting. And because the moon does not shrink in appearance with the addition of new sims, the size must also be increasing with the addition of new sims.

distance to the moon = (1/2 distance between observers) * (tangent of the
angle between the observer and the moon)

distance to the moon = (1/2 distance between max north and south sim) * (tangent of the angle 89.999999 the max angle)

distance to the moon = ((51 sims * 256 meters)*(1/2)) * (57295779.51)

distance to the moon = (13056 * (1/2)) * (57295779.51)

distance to the moon = (652 * (57295779.51)

distance to the moon = (3.740268487 * 10^11)

If you plugged in the smallest angle 0.000001...

distance to the moon = (1.139350936 *10^-4)

You could theoreticaly stretch a prim to the moon, if you were close enough to the edge of the world.

If I stuffed up, or just completly botched it let me know . At best this is a spiffy fact at worst I made it thru the morning without doing anything to useful .

And if I was more confident in this I wouldve tried to make a chart showing the relative closeness of the moon at every angle.

It'd be cool to reinact the bicycle moon scene from ET. haha I was just trying last night with a bicycle (only I was by myself). I couldn't get it to look right anyway. Seemed like I couldn't get close enough to the moon or position myself correctly. Would certinally take some thought.

There are some errors:

      /|\
     / | \
    /  |a \
   /   |   \
  /    |h   \  d
 /     |     \
/      |      \
p1------------p2
       s

The distance to the moon, h, using observers at p1 and p2 to estimate the distance would be:

h = s/2 cot(a)

Note that for a large distance, h, the angle a becomes very small and essentially a constant with respect to separation, s. The only real way to measure the height of the sun would be to measure its elevation at the exact same moment at two widely separated locations (or measuring the time delay from like-elevation points).

However, I don't think the game engine would allow that. First, the position of the sun and moon are relative to each observer (each of us experiences a different in-world time). Second, I have a hunch that the sphere on which the sky, sun, and moon are rendered is always done so with the avatar directly at the center of the sphere. Thus the use of parallax to estimate its size is impossible.

How big is the sky sphere anyway?

~Ulrika~

I do not claim to be a math wiz, but the angle is always the same for any two objects measuing the angle to the moon so with that in hand you know the angles for the observers and you can essentially plug in any value for the locations because SL is always growing. I plugged in 13056 as the distance between them that seemed like a goodly amount of distance to me. But your point may be very accurate and I may be spouting off at the mouth. Besides we have to come together as a people and unite behind this issue. We need to know the distance we must travel to arrive at the Linden home world of the moon and steal their mind control devices, which are powered by cheese naturally .

Ulrika puts on her tinfoil hat and looks at the moon suspiciously.

~Ulrika~

NO! You are not allowed to steal my style!
-Begins pasting random newspaper clippings together and mumbling under his breath about Lindens from the sky-

I suspect that no mater where you are in the world, the moon will allways appear to be the same distance away.

Why? There's this 3-d thing called a skybox (and I suspect ever sim has it's own. How do I know? Well, with my old, crappy video chip, when I was on a private island, I could fly to the corner of it and observe the seams of the skybox.) It's not a sky sphere like Ulrika mentioned (although she might still be right about the sun rendering being relative to the avatar/agent). They're probably rendered on a per-sim basis (which makes sense considering private island sims can controll the day/night cycles on their sim, and it becomes painfully obvious when you're flying among joined island sims that don't have their clocks synced up).

I don't know enough about skyboxes to describe them well, unfortunately.

This is a interisting discussion. The math confuses me, and I have no input on that.

But as for the skybox, I'm not sure if its actualy a box or not... Upon going into SL "space" the skybox naturualy exhibits some weird behaviors, one of which is showing more obviously "box" like meeting points. However at the same time, it also exhibited some sphere like behavior as well.

The two images display the box meetings and when the sky suddenly went from black to blue, the sky slowly formed a circle and the black circle was slowly eaten away by blue, it definitly looked spherical, not boxlike.

So I'm not exactly sure which the skybox is. It is fully possible for a skybox to be spherical in shape as well.

The stars, are rendered client side randomly I believe. I also believe the sky is client side from our ability to control the settings (via Debug menu) of the position of the sun, and such.