Celestia Forums

Well, I'm not sure if this is a bug, or an error, or anything out of the ordinary. I was checking out the Celestia software, viewing the moon orbiting the Earth. I kept speeding it up, then I slowed it down again when the year in the upper right hand corner was 150000 or something. The strange thing was that the moon was orbiting MUCH closer to the Earth, and the orbit was very strange, it was orbiting vertically, passing over the North and South pole, and the orbit was swaying constantly. Eventually, as I kept watching, the moon dissapeared on one side of the Earth and poped out of the other side of the Earth, then continued orbiting as it had before. I assumed from this that your software did not take collisions into account, and that it had just simulated the moon crashing into the Earth. Now, another thing I found wrong with this is that the moon is supposed to be 1 inch further away from the Earth every year. This says that it is getting closer. Is this a bug, or something someone missed?

What version of Celestia are you using?

This was fixed in v1.3.0 or maybe earlier, I think.

The high precision orbits for the moon and planets are only good for about +/- 2000 years from now. Outside that range it switches to using just a simple Keplerian ellipse. Celestia does not even try to simulate the long term orbital changes.