Celestia Forums

Just installed Celestia and have nothing to do with astronomy.. Just heard so much stuff about it on the net..
I was playing with the time and following calypso when I noticed this weird thing at the time of the topic.. can someone confirm that this will happen / is known?

03 / 09 / 5021 12:48 follow calypso

Whatever it is, it won't happen. The orbit simulation isn't reliable so far in the future.

Grant

It collides with Tethys. KaBoom!

O MY GOD ! Thetys ate my Calypso !

That's a good finding. Will it really happens ? The Celestia orbits aren't precise enough for that, I guess.

A 19 km wide asteroid falling on a small moon will makes a lot of sparks !

Tethys has a "custom orbit" calculated internally by Celestia, so it's extremely accurate for the near future. I dunno the time range: it varies with different bodies. Probably 1000 years or so. Past that time, however, its accuracy is much worse.

I think that beyond a certain date Celestia is supposed to revert to using its EllipticalOrbit calculations. Maybe that isn't happening with Tethys.

Cham wrote:O MY GOD ! Thetys ate my Calypso !

That's a good finding. Will it really happens ? The Celestia orbits aren't precise enough for that, I guess.

A 19 km wide asteroid falling on a small moon will makes a lot of sparks !

That's really the reason I posted on this forum.. I don't have a clue about astronomy but the loss of precission in Celestia can be replaced by the gravity of Thetys.. Can someone do some calculations?

Calypso is in a gravitationally stable orbit relative to Tethys ... it librates around a point 60 degrees behind Tethys in its orbit around Saturn; sometimes a little closer, sometimes a little farther. Barring disruption by the close passage of something massive, it'll keep on doing that indefinitely. Likewise Telesto, 60 degrees ahead.

Grant

selden wrote:I think that beyond a certain date Celestia is supposed to revert to using its EllipticalOrbit calculations. Maybe that isn't happening with Tethys.

Calypso's orbit is a simple ellipse in Celestia, so it eventually gets out of step with the more complex and accurate CustomOrbit of Tethys ... I'd guess that's what's caused this effect.
We've visited this topic before, when someone found Helene hitting Dione:
http://www.shatters.net/forum/viewtopic.php?t=4297

Grant

I've just found that changing the time of "only" 1000 years to the futur or to the past may change dramatically the relative distance between Telesto, Thetys and Calypso. Personnaly, I find this very disappointing.

But this is normal, as the solar system is very complex, maybe cahotic. It is very sensible to the initial conditions and a slight change in them may give a very different pattern in a not so far away futur (or past).

Wow, thats amazing. Even more amazing is that the probability of finding that event in Celestia is 1 in a 1 followed by many many ceros....

BTW: did you see the shadow covering Calyspo just before it crashes?

Wasn't there some mention a while back of creating custom orbits for the co-orbitals which basically just evaluate the main moon's position with a certain time displacement to put it in the right place?