Celestia Forums

Maybe i'm totally missing it, but it doesn't seem like precession and nutation are included in the body movements of earth. Is there a computational reason why this is not done...

I was just reading about precession for my mechanics class and thought it would be cool to see celestia show which way north would be and what star it would point to in 13000yrs...but it didnt work...

The code for handling precession in v1.4.1 and previous versions of Celestia interferes with the orientation of the Moon's orbit, so the Earth's precession is not enabled in solarsys.ssc.

Chris rewrote the relevant code for Celestia v1.5 and it should work better. I noticed that the precession specification in the cvs copy of solarsys.ssc is commented out, but I'm not sure why; perhaps the parameters aren't as accurate as they might be.

At any rate, if you run Windows, you might try uncommenting the precession specification that's in Celestia v1.5.0pre2 and see if it does reasonable things.

selden wrote:Chris rewrote the relevant code for Celestia v1.5 and it should work better. I noticed that the precession specification in the cvs copy of solarsys.ssc is commented out, but I'm not sure why; perhaps the parameters aren't as accurate as they might be.

Maybe this could be clarified by one of the developers. Chris?

Andy

It would be nice for Celestia to show precession, however, if you want to see the stars back in time, then try using Stellarium (another free planetarium software package).

Both these packages do different things, but compliment each other.