Comment 1 for bug 499971

Hi!

It seems the lunar rotation is modelled too simple. It also appears to show a polar libration, i.e., it swings considerably in selenographic latitude. Is the lunar body in a false reference system?

As preliminary fix for rotation, find the file Stellarium/data/ssystem.ini (on Mac, I guess it's in the Stellarium.app folder) and in section [moon], change

rot_periode = 655.7181

or some other slightly smaller value. This is no complete bugfix, beware, it just keeps the moon facing the earth well into the 4th millennium BC. The "polar swing" is not solved by this. More accurate libration formulae could be found in the literature.

Also, if Earth's rotation is really only taken from the data in ssystem.ini, this seems not to be enough for simulating long-time effects. (But I did not read enough code so far.)

Regards,
Georg