#248 Moon does not follow its orbit path

Britton LaRoche

I followed earth and drew the lunar orbit. After pushing time forward 1000x and watching the moon from many angles I'm pretty certain it is not following the green orbital path drawn on the screen.


  • This is on windows xp

  • Actually its 1,000,000x speed, and after a minute or so its way off. I guess you may need to redraw the orbit path based on the time.... perhaps once a virtual year.

  • the orbit path should be recalculated if you toggle the orbit on / off

  • I confirm, the moon goes way out of the orbit.

    According to Q14 of the shatters' FAQ (http://www.shatters.net/forum/viewtopic.php?p=17194) or Q16 of celestiamotherlode's FAQ ( http://www.celestiamotherlode.net/celestia_faq.php#orbits\), this would be due to approximations in orbit drawing, but I disagree for several reasons:
    - I tried to draw orbits with 10000 points instead of 100 points and it doesn't change anything.
    - The errors are anyway a lot larger than any drawing error.
    - When time goes fast, we can see that the drawn orbit isn't changing at all, whereas the trajectory of the moon is changing a lot.

    All of this makes me think that the orbit should be updated, and is not, or something like that...