Ok guys, I almost got my orbiting planets to work:
http://codepen.io/anon/pen/igrld
Everything seems ok if browser tab stays active. Reversing timeline rotations also works nicely if you click on the "sun".
But strangely enough, if you switch to other browser tab for a while (animation tab becomes inactive) the planets tend to come together and lose their position in the orbit. Is this a bug, expected behaviour or am I doing something wrong here?