Hi Werner,

Use the 'Proper Motion' button. It'll do what you're looking for.
The stars _will_ move, but only due to proper motion: that is,
unless you set a really high step size, you'll never know about it.

The 'RA/dec' button, in theory, animated just solar system objects:
at each step, the objects were 'un-drawn' at their old positions, then
drawn at their new positions. In practice, this didn't work very well.
Many things that _should_ have moved, such as the horizon, just
stayed where they were. The 'Proper Motion' button gives all of the
benefits, and none of the drawbacks, of the 'RA/dec' button.

Incidentally, given a high step size (of a century or so), you
can animate in 'Proper Motion' mode, and then you _will_ see the
stars gradually crawl around the screen, and constellations deform.
To me, it's strange that you can look at the sky as it was a few
millennia ago and not see much difference from what it looks like now.

-- Bill