Re: How do the constellations change over time?

Dear Mr. Morrison,
Fire up your web browser and go to Distant Suns where you can download a shareware version of Distant Suns computer planetarium software. Install it, type in a date of A.D. 30,000 and see the constellations of the future for yourself. Alternately, use the animation feature to watch the stars shift position in 100 or 1000 year intervals. There are many other such programs available. Follow links from the Grand Rapids Amateur Astronomical Association web site.

For a more quantitative approach, you can look up the proper motion (a star's angular motion perpendicular to our line of sight to it) and radial velocity (a star's motion towards or away from us calculated from the Doppler shift of its spectrum) at the Space Telescope Institute.

[Also see the US Naval Observatory and Hipparcos Web sites. Moderator]

Jim Foerch
Veen Observatory
Lowell, Michigan, USA