XEphem is a full-fledged planetarium
and astronomy laboratory for Unix-like systems, such as Linux, FreeBSD and Solaris. Ports to OS/2 and Mac OS X are planned.
"XEphem, the brainchild of programmer Elwood Downey, is a star-charting
sky-simulating, ephemeris-generating celestial virtuoso that can do just
about everything that the usual Windows and Macintosh star-charting
software can do -- and sometimes quite a bit more. And it's completely
free. What's not to like?"
- Jeff Medkeff, Xceptional Astronomical Software,
Sky and Telescope, Feb 2000
The official Web-site for this phenomenal piece of
software is http://www.clearskyinstitute.com/xephem/