Full description
Xephem is an interactive astronomical ephemeris program for X Windows
systems. It computes heliocentric, geocentric and topocentric
information for fixed celestial objects and objects in heliocentric
and geocentric orbits; has built-in support for all planet positions;
the moons of Jupiter, Saturn and Earth; Mars' and Jupiter's central
meridian longitude; Saturn's rings; and Jupiter's Great Red Spot.