paraphrase of the Web page:
   
This program draws the Solar System's bodies in simulated
3-dimensionality.  You can view all the planets, their moons and
a few spaceships in motion, trace them, follow them, orbit them
and even control them.

OpenUniverse was formerly known as Solar System Simulator (Ssystem).
It was initially released in 1997 with the intent of creating a
rotating display of the Earth on a mainstream PC.  Ssystem version
1.0 was only aware of the planets.  Version 1.2 added moons; and
1.6, more means of movement and better textures.

The program has been renamed OpenUniverse 1.0 to underline the
concept behind its further development:  openness for the whole
Universe, not just the solar system--open for anyone to use, extend
and change.

WWW:  http://openuniverse.sourceforge.net/