Orbit Xplorer
Educational orbit and gravitation simulator for high school, college and beginning university physics and astronomy. Input mass, radius, coordinates and velocity components of 2 to 10 bodies manually or by dragging and dropping predefined bodies. Then watch how the orbits evolve under the mutual... Simulations include elliptical satellite orbits, Kepler's laws, double star, geocentric and heliocentric world view, Lagrange points, gravity assist, Hohmann orbit, extrasolar planet, inner solar system.
http://www.ottisoft.com/orbitx20.exe - 3Mb - Download - Screenshot

Planet Pluto 3D Screensaver
Far far away, at the very edge of the Solar System lies Pluto, the ninth planet from the Sun. It is not only much smaller and less massive than every other planet, it is also smaller and less massive than seven moons of other planets. It has a highly eccentric orbit which takes it inside the... Pluto's atmosphere appears to extend out to include Charon, which suggests that they may share an atmosphere. ... There are many other interesting and controversial facts about this planet that you can learn if you download this screensaver.
http://www.space-screensavers.com/files/planetpluto3d.exe - 3Mb - Download - Screenshot

Solar System 3D Simulator
Solar System 3D Simulator is a FREE software application that generates a realistic solar system model and planets in 3 Dimension on the PC using advanced physics formulas. It can display the planets and their orbits, the sun and the moon. The nine planets including planet earth and their... The graphical output is in high-resolution 3D full color format and the orbit view can be adjusted and the orbits tilted & rotated to any angle. ... The program has a fully graphical menu oriented interface designed for ease of use.
http://www.sciencefair-projects.org/solarsystem/solarsystem.html - 5Mb - Download - Screenshot

Planet Neptune 3D Screensaver
Neptune is the eighth planet from the sun, and the outermost gas giant in our solar system. Interestingly enough due to Pluto's eccentric orbit, Neptune is sometimes the furthest planet from the Sun. Orbiting so far from it the planet receives very little heat. ... The planet has large, dark ovals on its surface which astronomers believe are hurricane-like storms. ... Neptune is never visible with the naked eye so your only chance to have a good look at it is if you download this high-quality Planet Neptune 3D screensaver.
http://www.space-screensavers.com/files/planetneptune3d.exe - 2Mb - Download - Screenshot

Sputnik Screen Saver
A simple screen saver with a Sputnik cruising space. Not in orbit of Earth (as a real satellite would be), but who cares?
http://www.desktop-backgrounds.net/download/sputnik.exe - 629Kb - Download - Screenshot

Planet's Orbits
Planet's Orbits (for Windows 98/ME/2000/XP) is an accurate digital orrery with a wealth of functionality. The program uses the DE404 ephemeris (accurate for dates between 2000 B. C. and 6000 AD) for the calculation of planetary (except Pluto) and lunar positions. ... The version 1. ... 7. ... shows the positions and trajectories of various spacecrafts. ... The most noteworthy functions are date specification (past, future), 2D/3D orbital animation and custom zoom, orbits of 10000+ asteroids and comets from different databases, simple database handling and updates, printing, statistic, and...
http://www.alcyone.de/POrbits/po17.exe - 15Mb - Download - Screenshot

American Space Shuttle
This screensaver shows beautiful and stunning images of every shuttle in NASA's Space Shuttle fleet. See shuttles lift off, carry out their mission in orbit, land, and return home aboard the 747 shuttle carrier. This screen saver contains 44 amazing images.
http://www.soft2d.com/graphics_&_m...eensavers/files/amspsh30trial.exe - 2Mb - Download - Screenshot

3D Space Station Adventure
Kids ages 5-12 love this new activity center learning and entertainment software from MVP. Design and build your own space station, landing module, and even your own rocket ship, and then watch it lift off into orbit. Then rescue the astronauts and blast asteroids in two exciting action-packed... Three fun learning activities and two games give you plenty to do as you learn about space travel and the international space station.
ftp://ftp.mvpsoft.com/pub/3dspace.exe - 15Mb - Download - Screenshot

3D Solar System Screensaver
Screensaver views all planets of our solar system on your desktop. You can set different cameras to view whole solar system. Screensaver makes you able to configure lot of other options. Included is also an informative mode which makes you able to see more details about all planets. ... Optional is also an arrangement of planets relative or realistic orbit with lovely background music. ... You can even set your own MP3 as a custom soundtrack and many more features.
http://www.soft2d.com/graphics_&_m...creensavers/files/solar_setup.exe - 4Mb - Download - Screenshot

ShooltzSaver
Experience the beauty of 3D raytraced objects moving on various trajectories. ShooltzSaver is a high-performance, multithreaded program that gives you total control over animation, from orbit parameters to actual sprite images - just right-click when saver works to open control center window. ... com, along with detailed info about creating your own objects. ... Also: multiple settings, randomizing options, sound playback (including MP3) and more. ... shooltz. ... Program reads new sprites from avi and bmp files - about 200 additional sprites available at http://www.
http://www.shooltz.com/zip/shooltzsaver.zip - 583Kb - Download - Screenshot