http://www.shatters.net/celestia/
Celestia: Celestia is a free real-time space simulation
that lets you experience our universe in three dimensions. Unlike most
planetarium software, Celestia doesn't confine you to the surface of the
Earth. You can travel throughout the solar system, to any of over
100,000 stars, or even beyond the galaxy. All travel in Celestia is
seamless; the exponential zoom feature lets you explore space across a
huge range of scales, from galaxy clusters down to spacecraft only a few
meters across. A 'point-and-goto' interface makes it simple to navigate
through the universe to the object you want to visit.
http://janus.astro.umd.edu/awtools.html#exploreorbits/ssbuild.html
Astronomy Workshop Tools: A set of animations of various
orbiting bodies, planets and moons. There is a lot of information
here, some of it suitable for high school and university physics
classes, some great for demos for elementary classrooms. Some
highlights are on the pages below:
http://janus.astro.umd.edu/orbits/ssbuild.html
Design Your Solar
System: World Builders, use
this!!! Put in some basic
information and find out if your
planets will support life!
http://janus.astro.umd.edu/javadir/orbits/ssv.html
Solar System Viewer: Animated
solar system with inner planets,
outer planets, asteroids, Kuyper
Belt bodies and comets.
Enjoy!
http://janus.astro.umd.edu/javadir/orbits/ess.html
Extrasolar Planets: models
of seven stars with real
planetary systems detected by
scientists.
http://ancientsuns.com/
Ancient Suns: This site
gives us information on our
closest neighboring star
system, Alpha Centauri, which
is actually a set of three
stars bound together in a
system by gravitational
forces. It also shows us the
orbits of three extra-solar
planets that have been
discovered by scientists, and
shows the orbits of these
planets in comparison with our
own solar system. There is
also a Viewing Cube animation
of nearby stars which shows
that we really do live in 3D
space. Also included are some
beautiful space scenes painted
by this artist (respect
copyright, please) and views
of the night skies from other
locations than our earth.
There are also two software
programs that you can
download.
http://liftoff.msfc.nasa.gov/academy/space/solarsystem/solarsystemjava.html
Explore the
Solar System by The
Exploratorium has an applet
that shows the planets and other
components of our solar system
from a number of different
perspectives. At the end of the
presentation the viewer is able
to tilt and rotate the solar
system and see it from many
different view points. Fun!
http://probability.ca/jeff/java/manymoons.html
Many Moons shows groups
of moons interacting according
to the laws of gravity. Watch
them go -- and notice that some
wind up being ejected from the
system and going off into space
alone. This can happen with
planets, too!