John Walker's "Home Planet" is pretty fine for what it is (freeware Win amateur astronomy app).
Joe-Mike says check out the Index Librorum Liberorum at
http://www.fourmilab.to/ (the USA mirror)
or http://fourmilab.ch/ (the Swiss site). Besides the stuff mentioned on
the home page, you can
click on the sidebar "Astronomy and Space" entry. Kewl.
Excerpts taken from the site:
Orbits in Strongly Curved Spacetime
An interactive Java applet which illustrates how orbits around compact
objects such as
neutron stars and black holes depart drastically from Kepler's laws, and explains why.
Source code for the applet is available.
Solar System Live
Solar System Live, an interactive orrery for the Web, lets you view the
solar system in
a variety of ways for any date between 4713 B.C. and A.D. 8000. An ephemeris can
be displayed for any location on Earth and, given orbital elements in the form published
in the IAU Circulars, the orbit and position of asteroids and comets can be plotted.
Your Sky makes custom maps of the sky for any location on Earth and any
4713 B.C. into the distant future. Maps can include stars as faint as magnitude 6.5,
constellation names, outlines, and boundaries, the Moon and planets, deep sky objects
from a database of more than 500, and a comet or asteroid whose position is calculated from its orbital elements. A variety of display options allow customising the
map for its intended use.
The Oh-My-God Particle (paper)
On October 15th, 1991 a proton with an energy of 3×1020 electron volts slammed into in the Earth's atmosphere. Let's crunch some numbers.... A performance comparison with 24th century Galaxy Class starship technology is presented.
Inconstant Moon explores a universally seen but seldom observed phenomenon:
different appearance of the Moon at perigee and apogee.
The only reason Einstein's special theory of relativity seems weird to
those learning it is
that the velocities we're familiar with are such a tiny fraction of the speed of light we've
never had a chance to gain an intuitive sense of relativistic effects. If the speed of light
were 100 kilometres per hour, footballers would have no trouble dealing with relativistic goal shots. C-ship uses computer image synthesis to put you aboard a
starship entirely consistent with the laws of physics and lets you look out the window
to experience special relativity with your own eyes.
Bending Spacetime in the Basement
At 19:45 99.04.18 -0400, you wrote:
>For years I've used "Dance of the Planets" as a valuable amateur astronomy
>reference tool and astronomy software toy, but sadly, the author of this
>piece of software stopped updating it some years ago. Likewise, I enjoyed
>playing around with Microsoft's "Space Simulator", and was disappointed that
>it wasn't commercially successful enough to support further development. So
>I'm wondering what recommendations folks on the list might have for
>top-quality current-generation astronomy and space simulation software.
> Greg Burch <GBurch1@aol.com>----<firstname.lastname@example.org>
> Attorney ::: Vice President, Extropy Institute ::: Wilderness Guide
> http://users.aol.com/gburch1 -or- http://members.aol.com/gburch1
> "Civilization is protest against nature;
> progress requires us to take control of evolution."
> -- Thomas Huxley