I know that unmannedspaceflight.com has a few Celestia users... For those who aren't familiar with Celestia, it's a free interactive 3D model of the universe that simulates the motions and appearance of stars, planets, moons, spacecraft, and other bodies. There are a few new capabilities that will be of particular interest to readers of this forum:

- Simulation of the effects of planetshine
- Overlays of longitude/latitude grids and the terminator on planets and moons
- Updated Cassini mission (now covers launch through the end of the extended mission, though you'll want Jason Perry's add-on for the most accurate Cassini simulation)
- Improved rendering of eclipses (especially nice for mutual events of the Saturnian satellites)
- Adaptive resolution grids for different celestial coordinate systems: equatorial, ecliptic, horizontal, and galactic
- More accurate models of the rotation states of solar system bodies
- Ability to use orientation information from SPICE kernels
- Triaxial shapes for Mimas, Haumea, and other noticeably non-spheroidal bodies
- New maps for the Saturnian satellites and Mercury

Click to view attachment

Some more details are here: http://www.shatters.net/celestia/features/160-features.html

Celestia can be downloaded for Windows, Mac OS X, or Linux from SourceForge: http://sourceforge.net/projects/celestia/files/

I hope that unmannedspaceflight readers find the new version fun and useful. Enjoy!

--Chris

Thanks for such a wonderful program!

I'm a long-term Celestia user - have found it extremely useful in my Outreach work - so I was very happy to see an update. Just installed it and I love what you've done with the place! The Mercury render is just brilliant. Thanks!

Thanks for the kind words! Please post or PM me if you have suggestions for how Celestia could be improved. We'll be working hard on improving the user interface for the next release. (And I'll finally take care of making Saturn's rings look right from the unilluminated side...)

--Chris