The macosxhints Rating:

[Score: 8 out of 10]

• Developer: Chris Laurel / Product Page
• Unofficial (but more recent builds) page: Celestia Download Center
• Price: Free

If you're fascinated by stars, planets, moons, comets, and the universe in general, you owe it to yourself to check out Celestia. This amazing free Java program lets you zip about the universe, displaying amazing pictures of various celestial bodies -- there are some great shots in the Celestia Screenshot Gallery. The program knows about our solar system, comets, over 100,000 stars, and even additional galaxies. If that's not enough, you can download even more from the Celestia Motherlode site.

To get a sense of what you can see in Celestia, launch the program, and then press 'D' to enter Demo mode. Then just sit back and watch the show.

You can fly throughout the Celestia universe with the keyboard, accelerating to some truly amazing speeds -- you really get a sense of the scale of the universe when you see how long it takes to move somewhere, even traveling at a rate measured in light years per second. Click on any object to find out its position, luminosity, and other related data. Zoom in and out on local objects to see some amazing surface details. And if those surface details look fuzzy to you, it's probably because the default texture resolution is set to "low." To fix this, go to the Preferences, and set the Texture Resolution pop-up to Medium or High.

I've only had one issue so far with Celestia: it just won't remember my texture resolution settings. So each time I launch the program, I have to reset them to High to see the pretty pictures. This is apparently a known glitch in 1.3.2, and is fixed in the not-yet-finished 1.4.0pre6 version. That's the good news.

The bad news is that this build was released in January of this year, and no final version has yet to be seen. Digging around on their forum site, I found another unofficial build, this one from July of 2005, with some specific OS X enhancements. I haven't tried either version yet, but will do so shortly. As a general statement, Celestia development seems to have slowed dramatically -- the News section of the site was last updated in February of this year, and 1.3.2 was released in March (I believe).

Update: A reader emailed me a link to an unofficial Celestia Download Center, where you can find version "1.4preFT1.1ish," dated October 13th, 2005.

Finally, if you run Celestia on Windows or Linux, you'll get some features the Mac version is missing, including movie capture, and a star and solar system browser. Like some other Mac versions of Windows apps, Celestia is missing some features. But that doesn't change the fact that this is still an amazing program...