Celestia takes data gathered by the European Space Agency and then maps it in 3D.
Imagine if there was a version of Google Earth for the entire solar system – and way beyond. Real-time 3D orbits and asteroid paths, add-on scripts and high resolution imagery. Actually, there's no need to imagine it, because Celestia has all that. This phenomenal open-source project takes data gathered by the European Space Agency, including imagery, telemetry and positional data for planets, asteroids and stars, and then maps it in 3D.
The default installation enables you to select any of the catalogued objects using a built-in browser and 'fly' directly to it. There you can use keyboard and mouse to move around in three dimensions, magnifying planets, orbiting them or selecting other objects (such as moons and asteroids) in the immediate area. You can even select stars outside our solar system and 'visit' those.
Celestia is a superb tool for educational purposes and enthusiastic astronomers with additional data available in overlays and labels, such as planet names and constellations. The highly configurable display features let you add or remove detail at will. Moving around through the solar system and beyond to other galaxies can be acheived using a combination of keyboard shortcuts, or
Celestia would be impressive if it was simply a static model of all this information. But it's more than that. The objects in Celestia are moving along their true paths, synchronised to your computer's time and date. To see this in action, you can speed up time, watch shadows move around planetary bodies, moons fly through their orbit or follow an asteroid on its journey through space.
The satellite imagery bundled with Celestia is fairly low resolution, breaking down as you zoom in more closely to planet surfaces. Never fear, though, there are free add-on packs that map Google Earth-like detail on to the planetary bodies found in the program. You can also download scripted tours, expanded data, and even add fictional spacecraft to the base installation. A collection of these can be found at www.celestiamotherlode.net.