Toolkit for stargazing
Astroweather is weather forecast dedicated to weather for astronomical observations
It also provides services including astronomical event forecast, light pollution map, satellite images, positions of stars, planets, moons.
Real-time universe simulator
Celestia is a 3D astronomy software program created by Chris Laurel. The program allows users to virtually travel through a simulated version of our universe. Celestia can display objects of various scales using OpenGL.