Astronomy Picture of the Day

Explanation: After a seven month voyage of nearly 500 million kilometers through interplanetary space, NASA's Spirit Rover has reached the surface of Mars. Scroll right and see a mosaic panorama of Spirit's first images returned from its landing site in Gusev Crater! Taken by Spirit's navigation camera, the panorama covers 360 degrees, with the spacecraft in the foreground and the floor of Gusev Crater, thought to be an ancient lake bed, extending to the horizon. The entry, descent, and landing phase of Spirit's mission - referred to by mission planners as "Six Minutes of Terror" - began Saturday night around 8:30pm PST as Spirit entered the martian atmosphere at about 20,000 kilometers per hour. Updates on Spirit's status will be posted throughout the day.