Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 October 27 Asteroid Gaspra's Best Face Credit: The Galileo Project, NASA Explanation: Asteroid 951 Gaspra is a huge rock tumbling in space. Gaspra became one of the best-studied asteroids in 1991 when the spacecraft Galileo flew by. In the above photograph, subtle color variations have been exaggerated to highlight changes in reflectivity, surface structure and composition. Gaspra is about 20 kilometers long and orbits the Sun in...