The Hubble Space Telescope is very big — about the size of a large school bus or tanker truck. The tubular part of Hubble's body is 14 feet across, and the telescope stands 43 feet tall — about as high as a five-story building. On the ground, it would weigh over 25,000 pounds, but in space it weighs nothing. When the space shuttle Discovery carried Hubble into orbit, the telescope completely filled Discovery's cargo bay. Hubble is pictured in Discovery's cargo bay during the December 1999 servicing mission.

Hubble orbits about 353 miles (569 kilometers) above the Earth, and it takes about 97 minutes to complete one orbit. It is designed to receive regular tune-ups from the astronauts, who keep Hubble healthy and fit it with the latest technology. It is about halfway through its 20-year mission. The Hubble Space Telescope is a joint effort between NASA and the European Space Agency.