Imagine the Universe!

Speed is greatest at the point in the orbit closest to the Earth, called perigee, and is slowest at the point farthest from the Earth, called apogee. It is important to note that the orbit followed by a satellite is not dependent on its mass. A large heavy satellite could be in the same orbit with a small light one, each sweeping out equal areas in equal periods of time.

Video shows artist concept of a satellite in orbit around the Earth. The perigee (closest to the Earth) and apogee (farthest from the Earth) are labeled. Three different areas of the orbit are shaded, to show that equal areas are swept out in equal times.

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

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