Imagine the Universe!

Kepler's Laws I, II, and III

Johannes Kepler (1571-1630) was a German astronomer and mathematician. He was the first to understand that the planets in our solar system move in ellipses, not circles. He then continued his investigations, finally arriving at three principles of planetary motion. Known as Kepler's Laws, these principles revolutionized planetary astronomy. Many years after Kepler, Sir Isaac Newton proved that all three of Kepler's Laws are a direct result of the laws of gravitation and physics which govern the forces at work between various massive bodies.

Kepler's First Law

Kepler's Second Law

More about Kepler's Second Law

Kepler's Third Law

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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