In 1609 and 1619 Kepler published his three laws of planetary motion.

He was notable for research on planetary motions and ephemeris.

"Consider the simple equations of planetary motion," I said.

What about all those star charts and planetary motions and so?

These relations are known as Kepler's laws of planetary motion.

He describes how a large body of data concerning planetary motion has been used to make an overall test.

Kepler's theory I take to be his three laws of planetary motion.

Some of these appeared to relate to planetary and lunar motions.

This result implies that planetary motion is not absolutely stable.

He is best known for his laws of planetary motion.