Keplers laws
GLOSSARY
KEPLER'S LAWS
Kepler's laws, established by Johannes Kepler at the beginning of the XVIIe century,
govern planetary motion. Binary stars also obey Kepler's laws.
Kepler's first law
The orbits of the planets are ellipses with the Sun at one focus.
Kepler's second law
A line from the planet to the Sun sweeps over equal areas in equal intervals of time.
Kepler's third law
The ratio of the squares of the orbital periods (P) for two planets is equal to the ratio of the cubes of their semi-major axes (a).
Kepler's first law
The orbits of the planets are ellipses with the Sun at one focus.
Kepler's second law
A line from the planet to the Sun sweeps over equal areas in equal intervals of time.
Kepler's third law
The ratio of the squares of the orbital periods (P) for two planets is equal to the ratio of the cubes of their semi-major axes (a).
