A shape with two focus points (foci) that lie on the major or longest axis, spaced equally on each side of the center
Kepler's First Law
All planets revolve around the Sun in elliptical orbits, with the Sun at one of the foci
Kepler's Second Law
The radius vector (line from Sun to planet) sweeps out equal areas in equal intervals of time
Semi-major axis
Half the distance of the major axis of an elliptical orbit
Kepler's Third Law
The square of the time period of revolution of a planet is directly proportional to the cube of its semi-major axis
Johannes Kepler was born prematurely, was a feeble child with weak vision, and at age 6 was sent to school but soon taken out to earn money for the family by working as a waiter in a hotel
