Orbits

Kepler’s Laws

•Kepler’s 1st Law:

•The orbit of every planet is an ellipse with the Sun at one of the two foci.

•Kepler’s 2nd Law:

•A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.

•Kepler’s 3rd Law:

•The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.

*For Kepler’s First Law one focus is the sun and is important but the second focus is insignificant.

Close and Far Names

•OBJECT – CLOSE :: FAR

•Sun – Perihelion :: Aphelion

•Earth – Perigee :: Apogee

•Any Star – Periastron :: Apastron

•Anything – Periapsis :: Apoapsis

•Anything v2 – Pericenter :: Apocenter