Kepler's Laws

Johannes Kepler, working with data painstakingly collected by Tycho Brahe (from 1576-1601) without the aid of a telescope, developed three laws which described the motion of the planets across the sky. 

Law of Orbits: All planets move in elliptical orbits, with the sun at 1 focus.

An ellipse is an oval shape centered on 2 points instead of 1 point.

The orbital period of a planet is how long it takes for it to travel a complete orbit around the Sun… a year!

Perihelion

Aphelion

Law of Areas: A line that connects a planet to the Sun sweeps out equal (=) areas in equal (=) times.

Earth sweeps out a longer path when it is closer to the Sun.

Earth moves fastest when it is closest to the Sun

Law of Periods: The square of the orbital period of any planet is proportional to the cube of the semi major axis of its orbit. 

P² = a³ If you know the distance of a planet to the Sun, you would be able to figure out its… orbital period. Basically… The closer a planet is to the Sun, the shorter its orbital period is. 

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