Kepler's first law is that planets move around the sun in ellipses with the sun at one focus. The second law is the line connecting a sun to a planet sweeps equal areas in equal times. The third law is the square of the orbital period of a planet is proportional to a cube of the mean distance from the sun. The first law is important because it tells us that motion is not uniform circular motion. The second law is important because it tells us that sometimes the plants move quickly and that sometimes the planets move slowly. The third law is important because it tells us that planets are all obeying some common rules. It lets us figure out how long a new planet will take to go around the sun if we know the size of its orbit. These three rules