KICKING AROUND THE PLANETS

Introduction
In physics, an orbit is the path that an object makes around another object while under the influence of a source of centripetal force, such as gravity.
Orbits were first analyzed mathematically by Johannes Kepler who formulated his results in his three laws of planetary motion. First, he found that the orbits of the planets in our solar system are elliptical, not circular as had previously been believed, and that the sun is not located at the center of the orbits, but rather at one focus. Second, he found that the orbital speed of each planet is not constant, as had previously been thought, but rather that the speed of the planet depends on the planet's distance from the sun. And third, Kepler found a universal relationship between the orbital properties of all the planets orbiting the sun. For each planet, the cube of the planet's distance from the sun, measured in astronaumical units(AU), is equal to the square of the planet's orbital period, measured in Earth years. Jupiter, for example, is approximately 5.2 AU from the sun and its orbital period is 11.86 Earth years. So 5.2 cubed equals 11.86 squared, as predicted.
Isaac Newton demonstrated that Kepler's laws were derivable from his theory of gravitation and that, in general, the orbits of bodies responding to the force of gravity were conic sections. Newton showed that a pair of bodies follow orbits of dimensions that are in inverse proportion to their Mass. Where one body is much more massive than the other, it is a convenient approximation to take the center of mass as coinciding with the center of the more massive body.
Dribbling a soccer ball is a method individual players use to move the ball from one point to another while preventing the opposition from gaining possession of it. The purpose of dribbling is practically the same as passing, except that only one player physically deals with the ball. In essence, dribbling is advancing a ball by bouncing it or giving it a series of short kicks or pushing it.

Notice that dribbling is not simply beating an opponent in a man-to-man confrontation. Moving with the ball in itself provides advantages.
Lesson Objective
In this activity, students will answer puzzles about the planets and their orbit around the sun. Gravity keeps the planets in their respective orbit. Students will learn that all planets revolve around the sun at the same time and do so without colliding.