Kepler's first law states that all planets move in elliptical orbits around the sun with the sun at one focus of the ellipse. An ellipse is shaped like a circle that has been flattened so that it is not perfectly round. The longest distance across an ellipse is called its major axis and half of this distance is called its semi major axis. The radius of a planet's orbit is approximately equal to its semi major axis. Distances in the system are often expressed in terms of Astronomical Units. 1 AU equals the length of the earth's semi major axis (average distance from the earth to the sun). Kepler's second law is the law of equal areas. It states that a radius vector drawn from any single planet to the sun will sweep out equal areas in equal times. This is a result of the conservation of energy. When the planet is far away from the sun, the radius vector a long, skinny pie slice because it is moving more slowly(less kinetic, more potential energy). When the planet is close to the sun, the radius vector forms a short, fat pie slice because it is moving faster(more kinetic, less potential energy). Kepler's third law is known as the harmonic law because of the name of the paper he wrote to describe it (Harmony of the Worlds). It states that the square of the sidereal period of a planet is proportional to the cube of its semi major axis. The equation is: T2 = kR3
Kepler's first law states that all planets move in elliptical orbits around the sun with the sun at one focus of the ellipse. An ellipse is shaped like a circle that has been flattened so that it is not perfectly round. The longest distance across an ellipse is called its major axis and half of this distance is called its semi major axis. The radius of a planet's orbit is approximately equal to its semi major axis. Distances in the system are often expressed in terms of Astronomical Units. 1 AU equals the length of the earth's semi major axis (average distance from the earth to the sun). Kepler's second law is the law of equal areas. It states that a radius vector drawn from any single planet to the sun will sweep out equal areas in equal times. This is a result of the conservation of energy. When the planet is far away from the sun, the radius vector a long, skinny pie slice because it is moving more slowly(less kinetic, more potential energy). When the planet is close to the sun, the radius vector forms a short, fat pie slice because it is moving faster(more kinetic, less potential energy). Kepler's third law is known as the harmonic law because of the name of the paper he wrote to describe it (Harmony of the Worlds). It states that the square of the sidereal period of a planet is proportional to the cube of its semi major axis. The equation is: T2 = kR3