Final answer:
Kepler's Third Law of Planetary Motion, also known as the Law of Harmonies, relates to the time a planet takes to orbit the Sun, called its period. This law states that the square of a planet's period is proportional to the cube of its semi-major axis distance from the Sun.
Step-by-step explanation:
Kepler's Third Law of Planetary Motion, also known as the Law of Harmonies, states that the period of a planet (the amount of time it takes to complete one orbit around the Sun) is related to its distance from the Sun in a precise mathematical way. The law asserts that the square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit. This means that if you take the length of the planet's year (how long it takes to go around the Sun once), square that number, and then compare it to the cube of the planet's average distance from the Sun, the ratio will be the same for every planet in our solar system.
Kepler's other laws include his First Law, which describes the elliptical shape of planetary orbits with the Sun at one focus, and his Second Law, known as the Law of Equal Areas, which says that a planet will sweep out equal areas in equal times, implying that the planet's speed increases when it is nearer to the Sun and decreases when farther away.