WORLD HISTORY

Detailed explanation-1: -Knowing then that the orbits of the planets are elliptical, johannes Kepler formulated three laws of planetary motion, which accurately described the motion of comets as well. Kepler’s First Law: each planet’s orbit about the Sun is an ellipse.

Detailed explanation-2: -Kepler’s First Law The orbit of each planet about the sun is an ellipse with the sun at one focus, as shown in Figure 7.2. The planet’s closest approach to the sun is called perihelion and its farthest distance from the sun is called aphelion.

Detailed explanation-3: -Kepler had all of Tycho’s data on the planets, so he was able to determine how long each planet took to complete one orbit around the Sun. This is usually referred to as the period of an orbit. Kepler noted that the closer a planet was to the Sun, the faster it orbited the Sun.

Detailed explanation-4: -Kepler’s first law-sometimes referred to as the law of ellipses-explains that planets are orbiting the sun in a path described as an ellipse. An ellipse can easily be constructed using a pencil, two tacks, a string, a sheet of paper and a piece of cardboard.

Detailed explanation-5: -Kepler’s 3rd Law is sometimes called The Law of Periods: The square of the period of any planet is proportional to the cube of the semimajor axis of its orbit.