Question

What are Kepler’s Three Laws and why are they important?

Answer 1

Kepler's three laws can be stated as:

• The path of the planets about the sun is elliptical in shape, with the center of the sun being located at one focus. (The is called theLaw of Ellipses).
• An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. (The is called the Law of Equal Areas).
• The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. (The is called theLaw of Harmonies)

Significance and application of kepler's law:

First law - we can study the locus or trajectory of planets. As we know the first law states that the trajectory of planets is an ellipse with sun as foci. We can apply ellipse equations to study the trajectory or the path traversed.

Second law - The Law of Equal Areas establishes that the fact that when planets are near the Sun in their orbit, they move faster than when they are far away. Hence physical quantities like angular speeds and the magnitude of acceleration at different points on the trajectory could be discussed.

Third law - orbital periods. As T^2 / a^3 ratio is constant for all the planet.The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.