Kepler’s laws of planetary motion have three laws which are described as the motion of planets around the sun.
1. First law: The law of orbits
2. Second law: The law of equal areas
3. Third law: The law of periods
1. First Law: The law of orbits: Kepler’s first law states that ” All the planets revolve around the sun in elliptical orbits having the sun at one of the foci”.
Note: The point at which the planet is close to the sun is called perihelion and the point at which the planet is farther away from the sun is called aphelion.
The characteristic of the eclipse is that the sum of the distances of any planet from two foci is constant. Hence, the elliptical orbit of a planet is responsible for the occurrence of seasons.
2. Second Law: The law of equal areas: According to the Kepler’s second law, ” The radius vector drawn from the sun to the planet sweeps out equal areas in equal intervals of time”
It means “The areal velocity of a planet revolving around the sun in elliptical orbit remains constant. Due to which the angular momentum of a planet also remains constant”. As a result, planetary motions display the planar motions, which concludes that it is due to central force.
3. Third law: The law of periods: Kepler’s law of periods states that” The square of the time period of revolution of a planet around the sun in an elliptical orbit is directly proportional to the cube of its semi-major axis”.
T^2 ∝ a^3
Shorter the orbit of the planet, shorter the time taken to complete one revolution.