Question

What are Kepler's three laws?

Answer 1

Kepler's First Law - The Law of Orbits:

1. According to Kepler's first law, "all the planets rotate in elliptical orbits around the sun, with the sun at one of the foci."
2. Perihelion is the point at which the planet is closest to the sun, while aphelion is the point at which the planet is furthest from the sun.
3. An ellipse has the property that the total of any planet's distances from two foci is constant.
4. A planet's elliptical orbit is responsible for the occurrence of seasons.

Kepler’s second law – The law of equal areas:

1. According to Kepler's second law, “the radius vector extended from the sun to the planet sweeps out equal regions at equal time intervals.”
2. Kepler's second rule may alternatively be phrased as "The areal velocity of a planet spinning around the sun in elliptical orbit remains constant, implying that a planet's angular momentum remains constant."
3. All planetary movements are planar because the angular momentum is constant, which is a direct result of central force.

Kepler’s Third Law – The Law of Periods:

1. The square of a planet's time period of revolution around the sun in an elliptical orbit is precisely equal to the cube of its semi-major axis, according to Kepler's law of periods.
2. ${\mathrm{T}}^2\propto {\mathrm{a}}^3$
3. The shorter the planet's orbit around the sun, the shorter the time it takes to complete one revolution.