Unit 4.1 Orbits and the wider universe

Question 1

What’s Kepler’s first law?

Answer 1

each planet moves in an ellipse with the Sun at one focus

Question 2

What’s Kepler’s second law?

Answer 2

The line joining a planet to the centre of the Sun sweeps out equal areas in equal times.

Question 3

What’s Kepler’s third law?

Answer 3

The square of the period of the planet’s motion is proportinal to r³, where r is the mean distance from the planet to the star, whent he orbit is close to circular.