Kepler’s Laws of Planetary Motion – Practice


1) Ganymede, a moon of Jupiter, has an orbital radius of 1,070,000km and a period of 7.155 Earth days. Calculate the mass of Jupiter:

2) Calculate the orbital period of Mars if it has an orbital radius of 228,000,000 km and the mass of the Sun = 1.99 × 1030 kg:

3) A planet with a period of 80 Earth days orbits a star. A second planet in the same system orbits the star at a radius which is equal to 5 times the radius of the first planet. Calculate the period of the second planet:

4) The mass of the Earth = 6.0 × 1024 kg and the orbital radius of the Earth = 1.5 × 1011 m. Calculate the orbital period of Neptune if it has an orbital radius of 4.5 billion km. Do not use the mass of the Sun in your calculation:

Quick Answers:

1) 1.897 × 1027 kg

2) 687.2 Earthdays

3) 894.4 Earth Days

4) 164.3 Earth years

Worked Answers: