5. Johannes Kepler published his third law of planetary motion in 1619. The third law is a mathematical equation to
find the amount of time that a planet takes to orbit once around the Sun based on how far away the planet is from
the Sun.
Orbits of the Planets (not drawn to scale)
Pluto
Sun
0 0
Mars
Neptune
Uranus
Earth
Saturn
Venus Jupiter
1914--
Mercury
3
Ops Third Law is: T = 0.2R2, where T is the time for a planet to go once around the Sun in Earth days (i. e.
24 hours), and R is t.
.) and R is the distance between the planet and the Sun in millions of kilometres. For example, Mercury
58 million kilometers from the Sun, therefore R = 58 for Mercury.
The distance between Mars and the Sun is 228 000 000 km. How many days does it take Mars to orbit
once around the Sun? How many “earth years" is it?
2 mai
b) It takes the former planet Pluto 248 years to orbit once around the Sun. How far away is Pluto?
217
c) Use the equation to determine Earth's distance from the Sun.