What is Kepler’s Third Law?

Kepler’s Third Law is about how long it takes planets to go around the Sun compared to how far away they are.

Imagine you and your friend both swing on swings at the park. If you’re closer to the center, you swing faster, you go around quicker. But if your friend is farther out, they take longer to complete each swing. It’s like a game of distance vs. time.

Kepler’s Third Law works like that swing ride. Planets farther from the Sun take more time to make one full trip around it, just like how your friend on the outermost swing takes longer than you do. This rule lets scientists figure out how far a planet is from the Sun if they know how long its year is, or vice versa.

Think of Earth and Mars. Earth is closer to the Sun, so it takes about 365 days to go around, that’s one year for us. Mars is farther away, so it takes longer: about 687 Earth days for one full year on Mars.

Kepler's Third Law gives scientists a way to compare all these planets’ distances and their years, like a universal swing ride rule in space!