The dwarf planet Pluto has an average orbital radius of 40 AU. Using Kepler's third law of planetary motion, what is Pluto's orbit in Earth-years?

1 Answer
Phillip E.
Jun 5, 2018

Pluto's period is 253 years using Kepler's third law.

Explanation:

In our solar system, anything orbiting the Sun obeys a simplified form of Kepler's third law if the period #T# is measured in years and the semi-major axis #a# distance is measured in AU.

$$T^2=a^3$$

If Pluto has a semi-major axis distance #a=40# then #T^2=40^3# which gives #T=253# years.

The actual period os Pluto is 248 years which is close.

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