If you know that the period is 76 years and the semi major axis is 17.94 AU, how do you calculate the distances of the perihelion and aphelion?

1 Answer
Phillip E.
Mar 28, 2016

There is not enough information to calculate the apses distances.

Explanation:

The period #P# and semi-major axis #a# are not sufficient to calculate the apses distances as the eccentricity of the orbit can't be determined.

If the eccentricity #e# is known then the perihelion distance is #a(1-e)# and the aphelion distance is #a(1+e)#.

In fact the period and semi-major axis can be calculated from each other using Kepler's third law. For our solar system if #P# is in years and #a# is in AU then #P^2=a^3#.

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