This is an adaptation of question 2.1. in Galactic Dynamics by Binney and Tremaine in case anyone owns it.(adsbygoogle = window.adsbygoogle || []).push({});

1. The problem statement, all variables and given/known data

Astronauts orbiting a planet find that

(i) the surface of the planet is precisely spherical.

(ii) the potential exterior to the planetary surface is [tex]\phi = \frac{-GM}{r}[/tex] exactly, that is, perfectly spherical.

Can you conclude from these observations that the mass distribution in the interior of the planet is spherically symmetric?

2. Relevant equations

3. The attempt at a solution

I think that it doesn't matter whether it is a point mass inside at the centre or whether there is a symmetric mass distribution but I don't really know why I think that!

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# Homework Help: Galactic Dynamics (spherical potential)

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