Mass of the Sun

To measure the mass of the Sun would seem to be hard, but actually it is easy.

Newton's laws of motion together with his law of gravity give a relation among (For our purposes, assume the orbits are circles. Also assume that the mass of a planet is tiny compared to the mass of the Sun.)

The relation is

Using this relation with P and a for the Earth gives the mass of the Sun.

M ~ 2 x 1030 kg.

We will use this relation later on to get the masses of other stars.

It can also be used to get the masses of galaxies!

Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA