Comment by readthenotes1

6 days ago

The moon has 1.2% the mass of earth, so earth still got embiggened

This is true, but it was surprising to me because I know that the gravity on the moon is 17% of the gravity on earth.

It turns out that what I was missing is that an object on the surface of the moon is much closer to the center of the moon than the same object would be on earth, because the radius of the moon is much less than the radius of the earth, and gravity is inversely proportional to the square of the distance between the two objects.

mass_ratio / radius_ratio^2 = gravity_ratio

0.0123 / 0.273^2 = 0.17

https://www.wolframalpha.com/input?i=mass+of+moon+%2F+mass+o...

https://www.wolframalpha.com/input?i=gravity+on+moon+%2F+gra...

https://en.wikipedia.org/wiki/Gravity#Characterization

https://www.wolframalpha.com/input?i=radius+of+the+moon+%2F+...