On a potato shaped object would gravity be the same all over?

29 July 2007

Question

Some Kuiper belt objects, such as 2003el61, are irregularly shaped unlike the spherical shaped planets. If you stood on the surface of this object would gravity vary depending on where you were standing?

Answer

Yes, these things are irregularly shaped, because they are not very large, their gravity is not enough to pull them into a sphere, so you are not always the same distance from the mass in the object so the gravity changes. Mars' moon Phobos is irregularly shaped and its gravity varies by about 50% depending on where you are standing which is important for the mission that is headed for this moon. With something this small the gravity is so weak that you want to land on the area with the most gravity or you will tend to float off or at least find it difficult to stay stable, so you may want to fire something like a harpoon into the ground to tie yourself down.

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