• Question: How much mass does an object need to have for its gravitational forces to pull it into a spherical shape?

    Asked by doppler to Adam, Sheila, Suzie on 24 Mar 2011 in Categories: .
    • Photo: Suzie Sheehy

      Suzie Sheehy answered on 24 Mar 2011:

      I’m not sure but I think it depends on other gravitational influences as well, like from the sun…

    • Photo: Sheila Kanani

      Sheila Kanani answered on 24 Mar 2011:

      Great question. Gravity doesnt like pointy bits! And the force of gravity is to do with the size and the mass of an object. I’m not sure about the mass, but I’ve heard (and thus worked out) that an object of more than 400 km diameter (tho this varies depending on density) will have a basically spherical shape because its internal gravity field will have equal strength on all surface points.

    • Photo: Adam Tuff

      Adam Tuff answered on 24 Mar 2011:

      Interesting one – maybe there’s an equation for it somewhere? I know the dwarf planet Ceres has enough mass to compress it into a sphere – it’s about 1/10000th of the Earth’s mass and about 500km wide, so there are some constraints on the lower limit.

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