btw why do planets become spherical over time? i thought it was because they spun around so much. it's the opposite for galaxies, which start off as spheres and then become flat spirals.
maybe planets are spherical because they are formed that way and just stay that way because they are strong enough to not be affected too much by centrifugal force. whereas galaxies are held togther by gravity alone, which is a weak force.
and yes i just had a conversation with myself there.
Phaze-Two
If it were spinning fast enough, it'd flatten out, but at it's current speed the gravity of the Earth is able to keep it ~spherical... The Earth is an oblate spheroid, not a sphere, Earth would lack a regular axis, just tumbling, if it were a perfect sphere.
Massive objects, when clumped, always push in on themselves, so they 'prefer' a spherical shape, but gravity is fairly weak and can't pull an object into a ~sphere until it's of enough mass and density.
I thought WMAP suggested that the universe itself is mostly flat.CptJSparrow
The 'shape' of the universe is unknown, there is no observable curvature, but on Earth it takes almost 70k feet above sea level to see it's curvature and it's tiny, so if we're not seeing curvature from our perspective... it could mean the universe is infinite in size, a shape we're not expecting, a hologram, or at least just a really really big sphere.
[/spoiler] 
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