a_civilianLikes seeing numbersJoin Date: 2003-01-08Member: 12041Members, NS1 Playtester, Playtest Lead
The reason a sphere is impractical is that it would require immense structural strength. With a ring, you can simply rotate it at the appropriate orbital velocity to counter the effect of gravity. If you have a sphere, however, no amount of rotation will keep the poles from collapsing.
Why would a sphere collapse? I mean, I can understand why a sphere on earth would, but in space there wouldn't be any gravity to make it collapse, right? Unless it's not large enough and it's close to the sun or something.
there's always gravity. always. a sphere around the sun would collapse inwards (towards the sun) from the two poles around the axis of rotation (you can rotate on multiple axes but i don't want to run the coordinate substitutions to show that it'll still collapse.)
a_civilianLikes seeing numbersJoin Date: 2003-01-08Member: 12041Members, NS1 Playtester, Playtest Lead
While the gravitational field strength decreases as distance squared, the area of the sphere <i>increases</i> as distance squared. Thus, barring changes to the thickness of the sphere, the force of gravity on a given fraction of the sphere is the same no matter how large you make the sphere (assuming the thickness is close to zero).
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a sphere around the sun would collapse inwards (towards the sun) from the two poles around the axis of rotation (you can rotate on multiple axes but i don't want to run the coordinate substitutions to show that it'll still collapse.)