Yahoo 知識+ 將於 2021 年 5 月 4 日 (美國東岸時間) 停止服務,而 Yahoo 知識+ 網站現已轉為僅限瀏覽模式。其他 Yahoo 資產或服務,或你的 Yahoo 帳戶將不會有任何變更。你可以在此服務中心網頁進一步了解 Yahoo 知識+ 停止服務的事宜,以及了解如何下載你的資料。
Is a sphere (possibly flattened) the only possible shape for a planet?
Could a torus (dough nut) be formed? Possibly by a stream of debris that loops in a circle due to gravity and then coalesces into the torus. With some spin it might just be stable, any thoughts?
Gravitation from other parts of the torus could be the inward force, Spin could give the outward force.
Maybe it could not form naturally, but could it be stable if manufactured (with the correct mass, size, spin, density etc) without relying on any cohesion between the particles?
5 個解答
- 最愛解答
I think it is very hard for a planet to be of some other shape, rather than a sphere, 'coz gravitational pool will attract that mass whatever its former shape may be from the centre.
Sorry couldn't be of much help though.
- kumorifoxLv 71 十年前
Not without two forces tugging at the torus in opposing directions: one from the centre of the torus and one from outside the torus. Otherwise, the torus will just collapse into a sphere due to gravity, or rip apart because there is not enough gravity to hold it together.
An example of a torus-like shape in our solar system are the rings of Saturn. However, they are kept in place by the planet's gravity from the inside and the system of satellites from the outside.
- 匿名1 十年前
If you believe in the multiverse hypothesis, yes there could be a universe that may have completely different physics than ours.
Then it's possible. But I don't think it's possible in the universe we live in.
I have to admit though, a torus shaped planet would be cool.
- wilde_spaceLv 71 十年前
Planets are spheres by definition. For an object to be considered a planet, it must be large enough for it's own gravity to have pulled it into a sphere. If it's not a sphere, it's not a planet but something else.
- DinDjinnLv 71 十年前
The current definition of a "planet" includes that it be spheroid; this disqualifies irregularly shaped objects like asteroids.