The solar system revolve around the sun like a disk which is more or less in 2 dimension. Also, the earth actually has a up and down (ok they can be inverted) that match the 2 sides of the disk. Galaxies also seem to work like that. But why? Is the universe like that too or is it more like a sphere? Why the solar system does not act as a sphere like an Atom?
2007-02-01 10:17:35 · 6 answers · asked by Guilôme 2 in Science & Mathematics ➔ Astronomy & Space
I know you know the solar system is 3-D, but are asking why it's so flat. Start with a rotating gas and dust cloud. Gravity pulls most of the gas into the centre. This becomes the sun. Gravity pulls little pockets of gas and dust together. These become the planets. Like a figure skater pulling her arms in, the whole thing increases its rotation rate. The planets pick up a spin (larger planets spin faster) and revolve about the sun in the same direction as the original cloud was spinning. Now, here's what makes it flat (i.e. 2-D). All the lumps of gas and dust that would have been planets (and moons) that are NOT in the plane or rotation get pulled into the sun by gravity. There is no way to resist the force. However, a few of the objects in the plane of rotation that have just the right speed for their radius of orbit (i.e. there distance from the sun) manage to stay in orbit. (Too slow...they fall in. Too fast...they get away.) All we have left are the few major planets and the minor planets (asteroids and comets) that have the correct orbital velocity. AFTER the formation of the solar system, other objects can come by, get trapped in strange orbits (like Pluto and Halley's comet). But the stuff that formed from the original gas cloud is all orbitting in the same plane. The solar system, therefore, is mostly flat.
2007-02-01 16:05:52 · answer #1 · answered by Rob S 3 · 0⤊ 0⤋
It is not 2 dimensional, just disk shaped.
You might as well ask whu a Pizza is not spherical - though, it still has depth.
A spinning cloud of dust and gas will accrete into a disk shape, as does the stars in a spinning galaxy.
The sun was formed from the gravitational condensing of the primal cloud, and the planets and most of the other matter are the leftovers that did their own local condensing.
The sun is the star - 99.9% of the Solar System is the sun. The rest, including Earth is just the debris leftovers.
2007-02-01 10:51:27 · answer #2 · answered by nick s 6 · 0⤊ 1⤋
The tendency for rotating objects is to conserve angular momentum and the flattening disk is an efficient way of doing that. But the solar system really is 3 dimensional. The orbit of the dwarf planet Pluto is quite inclined to the plane of the other planets, i.e. the invariable ecliptic plane.
Many galaxy's have very bright halos: M104; and globular clusters are by definition: round.
The local cluster of galaxies is definitely not lens-like, nor the enormous galactic cluster in Virgo.
Locally, yes, conservation of angular momentum predominates, but on a super-galactic scale it does not.
HTH
Charles
2007-02-01 10:58:32 · answer #3 · answered by Charles 6 · 1⤊ 0⤋
Because of the collisions (look at Saturn disk). Statistically, collisions make objects going into the rotating disk...
2007-02-01 10:25:49 · answer #4 · answered by Scanie 5 · 0⤊ 0⤋
it isn't 2 dimensional, it is three dimensional, it is formed after a disc only because of the magnetic influenc of the sun and dark matter........
2007-02-01 11:00:01 · answer #5 · answered by captsnuf 7 · 1⤊ 1⤋
It isn't. If you just said more or less 2D, then it is really 3D. But I believe you are referring to gravitational pull and angular momentum.
2007-02-01 11:02:47 · answer #6 · answered by Sparky 4 · 1⤊ 1⤋