4k views

### Why are our planets in the solar system all on the same disc/plane/layer? [duplicate]

I always see pictures of the solar system where our sun is in the middle and the planets surround the sun. All these planets move on orbits on the same layer. Why?
2k views

### Why does orbiting matter form an accretion disk? [duplicate]

Why does matter in orbital motion around a central body tend to form an accretion disk, as opposed to some other configuration like a sphere? I know this has something to do with angular momentum ...
353 views

### Why is the matter orbiting a black hole in the shape of a disk? [duplicate]

More generally, if a blackhole is a singularity...a point in space...why is matter only circling in a flat disk-like region. It would seem to me matter would circle it in a sphere surrounding the ...
157 views

### Why is our solar systems co-planar? [duplicate]

Even though moon and satellite orbit the planets in multiple planes why our solar system is co-planar? Not only that, ring systems of several planets are also co-planar. Is it the way they evolved ...
147 views

### How did the planets (in the Solar System) start to revolve around the sun if they were attracted towards the Sun via the gravitational force? [duplicate]

The planets in the Solar System revolve around the Sun in almost circular paths called orbits. The Sun pulls the planets with the gravitational force,but the planets do not get drawn to the Sun but ...
55 views

### The way planets rotate and revolve [duplicate]

Why is that the all planets move in the same plane?(correct me if I'm wrong) Why not some of them in anticlockwise direction and others in clockwise direction?
49 views

### Sun-path on the sky [duplicate]

We are standing on the Earth and we see Sun on the sky. We see it walking in a certain direction, with predictable moving. Earth is a spheroid, as we all know. It is circling around the Sun, and also ...
30k views

### Why the galaxies form 2D planes (or spiral-like) instead of 3D balls (or spherical-like)?

Question: As we know, (1) the macroscopic spatial dimension of our universe is 3 dimension, and (2) gravity attracts massive objects together and the gravitational force is isotropic without ...
1k views

### Are there planetary systems where the planes of orbits vary greatly?

Inspired by this question, are there any known planetary systems with largely varying planes of orbit? For example a system where two planets have perpendicular planes?
2k views

### Why do 3d spheres and gravity tend to rotating discs on one plane?

Whether is it our solar system or a whole galaxy, there is usually a massive object (star or black hole) at the centre with gas and objects rotating around it. The gravitational effect of the star/...
367 views

### Why are star systems flat but planets are spherical?

This video vaguely explains why the solar system (or other star systems and galaxies) are flat. So, does the same argument apply to planets? The general answer is that for a given volume, a sphere ...
659 views

### Why planets are orbiting only in one plane? [duplicate]

Since gravity is three dimensional why planets are orbiting only in one plane around sun.
1k views

### why galaxies look like discs rather than spheres? [duplicate]

Black holes have much gravitation to hold all stars and nebulas but why they are aligned in disc type shapes rather than spheres because gravitation is everywhere around black holes. Even on upper ...
When you look a sphere from a fixed observation point, you can easily mistake it for a circle, so I was wondering: are galaxies really "disk" shaped or we just don't have the means to detect the "$z$-...