Why are galaxies discs and not spheres?

Galaxies are disc shaped because they are gas rich and dynamically young. Stars are also gas rich but they are dynamically old so they have had time to rid themselves of their discs.

What is the force that causes galaxies to take on a flat disk like shape?

Rotation. Gravity causes the coalescing of smaller masses into larger masses. As masses approach, rotation is the result, this tends to produce the effect of disc-like planetary/moon, solar system, and galaxies.

Why do discs form in space?

Everything gets canceled out as all these things collide and interact, but the spin of the cloud is still there. And so over time, you collapse down into a disc. So the only reason you make discs is because of this law of conservation of angular momentum, and the idea of gravity brings things together.

Why do galaxies have a plane?

Why do solar systems and galaxies favor relatively flat orbital planes? This mainly has to deal with angular momentum. “In physics, angular momentum (or rotational momentum) is a vector quantity that represents the product of a body’s rotational inertia and rotational velocity about a particular axis.”

Why stars and planets are round?

The short answer. The closer you look into a question like this, the more you learn. But to answer it simply, the reason big astronomical objects are spherical (or nearly spherical) is because they’re massive enough that their gravitational pull can overcome the strength of the material they’re made from.

Why do galaxies rotate?

We know that galaxy rotation is happening because the Milky Way is a flattened disk, in the same way that the Solar System is a flattened disk. The centrifugal force from the rotation flattens out the galactic disk. All stars in the galactic disk follow roughly circular orbits around the center of the galaxy.

Why are galaxies not round?

Question: Why do stars and planets appear spherical when galaxies are flat? Answer: Galaxies aren’t completely flat. At the centre of every galaxy is a black hole, which is very dense matter that pulls everything towards it. That black hole is moving through space and spinning very fast.

How stars and galaxies are formed?

One says that galaxies were born when vast clouds of gas and dust collapsed under their own gravitational pull, allowing stars to form. The other, which has gained strength in recent years, says the young universe contained many small “lumps” of matter, which clumped together to form galaxies.

What forces shape the stars in galaxies?

What forces shape the stars in galaxies? Gravity is what causes stars to form. During accretion, gravity pulls matter into a core, which can be a star, planet or black hole.

Why do most galaxies have a disc shape?

Gas clouds produce stars, and so most stars will also be in the plane of the disc. Very old clusters of stars in globular clusters however can be found in a spherical pattern around the disc. So galaxies form disc shapes because the gas that makes stars falls into a disc shape. However, not all galaxies are discs.

Why are most of the planets in our Solar System disc shaped?

In some sense, many young astronomical objects are disc shaped because they contain (ed) gas which can radiate away non circular motion.

Why are spiral galaxies the most commonly depicted galaxies?

Spiral galaxies may be the most commonly depicted probably because we find ourselves in one, however, galaxies come in many sizes and shapes. Wikipedia’s page on Galaxy morphological classification explains the most common classifications. The basic answer to your question is Conservation of Angular Momentum.

Why can’t we see dark matter in a galaxy?

So if you look at mass, the galaxy isn’t a disc, it is a spheroid. But Dark Matter is invisible, and what we can see (stars, gas etc) is in a disk. The reason that Dark matter and the normal matter behave differently is that when gas flows there is “friction” (Dark matter doesn’t interact with itself or normal matter).