There are different types of galaxies including elliptical galaxies, spiral galaxies, and irregular galaxies. Elliptical galaxies do not have ongoing star formation while spiral galaxies do. Irregular galaxies do not fit into a defined shape category. The formation of galaxies is influenced by density - denser regions collapse first under gravity to form protogalaxies that then separate into cores and halos, with flatter structures forming when densities were highest.

1. Proficiency 1: Galaxies by Andii Boville

2. Definition Galaxy : A unit of cosmology, that contain stars, gas dust and dark matter. Protogalaxy: density either increases or decreases in a galaxy. Small protogalaxies that are dense collapse first. Large ones are formed slower and they keep fragmenting until the collapse. At the time of recombination, the collection of gas and dark matter collapse under the galaxy's gravity to form a protogalaxy. The protogalaxy then separates into two parts due to gravity, the core and the halo.

3. Elliptical vs. Spiral Galaxies these are the two very distinct types of galaxies. elliptical galaxies do not have a formation of ongoing stars, but spirals have a lot elliptical and spiral galaxies are both made from the same density enhancements but they grew and didn't have the same appearance or star formation the only difference between the spiral and elliptical galaxies was how fast the star formation was initially formed

4. Spiral Galaxy

5. Elliptical Galaxy

6. Irregular Galaxies there are also irregular galaxies that do not really fit into any other galaxy class. They have an odd formation and don’t really have a disc or spherical shape. No irregular galaxies are the same shape

7. Irregular Galaxy

8. Galaxies, such as elliptical galaxies, are mostly round and are often grouped together in a pack. Different kind of galaxies, such as a spiral galaxy, are flat and are more spread out. There are arguments about the formation of the stars that are giving the illusion of the star fragments being flat solar systems. Regions with the greatest compression would cause the density to rise, until sub fragmentation in stars would occur. With the higher densities, comes flatter the galaxies, because the cloud collapses into structures as flat as a pancake. When the flat galaxies formed, the fragmentation of stars began faster.

9. Milky Way Facts: It is a warped galaxy and the disk is roughly 120,000 light years across The halo in the Milky Way is difficult to see , but it still has one The Milky Way galaxy is only a middle size galaxy There is a black hole in the middle A really old galaxy; almost as old as the universe

10. Milky Way Facts Cont… It is moving through space It ‘eats’ other galaxies The Milky Way galaxy is a spiral galaxy The Milky Way is made up of dust and gas Contains over 200 billion stars inside of the single galaxy