What are Galaxies?

Galaxies make up most of the visible matter we can see in the universe. There are over a hundred billion galaxies in the universe. Galaxies are defined as a collection of stars, dust, gas, and planets, and they come in three versions
-Spiral
-Elliptical
-Irregular

                                            

 

  Galaxies come in a variety of shapes and sizes. The largest galaxies contain more than a trillion stars, on average most contain billions of stars. Galaxies are measured in Light Years. The largest galaxy in the universe is 6 million light years across.

 



 Example 1

An Elliptical galaxy is shaped like a sphere, like a ball. The stars in an Elliptical galaxy are often very close together making the center look like one giant star. Galaxies regularly combine, and often form Elliptical galaxies

Example 2

As the name suggests, an Irregular Galaxy has no specific form and can look like anything and have many different characteristics unlike the Elliptical and Spiral galaxies. Many of them are the results of galaxy collision or near misses.


The third type of galaxy, The Spiral, has three main components
-Bulge
-Disk
-Halo
This type of galaxy is what the Milky Way is.

Speaking of the Milky Way, that is the galaxy that earth is located, on one of the "Arms". Our solar system is located 28,000 light years from the center of the Milky Way. The Milky Way is about 100,000 light years across

 

The Expanding Universe

What are the diafferences between Cosmologists and Astronomers?
 The difference is that an Astronomer studies how planets, stars, or galaxies from and evolve, a Cosmologist studies how the entire universe is formed and tries to predict how it will change in the future. 

What do Cosmologists and Astronomers have in common?
Most cosmologists and astronomers both believe in the Big Bang Theory.


How do Cosmologists explain the "birth" of the universe,
and what evidence is there to support the theory?     

Cosmologists explain the (birth) of the universe through the Big Bang Theory. It is the theory that all matter and energy in the universe was compressed into a small volume that 13 to 15 billion years ago exploded and began expanding in all directions. In the year 1965 researchers had detected cosmic background radiation,  meaning it uniformly detected from every direction in space; considered a remnant of the big bang. Astronomers think that this background radiation formed after the big bang                                                          

 

Universe Rap Song

All along there was a theory
A cold sweat hot headed memory
I put my head through the scope
and found a new hope

Round and a Round and a Round and a Round we go
Ohh Please galaxy don't leave me no

Not really sure how to understand it
Its something in the way you spin
Makes me feel like I am spinning with you
You spin me all the way
I love you galaxy