Galaxies are a system that consists of a collection of stars and arranged space objects on a regular basis. Generally, galaxies consist of billions of stars with diverse colors, sizes, and characteristics. In the universe, there are many galaxies. The name of the galaxy we hear most often besides the Milky Way galaxy is the Andromeda Galaxy. The Andromeda Galaxy has several other names, Messier 31 (M31) or NGC 224. The andromeda galaxy is a neighboring galaxy from our galaxy, the Milky Way. This galaxy is a type of spiral galaxy that is 2.5 light years from the Milky Way galaxy. In addition to the Milky Way Galaxy can also be seen with the naked eye at night when a bright situation.

There are two small size galaxies that move close to each other to collide with each other. Because the collision formed an Andromeda galaxy in which there were stars bound to gravity. Until then the Andromeda Galaxy continued to develop by forming several components in it. These components include stars, gas and dust rings. Until now it is estimated that these stars number around 1 trillion stars. The collisions of the two small galaxies occurred about nine billion years ago. Development continues until the Andromeda Galaxy is shaped as we know it today.

Fowler explained that 12,000 million years ago the galaxy was still in the form of hydrogen gas with very large size. The hydrogen continues to move in a rotational motion so that it is round because it has a heavy force so it experiences a contraction. Its constituent components experience movements that rotate slowly and have a large specific gravity so that stars are formed. The temperature of these stars is decreasing more and more after tens of thousands of years. The shape of the star tends to remain like the sun. This hypothesis is believed by experts to occur at the center of the galaxy, namely the birthplace of new stars both slowly and explosively.

Based on this hypothesis we can explain that galaxies are formed from a collection of hydrogen gas that solidifies and forms stars. The star breaks, but due to its gravitational force it re-collects in a large area and forms galaxies. Similarly, the Andromeda galaxy.