Our closest neighbor, Andromeda Galaxy is the most distant object in the sky that we can see with our naked eye. This galaxy located about 2.5 million light-years away from the Earth, hence it is used by astronomers to understand the origin and evolution of such galaxies. Approximately in 4.5 billion years, astronomers expect Andromeda will collide with our galaxy Milky Way. The Andromeda galaxy is approaching Milky Way at approximately 100 to 140 kilometers per second.
There are three types of galaxies which are spiral, ellip and irregular. The Andromeda galaxy falls into spiral types galaxy. Andromeda galaxy has at least two spiral arms, a ring of dust in its center that may come from a smaller galaxy. Astronomers think that this dust may have formed when it swallowed an existing galaxy. The first known report of the Andromeda is from the year 964. It was described in the “Book of Fixed Stars” written by the Islamic astronomer, Abd Al-Rahman Al-Sufi as a “small cloud”.