Galaxy

A galaxy is a massive, gravitationally bound system that consists of stars, stellar objects (such as brown dwarfs and neutron stars), interstellar gas, dust, and dark matter. Galaxies are the building blocks of the universe and come in a variety of shapes and sizes.

Types of Galaxies

There are three main types of galaxies:

Spiral Galaxies: These galaxies have a central bulge with spiral arms extending outward. The Milky Way is an example of a spiral galaxy.
Elliptical Galaxies: These galaxies are shaped like ellipsoids and lack any noticeable structure. They are mainly composed of old stars.
Irregular Galaxies: These galaxies do not have a distinct shape and often appear chaotic. They typically contain a large amount of gas and dust, as well as young stars.

Formation and Evolution

Galaxies are thought to have formed from the gravitational collapse of protogalactic clouds of gas and dust. Over billions of years, galaxies evolve through interactions with other galaxies, mergers, and the ongoing formation of new stars.