A galaxy is made up of stars, planets, moons, comets, asteroids, clouds of gas and dust, and other objects. It’s also called a star system.
The word “galaxy” comes from ancient Greek, “galaxias kyklos”, meaning “milky circle (or vault”. Astronomers thought all stars were part of a single giant cloud of matter, but most stars were too far away to be connected. So they named each group of stars after its nearest neighbor, the Milky Way.
Galaxies are formed when large amounts of matter clump together. What eventually becomes a galaxy starts out as separate “objects”. Scientists believe that before a galaxy becomes a galaxy, it is a collection of separate clouds made out of stars and dust.
When these clouds pass by one another, gravity pulls them together irrevocably, creating larger celestial bodies, and just like that, the galaxy is born.