Galaxies
- Galaxy - a massive, grav'tationally bound system consisting of stars, stellar remnants, gas and dust, and other substances
- stellar remnants - asteroids, comets, planets, moons, etc
Three types of galaxies
- spiral
- Elliptical
- lrregular
How a galaxy is formed
1. Bodies of gas dust and young stars collide
2. Tge stars begin to rotate around the center of the mass
3. The rolation contracts the clound and forms a galactic disk
4. Motion created by the spinning disk cause spiral arm to form
Types of Galaxies / Spiral Galaxies
Consist of a flat rotating disc containing stars, gas and dust, and a central concentration of stars known as the bulge