1. Stars and Galaxies

2. Stars A star is made up of mostly helium and hydrogen gas particles.
Deep inside the star, its temperature is 15,000,000 C, which causes particles to move fastly, when they collide the fuse together, creating the sun (a star). The gas particles on the top become very hot and radiate light. This is how stars shine.

3. Brightness of a star A stars brightness depends on two-things:
The stars distance from Earth
Amount of energy that the star gives off
Absolute magnitude: how bright a star actually is
Apparent magnitude: how bright a star looks

4. Color of a Star
The color of a star is based on its average surface temperature
Color
Average surface temp
Blue-white
35,000
White
10,000
Yellow
5,500
red
3,000

5. Distance of Stars Light year: distance that light travels in one year.
1 light year = 9.5 trillion kilometers
Light travels 300,000 kilometers per second.

6. Life of a star
A star is born when a cloud of gas and dust are drawn together by gravity. This cloud is a nebula. As these particles pack tightly, temperatures rise and a star is born.

7. Death of a star
Red giant: Star that has expanded after using up its hydrogen
Nova: Explosion of a collapsed red giant
White dwarf: Small white star remains after a nova

8. Death of star
Supergiant: One of largest stars, expanded after using up its hydrogen
Supernova: Explosion of a collapsed supergiant
Neutron Star: very small, very dense star remains after a supernova
Black Hole: region of space with tremendous gravity, caused by collapse of a huge star

9. Groups of stars Constellations: patterns of stars seen from space
There are 88 constellations
Galaxies: Group of billions of stars
Milkway: Our galaxy
Universe everything that exists

10. Supernova