1. Star Formation
CH. 5

2. Stars form in vast clouds of gas and dust called nebulae Gas
Singular – nebula
Gas
Mostly hydrogen
Some helium
Small amounts of iron, magnesium, silicon, oxygen, nitrogen
Small amounts of more complex molecules like H2O
Dust
Small grains containing carbon and various silicates
Complex organic molecules including various hydrocarbons

3. Small regions within a nebula will begin to condense and collapse due to gravity
Once these regions begin to collapse, they rotate and flatten out into a disk shape with a bulge at the center
This disk is called a protoplanetary disk
The bulge at the center is called a protostar
Within the disk, small objects collide and stick together, eventually forming larger bodies
This process, called accretion, eventually gives rise to planets, moons, and other bodies

8. Asteroids, meteors, and comets are leftover material from the formation of the Solar System
Studying them provides insight into the Solar System’s origins
Radioactive dating of this material suggests that the formation of the Solar System was completed around 4.6 billion years old