1. Galaxies and Formation
Expectations: D3.1, D3.2

2. Galaxy
Collections of millions to hundreds of billions of stars, planets, gas and dust, up to ly (light years) across.
Types:
Elliptical
Spiral : Milky Way (our galaxy), spinning pinwheel
Lenticular
Irregular

3. Earth in the Universe

4. Formation of the Solar System
Solar Nebula Theory:
Solar system formed 5 billion years ago from a massive cloud of gas and dust that began to contract

5. Evidence
Theory explains observations that the planets orbit the Sun in the same direction, the planets are all in the same plane, Sun is at the centre, most planets rotate the same way, terrestrial are closer than gas

6. Origin of the Universe The Big Bang:
Universe began in an incredibly hot, dense expansion approximately 13.7 billion years ago

7. Expanding Universe
All galaxies appear to be moving away from each other and the farther the galaxy was the faster it was moving away.
Hubble made this discovery by studying the light emitted from galaxies.
Each galaxy had its own spectrum of light.
The light spectra was red shifted, meaning moving away.