Earth and Solar System

1. Orbit

1.1. gases

1.2. gravitational forces

1.3. conservation laws

2. gravity

2.1. patterens

2.2. ocean tides

3. Earth is tilted

3.1. seasons

3.2. time of day

4. Sun

4.1. reflects

4.2. shines

4.3. lights up moon

4.4. equator

5. Moon

5.1. conditions

6. Planets

6.1. sizes vary

6.2. patterns