1. Which two planets are closer to the sun than Earth?
2. What is Earth's only natural satellite?
3. What motion takes about 365.25 days to complete?
4. The gravitational interaction between Earth and the moon causes these.
5. Earth's axis is tilted, which results in the change of what?
6. The outer shell of Earth is called the ----------.
7. What term is used for the combined mass of water on, under and above Earth's surface?
8. Earth's atmosphere consists mostly of these two gases.
9. Earth's living organisms and their environment compose the ------------------.
ANSWERS:
1. Mercury and Venus
2. The moon
3. Earth's orbit around the sun
4. Tides
5. Seasons
6. Crust
7. Hydrosphere
8. Nitrogen and oxygen
9. Biosphere