1. Our solar system was created by the gravitational collapse of the______.
2. Our Moon was most likely formed by a collision between Earth and a Mars-sized_____.
3. The first few hundred million years of the solar system’s history were the time of the______, during which Earth suffered many large impacts.
4. Mars was formed by the_____of smaller objects.
5. The era of planet formation ended when the remaining hydrogen and helium gas of the solar nebula was swept into interstellar space by the_____.
6. Ice can form from a gas through the process of_____.
7. Hydrogen compounds in the solar system can condense into ices only beyond the_____.
8. ______allows us to determine the age of a solid rock.
- Solar nebula
- Heavy bombardment
- Solar wind
- Frost line
- Radiometric dating