Across
- 4. The beginning of the universe.
- 6. How hard it is to stop a moving object.
- 8. On Earth this is made up of nitrogen, oxygen and carbon dioxide.
- 9. Often called Earths twice due to their similar size and mass.
- 10. An ice giant in our solar system.
Down
- 1. Causes things to get further apart from one another.
- 2. A period of rapid expansion in the early universe.
- 3. Acronym for the oldest light we can see in the universe.
- 5. Jupiter and Saturn are both this type of planet.
- 7. How much "stuff" there is in an object.