Solve these clues to fill the grid.
- State of matter that fills any space, like air
- 2 Across
- Force that pulls objects toward the Earth
- 4 Across
- Mountain that erupts with lava
- 6 Across
- A reusable ___ with wings for a controlled descent through the Earth's atmosphere
- 8 Across
- An organization of ___ in a foreign land sent to carry on religious work
- 10 Across
- The planet we live on
- 12 Across
- The color of the sky on a clear day
- 13 Across
- Stony or metallic object that is the remains of a ___ that has reached the earth's surface
- 14 Across
- Any of the nine large celestial bodies in the solar system that revolve around the sun and shine (plural)
- 15 Across
- A bowl-shaped geological formation at the top of a volcano
- 1 Down
- A person trained to travel in a spacecraft
- 3 Down
- A relatively small extraterrestrial body consisting of a frozen mass that travels around the sun
- 5 Down
- Layer of air around the Earth
- 7 Down
- Natural satellite that orbits the Earth (plural)
- 9 Down
- A giant planet with a ring of ice particles
- 11 Down