Across
- 4. Mercury, Venus, Earth, and Mars, the planets closest to the Sun that are made of rock and metallic minerals and have solid outer layers.
- 7. a round depression formed on the surface of a planet, moon, or other space object by the impact if a meteorite.
- 11. regions of strong magnetic activity that are cooler than the rest of the suns photosphere.
- 12. a meteoroid that strikes a planet or moon.
- 14. the wide, outermost layer of a stars atmosphere.
- 16. a process that occurs when the nuclei of several atoms combine into one large nucleus.
Down
- 1. an object whose gravity is so great that no light can escape.
- 2. the distance light travels in one year.
- 3. the galaxy in which we live in, a spiral galaxy neighboring Andromeda that contains gas,dust,and almost 200 billion stars.
- 5. an instrument that spreads light into different wave lengths.
- 6. matter that emits n light at any wave length.
- 8. the football like planes that planets orbit.
- 9. layer of a star where hot gas moves up towards the surface and cooler gas moves deeper into the interior.
- 10. a large sphere of hydrogen gas, held together by gravity, that is hot enough for nuclear reactions to occur at it's core.
- 13. the shift to a different wave length on the electromagnetic spectrum.
- 15. a cloud of gas and dust.