Across
- 1. the way electromagnetic radiation travels through space
- 3. The part of the Sun that emits the radiation we see
- 5. the backwards motion of planets
- 7. the third largest object in the sky
- 9. the thin layer of gas on the outer edge of a planet
- 11. the most geologically active object in the solar system
- 12. A microorganism, especially an Archaean, that lives in conditions of extreme temperature, acidity, alkalinity, or chemical concentration
- 13. The dense, opaque region at the center is called a
- 15. Relating to the origin and development of the universe
- 16. a type of evolution we see in the sky and on planets
- 18. A celestial object, thought to be a rapidly rotating neutron star, that emits regular pulses of radio waves
Down
- 2. A pattern of lines or rays radiating from a central object or source of light
- 3. A star with a parallax of 1 arc second is 1
- 4. the inner planets they are small, dense, and rocky
- 6. the study of space and celestial objects
- 8. The central and most important part of an object, movement, or group forming the basis for its activity and growth
- 10. A star showing a sudden large increase in brightness and the slowly returning to it original state over a few months
- 14. a "light bucket" used to view space
- 17. a gargantuan collection of stellar and interstellar matter—stars, gas, dust, neutron stars, black holes