Across
- 3. emission of electromagnetic waves
- 5. non-luminous material that is postulated to exist in space
- 8. a theory that postulates a dense, hot start and then a cooling and expanding universe
- 12. catastrophic explosion where a star ejects most of its mass
- 13. a cloud of gas and dust in outer space
- 14. the envelope of gases surrounding the earth or another planet
- 16. the ability to perform work (usually motion)
- 19. a rapidly rotating neutron star, that emits regular pulses of radio waves
- 20. unit of length in astronomy equal to the distance that light travels in one year
- 21. the sun and the planets, asteroids, comets, and meteors that revolve around it
- 23. the curved path of a celestial object
- 25. a broad band of light that stretches across the sky and is caused by the light of a very great number of faint stars
- 27. mass multiplied by a velocity
- 28. short for nuclear fusion
- 29. the near vacuum extending between the planets and stars
- 30. a fixed luminous point in the night sky
Down
- 1. a planetary body moving around a star
- 2. a region of space having a gravitational field so intense that no matter or radiation can escape
- 4. an attractive force between all objects
- 6. a large rocky body orbiting the sun
- 7. a form of the same element with a differing number of neutrons
- 9. The National Aeronautics and Space Administration is an independent agency of the U.S. federal government
- 10. a system of millions of stars held by gravitation
- 11. a collection of stars forming a recognizable pattern
- 15. a small body of matter from outer space that enters the earth's atmosphere
- 17. the quantity of atoms contained in an object
- 18. a primary constituent of matter with a unique number of protons
- 22. a small bright heavenly body that develops a cloudy tail as it moves in an orbit around the sun
- 24. a massive and extremely remote celestial object, emitting exceptionally large amounts of energy
- 26. the basic unit of a chemical element
- 27. a natural satellite of any planet