Across
- 2. Study of how the universe began, what it is made of, and how it continues to evolve.
- 5. Gigantic explosion of a star in which the temperature within the collapsing star reaches 10 billion K, can evolve into a neutron.
- 10. Sequence- Section of the H-R diagram that is plotted from the upper left to the lower right and contains 90 percent of all known stars.
- 11. Bang Theory- Theory that about 13.7 billion years ago, the entire universe was contained in a single point that began expanding outward.
- 12. Darker, cooler areas of the Sun's photosphere.
- 14. Interstellar cloud of gas, ice and dust also where stars are born.
- 16. Large group of stars, dust, and gas held together by gravity.
- 17. Background Radiation- Residual radiation from the formation of the universe; predicted by the big bang theory and later detected in 1956.
- 19. Group- Group of about 50 galaxies including the Milky Way.
Down
- 1. Layer of the sun that emits light into space.
- 3. The space that contains all known matter and energy.
- 4. Energy- Energy that might be causing the accelerating expansion of the universe.
- 6. Oval-shaped, closed curve.
- 7. Late stage in a star's life cycle that occurs when its hydrogen fuel is depleted, its core contracts, and its outer layers expand and cool.
- 8. Dwarf- Giant star that has lost its outer layers, leaving behind a hot, dense core that continues to contract under gravity.
- 9. Fusion- A nuclear reaction in which atomic nuclei join together.
- 13. Electrically neutral particle inside the nucleus of an atom.
- 15. Hole- A region in space that is so dense that nothing can escape its inward pull of gravity.
- 18. Way- Spiral galaxy that is about 100,000 light-years in diameter and contains from 200 to 400 billion stars, including the sun.