Stars

5. relatively cool, dark spots appearing on the surface of the photosphere
6. a nuclear reaction in which an atomic nucleus splits into smaller, lighter nuclei releasing energy
7. small, extremely dense remnant of a star whose gravity is so immense that not even light can escape its gravity field
8. a sudden eruption of particles and radiation from the surface of the Sun
9. ancient Greek classification system based on how bright a star appears to be
10. two stars gravitationally bound together and orbiting about a common center of mass
11. top layers of the Sun’s atmosphere
12. a nuclear reaction in which lightweight nuclei combine into heavier nuclei

1. energy output from the surface of a star per second, measured in watts
2. group of stars that forms a pattern in the sky
3. brightness an object would have if it were placed at a distance of 10 pc
4. massive explosion that occurs when the outer layers of a star are blown off
5. a stream of high-speed, ionized particles flowing outward through the solar system from the Sun's corona
13. a cloud of interstellar dust or gas or both, which collapses on itself as a result of its own gravity