Space Systems

3. a nuclear reaction in which nuclei fuse together to form heavier nuclei and release energy
6. the curved path of a celestial object around a star, planet, or moon
12. A planet covers the same amount of space in the same amount of time no matter the point in its orbit
15. a system of stars, together with gas and dust, held together by gravitational attraction
16. A planet’s orbital period is proportional to the size of its orbit
18. the largest star in terms of volume; spectral class K or M
19. the physical universe beyond the earth’s atmosphere
20. a core of a star that is composed of mostly electron-degenerate matter

1. a catastrophic explosion that ejects most of the star’s mass
2. the different wavelengths of energy produced by a light source
4. more than 100 substances that cannot be chemically broken down or reduced
5. Planets move in elliptical orbits with the Sun as the focus
7. a way to describe the expansion of the universe.
8. a region in space with a gravitational pull so large that nothing can escape; forms after a supernova if the star has enough energy
9. the emission of energy as electromagnetic waves
10. an object of small radius but large density, made up of mostly neutrons; forms after a supernova
11. a giant cloud of dust and gas in space
13. a star with low or intermediate mass; surface temperature 5000K or less
14. a ring-shaped nebula formed from expanding gas around an aging star
17. a chemical process in which two or more substances work together and are changed into different substances