ASTRONOMY VOCAB

1. The Sun and everything that orbits it.
4. Rocky planets closest to the Sun (Mercury, Venus, Earth, Mars).
8. Day and night are equal in length. (March 20, September 22)
9. When the moon blocks sunlight from reaching Earth.
10. The appearance of the lit part of the moon from Earth. (takes 29.5 days or one MOONth).
11. All space, time, and matter. (Ours is 13.8 BILLION years old)
12. A galaxy with arms that spiral outward
13. Earth’s axis is tilted 23.5°, causing seasons
16. A ball of hot gas powered by nuclear fusion.
17. The spiral galaxy that contains our solar system.
18. A massive group of stars, dust, and gas held together by gravity
19. Turning around an axis (one day)

1. The longest or shortest day of the year. (December 21, June 21)
2. One complete orbit around another object. (one year)
3. The process where atoms combine to release energy.
5. When Earth blocks sunlight from the moon.
6. An imaginary line that Earth spins around.
7. The attraction between objects with mass
14. An object’s resistance to change in motion
15. Large outer planets made mostly of gases (Jupiter, Saturn, Uranus, Neptune)