The Universe

2. a chunk of rock or metal that orbits the Sun
4. a spinning neutron star that emits radio waves at regular intervals
6. a space pilot
8. turning around an axis
9. an imaginary line about which a body rotates
10. a scientist who studies the universe
13. the distance between the top of one wave and the top of another
16. a small object made of snow, dust, and ice that orbits the Sun
17. a force of attraction between two objects
19. an imaginary line along which the Sun appears to be moving across the sky
20. a streak of light in the sky caused by a small meteoroid burning up

1. a meteoroid that falls to the surface of a planet or a moon
3. a large collection of stars held together by gravitational forces
5. an explosive release of hot gases from the Sun’s surface
7. dark spots that appear on the surface of the sun from time to time
11. the explosion of an extremely large star
12. a star’s surface
14. the imaginary line that goes around the middle of Earth
15. an angled piece of glass that splits light into the spectrum of colors
18. the curved path of one object that travels around a larger, more mass object