Astronomy

2. hole A region in space with gravity so strong that nothing, not even light, can escape it.
4. The amount of matter in an object; it does not change based on location.
5. effect The change in wavelength or frequency of a wave as the source moves toward or away from an observer.
9. A model of the solar system where Earth is at the center.
11. Bang Theory The scientific explanation for the origin of the universe, starting from a single point and expanding over time.
12. nebula A cloud of gas and dust in space where stars are born.
14. A model of the solar system where the Sun is at the center.
16. dwarf A small, dense star that remains after a star has exhausted its fuel.
18. The force that pulls objects toward each other.
19. galaxy A type of galaxy with a flat, rotating disk and spiral arms.

1. brightness How bright a star truly is, regardless of its distance from Earth.
3. brightness How bright a star appears to an observer on Earth.
6. The process of small particles coming together to form larger objects, like planets or stars.
7. To move in a path around another object, like Earth around the Sun.
8. A massive explosion of a star at the end of its life cycle.
10. The path an object takes as it revolves around another object in space.
13. diagram A graph that shows the relationship between a star's brightness and temperature.
15. galaxy A type of galaxy shaped like an oval or football.
16. The force of gravity acting on an object's mass; it can change depending on location.
17. To spin on an axis, like Earth spinning once every 24 hours.