Unit 4 Vocabulary

1. eclipse an event during which the moon's shadow blocks all or some of the sun's light from reaching Earth
3. a collection of stars and their solar systems, dust, and gas
4. system a system of objects in space that includes at least one star, planets, their moons, asteroids, comets, and other space debris
7. a group of stars that forms a recognizable pattern in the sky
9. brightness how bright a star appears compared with other stars when all are viewed from Earth
11. brightness how bright a star is from a standard distance of 32.6 light-years
13. the distance that light travels in one Earth year

2. eclipse an event during which the moon passes directly behind Earth and into its shadows
3. A force that pulls objects toward each other
5. a space object that gives off its own heat and light
6. phase a stage in the repeating, predictable pattern of change in the moon's appearance from Earth
8. the oval-shaped path an object follows as it revolves around another object in space
10. an imaginary line through the center of an object that is a fixed point of reference
12. all of the existing matter and energy in space