Earth, Moon, and Sun

1. a moon phase that looks like a half-circle from earth
3. the star that is the main source of light at the center of our solar system
7. a moon phase that looks like a full circle from earth
9. something we observe to be similar over and over again
10. to shine light on an object and make it visible
13. the amount of time it takes for a planet to complete one orbit around a star or stars
14. an object, diagram, or computer program that helps us understand something by making it simpler or easier to see
16. the shape of the illuminated part of the moon as it appears from earth
17. a moon phase in which the moon is not visible from earth
18. a moon phase that looks like more than half a circle

2. the border between light and dark on the moon
3. the sun, the planets that orbit the sun, and other objects that orbit the sun
4. a planet outside our solar system
5. the nearly circular path a smaller object (like the moon) travels around a larger object (like earth)
6. when the moon is completely dark
8. a moon phase that looks like less than half a moon
11. a moon outside our solar system
12. the relative size of things
15. a rocky sphere that travels around a planet