Earth, Moon, and Sun

6. the border between light and dark on the Moon
10. a moon phase that looks like less than half a circle from Earth
13. a moon phase that looks like a full circle from Earth
14. a rocky sphere that travels around a planet
15. a planet outside our solar system
16. a moon phase in which the Moon is not visible from Earth
17. the relative size of things
18. something we observe to be similar over and over again
19. the sun, the planets that orbit the sun, and other objects that orbit the sun

1. a moon outside our solar system
2. the amount of time it takes for a planet to complete one orbit around a star or stars
3. the nearly circular path a smaller object (like the Moon) travels around a larger object (like Earth).
4. a moon phase that looks like a half-circle from Earth
5. when the Moon is completely dark
7. moon, a moon phase that looks like more than half a circle from Earth
8. to shine light on an object and make it visible
9. the star that is the main source of light at the center of our solar system
11. phase, the shape of the illuminated part of the Moon as it appears from Earth
12. an object, diagram, or computer program that helps us understand something by making it simpler or easier to see