Earth, Moon, Sun

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

1. a moon phase that looks like more than half a circle from Earth
2. the border between light and dark on the Moon
5. a rocky sphere that travels around a plant
6. something we observe to be similar over and over again
7. system the sun, the planets that orbit the sun, and other objects that orbit the sun
10. a moon phase that looks like a full circle from Earth
13. a moon phase that looks like less than half a circle from Earth
14. a moon outside our solar system