Earth, Moon, And Sun

Across
2.	the relative size of things
6.	something we observe to be similar over and over again
12.	a moon phase that looks like a half-circle from Earth
14.	an object, diagram, or computer program that helps us understand something by making it simpler or easier to see
15.	a moon phase in which the Moon is not visible from Earth
16.	the sun, the planets that orbit the sun, and other objects that orbit the sun
17.	the amount of time it takes for a planet to complete one orbit around a star or stars
18.	a moon outside our solar system

Down
1.	to shine light on an object and make it visible
2.	the star that is the main source of light at the center of our solar system
3.	when the Moon is completely dark
4.	the nearly circular path a smaller object (like the Moon) travels around a larger object (like Earth).
5.	a moon phase that looks like less than half a circle from Earth
7.	the border between light and dark on the Moon
8.	phase the shape of the illuminated part of the Moon as it appears from Earth
9.	moon a moon phase that looks like more than half a circle from Earth
10.	a moon phase that looks like a full circle from Earth
11.	a planet outside our solar system
13.	a rocky sphere that travels around a planet