a moon outside our solar system

a planet outside our solar system

a moon phase that looks like a full circle from Earth

a moon phase that looks like more than a half circle from Earth

to shine light on an object and make it visible

when the Moon is completely dark

an object, diagram, or computer program that helps us understand something by making it simpler or easier to see

a rocky sphere that travels around a planet

the shape of the illuminated part of the Moon as it appears from Earth

a moon phase where the Moon is not visible from the Earth

the nearly circular path a smaller object (like the Moon) travels around a larger object (like Earth)

something we observe to be similar over and over again

a moon phase that looks like half a circle from Earth

the relative size of things

the sun, the planets that orbit the sun, and other objects that orbit the sun

the star that is the main source of light at the center of our solar system

the border between light and dark on the Moon

the amount of time it takes for a planet to complete one orbit around a star or stars

the amount of time it takes for a planet to complete one rotation around its axis