- astronomy: the study of the moon, stars, and other objects in space
- autumnal equinox: The first day of Fall int he Northern hemisphere (around Sept. 22)
- axis: an imaginary line that passes through Earth about which the Earth rotates
- equinox: the 2 days of the year on which niether hemisphere is tilted toward or away from the sun
- latitude: the distance North or South of the equator
- orbit: the PATH of an object as it revolves around another object
- revolution: the movement of an object around another object
- rotation: the spinning motion of a planet about its axis
- solstice: the 2 days of the year when the sun is overhead at either 23.5 degrees North or South
- vernal equinox: The first day of Spring in the Northern hemisphere ( around March 22)