| A | B |
|---|
| perihelion | January 3rd, the date the northern hemisphere is closest to the Sun |
| aphelion | July 4th, the date the northern hemisphere is farthest from the Sun |
| axis of rotation | an imaginary line about which the Earth rotates |
| equinox | a time of year when daylight and darkness are nearly equal for most of Earth, the Sun's rays are most direct at the equator |
| revolution | the motion of one body around another, such as Earth in its orbit around the Sun |
| solstice | the time of year when days are either longest or shortest, and the angle of sunlight reaches its maximum and minimum |
| rotation | the spinning of an object on its axis |
| Summer Solstice | June 21st, the Earth is tilted so the Sun is positioned directly over the Tropic of Cancer |
| Winter Solstice | December 21st, the Earth is tilted so the Sun is directly over the Tropic of Capricorn |
| Vernal Equinox | March 21, the sun's rays are most direct at the equator |
| Autumnal Equinox | September 21, the sun's rays are most direct at the equator |
| Earth's tilt | 23 1/2 degrees |
