| A | B |
|---|
| Axis | imaginery vertical line that passes through the center of a body about which the body rotates, or spins. |
| 23.5 degrees | The angle at which the earth is tilted. |
| Rotation | Spinning around an axis. |
| Revolution | One object moving around another object. |
| Summer | Occurs when a hemisphere is tilting towards the sun. |
| Winter | Occurs when a hempishere is tilting away from the Sun. |
| Spring and Fall | Occurs when the earth is neither tilting towards or away from the Sun. |
| Summer Solstice for the Northern Hemisphere | June 20th or 21st |
| Summer Solstice for the Southern Hemisphere | December 21st or 22nd |
| Winter Solstice for the N. Hemisphere | December 21st or 22nd |
| Winter Solstice for the S. Hemisphere | June 20th or 21st |
| Equinox | equal day and equal night |
| Vernal Equinox | 1st day of Spring |
| Autumnal Equinox | 1st day of Fall |
| Vernal Equinox for the N. Hemphere | March 20th or 21st |
| Autumnal Equinox for the N. Hemisphere | September 22nd or 23rd |
| Vernal Equinox for the S. Hemphere | September 22nd or 23rd |
| Autumnal Equinox for the S. Hemisphere | March 20th or 21st |
| Ellipse | Shape of the Earth's orbit around the Sun |
| Factors that make the warm summer temperatures | Length of day and direct sunlight. |
| 24 hours | Length of time it takes the Earth to make one complete rotation |
| 365.26 days | Length of time it takes the Earth to make one complete revolution. |
| Polaris | The star the North Pole points to. |
| Day | Time period that it takes to make one rotation. |
| Year | Time period it takes to make one revolution. |
| Night | When that portion of the Earth is out of the Circle of Illumination. |
| Day | When that portion of the Earth is within the Circle of Illumination. |
| Circle of Illumination | The light from the Sun that shines on the part of the Earth that is facing it. |
