| A | B |
|---|
| Precession | The wobbling of the Earth on its axis |
| Vernal Equinox | Sun strikes the equator at 90 degree angle, start of Spring |
| Autumnal Equinox | Sun strikes the equator at 90 degree angle, start of Autumn |
| Summer Solstice | Sun rays strike Tropic of Cancerat 90 degrees |
| Winter Solstice | Sun rays strike Tropic of Capricorn at 90 degrees |
| Crust | Earth's outermost layer |
| Mantle | Earth's thickest layer |
| Lithoshprere | Upper part of Mantle |
| P Waves | Primary waves |
| S Waves | Secondary Waves |
| Outer Core | Center of Earth that is liquid |
| Inner Core | Center of Earth that is solid rock of iron |
| Rotation | Spinnning of Earth around its axis |
| Revolution | Spinning of Earth around the sun |
| Daylight Savings Time | Move the clocks one hour ahead |
| Perihelion | When Earth is closest to sun |
| Aphelion | When Earth is Farthest from the sun |
| Perigee | When Satellites are closest to the Earth |
| Apogee | When satellites are farthest from the Earth |
| Polar Orbit | Orbit of satellite from North to South |
| Geosynchronous Orbit | Orbit of satellite on the equator rotating with the Earth |
