| A | B |
|---|
| Oblate Spheroid | a slightly flattened sphere |
| Axis | an imaginary straight line that runs through the earth from North to Sounth Pole |
| Hydrosphere | all of the wtaer that makes up the earth |
| Atmosphere | A blanket of gases that surrounds the earth |
| Gases that make up the Atmosphere | Nitrogen; Oxygen; Argon; Carbondioxide and Helium |
| Seismic Waves | vibrations that travel through the earth |
| What procuces seismic waves | Earthquakes and explosions |
| Magnetosphere | the region around the earth that is affected by the earth's magnetic field |
| The source of the magnetic field may be from ... | liquid iron in the outer core of the earth; iron is a good conductor |
| Gravity | the force of attraction that exists between all matter in the universe |
| Law of gravitation | states that the force of attraction between 2 objects depends on their mass and the distance between them |
| Mass | a measure of matter in an object |
| Weight | the force of gravity on the mass |
| Revolution | the movement of the earth around the sun |
| Rotation | on complete spin on the earth's axis |
| Perihelion | occurs when the earth is closest to the sun |
| Aphelion | occurs when the earth is farthest from the sun |
| Ellipse | the revolution shape of the Earth around the Sun |
| Solstice | Sun Stop |
| Equinox | Equal Night |
| Precession | the circular motion of the earth on it's axis |
| International Date Line | a point on the earth that separates on day to the next; does not cut a country |
