Physics Glossary
| Axis | The center around which something rotates |
| Crater | A hole caused by an object hitting the surface of a planet or moon. |
| Diameter | A straight line connecting the center of a circle with two points on its perimeter (edge). |
| Gravity | Gravity is a force of attraction that exists between any two masses, any two bodies, or any two particles. It is the attraction that exists between all objects. |
| Meteor |
A bright trail or streak that appears in the sky when a meteoroid is heated to incandescence by friction with the earth's atmosphere. Also called falling star, meteor burst, shooting star |
| Orbit | An orbit is a very special combination of height and speed, that if chosen properly, will keep a satellite in a stable, predictable, path around the earth, without ever crashing. |
| Rotation | A single complete turn (axial or orbital). Example: The rotation of the earth on its axis takes one day; The rotation of the earth about the sun takes one year. |
| Satellite | |
| Tide | The vertical rise and fall of water caused by gravitational forces of the moon and sun on the oceans of the earth. |
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