| A | B |
|---|
| Ptolemy | A Grek astronomer who said the earth was the center of the solar system. |
| Copernicus | An astronomer who said the plantets revolved around the SUN in a circular orbit |
| Galileo | Was the first person to use the telescope to study the skies. Discovered the 4 moons of Jupiter |
| Brahe | He showed that the movement of Mars could not be a circular orbit. |
| Kepler | Said that the planets orbit the sun, but the orbit is an ellipse |
| Newton | said all objects in the universe attract each other trhough a force called gravity |
| Gravity | Is the corce that enables the planets to revolve around the sun |
| Orbit | Is the path that objects take around other objects |
| Satellite | is a smaller body revolving around a larger body |
| Focus | One of 2 points needed to draw ellipse |
| Perihelion | is the point in a planets orbit where it is closest to the sun |
| Aphelion | the pint in a planet's orbit where it is farthest from the sun |
| ellipse | is the closed oval shaped curve with foci |
| eccentricity | the ratio of the distance of the center of the orbit of a heavenly body from the center of a both which it revolves to the semi-transverse axis of the orbit- off center |
| period of revolution | the act o f revolving or turning on an axis or a center the motion of a body around a fixed point or line |
