| A | B |
|---|
| geocentric | the Earth is the center of the universe |
| heliocentric | the sun is the center of the universe |
| Aristotle | first to believe that the Earth was round |
| Eratosthenes | first to calculate Earth's circumference |
| Ptolemy | stated that the stars did not move |
| Brahe | made measurements of planet motion in the sky |
| Kepler | put Brahe's data into good use and created three laws of planetary motion |
| Copernicus | first to state that the sun is the center of the universe |
| Galileo | first to use the telescope |
| Newton | came up with the law of gravitation |
| retrograde motion | the apparent westward drift of the planets |
| In what shape do planets orbit? | ellipse (elliptical) |
| perihelion | when Earth is closest to the sun |
| aphelion | when Earth is farthest from the sun |
| apogee | moon farthest from the Earth |
| perigee | moon closest to Earth |
| precession | a slow motion of Earth's axis |
| rotation | turning or spinning (24 hours) |
| revolution | motion of a body moving about another body (usually planets--like Earth around the sun) |
| 1st law of planetary motion | planets orbit the sun in an ellipse NOT a circle |
| 2nd law of planetary motion | planets move fast when closest to the sun |
| 3rd law of planetary motion | the farther the distance, the longer it takes to get around the sun |
| What causes the seasons? | the tilt of the Earth's axis |
| Name the phases of the moon. | full, crescent, gibbous, new |
| How long does it take to go from one full moon to the next full moon? | days |
| How long does it take to go from a full moon to a new moon? | 14 days |
| waxing | visible part of the moon is increasing |
| waning | visible part of the moon is decreasing |
| solar eclipse | when the moon is directly in front of the sun and Earth (the moon casts its shadow on the Earth) |
| lunar eclipse | when the Earth is directly between the moon and the sun |
| craters | round (bowl-shaped) depressions on the moon |
| maria | smooth, dark areas of the moon |
| highlands | pitted light-colored areas |
| How old is the moon compared to the Earth? | they are the same age |
