| A | B |
|---|
| apogee | farthest point away in orbit |
| perigee | closest point away in orbit |
| escape velocity | smallest speed needed to get infintely far away from source of gravity |
| eccentricity | measure of elongation of ellipse |
| spring tide | occurs when Earth, Sun, Moon all in a line |
| neap tide | occurs when Sun, Earth, Moon form a right triangle |
| Black Hole | gravity so intense not even light can escape |
| Kepler's 1st Law | Planets move in elliptical orbits with the Sun at one focus |
| Kepler's 2nd Law | An imaginary line from planet to Sun sweeps out equal areas in equal times |
| Kepler's 3rd Law | square of period ~ cube of distance |
