| A | B |
|---|
| rotation | to turn on an axis; one rotation = 24 hrs. |
| axis | imaginary line from pole to pole |
| time zones | occur approx. every 15 degrees longitude(24 in all) |
| inclination | tilt--earth's is 23.5 degrees-causes seasons |
| orbit | path taken during revolution |
| revolution | movement of one heavenly body around another |
| summer solstice | most hrs. daylight; about June 22 |
| winter solstice | least daylight, most hrs. darkness; about Dec. 22 |
| vernal equixox | hours of day and night equal; sun directly over equator |
| tropic of cancer | direct rays of sun strike here at summer solstice |
| tropic of capricorn | dierct rays of sun strike here at winter solstice |
| autumnal equinox | length of day and dark equal; about Sept. 22 |
| phases of moon | changes in appearance of moon as revolves around earth, due to light reflected from Sun; one complete cycle takes approx. 28 da. |
| new moon | disk of moon not visible |
| waxing | growing larger |
| first quarter moon | right 1/2 of moon is illuminated |
| full moon | full disk of moon illuminated; occurs approx 7 da. after first qtr. |
| last (third) quarter moon | left 1/2 of moon is illuminated, occurs approx 7 da. after full |
| gibbous | rounded on both sides |
| waning | growing smaller |
| lunar eclipse | earth's shadow obscures the moon |
| unbra | zone of complete shadow |
| penunbra | zone of partial shadaw |
| solar eclipse | moon's shadow falls on earth |
| synchronous rotation | accounts for why we see only one side of the moon |
