| Term | Definition |
|---|
| where does the moon rise? | the east |
| how long does it take the moon to go around the earth? | 27 1/3 days |
| where is the moon when you see it in the night sky? | when the moon is on the side of earth opposite the sun |
| where is the moon when you see in the day sky? | when the moon is between the earth and the sun |
| does the moon orbit in the same plane as the earth? | no |
| why does the moon rise above the horizon at a different time each day(or night)? | because every time Earth spins around once the moon moves about 13 degrees east along its orbit.Thus, the Earth must rotate an extra 13 degrees more each day for a point on its surface to be roughly under the moon again. since earth takes about 50 minutes to spin 13 degrees the moon rises about 50 minutes later each day and sets about 50 minutes later too. |
| perigee | when the moon is nearest earth |
| apogee | when the moon is farthest from earth |
| phases | the daily changes in the moons appearance as viewed from earth |
| Why do moon phases occur? | 1) We see the moon only because it reflects sunlight 2)The moon is in orbit around earth. The sun lights the half of the moon that is facing it. However, we see changing amounts of the sunlight half. |
| waxing | new moon to full moon |
| waning | full moon to new moon |
| gibbous phases | almost all of the bright half of the moon faces Earth |
| How can we tell when the moon is waxing? | light up from the right side |
| How can we tell when the moon is waning? | light up from the left side |
| umbra | the area of total shadow |
| penumbra | the area of partial shadow surrounding the umbra |
| the earth's umbra and penumbra | The earth's umbra is a long, narrow cone. The penumbra is also cone-shaped, but as it stretches into space it becomes wider and more faint. |
| the moon's umbra and penumbra | because the moon is smaller than Earth, the moons umbra and penumbra are smaller and shorter. |
| lunar eclipse | an event during which Earth's shadow prevents the sunlight from reaching the moon. a lunar eclipse can only occur at the full moon phase. a full moon occurs every month, but a lunar eclipse occurs less often because of the 5 degree angle between the plane of Earth's orbit and the plane of the moon's orbit. the full moon is usually above or below the earth's umbra, and no eclipse occurs. when an eclipse does occur, the moon usually remains visible, but it is red. |
| Why is the moon red red during a lunar eclipse? | the moon is red when Earth's atmosphere bends some sunlight-mostly longer red wavelenghts-into an umbra. |
| total lunar eclipse | occurs when the moon is fully within Earth's umbra |
| partial lunar eclipse | occurs only when only a part of the moon is in Earth's umbra |
| How often does a lunar eclipse occur? | once a year |
| solar eclipse | occurs when the moon comes between the sun and the earth and the moon's shadow hits earth's surface. a solar eclipse only occurs at the new-moon phase. because of the plane of the moon's orbit, the shadow usually falls above or below Earth. because of this it doesn't occur every month. |
| How often does a solar eclipse occur? | once a year |
| How often does a solar eclipse occur in a given area and why? | once every 300 or 400 years. it happens that often because the umbra of the moon is very small. the moon's revolution makes the narrow shadow, called the eclipse path, go across the earth at over 1500 kmp. The eclipse path is thousands of km long, but at any one place a total solar eclipse can last at most only 71/2 minutes. |
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