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9 Cards in this Set
- Front
- Back
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Lunar Phases
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The phases of the moon that occur because light from the moon is actually reflected sunlight. as the relative positions of the earth, the moon and the sun change, we see more or less of the illuminated half of the moon.
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Length of the Month
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Two types: with respect to the stars, the moon completes one orbit around the Earth in a sidereal month, 27.32.
the moon completes one cycle of phases in a synodic month, averageing 29.53 |
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The moon's orbit
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The plane of the moon's orbit is tilted by about 5* from the plane of the earths orbit or ecliptic
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The line of nodes
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the line where the planes of the moons orbit intersect. the gravitational pull of the sun gradually shifts the orientation of the line of nodes with respect to the stars
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conditions for an eclipse
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during a lunar eclipse, the moon passes through the earths shadow. During a solar eclipse the earth passes through the moon's shadow. Lunar eclipses occur at full moon while solar eclipses occur at new moon. Either type of eclipse can occur only when the sun and moon are both on or very near the line of nodes. if this condition is not met, the earth's shadow cannot fall on the moon and the moon's shadow cannot fall on the earth.
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Umbra and Penumbra
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the shadow of an object has two parts: the umbra within the light source is completely blocked, and the penumbra, where the light source is only partially blocked.
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Lunar Eclipses
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Depending on the relative positions of the sun, moon and earth, lunar eclipses may be total partial penumbral
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solar eclipses
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solar eclipses may be total partual or annular. during a total eclipse the moon's umbra traces out an eclipse path over the earth's surface as the earth rotates. observers outside the eclipse path but with in the penumbra see only a partial eclipse.
during an annular eclipse the umbra falls short of the earth and the outer edge of the sun's disk is visible around the moon at mid eclipse. |
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Moon phases
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1. new moon
2. waxing crescent 3. first quarter 4. waxing gibbous 5. full moon 6. waning gibbous 7. third quarter 8. waning crescent |
