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15 Cards in this Set
- Front
- Back
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solar day
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time from one noon until the next
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sidereal day
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relative to stars
lasts 23 hours, 56 min and 4 seconds to rotate |
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seasons
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due to tilt of earth's axis, not relative distance to sun
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Earth's tilt
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longer days in summer, shorter days in winter
directness of sun's rays over time |
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legnth of day
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when northern hemisphere is tilted towards sun and sun is north of celestial equator, more than half of small circle is above horizon--> sun is up for more than half the day
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position of sun
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when sun is north of celestial equator, rises north of east and sets north of west.
when sun is south of celestial equator, rises south of east and sets south of west. rises due east and sets due west when sun is on celestial equator (twice a year) |
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position of sun
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changes over course of year
path of sun in sky @ noon= analemma |
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Moon
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phases relative to positions of Earth, moon and sun
@ every position, half is illuminated, but not the amount we see New moon=see nothing New to full=waxing full to new=waning |
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waxing vs. waning
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in northern hemisphere, right=waxing phase
left=waning phase |
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Lunar eclipse
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Moon passing thru the Earth's shadow; full moon phase, lasts for ~1 hour, half the earth can see
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types of lunar eclipse
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Total: entire moon passes thru the umbra (total shadow)
Partial: past of moon passes thru the umbra, part thru the penumbra (partial shadow) red b/c atmosphere refracts light as it passes thru and scatters away blue light; red light cruves around earth |
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Solar Eclipse
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Earth passing thru the Moon's shadow, lasts for minutes, need to be on specific part of Earth
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Types of solar eclipse
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Total: Moon completely blocks the sun
Partial: Moon blocks only part of sun Annular: Moon doesnt competely cover sun, at farthest point |
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Annular eclipse?
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b/c moon's orbit is slightly elliptical (not completely circular), moon appears smaller @ apogee than when @ perigee.
when moon is farther from Earth during eclipse, doesnt completely block sun |
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Month
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Sidereal month= 1 rotation relative to background stars
Synodic month=1 rotation relative to Sun (1 lunar cycle) |
