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13 Cards in this Set
- Front
- Back
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What evidence did Aristotle cite for a spherical Earth?
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Curved shadow earth casts on the moon
-new stars seen when sailing south |
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What is the point in the sky above the north pole? What star is near that point?
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Celestial North Pole
-Polaris or The North Star |
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What is diurnal motion? What causes it?
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Daily motion that the Earth rotates once (west to east) on its axis
-Diurnal motion is caused by Earth's spin on its axis |
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What is the ecliptic?
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Ecliptic- the path the Sun takes across heavens
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Why can we see some constellations only during part of the year?
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Because the sun is bright, we can only see the zodiac constellations at certain times of the year
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How are the zodiac constellations different from others?
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Because the ZC's are aligned with the orbital plane around the sun, they only appear at certain times of the year
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What causes the seasons?
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23.5 degree tilt of the earth's spin axis relative to the plane of the earth's elliptic orbit
NOT caused by earth changing it's distance from the sun |
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What are the solstices and equinoxes?
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Because of the tilt, the directness of sunlight changes during the year, causing solstices and equinoxes
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North hemisphere tilted toward the Sun
(North hemi- summer (USA) south hemi- winter (australia) |
Summer solstice
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South hemisphere tilted toward the sun
north hemi- winter (USA) south hemi- summer (australia) |
Winter Solstice
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Neither hemisphere is tilted toward the sun
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Vernal and Autumnal equinox
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How does the maximum height of the Sun in the sky change over the course of the year?
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Summer- sun is high in the sky
Winter- sun is low in the sky |
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What is precession? What is its period? How does it affect the way we see the sky?
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Precession is the slow wobble of the earth on its spin axis
-1 period = 26,000 years -Because of precession: Polaris won't always be the North Star The season during which we see constellations appear changes slowly over time |
