Term
| Where was the July 11, 1991 solar eclipse seen from? Why was this a big deal? |
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Definition
| Mauna Kea in Hawaii, it was the largest telescopes every to be able to point directly at the sun |
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Term
| What is positional astronomy? |
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Definition
| study of positions of objects in sky and how they change |
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Term
| What is remarkable about Stonehenge, the Incan stone temple, and the Anasazi stone petroglyphs? |
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Definition
| They were built to predict where the sun would rise and set during key times in the year, Incas had a window that the sunlight would go through on the summer solstice, anasazi had carvings that have a single band of light strike the center of a spiral on the first day of winter |
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Term
| What is about the great pyramids of egypt? |
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Definition
| they are oriented north-south and east-west with an accuracy of far less than 1 degree |
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Term
| Mayan astronomers studied which planet most? |
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Definition
| Venus, the believed it to be associated with war and chose the dates to attack based on its phases |
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Term
| What is the daily motion of the stars called? |
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Definition
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Term
| Constellations rise in ____ and set in ____, but do so approx. _____ (time) earlier each night. |
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Definition
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Term
| Earth rotates which direction? |
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Definition
| west to east (which is why stars seem to move from east to west) |
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Term
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Definition
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Term
| What is the point in the sky directly overhead an observer anywhere on Earth called? The distance from the horizon to this point is thus ______. |
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Definition
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Term
| Why is Polaris able to be seen at any time of night on any night of the year in N. America or Europe? |
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Definition
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Term
| how does where you are standing on the earth relative to the celestial poles/sphere change the stars you see and their motion? |
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Definition
| if you are standing at the poles then you always see the same stars and they never rise or set, they just go around, if you are standing at the equator you see all the stars and they always rise and set, for most people stars move at an angle (rise in east & set in west) |
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Term
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Definition
| the earth's tilt, when the northern hemisphere is tilted towards the sun it is summer there and winter in the southern hemisphere tilted away |
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Term
| what is the plane of the earth's orbit around the sun called? |
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Definition
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Term
| how many days does it take the earth to go around the sun? what fixes (and who fixed) this time difference? |
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Definition
| 365.2442, leap year (as established by Caesar) fixed this to 365.24 but it was still off 11 min and 14 sec which over time added up, pope Gregory instituted a Gregorian calendar which fixed this by dropping 10 days that year and then modifying caesar's leap year system by saying that only centuries evenly divisible by 400 should be leap years instead of all calendar years divisible by 4 |
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Term
| how long does it take the earth to rotate around its axis once? what fixes this time difference from 24 hours? |
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Definition
| 23 hours and 56 minutes, the earth's rotations around the sun |
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Term
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Definition
| the 2 times a year when the ecliptic and the celestial equator intersect, at this time day and night are equal |
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Term
| what is march 21 and sept 22? |
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Definition
| vernal equinox and autumnal equinox |
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Term
| what is the point on the ecliptic farthest north of the celestial equator? what day is that? farthest south? what day is that? [all according to n. hemisphere] |
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Definition
summer solstice, june 21
winter solstice, december 21 |
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Term
| what is the circular path the sun appears to trace out against the background of the stars? |
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Definition
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Term
| what is 23.5 degrees south & north latitude called? |
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Definition
tropic of capricorn
tropic of cancer |
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Term
| who was the first person to use a telescope? what year? |
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Definition
| Galileo (although a man in holland invented it), 1709 |
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Term
| what planets can we see without a telescope? |
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Definition
| mercury, venus, mars, jupiter, and saturn |
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Term
| when was Haley's comet first seen to have appeared in the sky? |
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Definition
| 1066 AD, we know this because we found a tapestry with the comet on it (it was thought to be a portent of good or evil at the time) |
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Term
| when is the sun never directly overhead? |
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Definition
| north or south of 23.5 degrees latitude |
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Term
what does the north pole look like june 21? december 21?
the south pole? |
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Definition
light all the time/always day/sun never goes below horizon
dark all day/always night/sun never rises above horizon
opposite |
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Term
baton rouge is at what latitude?
what is it like june 21? december 21?
australia? |
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Definition
+30 degrees
longer day than night/hot/sun higher up in sky
opposite
-30 degrees, opposite |
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Term
| what is the equator like on june 21? sept 21? march 21? |
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Definition
| sun is at 23.5 degrees. sun directly overhead moving south. sun directly overhead moving north. |
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Term
| the moon moves about how many degrees in the sky each day? |
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Definition
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Term
| the moon moves along a band called what? |
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Definition
| its own ecliptic, the zodiac |
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Term
| does the moon cause a change in Earth's rotation? if so, how? |
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Definition
yes, it has a gravitational pull on the Earth
because the earth is bigger around then from pole to pole, it has a "equatorial bulge" which the gravitational pulls of the moon and sun affect
precession (slow, conical motion of Earth's axis of rotation caused by the gravitational pulls) |
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Term
| the gravitational pull of the moon and sun try to twist the Earth's axis of rotation to be perpendicular to the plane of the ecliptic but the Earth only has a 23.5 degree tilt. what motion fights against this gravitational pull? |
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Definition
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Term
| how long does it take for the earth to make one precessional circle? |
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Definition
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Term
| because the Earth's axis of rotation precesses, so does the ___________? |
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Definition
celestial equator and thus the intersection of the celestial equator with the ecliptic and thus the equinoxes
thus the precession of earth is aka precession of equinoxes |
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Term
| who was the first person to detect precession of equinoxes? |
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Definition
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Term
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Definition
| line between celestial poles (hits zenith), used to measure time |
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Term
what is an apparent solar day?
why is it different at different times of the year? |
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Definition
the interval between 2 successive upper meridian transits of the sun
b/c Earth's orbit is an ellipse and Earth moves on its orbit faster when farther away thus the solar day is longer in january when the Earth is moving slower along its orbit |
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Term
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Definition
| system of time based on the apparent motion of stars |
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Term
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Definition
| the time required for the sun to return to the same position with respect to the stars |
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Term
| what type of solar year do we use? |
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Definition
| the tropical year, the time needed for the sun to return to the vernal equinox |
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Term
| what is parallax and what does it measure? |
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Definition
| angular shift (the apparent displacement of an object due to the motin of the observer), distance |
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Term
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Definition
a star with a distance of 1 parsec is one with a parallax angle of 1 second of arc
(yet all stars are father away than that) |
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Term
| what is the closest star? how far away is it? |
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Definition
| proxima/alpha centauri, 4.2 ly so just over 1 parsec |
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