Study Guide ASTR 101
35 Cards in this Set
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vernal/ automnal equinoxes
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points on celestial equator where the sun crosses celestial equator while moving north/south.
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zodiac
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the stars that the sun passes during its way around the celestial sphere. the band tha tlies 9 degres on either side of the ecliptic on t he celestial sphere
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Rotation
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spinning of an object on its axis.
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milky way
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the galaxy we are in. composes of really far other stars.
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smallest/biggest planet in our solar system
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mercury/jupiter.
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1 AU
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distance from earth to sun
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ecliptic
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apparent path of the sun on celestial sphere.
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celestial equator
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line on celestial sphere directly above earth's equator
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right ascension
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where a star is, north or south of the celestial equator.
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arcminutes/arc seconds
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a measurement of angle. to describe the angle difference between two stars using your fist or pinky
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celestial sphere
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the make believe sphere around the earth that composes of all celestial objects.
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constellation /asterism difference
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constellation is something humans made up and is recognized. asterism is just a recognizeable grouping of stars.
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altitude
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the angle at which a star is measured from the equator , above the horizon.
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summer/ winter solstices
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points on celestial sphere where the sun reaches its most north / south positions, respectively.
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angular separation
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?
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elongation
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angle between sun and planet from earth.
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kepler's law 1
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planets move in ellipses
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kepler's law 2
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planets move faster when they're closer to sun
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newton's law 1
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law of inertia: body at rest will remain at rest / body in motion will remain in motion in straight line at same speed.
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newton's law 2
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acceleration = proportional to net force and inversely proportional to mass and is in the same direction as net force. as mass goes up, accell goes down
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newton's law 3
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action - reaction: forces come in pairs. no exceptions. opposite directions.
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mass
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how much matter in an object, same everywhere
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weight
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how hard gravity pulls on object, depends where u are
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universal law of gravitation
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Every point mass attracts every other point mass by a force pointing along the line intersecting both points. The force is proportional to the product of the two masses and inversely proportional to the square of the distance between the point masses:
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neap tides
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neap: sun and moon on 90 dg. angle with earth, making it the LEAST differences in high/low tides.
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spring tides
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spring: when sun moon and earth are in align, making tides on both sides alot stronger: BIGGEST DIFFERENCE between high/low tides
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parallax
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apparent shifting of near/far objects as position of observer changes
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kepler's law 3
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to measure a cellestial object's year - revolution around sun.
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things that heliocentric model explained
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1. retrograde
2. elongations of merc/venus
3. variations in brightness
4. seasons
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synodic period
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time it takes for the moon to rotate and come back to the same position.
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triangulation
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use of parallax to determing distance to an object
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troposphere
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lowest level of the earth's and other planets atmospheres
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aurora
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light radiated in the upper atmosphere due to impacts from charged particles
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mare/maria
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any of the lowlands of the moon/mars taht resemble a sea when viewed from earth.
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fission theory
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theory that holds the moon formed when material was spun off from the earth
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Study Guide ASTR 101