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93 Cards in this Set
- Front
- Back
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angular diameter |
the angle (extended) by the diameter of an object |
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arcminute |
1 degree = 60 arcmin (60') |
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arcsecond |
1' (arcmin) = 60 arcseconds (60") |
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small angle formula |
D = ad/206,265
D = width, a = angular size of object (in arcsec), d = distance to object |
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mega- |
million |
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astronomical unit (AU) |
average distance between Earth and Sun
1 AU = 1.496 X 10^8km |
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speed of light |
3.00 X 10^5 kim/s |
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light year |
1ly = 9.46 X 10^12km
= 63,240 AU
preferred measurement by physicists |
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parcsec |
1 pc = 3.09 X 10^13 km
= 3.26 ly
preferred measurement by astronomers (because it relates to the length of the angle) |
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parallax |
The apparent displacement of an object due to the motion of the observer |
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occham's razor |
The notion that a straightforward explanation of a phenomenon is more likely to be correct than a convoluted one. |
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constellation |
a configuration of stars in the same region of the sky |
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star labels |
letters of the greek alphabet are assigned to each star followed by the name of the constellation:
Example: Alpha Orionis |
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celestial sphere |
an imaginary sphere of very large radius centered on an observer;
the apparent sphere of the sky |
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how celestial sphere looks from earth |
the celestial sphere appears to be rotating around the Earth from east to west
Though not actually rotating |
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Right ascension (RA) |
A coordinate for measuring east-west positions of objects on the celestial sphere
Time for earth to shift through the angle
Compare to Longitude |
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Declination (Dec) |
angular distance of a celestial object north or south of the celestial equator |
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diurnal motion |
any apparent motion in the sky that repeats on a daily basis |
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Tilt of Earth's Axis |
23 1/2 degrees |
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Impact of Earth's tilt on position of sun and moon in the sky |
Look up |
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solar days |
The time for a single rotation of a earth on its tilt in respect to the sun |
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sidereal days |
the interval between successive meridian passages of the vernal |
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sidereal years |
the orbital period of Earth about the sun with respect to the stars |
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tropical years |
the period of revolution of Earth about the sun with respect to the vernal equinox |
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meridian |
the great circle on the celestial sphere that passes through an observer's zenith and the north and south celestial poles. |
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zenith |
the point on the celestial sphere directly overhead on observer |
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vernal equinox |
the point on the ecliptic where the sun crosses the celestial equator from south to north. |
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summer solstice |
sun is as far north from the celestial as it can get
Rises Northeast Sets Northwest |
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celestial equator |
a great circle on the celestial sphere 90 degrees from the celestial poles |
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ecliptic |
the apparent annual path of the sun on the celestial sphere |
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sidereal |
In comparison to the stars |
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precession |
slow, motion of Earth's axis of rotation caused by the gravitational pull of the Moon and Sun on Earth's equatorial bulge. |
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The motion of moon around earth |
Look Up |
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Eudoxus |
Spheres of Sun, Moon and Planets to explain the daily motion, monthly or yearly motion and retrogradation
Introduced 365 days and 6 hours |
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Apollonius |
Look Up |
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Aristotle |
believed in conjunct spheres
couldn't see stars movement, so couldn't believe earth was moving |
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Aristarchus |
First to believe in heliocentric model (way before Copernicus)
Correctly assumed order of planets and the sun not revolving around the earth |
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Hipparchus |
Extensive contribution. Alexandrian School
Measured distance of stars, poles
classified stars by magnitudes |
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Ptolemy |
Wrote Almagest
Predicted movement of planets |
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Eratosthenes |
Diameter of the Sun, through calculations of sun's shadows |
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Historical order of ancient astronomers |
Eudoxus Aristotle Aristarchus Erastosthenes Hipparchus Ptolemy |
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Copernicus |
Heliocentric
Position of planets due to size
1/P=1/E+1/S for calculating sidereal period from earth's sidereal and planet's synodic |
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Contribution from the Middle East |
to perfect religious calendars
predicted eath's rotation on its own axis, something not done by Galileo for 600 years |
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Brahe's obervations |
Believed earth was at rest, but believed the heavens were not unchangeable as believed
Believed in shifting (parallax) though did not support heliocentric model |
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Newton's Laws |
1) an object remains at rest, or moves in a straight line at a constant speed, unless acted upon by a net outside force
2) Force = Mass X Acceleration
3) Whenever one object exerts a force on a second object, the second objects exerts an oppositely directed force of equal strength |
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Waves |
disturbance or oscillation that travels through a matter accompanied by a transfer in energy |
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frequency period |
the number of crests that pass a given point in one second
indicated by v (nu); unit is referred to as hertz
number of vibrations per unit of time |
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wavelength |
the distance between two successive wave crests |
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diffraction |
the spreading out of light passing through an aperture or opening in an opaque object |
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how speed of light was determined |
Romer
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wavelength of visible light |
400-700nm |
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Romer |
Look UP |
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Young |
Look Up |
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Newton |
Laws of Motion Law of Universal Gravitation |
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colors of visible light (by wavelength) |
Violet (380-450nm) Blue (450-495nm) Green (495-570nm) Yellow (570-590nm) Orange (590-620nm) Red (620-750nm) |
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geocentric model |
an earth centered theory of the universe |
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direct/prograde motion |
Look Up |
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retrograde motion |
Look Up |
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ptolemaic system |
the definitive version of the geocentric cosmogony of ancient Greece |
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epicycle |
a moving circle in the Ptolemaic system about which a planet revolves |
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deferent |
a stationary circle in the ptolemaic system along which another circle (an epicycle) moves, carrying a planet, sun or moon |
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heliocentric model |
a sun centered theory of the universe |
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superior planets |
a planet that is more distant from the sun than is Earth |
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greatest eastern elongation |
the configuration of an inferior planet at its greatest angular distance east of the Sun |
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elongation |
the angular distance between a planet and the Sun as viewed from Earth |
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inferior conjunction |
the configuration when an inferior planet is between the Earth and the Sun |
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superior conjunction |
the configuration of a planet being behind the Sun as viewed from Earth |
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opposition |
the configuration of a planet when it is at an elongation of 180 degrees and thus appears opposite the Sun in the sky
(on other side of Earth) |
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conjunction |
arrangement of planet in the same part of the sky as the sun |
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focus |
one of two points inside an ellipse such that the combined distance from the two foci to any point on the ellipse is constant |
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aphelion |
the point in its orbit where a planet is farthest from the sun |
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perihelion |
the point in its orbit where a planet or comet is nearest the sun |
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Galileo |
Jupiter's Moons Phases of Venus
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Phases of Venus |
Galileo |
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Moons of Jupiter |
Galileo |
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Law of Universal Gravitation |
Two objects attract each other with a force that is directly proportional to the mass of each object and inversely proportional to the square of the distance between them
Force = Gravity X mass1*mass2/distance between^2 |
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Kepler's First Law |
The statement that each planet moves around the Sun in an elliptical orbit with the Sun at one focus of the ellipse |
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Kepler's Second Law |
The statement that a planet sweeps out equal areas in equal times as it orbits the sun;
also called law of equal areas |
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Kepler's Third Law |
the square of the sidereal period of a planet is directly proportional to the cube of the semimajor axis of the orbit
P^2 (Years) = a ^3 (AU) |
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major axis |
the longest diameter of an ellipse |
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semimajor axis |
half the distance of the major axis |
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relationship between wavelength and frequency |
if wavelength is made shorter
frequency must increase
Frequency (v) = Speed of light (c)/Wavelength(A) |
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Winter Solstice |
Sun is farthest south of the celestial equator
Rises Southeast Sets Southwest |
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phases of moon |
New Moon Waxing Crescent Moon First Quarter Moon Waxing Gibbous Moon
Full Moon
Waning Gibbous Moon Third Quarter Moon Waning Crescent Moon |
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Timeline of Moon |
Approximately 4 weeks to transfer
On average moon rises and sets 1 hour later each night |
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New Moon |
Rise: 6am High: Noon Set: 6pm |
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Waxing Crescent Moon |
Rise: 9am High: 3pm Set: 9pm |
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First Quarter Moon |
Rise: Noon High: 6pm Set: Midnight |
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Waxing Gibbous Moon |
Rise: 3pm High: 9pm Set: 3am |
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Full Moon |
Rise: 6pm High: Midnight Set: 6am |
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Waning Gibbous Moon |
Rise: 9pm High: 3am Set: 9am |
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Third Quarter Moon |
Rise: Midnight High: 6am Set: Noon |
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Waning Crescent Moon |
Rise: 3am High: 9am Set: Noon |
