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92 Cards in this Set
- Front
- Back
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geocentric model
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earth is at center of solar system
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retrograde motion
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motion of planet in the backward (westward) loops
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epicycles
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small circle that each planet moves around whose center moves uniformly around earth
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heliocentric model
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sun is at center of solar system
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solstice
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happens twice each year as the Sun reaches its highest or lowest excursion relative to the celestial equator on the celestial sphere
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diurnal model
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apparent daily motion of the stars, caused by earths rotation
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equinox
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neither hemisphere is pointed at sun, sun is overhead at equator
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horizon
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apparent line that separates earth from sky
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zenith
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imaginary point directly above a particular location
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meridian
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line of longitude (degrees east or west of meridian)
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equator
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plane perpendicular to the sphere's axis of rotation
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tropics
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region of earth surrounding equator
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pseudoscience
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claim presented as scientific not adhering to scientific method
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north celestial pole
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point on the celestial sphere directly above earths north pole
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celestial equator
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the projection of earths equator onto the celestial sphere
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right ascension
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celestial coordinate used to measure longitude on the celestial sphere
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declination
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celestial coordinate used to measure latitude above or below the celestial equator
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ecliptic
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the apparent path of the sun, relative to the stars on the celestial sphere, over the course of a year
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zodiac
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the 12 constellations on the celestial sphere through which the sun appears to pass during the course of the year
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precession
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earth wobbles as it spins, causing the earths axis to point at different parts of the sky
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latitude
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degrees north of the equator
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longitude
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degrees east or west of prime meridian
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new moon
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see none of illuminated side
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quarter moon
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see 1/2 of illuminated side
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full moon
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see whole illuminated side
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crescent moon
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less than 1/2 of illuminated side
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gibbous moon
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more than 1/2 of illuminated side
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waxing moon
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increasing brightness
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waning moon
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decreasing brightness
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sidereal period
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time for moon to return to initial position with respect to the stars (27.3 days)
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synodic period
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time for moon to return to initial position with respect to the sun (29.5 days)
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line of nodes
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line where the orbital plane of the earth and moon intersect
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umbra
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darkest part of the shadow on the moon
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penumbra
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less dark part of the shadow on the moon, region is still getting some sunlight
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total lunar eclipse
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moon is completely covered
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partial lunar eclipse
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moon is partially covered
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penumbral lunar eclipse
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only the penumbra covers the moon
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total solar eclipse
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sun is completely covered
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partial solar eclipse
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sun is partially covered
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annular solar eclipse
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ring of sunlight is still visible during eclipse
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Tycho Brahe
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Danish astronomer who made careful measurements of the motions of the planets
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Johannes Kepler
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astronomer who pioneered telescopic observations and promoted the Copernican system
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ellipse
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bound orbits of objects moving under gravity are elliptical
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focus
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in a bond orbit, planets orbit in ellipses with the sun at one focus
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semi-major axis
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1/2 of the major axis of an ellipse,
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astronomical unit
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the average distance from earth to the sun (AU)
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inertia
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an object in motion stays in motion unless acted on by another force
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Galileo
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observed that other planets have moons, and used telescope to observe the moon, sun, and venus
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acceleration of gravity
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the acceleration of an object is inversely proportional to its mass
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Isaac Newton
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used Kepler's laws to discover gravity, and discovered planets follow same physical laws as on earth
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force
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action on an object that causes is momentum to change
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action/reaction
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for every action there is an equal and opposite reaction
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gravity
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a force that all objects exert in each other proportional to their mass and inversely proportional to the distance squared
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conservation of angular momentum
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planets move faster when closest to the sun
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tides
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when gravity pulls more strongly on one part of an object than another
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tidal effects
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tidal force (stretching), mostly effects oceans
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spring tide
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sun and moon pulling together (makes for strongest tides)
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neap tide
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sun and moon pulling against (makes for lowest tides)
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tidal locking/synchronous rotation
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the moon is tidally locked, meaning we always see the same side
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dynamo effect
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as liquid interior moves around it produces currents that produce magnetic fields
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aurora borealis
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atmospheric molecules are excited by incoming charged particles from solar wind (northern lights)
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solar wind
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the suns magnetic field heats up its outer layers which produces a stream of fast moving ionized particles
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megnetosphere
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magnetic field and solar wind protect planets with magnetosphere (gets deformed by wind pressure)
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VanAllen Belts
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earths particle belt
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lens
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bend light and focus all of the light incident on the front to a point a certain distance behind the lens
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refraction
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the tendency of a wave to bend as it passes from one transparent medium to another
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cassegrain telescope
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incoming light hits the primary mirror and is reflected upward upward towards the prime focus
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focal length
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distance from a mirror or the center of a lens to the focus
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eyepiece
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secondary lens through which an observer views an image
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photon
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individual packet of electromagnetic energy that makes up electromagnetic radiation
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refracting telescope
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a telescope that uses a lens to gather and focus light from a distant object
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wavelength
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the distance from one wave crest to the next
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reflecting telescope
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a telescope which uses a mirror to gather and focus light from a distant object
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electromagnetic spectrum
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the complete range of electromagnetic radiation
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radio and millimeter
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used for communication, penetrates atmosphere and everything else
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infrared (IR)
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felt as heat, some penetrates atmosphere but to observe all IR wavelengths we must go into space
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optical
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what our eyes can see, helps to get above the atmosphere
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ultraviolet (UV)
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high energy radiation, some penetrates atmosphere
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X-ray
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very high energy wavelengths, all blocked by atmosphere
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gamma ray
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the highest energy wavelengths, all blocked by atmosphere
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orbiter
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spacecraft that orbits an object to make observations
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lander
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spacecraft that lands on object it is studying
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least energy orbit
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easiest way to get to a planet
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Fly-by
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unbound trajectory of a spacecraft around a planet or other body
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star
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glowing ball of gas held together by its own gravity and powered by nuclear fusion
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disk
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rapid rotation of stars causes outer layers to form disk
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solar nebula
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initial disk of material that solar system formed from
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gas
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mostly hydrogen, some helium
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dust
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made of rock, metal, ices,
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planetesimals
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when grains of dust stick together to form larger bodies
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volatile
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material with low boiling point (ices) in solar nebula
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refractory material
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material with high boiling point (silicates and metal) in solar nebula
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