the horizontal circle defining the lower edge of the sky
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altitude
the angular distance from a point on the sky to the point on the horizon directly below it
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latitude
a measure of location specifying north-south position on earth running from 0 degrees to the equator @ 90 degrees north & 90 degrees south
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Longtitude
a measure of location specifying east-west position on earth
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angular size
angular distance measured on a sphere in degrees, minutes, arcminutes, and arcseconds
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celestial sphere
an imaginary transparent sphere surrounding earth, on which positions of the stars, planets, and other celestial bodies are projected from extensions of earth's coordinate system
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celestial equator
the extension of earth's equator onto the celestial sphere
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Polaris
the star that is found very near earth's celestial pole
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north celestial pole
the extension of earth's north pole on the celestial sphere
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south celestial pole
the extension of earth's south pole on the celestial sphere
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zenith
the point on the sky directly overhead from the observer
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meridian
a circular arc crossing the celestial sphere and passing through the local zenith and celestial pole
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declination
the position of an object on the celestial sphere, measured similarly to the latitude on earth
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sidereal day
the time taken by the earth to rotate on its axis relative to the stars
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solar day
the time between successive crossings of the same meridian on the sky by the sun
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small angle formula
a mathematical relationship between the angular size of an object, as measured on the sky, and the object's distance and physical size
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analemma
the figure-8 pattern formed by charting the daily position of the sun @ the same time of the day over the course of 1 year
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summer solstice
the day (june 21st) with the most hours of sunlight, when the sun appears highest in the sky
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winter solstice
the day (december 21st) with the fewest hours of daylight, when the sun appears lowest in the sky
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equinox
A day when the hours of daylight and darkness are equal
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orbit
the cyclical path in space that one object makes around another object
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axial tilt or obliquity
the angle between a planet's rotation axis and a line perpendicular to the planet's orbital plane
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precession
the rotation of a planet's spin axis, similar to that of a wobbling toy
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constellations
a group of stars that form a pattern, and the designated region of the sky surrounding them
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circumpolar constellation
a constellation that, from the viewer's perspective, never rises or sets.
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ecliptic
the path that the sun appears to follow against the background as defined by earth's orbit around the sun
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zodiac
13 constellations that lie close to the plane of the ecliptic
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phase (of the moon)
as seen by observation of the earth, the appearance of the illuminated portion of the moon, which change cyclically so the moon orbits the earth
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scientific model
an idea or set of ideas used to create testable explanations
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New moon
moon is between earth and the sun lunar face illuminated points away from the earth
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waxing crescent
appears in the late afternoon sky as sun sinks in the west
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first quarter moon
moon at its highest altitude @ sunset occurs seven days after new moon
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waxing gibbous
after first quarter
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full moon
the time when the Moon is fully illuminated 7 days after first quarter highest point in the night sky @ 12
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waning gibbous
appears on eastern horizon closer to midnight
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third quarter
7 days after full moon rises @ midnight
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waning crescent
last phase before it starts back over
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synodic month
the amount of time it takes the moon to cycle through its phases (29.5 days)
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sidereal month
the amount of time it takes the moon to make a complete orbit
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Eclipse
the passing of one celestial body through the shadow of another
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penumbra
the outer region of a shadow cast by an extended object
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umbra
the inner region of a shadow cast by an extended object
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Total lunar eclipse
an eclipse that occurs when the moon passes through Earth's umbral shadow
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partial lunar eclipse
an eclipse that occurs when the moon passes partially through the earth's umbral shadow
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total solar eclipse
an eclipse that occurs when a region of earth's surface passes under the moon's umbral shadow and the sun disk is fully blocked
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totality
the moment or duration of total concealment of the sun or moon during an eclipse
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apogee
the distance of farthest approach of an object orbiting earth
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perigee
the distance of closest approach of an object orbiting earth
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aphelion
the distance of farthest approach of an object orbiting the sun
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perihelion
the distance of closest approach of an object orbiting the sun
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annular eclipse
a solar eclipse that occurs when the positions of the moon and sun are such that the lunar disk does not fully block out the solar disk
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partial solar eclipse
an eclipse that occurs when a region of earth's surface passes under the moon's penumbral shadow
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line of nods
the line defined by the intersection of the moon's orbital plane and earth's orbital plane around the sun.
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mythology
a collection of stories used to explain phenomena whose physical basis is not understood
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megalith
a large stone used as a monument or part of a monument
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paleolithic period
the period extending from 2.6 million years to 10,000 years ago (earliest known use of stone tools)
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neolithic period
the period extending from 10,000 BCE to between 4500 and 2000 BCE, when farming was introduced
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geocentric model
a model stating that earth is the body around which all other solar system objects orbit
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heliocentric model
a model stating that the Sun is the body around which all other solar system objects orbit
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parallax
a displacement or difference in the apparent position of an object viewed along two different lines of sight
Studied by 4 people
Note 
Flashcard (20)