Celestial Sphere

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Celestial Sphere
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Terms in this set (20)
Celestial Sphere
The imaginary sphere on which objects in the sky appear to reside when observed from Earth.
Image: Celestial Sphere
Zenith
the point directly overhead
Image: Zenith
Meridian
An arc drawn on a map between the North and South poles.
Image: Meridian
Altitude (Alt)
angle above the horizon
Image: Altitude (Alt)
Azimuth (Az)
the direction of a celestial object from the observer, expressed as the angular distance from the north point of the horizon to the point at which a vertical circle passing through the object intersects the horizon.
Image: Azimuth (Az)
Nadir
the point directly below the observer
Image: Nadir
North Pole
the northernmost point of the Earth's axis
Image: North Pole
South Pole
the southernmost point of the Earth's axis
Image: South Pole
North Celestial Pole (NCP)
The point on the celestial sphere directly above Earth's North Pole.
Image: North Celestial Pole (NCP)
South Celestial Pole (SCP)
The point on the celestial sphere directly above Earth's South Pole.
Image: South Celestial Pole (SCP)
EquatorAn imaginary circle around the middle of the earth, halfway between the North Pole and the South PoleCelestial EquatorAn imaginary circle created by extending Earth's equator into spaceRight Ascension (RA)Analogous to longitude, but on the celestial sphere; the angular east-west distance between the spring equinox and a location on the celestial sphere.Declination (DEC)Analogous to latitude, but on the celestial sphere; it is the angular north-south distance between the celestial equator and a location on the celestial sphere.Latitudedistance north or south of the Equator, measured in degreesLongitudeDistance east or west of the prime meridian, measured in degreesplane of the eclipticThe plane that passes through the sun and earth, enscribing the orbital path of the earth around the sunHorizonthe line at which the sky and Earth appear to meetCircumpolar Starsstars that can be seen at all times of the year and all times of night.Angle of Hours, Min, SecondsUnits used to measure Latitude, Longitude and Right Ascension

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