classical-terms

classical-terms - Astronomy 135: Archaeoastronomy Classical...

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Astronomy 135: Archaeoastronomy Classical Astronomy Terms Altitude (h) The angle between the horizon and an object in the sky. Azimuth (A) The angle between due north on the horizon and a point on the horizon directly below an object in the sky. Celestial Equator An imaginary circle on the Celestial Sphere that is the projection of the earth’s equator up onto the Celestial Sphere. The CE divides the Celestial Sphere into a northern hemisphere (where Declination measures are positive) and a southern hemisphere (where Declination measures are negative). The Declination of the CE is 0°. Celestial Sphere An imaginary sphere concentric with the earth but infinitely far away. The entire Celestial Sphere rotates around the earth from east to west once per day. Objects on the Celestial Sphere have coordinates of Right Ascension and Declination. The RA and Dec of the “fixed” stars do not change significantly over short timescales. The RA and Dec of the Sun changes over the course of a year due to the orbit of the earth around the sun. Circumpolar An object that never sets (i.e., crosses the horizon), but just circles the Celestial Pole in the sky. Declination (Dec, or sometimes δ ) The angle between an object on the Celestial Sphere and the Celestial Equator. Declination is typically measured in degrees, arcminutes, and arcseconds. Declination can be thought of as a kind of Celestial Latitude, since it gives the north-south position of an object on the Celestial Sphere. Ecliptic
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classical-terms - Astronomy 135: Archaeoastronomy Classical...

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