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Capricornus

(Encyclopedia)Capricornus kăprĭkôrˈnəs [key] [Lat.,=the goat horn], inconspicuous southern constellation lying on the ecliptic (the sun's apparent path through the heavens) between Sagittarius and Aquarius; it...

Gemini

(Encyclopedia)Gemini jĕmˈənī, –nē [key] [Lat.,=the twins], northern constellation lying on the ecliptic (the sun's apparent path through the heavens) between Taurus and Cancer, N of Canis Minor; it is one of...

Polaris

(Encyclopedia)Polaris pōlârˈĭs [key] or North Star, star nearest the north celestial pole (see equatorial coordinate system). It is in the constellation Ursa Minor (see Ursa Major and Ursa Minor; Bayer designat...

node

(Encyclopedia)node, in astronomy, point at which the orbit of a body crosses a reference plane. One reference plane that is often used is the plane of the earth's orbit around the sun (ecliptic). Since the moon's o...

precession

(Encyclopedia)precession: see gyroscope.

zodiac

(Encyclopedia) CE5 Signs of the zodiac CEE zodiac zōˈdēăk [key] [Gr. zoion=animal], in astronomy, zone of the sky that includes about 8° on either side of the ecliptic. The apparent paths of the sun, the...

Ptolemy

(Encyclopedia)Ptolemy (Claudius Ptolemaeus), fl. 2d cent. a.d., celebrated Greco-Egyptian mathematician, astronomer, and geographer. He made his observations in Alexandria and was the last great astronomer of ancie...

cycle

(Encyclopedia)cycle, in astronomy, period of time required for the recurrence of some celestial event. The length of a cycle may be measured relative to the sun or to the fixed stars (see sidereal time). A frequent...

gyroscope

(Encyclopedia) CE5 Three-frame gyroscope gyroscope jīˈrəskōpˌ [key], symmetrical mass, usually a wheel, mounted so that it can spin about an axis in any direction. When spinning, the gyroscope has special p...

tropical year

(Encyclopedia)tropical year, time between successive vernal equinoxes; 365 days, 5 hr, 48 min, 46 sec of mean solar time (see solar time). The tropical year is the basis of the year used in the Gregorian calendar. ...
 

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