HE A YENS. 73 



As'terism. — A small clustei* of stars, eitlier included or not in 

 a constellation. 



As'teroids'. — The small planets that circulate between the 

 orbits of Mars and Jupiter. 



Astro^'nosy (Grr. astron, a star, and gnosis, knowledge). — 

 The science of the stars. 



Astrog'raphy (Gr. asfron, a star, and graphe, a description). 

 — A description of the stars, or the science of describing 

 them. 



Astrom'etry (Gr. asfron, a star, and vietreo, I measure). — 

 Tlie art of making mcasiirements among the stars, or of 

 determining their relative magnitudes. 



Astros'copy (Gr. asfron, a star, and shopeo, I view). — Oh- 

 servafion of the stars. 



Ax'is. — The imaginary line passing through the centre and 

 poles of the earth, on which it performs its diurnal revolu- 

 tion from west to east. 



Az'imuth. — An arc of the horizon intercepted between the 

 meridian of the place and the vertical circle passing through 

 the centre of a celestial object. 



Can'cer (Lat., a crab). — The fourth sign of the zodiac, being 

 tliat of the summer solstice, which the sun enters about 

 the 21sc of June. 



Cap'ricom (Lat. caper, a he-goat, and cormi, a horn). — The 

 tenth sign of the zodiac, which the sun enters about the 

 21st of December, at the winter solstice. 



Colure'. — Two great circles, supposed to intersect each other 

 at right angles in the poles of the world, one of them pass- 

 ing through the solstitial and the other through the equi- 

 noctial points of the ecliptic, viz., Cancer and Capricorn, 

 Aries and Libra, dividing the ecliptic into four equal 

 parts. 



Co'ma. — A dense, nebulous covering, which surrounds the 

 nucleus or body of a comet. 



Com'et.— A member of the solar system, commonly consisting 

 of three parts : the nucleus, the envelope or coma, and the 

 tail ; but one or more of these parts is frequently wanting. 



Conjuiic'tioil. — The meeting of two heavenly bodies in the 

 same point or place in the heavens. 



Constella'tion. — A number of stars which appear as if situated 

 near each other in the heavens, and are considered as form- 

 ing a particular division. 

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