## The Elements of the Theory of Astronomy |

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aberration altitude angle angular apparent axis becomes beginning calculated called caused circle clock conjunction consequently considered correction corresponding declination described determined diameter diminishes direction disk Earth Earth's surface east ecliptic effect equal equator equinox error expressed fixed stars given gives greater greatest heavenly body heavens Hence horizon hour angle inclination increase intersection interval known latitude length less light longitude manner mean measured meridian method Moon Moon's motion moves nearly node observed obtained opposition orbit parallax parallel passing period perpendicular plane pole portion position preceding produced quantities radius refraction respectively right ascension rotation round satellite seen shadow side sidereal sinē solar solstice Sun's supposed taking tion transit triangle true values varies vertical visible whole zenith distance

### Popular passages

Page 55 - The third, viz. that the squares of the periodic times are proportional to the cubes of the mean distances...

Page 264 - If the mean angular velocity of the first satellite be added to twice that of the third, the sum will be equal to three times that of the second ;" and "from this it results that the situations of any two of them being given, that of the third can be found.

Page 81 - An account of experiments for determining the length of the pendulum vibrating seconds in the latitude of London.

Page 16 - IV. The ecliptic and its pole may be taken as the standards of reference. The co-ordinates of the star are then called its latitude and its longitude. The Latitude of a star is its angular distance from the ecliptic measured on a circle of latitude. The Longitude of a star is the arc of the ecliptic included between the vernal equinox and the point where the circle of latitude through the star cuts the ecliptic.

Page 137 - Wollaston concludes, that all the phenomena accord entirely with the supposition that the Earths atmosphere is of finite extent, limited by the weight of ultimate atoms, of definite magnitude, no longer divisible by repulsion of their parts.

Page 293 - The greatest number of eclipses that can happen in a year is seven; five of the sun and two of the moon, or four of the sun and three of the moon.

Page 114 - B . sin c = sin b . sin C cos a = cos b . cos c + sin b . sin c cos b = cos a . cos c + sin a . sin c cos A cos B cos c = cos a . cos b + sin a . sin b . cos C ..2), cotg b . sin c = cos G.

Page 312 - Time, the angular distances between the apparent centres of the Moon and certain heavenly bodies, such as they would appear to an observer at the centre of the Earth. When a Lunar Distance has been observed on the surface of the Earth, and reduced to the centre, by clearing it of the effects of parallax and refraction, the numbers...

Page 55 - Sun, moves from west to east ; or according to the order of the signs, or, as the phrase may still be varied, in consequentia.

Page 48 - NODE, (1) in astronomy, the two points in which the orbit of a planet intersects the plane of the ecliptic; the one through which the planet passes from the south to the north side of the ecliptic being called the ascending node, and the other the descending node. As all the bodies of the solar system, whether planets or comets, move in orbits variously inclined to the ecliptic, the orbit of each possesses two nodes, and a straight line drawn joining these two points is called the line of nodes of...