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aberration altitude angle angular distance argument astronomical axis called celestial centre circle circle of latitude comet computed determined direction disc disturbing force diurnal diurnal motion earth eccentricity eclipse epoch equal equator equatorial fixed stars given greater greatest heavenly body heavens heliocentric horizon horizontal parallax hourly motion inclination inequalities inferior planet interval Jupiter length less light limb longitude and latitude luminous lunar magnitude mean anomaly mean distance mean longitude meridian miles moon moon's orbit motion in longitude nearly nebula node nucleus nutation obliquity observed obtained opposite orbit parallax parallel passing perigee perihelion period perpendicular photosphere planet pole position quantity radius-vector refraction result retrograde motion right ascension rotation satellites seen semi-diameter shadow sidereal solar solstice sphere spots sun's supposed Table tang telescope tion true true anomaly tude variations velocity Venus vernal equinox vertical visible wires zenith distance Zodiacal Light
Page 188 - Insulated mountains, which rise from plains nearly level, like a sugar loaf placed on a table, and which may be supposed to present an appearance somewhat similar to Mount Etna or the peak of Teneriffe. The shadows of these mountains, in certain phases of the moon, are as distinctly perceived as the shadow of an upright staff when placed opposite to the sun ; and their heights can be calculated from the length of their shadows.
Page 20 - LONGITUDE of a place, in geography, is an arch of the equator, intercepted between the first meridian and the meridian passing through the...
Page 220 - ... probability, to be snow ; as they disappear when they have been long exposed to the sun, and are greatest when just emerging from the long night of their polar winter, the snow line then extending to about six degrees (reckoned on a meridian of the planet) from the pole.
Page 222 - ... forming tracts of comparatively clear sky, determined by currents analogous to our trade-winds, but of a much more steady and decided character, as might indeed be expected from the immense velocity of its rotation. That it is the comparatively darker body of the planet which appears in the belts is evident from this, — that they do not come up in all their strength to the edge of the disc, but fade away gradually before they reach it. (See Plate III. Jig. 2.) The apparent diameter of Jupiter...
Page 106 - 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...
Page 101 - XIII, by the omission of 10 nominal days after the 4th of October, 1582, so that the next day was called the 15th and not the 5th. This change was immediately adopted in all Roman Catholic countries, but tardily in the countries of Protestantism. In England, the change of style...
Page 436 - Let P be the point of equal attraction between any planet and the one next interior, the two being in conjunction ; P', that between the same and the one next exterior. Let also D = the sum of the distances of the points P, P...
Page 150 - A singular law obtains among the mean motions and mean longitudes of the three first satellites. It appears from observation that the mean motion of the first satellite, plus twice that of the third, is equal to three times that of the second ; and that the mean longitude of the first satellite, minus three times that of the second, plus twice that of the third, is always equal to two right angles. It is proved by theory, that if these relations had only been approximate...