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Elements of Astronomy With Explanatory Notes, and Questions for Examination ...
Sin vista previa disponible - 2017
altitude angular aphelion apparent diameter apparent motion appear apsides ascertained asteroid astronomers atmosphere axis celestial equator celestial sphere centre changes circle of illumination circumference comet constellation declination degrees describe difference direction disk earth earth's orbit equal Explain from figure extent fixed stars force globe gravity half heavenly body heavens hemisphere Herschel horizon inclination Jupiter latitude latter length libration light longitude lunar eclipse magnitude mean solar measured Mercury meridian miles moon mountains move nearly nebula nodes north pole nutation observations occur parallax passing path penumbra perigee perihelion period planet position precession Prof radius rays refraction respecting revolution revolve right angles right ascension ring rotation satellites Saturn seen shadow sidereal sidereal day solar day solar distance solar eclipse south pole space spectator spots summer solstice surface synodical month telescope termed tides tion triangle velocity Venus vernal equinox visible west to east winter solstice zenith Zodiac
Página 294 - The fourth term is found by multiplying the second and third terms together and dividing by the first § 14O.
Página 162 - These phenomena do not, however, occur at every new and full moon ; and the reason is, that the plane of the moon's orbit is inclined to that of the ecliptic, and that these two planes' meet one another only in their line of common section, which passes through the centre of the earth.
Página 303 - On a careful re-examination of the heavens, too, and a comparison of catalogues, many stars are now found to be missing-; and although there is no doubt that these losses have often arisen from mistaken entries, yet in many instances it is equally certain that there is no mistake in the observation or entry, and that the star has really been observed, and as really has disappeared from the heavens...
Página 24 - A SPHERE is a solid bounded by a curved surface, every part of which is equally distant from a point within, called the centre.
Página 160 - In some of the principal ones, decisive marks of volcanic stratification, arising from successive deposits of ejected matter, and evident indications of Lava currents streaming outwards in all directions, may be clearly traced with powerful telescopes.
Página 331 - Dodd, I find it greatly superior to all others which have come under my notice, in system, completeness, and nomenclature. The arrangement is natural, the system complete, and the nomenclature greatly improved. These improvements are not slight; they are fundamental— eminently worthy the attention of the mathematical teacher, and give a character of unity to the work which at once distinguishes it from all others on this subject.
Página 50 - ... the sun. More Accurate Computations. — A more accurate determination of the phases as visible at any point of the earth's surface may be obtained from the Besselian elements which are given for every ten minutes of Greenwich mean time. Their geometric signification is as follows: — Let us imagine a plane passing through the centre of the earth, perpendicular to the right line joining the centres of the sun and moon. This latter line is the axis of the moon's shadow, and the plane is called...
Página 51 - Circles are great circles passing through the zenith of an observer, and perpendicular to his horizon. The vertical circle passing through the east and west points of the horizon is called the Prime Vertical ¡ that passing through the north and south points coincides with the celestial meridian.
Página 316 - This is an irresolvable nebula, figured by Sir John Herschel, during his residence at the Cape of Good Hope. Its favourable position, as seen in southern latitudes, enabled Herschel to trace the outline of the nebula much farther than any preceding observer had done. The singular figure of this object seems to suggest some power of attraction operating on the particles of matter, or the...