Outlines of Astronomy: By Sir John F. W. Herschel, Del 1American Home Library, 1902 - 463 sider |
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altitude amount angle angular angular velocity apparent diameter appear arise ascertained astronomical atmosphere axis body calculated called cause celestial circle clock course degree described determined difference direction disk distance diurnal motion earth earth's surface ecliptic equal equator equatorial equinoctial equinox error exact excentricity fixed former globe gravity greater heavens heliocentric hemisphere horizon hour angle instrument interval Jupiter latitude latter law of Kepler light limb longitude lunar mean measure Mercury meridian micrometric moon moon's nearly node nutation object observed opposite orbit parallax parallel passing perihelion period perpendicular phenomena planet polar pole portion position precession precisely proportion radius rays reckoned refraction render respect revolution revolve right ascension ring rotation round satellites Saturn seen side sidereal sidereal period situation solar spectator sphere spherical spots stars station sun's suppose telescope tion triangle Uranus velocity vernal equinox vertical visible weight whole zenith
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Side 252 - This remarkable belt has maintained, from the earliest ages, the same relative situation among the stars ; and, when examined through powerful telescopes, is found (wonderful to relate ! ) to consist entirely of stars scattered by millions, like glittering dust, on. the black ground of the general heavens.
Side 370 - that every particle of matter in the universe attracts every other particle, with a force whose direction is that of the line joining the two, and whose magnitude is directly as the product of their masses, and inversely as the square of their distances from each other.
Side 328 - The sun's rays are the ultimate source of almost every motion which takes place on the surface of the earth. By its heat are produced all winds, and those disturbances in the electric equilibrium of the atmosphere which give rise to the phenomena of lightning, and probably also to terrestrial action and the aurora.
Side 441 - As to getting correct notions on this subject by drawing circles on paper or, still worse, from those very childish toys called orreries, it is out of the question.
Side 438 - ... satellites. But we shall do wrong to judge of the fitness or unfitness of their condition from what we see around us, when, perhaps, the very combinations which convey to our minds only images of horror, may be in reality theatres of the most striking and glorious displays of beneficent contrivance.
Side 311 - Its ground is finely mottled with an appearance of minute dark dots, or pores, which, when attentively watched, are found to be in a constant state of change. There is nothing which represents so faithfully this appearance as the slow subsidence of some flocculent chemical precipitates in a transparent fluid, when viewed perpendicularly from above...
Side 358 - ... after the manner of the little instrument called a cryophorus. The consequence must be absolute aridity below the vertical sun, constant accretion of hoar frost in the opposite region, and perhaps a narrow zone of running water at the borders of the enlightened hemisphere.
Side 175 - ... since the altitude of the pole is equal to the latitude of the place (art.
Side 71 - ... we have ourselves heard it stated by a celebrated optician, that the earliest circumstance which drew his attention to astronomy was the regular appearance, at a certain hour, for several successive days, of a considerable star, through the shaft of a chimney.
Side 44 - ... on a globe of sixteen inches in diameter, such a mountain would be represented by a protuberance of not more than one hundredth part of an inch, which is about the thickness of ordinary drawing paper.