An Introduction to Astronomy: Designed as a Textbook for the Use of Students of Yale College

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Collins, Keese, & Company, 1839 - Astronomy - 276 pages
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Page 79 - GRAVITATION, is that influence by which every body in the universe, whether great or small, tends towards every other, with a force which is directly as the quantity of matter, and inversely as the square of the distance.
Page 247 - It was then as bright as Sirius, and continued to increase till it surpassed Jupiter when brightest, and was visible at mid-day. It began to diminish in December of the same year, and in March 1574, had entirely disappeared.
Page 189 - ... 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.
Page 249 - IN 1803, Sir William Herschel first determined and announced to the world, that there exist among the stars separate systems, composed of two stars revolving about each other in regular orbits. These he denominated binary stars, to distinguish them from other double stars where no such motion is detected, and whose proximity to each other may possibly arise from casual juxtaposition, or from one being in the range of the other.
Page 191 - These satellites offer remarkable, and indeed quite unexpected and unexampled peculiarities. Contrary to the unbroken analogy of the whole planetary system, the planes of their orbits are nearly perpendicular to the ecliptic, being inclined no less than 78 58' to that plane, and in these orbits their motions are retrograde; that is, instead of advancing from west to east around their primary, as is the case with all the other planets and satellites, they move in the opposite direction. With this...
Page 223 - Their tails consist of matter of such tenuity that the smallest stars are visible through them. They can only be regarded as great masses of thin vapor, susceptible of being penetrated through their whole substance by the sunbeams, and reflecting them alike from their interior parts and from their surfaces.
Page 248 - ... a red and a green, or a yellow and a blue one — must afford a planet circulating about either; and what charming contrasts and "grateful vicissitudes," — a red and a green day, for instance, alternating with a white one and with darkness, — might arise from the presence or absence of one or other, or both, above the horizon.
Page 246 - This remarkable law of variation appears strongly to suggest the revolution round it of some opaque body, which, when interposed between us and Algol, cuts off a large portion of its light. " It is,
Page 218 - Place, that the arrangements of the solar system are stable, that in the long run the orbits and motions remain unchanged, and that the changes in the orbits which take place in shorter periods never transgress certain very moderate limits. Each orbit undergoes deviations on this side and on that of its average state ; but these deviations are never very great, and it finally recovers from them, so that the average is preserved.
Page 27 - Were it not for the reflective and scattering power of the atmosphere, no objects would be visible to us out of direct sunshine; every shadow of a passing cloud would be pitchy darkness ; the stars would be visible all day, and every apartment, into which the sun had not direct admission, would be involved in nocturnal obscurity.

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