Outlines of Astronomy, Volume 1American Home Library, 1902 |
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Common terms and phrases
61 Cygni action amount angle angular aphelion appearance astronomers attraction average axis bright calculation Centauri centre coincidence comet conjunction considerable curve Cygni described diameter difference direction distance disturbed body disturbed orbit disturbing force Ditto double stars earth effect elements elliptic epoch equal equator excentricity fixed force acting greater heavens Hind inclination increase inequality instance interval Julian Julian period Jupiter latter length less light line of apsides longitude lunar magnitude mass mean motion meteors minute momentary moon moon's nearly nebula node normal force nucleus nutation observed Orionis P's orbit parallax perigee perihelion perihelion passage period perturbations planetary portion precisely produced proper motion quadratures recede recess regarded remarkable respect result retrograde revolution round Saturn seen semiaxis sidereal sidereal day situation solar solar apex sun's supposed surface syzygies tail tangential force telescopes tion tricity turbing Uranus variation velocity visible whole
Popular passages
Page 763 - This earth ? reciprocal, if land be there, Fields and inhabitants. Her spots thou seest As clouds, and clouds may rain, and rain produce Fruits in her soften'd soil, for some to eat Allotted there ; and other suns, perhaps, With their attendant moons, thou wilt descry, Communicating male and female light, Which two great sexes animate the world, Stored in each orb, perhaps, with some that live...
Page 886 - Here one is reminded, by the fleecy, infinitely delicate cloud-films, of an English hedgerow with luxuriant elms ; here of a densely intertwined tropical forest, the intimately interwoven branches threading in all directions, the prominences generally expanding as they mount upwards, and changing slowly, indeed almost imperceptibly.
Page 509 - ... tails. Perhaps it is not too much to hope that future observation, borrowing every aid from rational speculation, grounded on the progress of physical science generally (especially those branches of it which relate to the ethereal or imponderable elements), may...
Page 735 - It appears about twelve times in eleven years, — or, more exactly, in a period of 334 days; remains at its greatest brightness about a fortnight, being then, on some occasions, equal to a large star of the second magnitude ; decreases during about three months, till it becomes completely invisible...
Page 802 - It is not easy for language to convey a full impression of the beauty and sublimity of the spectacle which this nebula offers, as it enters the field of the telescope (fixed in RA) by the diurnal motion, ushered in as it is by so glorious and innumerable a procession of stars, to which it forms a sort of climax.
Page 763 - In such instances, the larger star is usually of a ruddy or orange hue, while the smaller one appears blue or green, probably in virtue of that general law of optics, which provides, that when the retina is under the influence of excitement by any...
Page 480 - ... 1st. That the matter of the nucleus of a comet is powerfully excited and dilated into a vaporous state by the action of the sun's rays, escaping in streams and jets at those points of its surface which oppose the least resistance, and in all probability throwing that surface or the nucleus itself into irregular motions by its reaction in the act of so escaping, and thus altering its direction.
Page 769 - It was thus that the grand discovery of the precession of the equinoxes resulted, as a residual phenomenon, from the imperfect explanation of the return of the seasons by the return of the sun to the same apparent place among the fixed stars. Thus, also, aberration and nutation resulted as residual phenomena from that portion of the changes of the apparent places of the fixed stars which are left unaccounted for by precession.
Page 800 - Trapezium, forming the square front of the head, is shown with 18-inch reflector broken up into masses, whose mottled and curdling light evidently indicates by a sort of granular texture its consisting of stars; and when examined under the great light of Lord Rosse's reflector or the exquisite defining power of the great achromatic at Cambridge, US, is evidently perceived to consist of clustering stars. There can therefore be little doubt as to the whole consisting of stars, too minute to be discerned...
Page 805 - They are, generally speaking, round, or somewhat oval, and the larger, which deviates most from the circular form, exhibits the appearance of an axis of light, very ill defined, and by no means strongly distinguished from the general mass, which seems to open out at its extremities into somewhat oval sweeps, constituting the preceding and following portions of its circumference.