An Introduction to AstronomyRobert B. Collins, 1856 - 445 pages |
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Common terms and phrases
altitude angular distance aphelion apparent diameter appear astronomical axis azimuth celestial celestial sphere comet corresponding declination degree described determined direction disk diurnal motion earth earth's orbit earth's shadow ecliptic elevation equal equator equinoctial figure force globe gravity greater greatest heavenly bodies heavens Hence horizon horizontal parallax hour inclination increase inferior conjunction inferior planets instrument Jupiter known latitude learner light limb longitude lunar measured Mercury meridian miles moon motion moves nearer nearly node oblique observations opposite parallel passing perigee perihelion period perpendicular planet planetary pole quadrant radius vector refraction represent respect revolve right angles right ascension ring satellites Saturn seen semi-diameter side sidereal sidereal day solar solstice spectator sphere star sun and moon superior conjunction superior planets supposed surface syzygies telescope tide tion transit triangle tropic tude Uranus velocity Venus vernal equinox west to east zenith distance
Popular passages
Page 90 - 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 310 - The first philosophical systems, in the same manner, are always the most complex, and a particular connecting chain, or principle, is generally thought necessary to unite every two seemingly disjointed appearances, but it often happens that one great connecting principle is afterward found to be sufficient to bind together all the discordant phenomena that occur in a whole species of things.
Page 295 - This remarkable law of variation certainly appears strongly to suggest the revolution round it of some opaque body, which, when interposed between us and Algol, cuts off a large...
Page 294 - Insulated stars of a red color, almost as deep as that of blood, occur in many parts of the heavens, but no green or blue star, of any decided hue, has, we believe, ever been noticed unassociated with a companion brighter than itself.
Page 257 - They can only be regarded as 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 299 - ... sharply terminated, in others a little hazy at the borders, and of a light exactly equable or only a very little mottled, which, in some of them, approaches in vividness to that of actual planets. Whatever be their nature, they must be of enormous magnitude. One of them is to be found in the parallel of v Aquarii, and about 5m preceding that star. Its apparent diameter is about 20".
Page 38 - 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.
Page 204 - ... and less strongly marked than those of Jupiter, and owing, doubtless, to a similar cause. That the ring is a solid opake substance is shown by its throwing its shadow on the body of the planet, on the side nearest the sun, and on the other side receiving that of the body, as shown in the figure.
Page 165 - The tides are an alternate rising and falling of the waters of the ocean, at regular intervals. They have a maximum and a minimum twice a day, twice a month, and twice a year. Of the daily tide, the maximum is called High tide, and the minimum Low tide. The maximum for the month is called Spring tide, and the minimum Neap tide. The rising of the tide is called Flood and its falling Ebb tide. Similar tides, whether high or low, occur on opposite sides of the earth at once.
Page 300 - Another, in the constellation Andromeda, presents a visible disk of 12", perfectly defined and round. Granting these objects to be equally distant from us with the stars, their real dimensions must be such as would fill, on the lowest computation, the whole orbit of Uranus. It is no less evident that, if they be solid bodies of a solar nature, the intrinsic splendor of their surfaces must be almost infinitely inferior to that of the sun's.