Popular Astronomy: A Concise Elementary Treatise on the Sun, Planets, Satellites and CometsPhinney, Blakeman & Mason, 1860 - 376 |
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angle Annual variation aphelion apparent diameter appearance asteroids astronomers attraction celestial celestial sphere centrifugal force Cincinnati Observatory circle circular clock comet computed conjunction determined direction discovered discovery disk disturbing earth earth's orbit eccentricity ecliptic entire equal equator exact examination exerted fact fall figure fixed stars globe gravitation heavenly bodies heavens hence Hipparchus hypothesis inclination inferior conjunction instruments John Herschel Jupiter Jupiter's Kepler law of Kepler laws of motion light line of nodes longitude lunar major axis Mars mass Mean distance measure Mercury meridian millions of miles moon moon's orbit nearly observation Observatory pass perihelion period of revolution phenomena planet planetary orbits pole position precisely present problem radius reached retrograde revolution in days revolving ring rotation round satellites Saturn seen Sidereal revolution space spots sun's center surface telescope tion transit Uranus velocity Venus vernal equinox visible visual ray weight worlds
Popularne fragmenty
Strona 185 - ... time. The problem then resolved itself into a computation of the line M M', or the distance through which the moon. ought to fall in one second, in case the assumed law of gravitation be true, and the exact measurement instrumentally of the distance M'" M", the space through which the moon did fall in one second. An exact equality between these two quantities would establish the law of the decrease of the earth's power of attraction to be in the inverse ratio of the square of the distance. It...
Strona 302 - Thus the law of universal attraction becomes pure Metaphysics if we withdraw from it the verifiable specification of its mode of operation. Withdraw the formula " inversely as the square of the distance and directly as the mass," and Attraction is left standing a mere
Strona 302 - Law of gravitation: Every particle of matter in the universe attracts every other particle with a force varying directly as the product of their masses and inversely as the square of the distance between them.
Strona 262 - ... the sun ; that the sun and all the planets rotate on their axes in the same direction in which they revolve in their orbits. We have found, in like manner, that all the satellites of every planet revolve around their primaries in the same direction, and in planes nearly coincident with the planes of the equators of their primaries ; so that it became a settled opinion that there was but one direction in which any rotation or revolution could be performed by a member of the planetary system ;...
Strona 183 - ... the elements of a particle of water, for instance, is subject to an attractive and a repulsive force, acting in contrary directions, the centres of action of which are reciprocally opposed. The action of each force in relation to a molecule of water situated in the course of the electric current is in the inverse ratio of the square of the distance at which it is exerted, thus giving (it is stated) for such a molecule a constant force-\-.
Strona 120 - a singular phenomena connected with the snow-zone, which, so far as I know, has not been noticed elsewhere. On the night of July 12, 1845, the bright polar spot presented an appearance never exhibited at any preceding or succeeding observation. In the very centre of the white surface was a dark spot, which retained its position during several hours, and was distinctly seen by two friends who passed the night with me in the observatory. It was much darker, and better defined than any spot previously...
Strona 188 - ... modern terms, they knew the " law of the inverse ratio of the square of the distance from the centre of the revolution." Some have thought, that in Empedocles's system the foundation of Newton's was to be found ; imagining, that under the name of
Strona 211 - ... construction of instruments of the highest order of power, delicacy and perfection. To WEIGH THE SUN AND PLANETS. — Let it be borne in mind that the law of gravitation asserts that bodies attract with a force or power directly in proportion to their mass or weight. Hence a sun, weighing twice as much as the central orb of the solar system, would (at the same distance) attract with a double force. The same is true of the earth ; and if it were possible to hollow out the interior of the earth...
Strona 121 - I observed for the first time a small bright spot, nearly or quite round, projecting out of the lower side of the polar spot. In the early part of the evening the small bright spot seemed to be partly buried in the large one. After the lapse of an hour or more my attention was again directed to the planet, when I was astonished to find a manifest change in the position of this small bright spot.
Strona 319 - We shall see hereafter that the centrifugal force at the earth's equator is equal to -%^-g of the force of gravity. Now, if the sun rotated in the same time as the earth, and their diameters were equal, the centrifugal force on the equators of the two orbs would be equal. But the sun's radius is about 111 times that of the earth ; and, if the period or rotation were the same, the centrifugal force at the sun's equator would be greater than that at the earth's, in the ratio of (111)2 to 1, or more...