History of Astronomy |
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Page 22
... pass , thus facilitating the determination of planetary mo- tions . Aristarchus ( 320-250 B.C. ) showed that the sun must be at least nineteen times as far off as the moon , which is far short of the mark . He also found the sun's ...
... pass , thus facilitating the determination of planetary mo- tions . Aristarchus ( 320-250 B.C. ) showed that the sun must be at least nineteen times as far off as the moon , which is far short of the mark . He also found the sun's ...
Page 23
... passes over equal arcs on the equant in equal times . He then computed tables for predicting the place of the sun . He proceeded in the same way to compute Lunar tables . Making use of Chaldæan eclipses , he was able to get an accurate ...
... passes over equal arcs on the equant in equal times . He then computed tables for predicting the place of the sun . He proceeded in the same way to compute Lunar tables . Making use of Chaldæan eclipses , he was able to get an accurate ...
Page 28
... passing through the sun , and to be between the earth and the sun . The centres of the epicycles of Mars , Jupiter , and Saturn were supposed to be further away than the sun . Mercury and Venus were sup- posed to revolve in their ...
... passing through the sun , and to be between the earth and the sun . The centres of the epicycles of Mars , Jupiter , and Saturn were supposed to be further away than the sun . Mercury and Venus were sup- posed to revolve in their ...
Page 35
... pass through it , and their points of least and greatest velocities were also deter- mined with reference to it . By this arrange- ment the sun was situated mathematically near the centre of the planetary system , but he did not appear ...
... pass through it , and their points of least and greatest velocities were also deter- mined with reference to it . By this arrange- ment the sun was situated mathematically near the centre of the planetary system , but he did not appear ...
Page 36
George Forbes. through the sun , and the lines of apses do not pass through to the sun . Such was the theory advanced by Copernicus : The earth moves in an epicycle , on a deferent whose centre is a little distance from the sun . The ...
George Forbes. through the sun , and the lines of apses do not pass through to the sun . Such was the theory advanced by Copernicus : The earth moves in an epicycle , on a deferent whose centre is a little distance from the sun . The ...
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Common terms and phrases
accurate Airy ancient astron Astronomer Royal astronomical units bright calculations Cape catalogue centre century Chaldæans Chinese comet Copernicus diameter discovered discovery earth Egyptian epicycles equatorial error excentric explain fact fixed stars Galileo Greenwich Halley heavenly bodies heavens heliometer Hipparchus History of Astronomy instruments JOHANNES KEPLER John Herschel Jupiter Jupiter's Kepler Laplace Lick Observatory light line of apses line of sight lunar Mars mathematical mean distance mean motion measured ment Mercury meteor miles a second moon moon's nebulæ Newton observations Observatory orbit parallax period photographic physical planet planetary pole position predicted proper motion proved Ptolemy R. S. Phil records refractor retrograde retrograde motion revolving round ring rotation satellites Saturn seems showing Sir William Herschel Sirius solar eclipse solar system spectra spectroscope spectrum sphere spots stellar sun-spot supposed tables telescope theory tion Trans Tycho Brahe universal gravitation Uranus velocity Venus Verrier
Popular passages
Page 67 - 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.
Page 26 - So he sate and cunningly guided the craft with the helm, nor did sleep fall upon his eyelids, as he viewed the Pleiads and Bootes, that setteth late, and the Bear, which they likewise call the Wain, which turneth ever in one place, and keepeth watch upon Orion, and alone hath no part, in the baths of Ocean. This star, Calypso, the fair goddess, bade him to keep ever on the left as he traversed the deep.
Page 53 - The third, viz. that the squares of the periodic times are proportional to the cubes of the mean distances...
Page 79 - Wherefore if according to what we have already said it should return again about the year 1758, candid posterity will not refuse to acknowledge that this was first discovered by an Englishman.
Page 122 - ... They have not been regarded as so successful as his geometrical analysis of the observed phenomena. It is only just to add that he himself did not attach equal weight to them ; for in answer to objections urged by Lalande to his theory that the spots are depressions, Wilson wrote thus in 1783 : — ' Whether their first production and subsequent numberless changes depend upon the eructation of elastic vapours from below, or upon eddies or whirlpools commencing at the surface, or upon the dissolving...
Page 51 - He then said boldly that it was impossible that so good an observer as Tycho could be wrong by eight minutes* and added, " out of these eight minutes we will construct a new theory that will explain the motions of all the planets.