History of Astronomy |
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Page 70
... velocity in free space , subject only to a central force , vary- ing inversely as the square of the distance , the body must revolve in a curve which may be any one of the sections of a cone a circle , ellipse , parabola , or hyperbola ...
... velocity in free space , subject only to a central force , vary- ing inversely as the square of the distance , the body must revolve in a curve which may be any one of the sections of a cone a circle , ellipse , parabola , or hyperbola ...
Page 98
... velocity is 186,000 miles per second . In 1681 he took up his duties as astronomer at Copen- hagen , and built the first transit circle on a window - sill of his house . The iron axis was five feet long and one and a half inches thick ...
... velocity is 186,000 miles per second . In 1681 he took up his duties as astronomer at Copen- hagen , and built the first transit circle on a window - sill of his house . The iron axis was five feet long and one and a half inches thick ...
Page 107
... mass of the moon , and to fix its ratio to the earth's mass = 0.012240 . Another method of getting the distance from the sun is to measure the velocity of the earth's orbital motion , giving the circumference traversed in a Observation 107.
... mass of the moon , and to fix its ratio to the earth's mass = 0.012240 . Another method of getting the distance from the sun is to measure the velocity of the earth's orbital motion , giving the circumference traversed in a Observation 107.
Page 108
... velocity to the velocity of light . The velocity of light is 186,000 miles a second ; whence the distance to the sun is 92,780,000 miles . There seems , however , to be some uncertainty about the true value of the aberration , any ...
... velocity to the velocity of light . The velocity of light is 186,000 miles a second ; whence the distance to the sun is 92,780,000 miles . There seems , however , to be some uncertainty about the true value of the aberration , any ...
Page 116
... velocity of approach or recession . Everyone has noticed on a railway that , on meeting a locomotive whistling , the note is lowered after the engine 1 The experiment had been made before by one who did not understand its meaning . But ...
... velocity of approach or recession . Everyone has noticed on a railway that , on meeting a locomotive whistling , the note is lowered after the engine 1 The experiment had been made before by one who did not understand its meaning . But ...
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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.