## History of Astronomy |

### From inside the book

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Page 31

His

century, seems to have discovered the moon's “variation.” Meanwhile the Moors

were leaders of science in the west, and Arzachel of Toledo improved the solar

His

**tables**were much more accurate than Ptolemy's. Abul Wefa, in the tenthcentury, seems to have discovered the moon's “variation.” Meanwhile the Moors

were leaders of science in the west, and Arzachel of Toledo improved the solar

**tables**... Page 32

accuracy of the calculations and the

printed just before his death in an interesting book, De Revolutionibus Orbium

Celestium. It is only by careful reading of this book that the true position of ...

accuracy of the calculations and the

**tables**. The results of his cogitations wereprinted just before his death in an interesting book, De Revolutionibus Orbium

Celestium. It is only by careful reading of this book that the true position of ...

Page 36

... to accept his system as showing the real motions; that it does not matter

whether they be true, even approximately, or not, so long as they enable us to

compute

predicted.

... to accept his system as showing the real motions; that it does not matter

whether they be true, even approximately, or not, so long as they enable us to

compute

**tables**from which the places of the planets amongst the stars can bepredicted.

Page 39

Both were introduced only to illustrate the mathematical conception upon which

the solar, planetary, and lunar

represented nothing more nor less than the first terms in the Fourier series, which

in the last ...

Both were introduced only to illustrate the mathematical conception upon which

the solar, planetary, and lunar

**tables**were constructed. The epicyclesrepresented nothing more nor less than the first terms in the Fourier series, which

in the last ...

Page 45

He felt it his duty to catalogue all the principal stars, so that there should be no

mistake in the future. During the construction of his catalogue of 1,000 stars he

prepared and used accurate

observations.

He felt it his duty to catalogue all the principal stars, so that there should be no

mistake in the future. During the construction of his catalogue of 1,000 stars he

prepared and used accurate

**tables**of refraction deduced from his ownobservations.

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### Common terms and phrases

accurate Airy ancient Astronomer Royal astronomical units bright calculations Cape catalogue centre century Chaldaeans 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 Huggins instruments JOHANNEs KEPLER John Herschel Jupiter Jupiter's Kepler Laplace Lick Observatory light line of apses line of sight lunar Mars mathematical mean distance measured ment Mercury meteor miles a second moon nebulae Newton º º 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.