Identifier: adolfostahllectu00astruoft (find matches)
Title: The Adolfo Stahl lectures in astronomy, delivered in San Francisco, California, in 1916-17 and 1917-18, under the auspices of the Astronomical Society of the Pacific
Year: 1919 (1910s)
Authors: Astronomical Society of the Pacific Aitken, Robert Grant, 1864-1951
Subjects: Astronomy
Publisher: San Francisco Stanford University Press
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: MSN

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and the same comet at about 75-year inter-vals. He predicted the return of the comet. He did not liveuntil the predicted year, but the comet appeared on schedule.This is the first instance of the kind in history, and the cometis named, as you know, Halleys comet, in honor of the manwho first predicted its return. The return which he announcedtook place in 1759. It has returned again twice since then, in1835 and in 1910. This marked another advance in astronomyin that it added other moving bodies to the solar system, andshowed the people that comets were no longer to be feared,that they were merely members of the solar system, movingunder the attraction of the Sun, and that their motions andpositions could be computed in accordance with Newtons andKeplers Laws just the same as in the case of the planets. Among other things done by Halley of a largely developingcharacter may be mentioned his discovery of the proper motionsof the stars : and his scheme for determining the solar parallax.
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PLATE XXXIV. Sir William Huggins. 1824-1910. Important Epochs in Astronomy 137 and hence the distance from the Sun to the Earth, by observa-tions of the transit of Venus. Bradley, the successor of Hahey, discovered aberration andnutation. All of the objects in the sky are displaced somewhat,due to the facts that the Earth is moving and that the velocityof light is not infinite. This displacement is known as aberra-tion. It was discovered by Bradley quite by accident in seeking-to find a displacement of the stars due to parallax. We must credit Bradley also with improving the accuracyof observational work. Not only was he a keen observer, buthe had his instruments constructed by the most skillfulmechanics and mounted in the best possible manner. Further,he was one of the first to take into account possible errorsarising from defects of his instruments. Contrary to natural expectation we find but little done inthe 18th century in England along the lines of GravitationalAstronomy. This c

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