Astronomy |
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Page 39
... rotation is not likely to be overcome by direct observation . If the planet's rotational period were exactly 225 days one hemisphere would be constantly turned towards the sun and the other would be in perpetual darkness ; in this event ...
... rotation is not likely to be overcome by direct observation . If the planet's rotational period were exactly 225 days one hemisphere would be constantly turned towards the sun and the other would be in perpetual darkness ; in this event ...
Page 79
... rotated about an axis , and Galileo deduced that the period of rotation was about twenty- five days . Plate 11 , facing p . 81 , shows two photo- graphs , three days apart , to illustrate the sun's rotation as deduced from the motion of ...
... rotated about an axis , and Galileo deduced that the period of rotation was about twenty- five days . Plate 11 , facing p . 81 , shows two photo- graphs , three days apart , to illustrate the sun's rotation as deduced from the motion of ...
Page 153
... rotating about the shortest axis of the system . On general grounds , then , we might expect that a similar kind of motion would be characteristic of the galactic system . This rotation , however , is not analogous to the rotation of ...
... rotating about the shortest axis of the system . On general grounds , then , we might expect that a similar kind of motion would be characteristic of the galactic system . This rotation , however , is not analogous to the rotation of ...
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absolute magnitudes actually angle apparent magnitudes appear astronomer atmo atmosphere atoms average density axis B-type binary star brighter brightest stars brightness calculated called celestial Cepheids CHAPTER clouds colour comet comparatively component considerable constellation craters dark deduced diameter direction discovery double stars earth earth's orbit earth's surface eclipse galactic centre galactic system globe globular clusters gravitation heavens hemisphere Herschel hundred Jupiter Kepler's known light light-changes light-curve light-years lines lunar Mars Martian measured Mercury meteors miles per second Milky million miles minor planets moon moon's moving Neptune observations Observatory open clusters orbital periods photographic plate planetary Pluto position proper motions radial velocities revolve ring rotation satellites Saturn scale seen shown similar Sirius solar spectrum solar system space spectra Spectroscopic speed spiral nebulae spots star's stellar stellar distances sun-spot sun's mass sunlight supposed telescope temperature terrestrial tions Uranus variable star Venus violet visible wave-length