Letters on Astronomy, ... in which the elements of the science are familiarly explained in connexion with its literary history1842 |
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angle appear ascertain astronomers atmosphere attraction axis called celestial centre circle comet conjunction constellation degrees diameter direction discovery disk distance diurnal motion diurnal revolution doctrine double stars earth ecliptic equal equator equinox exhibit fact fixed stars force Galileo globe gravity greater greatest half Halley's comet heavenly bodies heavens Hence Herschel horizon inferior conjunction instrument John Herschel Jupiter Kepler latitude laws length less light longitude lunar lunar eclipse magnitude measure Mercury meridian meteors millions of miles minutes moon moon's motion move nearer nearly node objects observations opposite orbit parallax passing perihelion period phenomena planetary planets pole respect revolve right ascension ring round satellites Saturn seen shadow side solar system space spectator sphere sun's superior planets supposed surface tance telescope thousand tides tion truth Tycho Tycho Brahe universal gravitation Uranus velocity Venus vernal equinox visible west to east