Astronomy |
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altitude amount angle angular distance apparent astronomers average axis binary binary stars bodies celestial equator celestial pole celestial sphere centimeter circle clusters comet Consequently constellation craters crosses the meridian declination density determined diameter direction diurnal diurnal motions earth earth's atmosphere energy equal equatorial equinox eyepiece fact faint first-magnitude focal plane galactic galaxy gravity greater horizon interval Jupiter kilometers per second known latitude length Lick Observatory light light-years luminosity lunar eclipse magnitude Mars mass mean solar measured Mercury meteorites meteors miles Milky moon Mount Wilson Observatory move nearly nebulae object oblate observer orbit parallax period phenomena photograph planetary planetoids planets polar position probably radiation rays refraction relative respect revolve right ascension rotation satellites Saturn sidereal solar eclipses solar system spectral classes spectroscopic spectrum Suppose surface synodic month telescope temperature theory tides tion velocity Venus visible Yerkes Observatory zenith