Astronomy |
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altitude amount angle angular distance apparent approximately astronomers average axis binary binary stars bodies brightness celestial equator celestial pole celestial sphere circle clusters comet Consequently constellation craters density determined diameter direction diurnal earth earth's atmosphere eccentricity equal equatorial equinox eyepiece fact faint follows galactic galaxy gravity greater horizon interval Jupiter kilometers per second known latitude length light light-years luminosity lunar eclipse magnitude Mars mass mean solar measured Mercury meteorites meteors miles Milky month moon motion Mount Wilson Observatory move nearly nebulae object oblate observed parallax passes perihelion period of rotation phenomena photograph planetesimal planetoids planets polar position probably radiant energy radiation rays refraction relatively respect revolve right ascension satellites Saturn sidereal solar eclipses solar system spectral classes spectral lines spectroscope spectrum sun spots sun's surface synodic synodic month telescope temperature theory tion Uranus velocity Venus visible wave-lengths Yerkes Observatory