Elementary Lessons in Astronomy

angle aphelion appear astronomers atmosphere attracted bodies base line Boötes called celestial equator celestial pole celestial sphere centre clock comet constellation declination density determined diameter direction Earth Earth's axis Earth's rotation Earth's surface ecliptic equal equatorial exactly eye-piece fact globe Greenwich heavenly bodies heavens horizon hydrogen inclination Jupiter latitude length lens LESSON light longitude Mars mass mean measured meridian meteorites meteors miles Moon Moon's motion nearly nebula Neptune node object-glass Observatory observed occupied orbit parallax particles passes path perihelion photographs planet Plate point of Aries polar pole portion position precession prism proto rays refraction represent revolve round right ascension ring round the Sun satellites Saturn seen shows side sidereal silicium solar solstice spectra spectroscope spectrum spots stars Sun's supposed telescope temperature tion transit circle triangle true sun Uranus Ursa Ursa Major vapour varies velocity Venus vernal equinox visible zenith distance