An Introduction to Astronomy: Designed as a Text Book for the Students of Yale College

altitude angular distance aphelion apparent diameter apparent motion appear apsides astronomers axis azimuth celestial celestial sphere circle comet constellation declination degree described determined direction disk diurnal diurnal motion earth earth's orbit earth's shadow eccentricity ecliptic equal equator equinox figure fixed stars force globe gravity greater greatest heavenly bodies heavens Hence Herschel horizon horizontal parallax hour inclination increase inferior conjunction inferior planets instrument Jupiter known latitude light longitude lunar magnitude mean distance measured Mercury meridian miles moon moon's orbit moves nearer nearly node oblique observations opposite parallax parallel passing perigee perihelion period perpendicular planetary pole refraction represent respect revolution revolve right angles right ascension ring satellites Saturn seen semi-diameter side sidereal spectator sphere square sun and moon superior conjunction superior planets supposed surface syzygies telescope tides tion Uranus velocity Venus vernal equinox visible west to east zenith