Rudimentary Astronomy

61 Cygni aberration accuracy angular distance appeared apsides axis calculated catalogue centre comet computed constellations correction describe determining diameter direction discovered discovery disk disturbing diurnal diurnal motion earth earth's orbit earth's surface ecliptic effect elements elliptic orbit epoch equal equator equatorial equinox error evection excentricity fixed force geocentric gravitation greater number Greenwich heavens Heliometer Hence Herschel horizontal inclination instrument Jupiter Kepler's known latitude longitude lunar orbit magnitude mass mean anomaly mean distance measured meridian micrometer moon moon's moving mural circle nearly Neptune node nutation object observations Observatory Otto Struve parallax perigee perihelion period phenomena planet planetary polar distance pole position precession proper motions quantity radius reader refraction remarkable revolution revolve right angles right ascension round the sun satellites Saturn sidereal sidereal period space stars sun's superior planets supposed syzygy telescope tion transit treatise true anomaly velocity Venus vertical wire zenith distances