Handbook of Astronomy

altitude angular aphelion apparent diameter apparent magnitude apparent motion appear ascertained astronomers atmosphere attraction axis bodies called celestial equator celestial pole celestial sphere centre circle comet degree density determined direction disk disturbing diurnal motion diurnal rotation earth east ecliptic edge effect equal equinoxial points excentricity explained firmament fixed globe greater heavens hemisphere Herschel horizon increase inferior conjunction instrument interval Jupiter latitude length less light limb line of collimation longitude lunar mass matter mean distance measured meridian millions of miles moon moon's motion of rotation move nearly nebula object observatory observed orbit parallax passes the meridian pendulum perihelion period phenomena planet Plate prime vertical produced ratio represented revolve right angles right ascension ring satellites Saturn seen sidereal solar system spots stars sun's superior conjunction supposed surface synodic period telescope terrestrial tion transit Uranus velocity visible visual wires zenith distance