Astronomy

action altitude amount angle angular angular velocity appear arise ascertained astronomical atmosphere attraction axis body bright calculation called cause celestial circle clock comet described determined deviation diameter difference direction disc distance disturbing force diurnal motion double stars earth earth's surface ecliptic effect ellipse equal equator equinoctial equinox error exact exactly excentricity fixed former globe gravity heavens heliocentric hemisphere horizon inclination instance instrument interval Jupiter latitude latter law of Kepler length less light longitude lunar magnitude mass mean measure meridian moon moon's nearly nodes nutation object observed orbit parallax perihelion period planet planetary pole portion position precession produce proportion radius reckoned refraction respect retrograde revolution revolving right ascension ring rotation round satellites Saturn seen sidereal sidereal period situation solar spectator sphere spherical stars station sun's suppose synodical period telescope tion triangle Uranus variation velocity visible whole zenith