Astronomy: A Popular Handbook

accurately actual already angle angular appear approximately ascertain astronomers atmosphere attraction axis bodies calculate calendar called cause celestial sphere compared complete Consequently consider correct corresponding course determine diameter difference direction distance diurnal divided earth ecliptic circle effect equal equator equinox exactly existing explained fact figure fixed follows force given gives gravitational half horizon hour important increase indicates interest Jupiter kind known later latitude length light longitude lunar Mars mass matter means measured meridian method miles minutes moon motion move night Note object observations occur once opposite orbit pass period planet planetary Plate pole position possible problem projected remainder result rise rotation seen shown shows sidereal simple solar space stars successive supposed surface telescope terrestrial theory tion turned Venus visible zenith