astronomy n

OFr < L. < Gk 'star-arranging', 'one who classes or arranges the stars'; see astrology.

  1. System of planets, stars, and other bodies in space; science that governs heavenly bodies; study of the laws and features of the universe; [NW] “knowledge of celestial bodies, their magnitudes, motions, distances, periods of revolution, aspects, eclipses, order … This science depends on observations, made chiefly with instruments, and upon mathematical calculations.”