The definition of astronomy is the scientific study of matter outside of the atmosphere of the Earth including stars, planets and what they are made of and how they move.
Someone who examines moon rocks to determine their composition is an example of someone who engages in astronomy.
- the science of the universe in which the stars, planets, etc. are studied, including their origins, evolution, composition, motions, relative positions, sizes, etc.
- pl. -·mies a book or treatise on this
Origin of astronomyMiddle English and amp; Old French astronomie ; from Classical Latin astronomia ; from Classical Greek ; from astron, star + nomos, law: see -nomy
- The scientific study of matter and phenomena in the universe, especially in outer space, including the positions, dimensions, distribution, motion, composition, energy, and evolution of celestial objects.
- A system of knowledge or beliefs about celestial phenomena: the various astronomies of ancient civilizations.
Origin of astronomyMiddle English astronomie, from Old French, from Latin astronomia, from Greek astronomiā : astro-, astro- + -nomiā, -nomy.
aerolithology the branch of astronomy that studies meteors. aerolitics the branch of astronomy that studies aerolites, or stony meteors. albedo the ratio between the light reflected from a surface and the total light falling upon that surface, as the albedo of the moon. aphelion the point in the orbit of a heavenly body where it is farthest from the sun. Cf. perihelion. apolune in an orbit around a moon, the point furthest from the moon. Cf. perilune. areology the astronomical studies of the planet Mars. —areologist, n. —areologic, areological, adj. asterism Rare. a constellation or small group of unrelated stars. —asterismal, adj. astrogation the art of navigating in space. Cf. astronavigation. —astrogator, n. astrogeny, astrogony the theory of the evolution of heavenly bodies. astrogeology a geological specialty that studies celestial bodies. astrognosy the branch of astronomy that studies the fixed stars. astrography a scientific analysis and mapping of the stars and planets. —astrographic, adj. astrolatry the worship of the heavenly bodies. Also called Sabaism. — astrolater, n. astromancy 1. a form of divination involving studying the stars. 2. Rare. astrology. Also called sideromancy. —astromancer, n. —astromantic, adj. astrometry the branch of astronomy that studies the dimensions of heavenly bodies, especially the measurements made to determine the positions and orbits of various stars. —astrometric, astrometrical, adj. astronautics the science of space travel, concerned with both the construction and the operation of vehicles that travel through interplanetary or interstellar space. Also called cosmonautics. —astronautic, astronautical, adj. —astronaut, n. astronavigation a type of navigation involving observations of the apparent positions of heavenly bodies. Also called celestial navigation, celo-navigation. —astronavigator, n. astronomy the science that studies the stars and other features of the material universe beyond the earth’s atmosphere. —astronomer, n. —astronomical, adj. astrophile a person strongly attracted to knowledge about the stars. —astrophilic, adj. astrophotography a form of photography used to record astronomical phenomena. astrophysics the branch of astronomy concerned with the origin, and the chemical and physical nature of heavenly bodies. —astrophysicist, n. celestial navigation astronavigation. Also called celo-navigation. chromatoscopy the study of stars through a telescope in which the star appears as a ring of light, in order to observe the star’s scintillation. —chromatoscope, n. Copernicanism the fundamental theoretical basis of modern astronomy, first demonstrated in the early 16th century by Copernicus, who showed that the earth and the other planets orbit around the sun. Cf. Ptolemaism. cosmolabe Obsolete, an instrument, like an astrolabe, used for astronomical observations. cosmonautics astronautics. —cosmonaut. n. —cosmonautical, adj. heliodon an instrument used in astronomy to show the apparent movement of the sun. heliometer an instrument originally designed for measuring the sun’s diameter, now used for measuring the angular distance between stars. heliometry the practice of measuring the angular distance between stars by means of a heliometer. —heliometric, heliometrical, adj. interlunation the period between the old moon and the new when the moon is invisible each month. —interlunar, adj. meridian an imaginary great circle in the sphere of the heavens, passing through the poles and the zenith and nadir of any point and intersecting the equator at right angles. See also 178. GEOGRAPHY. —meridian, meridional, adj. metagalaxy the entire system of galaxies, including the Milky Way. —metagalactic, adj. nutation the periodic oscillation that can be observed in the precession of the earth’s axis and the precession of the equinoxes. See also 133. EARTH. — nutational, adj. obliquity the inclination of the earth’s equator or the angle between the plane of the earth’s orbit and the plane of the equator (23°27’). Also called obliquity of the ecliptic. See also 133. EARTH. —obliquitous, adj. occultation the process of one heavenly body disappearing behind another as viewed by an observer. paraselene a false moon, in reality a bright spot or a luminous ring surrounding the moon. perihelion the point in the orbit of a heavenly body where it is nearest the sun. Also spelled perihelium. Cf. aphelion. perihelium perihelion. perilune in orbit around a moon, the point nearest the moon. Cf. apolune. phantasmatography Rare. a work or treatise on astronomy or celestial bodies. planetarium 1. a representation of the planetary system, particularly one in which the movements of the planets are simulated by projectors. 2. a room or building housing such an apparatus. planetology the branch of astronomy that studies the planets. —planetologist, n. — planetologic, planetological, adj. planisphere a map showing half or more of the sphere of the heavens, indicating which part is visible at what hour from a given location. —planispheric, planispherical, adj. Ptolemaism the complicated demonstration of Ptolemy, 2nd-century geographer and astronomer, that the earth is the fixed center of the universe around which the sun and the other planets revolve; now discredited. Cf. Copemicanism. Ptolemaist a supporter of the Ptolemaic explanation of planetary motions. radioastronomy the branch of astronomy that studies radio frequencies emitted by the sun, planets, and other celestial bodies. Sabaism astrolatry. Sabianism, Sabaeanism, Sabeanism the religion of the Sabians, a group sometimes associated with worship of the sun, moon, and stars. See also religion. schematism the combination or configuration of the aspects of the planets and other heavenly bodies. selenography the scientific analysis and mapping of the moon’s physical features. —selenographer, selenographist, n. —selenographic, selenographical, adj. selenology the branch of astronomy that studies the moon. —selenologist, n. —selenologic, selenological, adj. sideromancy a form of divination involving observations of the stars. Also called astromancy. —sideromancer, n. —sideromantic, adj. siderophobia an abnormal fear of the stars. uranianism Obsolete, astronomy. uranography the branch of astronomy that deals with the description of the heavens by constructing maps and charts, especially of the fixed stars. Also called uranology. —uranographer, uranographist, n. —uranographic, uranographical, adj. uranology 1. a written description of the heavens and celestial bodies. 2. another term for astronomy. uranometry 1. a treatise recording the positions and magnitudes of heavenly bodies. 2. the science of measuring the real or apparent distances of heavenly bodies from Earth. —uranometrical, adj.