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 astronomia : astro-, astro- + -nomia, -nomy.
aerolithologythe branch of astronomy that studies meteors.aeroliticsthe branch of astronomy that studies aerolites, or stony meteors.albedothe ratio between the light reflected from a surface and the total light falling upon that surface, as the albedo of the moon.aphelionthe point in the orbit of a heavenly body where it is farthest from the sun. Cf. perihelion.apolunein an orbit around a moon, the point furthest from the moon. Cf. perilune.areologythe astronomical studies of the planet Mars. —areologist, n. —areologic, areological, adj.asterismRare. a constellation or small group of unrelated stars. —asterismal, adj.astrogationthe art of navigating in space. Cf. astronavigation. —astrogator, n.astrogeny, astrogonythe theory of the evolution of heavenly bodies.astrogeologya geological specialty that studies celestial bodies.astrognosythe branch of astronomy that studies the fixed stars.astrographya scientific analysis and mapping of the stars and planets. —astrographic, adj.astrolatrythe worship of the heavenly bodies. Also called Sabaism. — astrolater, n.astromancy1. a form of divination involving studying the stars.2. Rare. astrology. Also called sideromancy. —astromancer, n. —astromantic, adj.astrometrythe 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.astronauticsthe 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.astronavigationa type of navigation involving observations of the apparent positions of heavenly bodies. Also called celestial navigation, celo-navigation. —astronavigator, n.astronomythe science that studies the stars and other features of the material universe beyond the earth’s atmosphere. —astronomer, n. —astronomical, adj.astrophilea person strongly attracted to knowledge about the stars. —astrophilic, adj.astrophotographya form of photography used to record astronomical phenomena.astrophysicsthe branch of astronomy concerned with the origin, and the chemical and physical nature of heavenly bodies. —astrophysicist, n.celestial navigationastronavigation. Also called celo-navigation.chromatoscopythe 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.Copernicanismthe 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.cosmolabeObsolete, an instrument, like an astrolabe, used for astronomical observations.cosmonauticsastronautics. —cosmonaut. n. —cosmonautical, adj.heliodonan instrument used in astronomy to show the apparent movement of the sun.heliometeran instrument originally designed for measuring the sun’s diameter, now used for measuring the angular distance between stars.heliometrythe practice of measuring the angular distance between stars by means of a heliometer. —heliometric, heliometrical, adj.interlunationthe period between the old moon and the new when the moon is invisible each month. —interlunar, adj.meridianan 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.metagalaxythe entire system of galaxies, including the Milky Way. —metagalactic, adj.nutationthe 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.obliquitythe 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.occultationthe process of one heavenly body disappearing behind another as viewed by an observer.paraselenea false moon, in reality a bright spot or a luminous ring surrounding the moon.perihelionthe point in the orbit of a heavenly body where it is nearest the sun. Also spelled perihelium. Cf. aphelion.periheliumperihelion.perilunein orbit around a moon, the point nearest the moon. Cf. apolune.phantasmatographyRare. a work or treatise on astronomy or celestial bodies.planetarium1. 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.planetologythe branch of astronomy that studies the planets. —planetologist, n. — planetologic, planetological, adj.planispherea 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.Ptolemaismthe 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.Ptolemaista supporter of the Ptolemaic explanation of planetary motions.radioastronomythe branch of astronomy that studies radio frequencies emitted by the sun, planets, and other celestial bodies.Sabaismastrolatry.Sabianism, Sabaeanism, Sabeanismthe religion of the Sabians, a group sometimes associated with worship of the sun, moon, and stars. See also religion.schematismthe combination or configuration of the aspects of the planets and other heavenly bodies.selenographythe scientific analysis and mapping of the moon’s physical features. —selenographer, selenographist, n. —selenographic, selenographical, adj.selenologythe branch of astronomy that studies the moon. —selenologist, n. —selenologic, selenological, adj.sideromancya form of divination involving observations of the stars. Also called astromancy. —sideromancer, n. —sideromantic, adj.siderophobiaan abnormal fear of the stars.uranianismObsolete, astronomy.uranographythe 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.uranology1. a written description of the heavens and celestial bodies.2. another term for astronomy.uranometry1. 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.