List of astronomical topics

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Numbers

1 Ceres -- 2 Pallas -- 3C9 -- 3C48 -- 3C191 -- 3C273 -- 3 Juno -- 4 Vesta -- 10 Hygeia -- 14 Herculis -- 15 Eunomia -- 16 Cygni -- 16 Psyche -- 24 Themis -- 31 Euphrosyne -- 34 Tauri -- 45 Eugenia -- 47 Ursae Majoris -- 48 Doris -- 51 Pegasi -- 52 Europa -- 55 Cancri -- 61 Cygni -- 61 Cygni A -- 61 Cygni B -- 65 Cybele -- 70 Virginis -- 71 Niobe -- 87 Silvia -- 92 Undina -- 94 Aurora -- 95 Arethusa -- 106 Dione -- 110 Lidia -- 154 Bertha -- 221 Eos -- 243 Ida -- 253 Mathilde -- 324 Bamberga -- 433 Eros -- 451 Patienta -- 511 Davida -- 588 Achilles -- 624 Hektor -- 674 Rachele -- 704 Interamnia -- 951 Gaspra -- 1221 Amor -- 1566 Icarus -- 1620 Geographos -- 1685 Toro -- 1862 Apollo -- 2001 KX76 -- 2060 Chiron -- 2062 Aten -- 3200 Phaethon -- 3753 Cruithne -- 4179 Toutatis -- 4544 Xanthus -- 4593 Reipurth -- 4769 Castalia -- 5145 Pholus -- 5261 Eureka -- 5381 Sekhmet -- 7066 Nessus -- 11169 Alkon -- 28978 Ixion --

A

A New Theory of Magnetic Storms -- Aaronson, Marc -- Abdulmelik, Chalid Ben -- Abell, George Ogden -- Abell 2142 -- Aberration in optical systems -- Aberration of light -- Absolute date -- Absolute magnitude -- Absorption line -- Accelerating universe -- Acceleration -- Accretion disk -- Achernar -- Achondrites -- Achromatic lens -- Achromatic doublet -- Acrux -- Active Galactic Nuclei -- Active galaxy -- Active optics -- Adams, John Couch -- Adaptive optics -- Adara -- Adelard of Bath -- Adhara -- Adler Planetarium -- Adrastea -- Aether theory -- Afterglow -- Age of the Earth -- Age of the Universe -- Airglow -- Airy disc -- Airy, George -- Aitken, Robert -- Al-Batani -- Albategnius -- Albedo -- Albireo -- Alcor -- Aldebaran -- Aldhelm, Bishop of Sherborne -- d'Alembert, Jean le Rond -- Alfonsine tables -- Alfonso X of Castile -- Alfvén, Hannes Olof Gösta -- Alfven universe -- Algieba -- Algol -- ALH84001 -- Alioth -- Alkaid -- Al-Khwarizmi -- Allegheny Observatory -- Almach -- Almagest -- Alnilam -- Alnitak -- Alniyat -- Alpha Centauri -- Alpha Centauri B -- Alpha particle -- Alpha Persei -- Alpha process -- Alpher-Bethe-Gamow theory -- Alpheratz -- Alphonsine tables -- Al Sufi -- Al Sufi, 'Abd Al-Rahman -- Altair -- Altazimuth mount -- Altitude -- Aludra -- Alura -- Amalthea (moon) -- Amateur astronomy -- Amateur telescope making -- American Astronomical Society -- American Nebula -- Amor -- Amort, Eusebius -- Amplitude -- Ananke (moon) -- Analemma -- Anaximander -- Andromeda -- Andromeda (constellation) -- Andromeda Galaxy -- Andronicus of Cyrrhus -- Angle -- Angular diameter -- Angular diameter distance -- Angular frequency -- Angular measurement -- Angular momentum -- Angular resolution -- Angular velocity -- Anomalistic month -- Anomalistic year -- Anomalous cosmic ray -- Anomalous phenomenon -- Anomalous X-ray pulsar -- Anomaly (astronomy) -- Anorthosite -- Antares -- Antarctic Circle -- Anthropic principle -- Antlia -- Antikythera mechanism -- Apastron -- Apennine Mountains -- Aperture -- Aperature synthesis -- Apoapsis -- Apollo asteroid -- Apparent magnitude -- Apparent motion -- Apparent solar day -- Apsides -- Apus -- Aquarius -- Aquila -- Ara -- Arago, Dominique -- Arago, François Jean Dominique -- Aratus -- Archaeoastronomy -- Arcminute -- Arcsecond -- Arctic Circle -- Arcturus -- Area -- Arecibo Observatory -- Arecibo radio telescope -- Argo Navis -- Ariel -- Aries -- Aristarchus -- Aristotle -- Arjuna -- Armillary sphere -- Arp, Halton -- Arrhenius, Svante -- Artemova, Ioulia Vladimirovna -- Asteroid -- Asteroid belt -- Asteroid deflection strategies -- Asteroid moon -- Asteroseismology -- Astigmatism -- Aston, Francis William -- Astrobiology -- Astrochemistry -- Astrolabe -- Astrologer -- Astrology -- Astrometric binary -- Astrometry -- Astronaut -- Astronautics -- Astronomer -- Astronomer Royal -- Astronomical aberration -- Astronomical body -- Astronomical conjunction -- Astronomical distance -- Astronomical Journal -- Astronomical Julian calendar -- Astronomical object -- Astronomical Society -- Astronomical Society of the Pacific -- Astronomical unit -- Astronomical year numbering -- Astronomy -- Astronomy and astrophysics -- Astronomy and Astrophysics basic concepts -- Astrophotography -- Astrophysical Journal -- Astrophysics -- Asymptotic giant branch -- Aten -- Atkinson, Robert -- Atmosphere -- Atom -- Atomic clock -- Atomic nucleus -- Atlas (moon) -- Atria -- Aura -- Auriga (constellation) -- Auroral light -- Autumn -- Autumnal equinox -- Auva -- Avior -- Axial tilt -- Axis -- Azimuth -- Aztec calendar

B

Baade, Walter -- Babylonian and Assyrian religion -- Babylonian literature and science -- Background (astronomy) -- Background radiation -- Bacon, Roger -- Bahai calendar -- Bahcall, John -- Bainbridge, John -- Balthasar Behem Codex -- Barycenter -- Banneker, Benjamin -- Barnard's star -- Barnard, Edward Emerson -- Barsoom -- Baryon -- Baryonic matter -- Bayer designation -- Bayer, Johann -- Be star -- Be X-ray binaries -- Becrux -- Bedford Catalogue -- Bekenstein, Jacob -- Bell, Jocelyn -- Bellatrix -- Belinda -- Benetnash -- BeppoSAX -- Berlin Observatory -- Bernoulli, Jakob -- Bernoulli, Johann -- Bessel, Friedrich -- Beta Centauri -- Beta Pictoris -- Betelgeuse -- Beyond the standard Big Bang model -- Bianca -- Big Bang -- Big bang nucleosynthesis -- Big Bear Solar Observatory -- Big Crunch -- Big Dipper -- Big Rip -- Binary star -- Binary system -- BL Lac object -- Blackbody -- Black body -- Black hole -- Black hole thermodynamics -- Blazar -- Bliss, Nathaniel -- Blue straggler -- Bode, Johann Elert -- Bohr, Niels -- Bolometer -- Bolometric magnitude -- Bolyai, Janos -- Bond, William Cranch -- Boomerang nebula -- Boötes -- Boss, Lewis -- Boulder Sunspot Number -- Bradley, James -- Brahe, Tycho -- Brane -- von Braun, Wernher -- Brera Observatory -- Bright nebula -- Brocchi's Cluster -- Broglie, Louis-Victor de -- Brown dwarf -- Bruce Medal -- Brudzewski, Albert -- Brussels Observatory -- Burbidge, Geoffrey -- Burbidge, Margaret -- Bureau des Longitudes -- Butterfly Cluster --

C

C-type asteroid -- Caelum -- Calendar -- Calendar Round -- Caliban (moon) -- Callisto (moon) -- Calypso (moon) -- Camelopardalis -- Canada-France-Hawaii telescopes -- Canadian Arrow -- Canadian Space Agency -- Cancer (constellation) -- Canes Venatici -- Canis Major -- Canis Minor -- Cannon, Annie -- Canopus -- Capella -- Capricornus -- Carbon -- Carbon star -- Carbonaceous chondrite -- Cardinal directions -- Carina -- Carme -- Carpathian Mountains -- Carrington, Richard -- Cartesian coordinate system -- Cartier, Pierre -- Cartwheel Galaxy -- Cassegrain, Guillaume -- Cassegrain telescope -- Cassiopeia -- Chrétien, Henri -- Cassini probe -- Cassini, Giovanni -- Cassini, Giovanni Domenico -- Castor -- Cataclysmic variable star -- Catalogue of Galaxies and of Clusters of Galaxies -- Caucasus Mountains -- Cavalieri, Bonaventura -- Ceiba -- Centaurus -- Celestial body atmosphere -- Celestial coordinate system -- Celestial dynamics -- Celestial equator -- Celestial mechanics -- Celestial navigation -- Celestial pole -- Celestial sphere -- Celsius, Anders -- Celtes, Conrad -- Centaur -- Centaur rocket -- Cepheid variable -- Cepheus -- Cerro Tololo telescope -- Cetus -- Chamaeleon -- Chandler wobble -- Chandra X-ray Observatory -- Chandra X-ray Telescope -- Chandrasekhar limit -- Chandrasekhar, Subrahmanyan -- Charge -- Charge-coupled device -- Charon (moon) -- Chatelet, Emilie du -- Chinese calendar -- Chinese constellation -- Chiron -- Chondrites -- Chrétien, Henri -- Christie, William -- Chromatic aberration -- Chromosphere -- Circinus -- Circle -- Circle of confusion -- Circle of latitude -- Circumference -- Circumpolar star -- Circumstellar disk -- Civil Year -- Clark, Alvan -- Classical mechanics -- Climate change -- Cnidus -- CNO cycle -- Coalsack Nebula -- Cobalt -- Cold dark matter -- Collinder, Per -- Collinder catalogue -- Color -- Color (disambiguation) -- Color temperature -- Columba (constellation) -- Coma -- Coma aberration -- Coma Berenices -- Comet -- Comet Encke -- Comet Halley -- Comet Shoemaker-Levy 9 -- Comet Tempel-Tuttle -- Common Era -- Comoving distance -- Compact object -- Compact star -- Compton Gamma ray Observatory -- Compton effect -- Compton scattering -- Cone nebula -- Conon of Samos -- Constellation -- Contact binary -- Coordinate grid -- Coordinate system -- Coordinated Universal Time -- Copenhagen interpretation -- Copernican -- Copernican heliocentric system -- Copernican principle -- Copernican revolution -- Copernicus, Nicolaus -- Coptic calendar -- Cordelia -- Cordillera Mountains -- Coriolis effect -- Corona -- Corona Australis --

Corona Borealis -- Coronal gas -- Coronagraph -- Corvus (constellation) -- Cosmic Background Explorer satellite -- Cosmic Background Radiation -- Cosmic censorship hypothesis -- Cosmic inflation -- Cosmic microwave background radiation -- Cosmic radiation -- Cosmic ray -- Cosmic ray spallation -- Cosmogony -- Cosmological constant -- Cosmological Principle -- Cosmological time -- Cosmology -- Cosmonaut -- Côte d'Azur Observatory -- Coudé design -- Crab Nebula -- Crater (constellation) -- Crater -- Creation of the Universe -- Cressida -- CRESU experiment -- Crisium basin -- Crux -- Cubewano -- Culmination -- Curvature -- Cygnus -- Cygnus A -- Cygnus X-1

D

Dactyl (asteroid) -- Danjon, André -- Danjon Scale -- Dark energy -- Dark matter -- Dark moon -- Dark nebula -- Darwin crater -- Date -- Dawn -- Day -- Declination -- Deep sky object -- Deferent and epicycle -- Degenerate matter -- Deimos (moon) -- de Lacaille, Nicolas Louis -- de Vaucouleurs, Gérard -- Delphinus -- Deneb -- Denebola -- Desdemona -- Despina -- Despina (moon) -- Detached binary -- Diameter -- Diffraction-limited -- Diffuse sky radiation -- Dimension -- Dingle, Herbert -- Dione (moon) -- Dirac, Paul -- Dispersion -- Dispersion (optics) -- Distance -- Diurnal motion -- Dobsonian mount -- Dollfus, Audouin -- Doppler effect -- Dorado -- Double pendulum -- Double star -- Draco -- Drake equation -- Drake, Frank -- Draper, Henry -- Dreyer, John -- Drift velocity -- Dubhe -- Dumbbell Nebula -- Duncan, Robert -- Dusk -- Dwarf elliptical galaxy -- Dwarf galaxy -- Dwarf spheroidal galaxy -- Dynamical system -- Dynamical systems and chaos theory -- Dynamics (mechanics) -- Dyson, Frank -- Dyson, Freeman

E

E-type asteroid -- Early Imbrian -- Earth -- Earth atmosphere -- Earth impacts -- Earth science -- Earthshine -- Eccentricity -- Eclipse -- Eclipse cycle -- Eclipsing binary -- Ecliptic -- Ecliptic coordinate system -- Ecliptic longitude -- Ecliptic year -- Eddington, Arthur -- Eddington luminosity -- Egyptian calendar -- Einstein, Albert -- Einstein shift -- Elara (moon) -- Electric field -- Electromagnetic radiation -- Electromagnetic spectrum -- Electromagnetism -- Electron -- Electronuclear force -- Electroweak force -- Electroweak theory -- Ellipse -- Elliptical galaxy -- Elnath -- Elongation -- Elve -- Emission line -- Emission nebula -- Enceladus (moon) -- Encke, Johann Franz -- Encke division -- Energy -- Energy density -- English equatorial mount -- Entropy -- Ephemeris -- Ephemeris time -- Epimetheus (moon) -- Epoch -- Epoch (astronomy) -- EPR paradox -- Epsilon Eridani -- Epsilon Indi -- Equation of time -- Equator -- Equatorial bulge -- Equatorial coordinate system -- Equatorial mount -- Equinox -- Equuleus -- Eratosthenian -- Eratosthenes -- Eridanus -- Eridanus (constellation) -- Eruptive variable -- Escape velocity -- Eta Carinae -- Euclidean geometry -- Euctemon -- Eudoxus of Cnidus -- Eugenia -- Euler's angle -- Euler angles -- Euler, Leonhard -- Europa (moon) -- European Southern Observatory -- European Space Agency -- Event horizon -- Everett many-worlds interpretation -- Everett, Hugh -- Exeligmos -- Exit pupil -- Exoplanet -- Exterrestrial intelligence -- Extragalactic astronomy -- Extrasolar planet -- Extraterrestrial life -- Eye -- Eyepiece -- Eye relief

F

F-number -- Fabricius, David -- Fabricius, Johannes -- Facula -- Fermi paradox -- Fermi, Enrico -- Feynman, Richard -- Field curvature aberration -- Finderscope -- First light -- First Point of Aries -- First Point of Libra -- FITS -- FitzGerald-Lorentz Contraction -- Flamsteed designation -- Flamsteed, John -- Flat earth -- Flatness problem -- Fomalhaut -- Forbidden line -- Force -- Fork mount -- Fornax -- Fountain, John -- Fowler, William -- Frame of reference -- French Revolutionary calendar -- Frequency -- Full moon -- Fundamental plane -- Furud --

G

Gacrux -- Galactic astronomy -- Galactic bulge -- Galactic coordinate system -- Galactic cosmic ray -- Galactic disk -- Galatea -- Galatea (moon) -- Galaxy -- Galaxy bulge -- Galaxy disk -- Galaxy classification -- Galaxy formation and evolution -- Galaxy halo -- Galaxy morphology -- Galaxy nuleus -- Galaxy rotation problem -- Galileo Galilei -- Galileo probe -- Galilean moon -- Galilean transformation -- Galle, Johann Gottfried -- Gamma ray -- Gamma-ray astronomy -- Gamma ray burster -- Gamow, George -- Ganymede (moon) -- Gas giant -- Gassendi -- Gassendi crater -- Gathmann, Louis -- Gauss, Carl Friedrich -- Gegenschein -- Gaussian gravitational constant Gaussian year Geller, Margaret -- Gemini -- Geminids -- General relativity -- Geocentric model -- Geocentric universe -- Geodesic -- Geographic coordinate system -- Geoid -- Geomagnetic storm -- Geometric solid -- German equatorial mount -- Giacconi, Riccardo -- Giant (star) -- Giant impact theory -- Giant molecular cloud -- GJ 1061 -- Gliese, Wilhelm -- Global warming -- Globular cluster -- Gluon -- Gnomon -- Gold, Thomas -- Goldstone Radio Telescope -- Goodman-Martínez-Thompson correlation -- Grandfather paradox -- Grand unification epoch -- Grand unification theory -- Gravitational binding energy -- Gravitational constant -- Gravitational force -- Gravitational instability -- Gravitational lens -- Gravitational micro-lensing -- Gravitational redshift -- Gravity -- Gravity wave -- Great Attractor -- Great circle -- Great Pyramid of Giza -- Great Wall (astronomy) -- Greek mythology -- Greenwich Mean Time -- Gregorian calendar -- Gregorian telescope -- Gregory, James -- Greisen-Zatsepin-Kuzmin limit -- Groups and clusters of galaxies -- GRS80 -- Grus -- Guldin -- Guth, Alan --

H

H II region -- Hadar -- Haemus Mountains -- Hale, George Ellery -- Hale telescope -- Hale Telescope -- Hall, Asaph -- Halley, Edmond -- Halo -- Hamal -- Hamiltonian -- Hamilton, William Rowan -- Harvard College Observatory -- Hawking, Stephen -- Hawking radiation -- HE0107-5240 -- Heat-death of the Universe -- Hebrew calendar -- Heisenberg, Werner -- Heisenberg, Werner Karl -- Heka -- Helene (moon) -- Heliacal rising -- Heliocentric model -- Heliopause -- Helioseisomology -- Helium -- Helium flash -- Helix Nebula -- Hemisphere -- Henry Draper Catalogue -- Herbig-Haro object -- Hercules (constellation) -- Hercules Globular Cluster -- Herman of Carinthia -- Hero of Alexandria -- Herschel, Caroline -- Herschel, John -- Herschel, William -- Hertzsprung-Russell diagram -- Hertzsprung, Ejnar -- Hevelius, Johannes -- Hewish, Antony -- Heze -- High-energy astronomy -- High-mass X-ray binaries -- Himalia (moon) -- Hindu calendar -- Hipparchus -- Hipparcos -- History of astronomy -- History of mathematics -- History of physics -- History of science and technology -- History of telescopes -- Hoag, Art -- Hoag's object -- Hobby-Eberly Telescope -- Hooker Telescope -- Horizon problem -- Horizontal branch -- Horizontal coordinate system -- Horologium -- Horrendous Space Kablooie -- Horrocks, Jeremiah -- Horsehead nebula -- Horsehead Nebula -- Hot dark matter -- Hour angle -- Hourglass Nebula -- Houtermans, Fritz -- Hoyle, Fred -- HPMS -- H-R diagram -- Hubble, Edwin -- Hubble flow -- Hubble Nebula -- Hubble sequence -- Hubble's law -- Hubble Deep Field -- Hubble Space Telescope -- Huchra, John -- Huggins, William -- Humanson, Milton -- von Humboldt, Alexander -- Hulse, Russell -- Huygens, Christiaan -- Huygens Region -- Hyades -- Hydra -- Hydra (constellation) -- Hydrogen -- Hydrostatic equilibrium -- Hydrus -- Hyperbola -- Hypergalaxy -- Hyperion (moon) -- Hypernova -- Hypothetical planet

I

Iapetus (moon) -- IAU -- Icy moon -- Io (moon) -- Imbrian -- Impact basin -- Impact event -- Inclination -- Indus (constellation) -- Inertia -- Inertial force -- Inex -- Inferior planet -- Inflationary epoch -- Infrared -- Infrared astronomy -- Inner Rook Mountains -- Integrated Sachs Wolfe effect -- Intellectual history of time -- Interacting binary stars -- Intercalary day -- Intercalary month -- Intercalation -- Interferometer telescope -- Interferometry -- Intergalactic medium -- International Astronomical Union -- International Atomic Time -- International Earth Rotation Service -- International Fixed calendar -- International Geophysical Year -- International Space Station -- International Star Registry -- International Sunspot Number -- Interstellar cloud -- Interstellar medium -- Ionosphere -- Iranian calendar -- IRAS -- Irregular galaxy -- Irregular variable -- Isa, Ali Ben -- I Sin -- Islamic calendar -- Isolated singularity -- Ithaca Chasma

J

Jahreiss, Hartmut -- jansky -- Jansky, Karl Guthe -- Janus (moon) -- Japanese calendar -- Jeans, James -- Jodrell Bank -- Jodrell Bank Observatory -- Johannesburg Observatory -- Jones, Harold -- Jovian planet -- Julian Calendar -- Julian date -- Juliet -- Jupiter (planet)

K

Kamacite -- Kapteyn's Star -- Kapteyn, Jacobus -- Keck telescope -- Keck Observatory -- Keeler, James Edward -- Kelvin-Helmholtz mechanism -- Kepler's laws of planetary motion -- Kepler, Johannes -- Keplerian harmonic law -- Khayyám, Omar -- Kidinnu -- Kinetic energy -- Kirkwood, Daniel -- Kirkwood gap -- Kitt Peak National Observatory -- Kruger 60 A -- Kruger 60 B -- KStars -- Kubiak, Marcin -- Kuiper Airborne Observatory -- Kuiper belt -- Kuiper, Gerard

L

Lacaille 9352 -- Lacaille, Nicolas Louis de -- Lacerta -- Lacus Aestatis -- Lacus Autumni -- Lacus Bonitatis -- Lacus Doloris -- Lacus Excellentiae -- Lacus Felicitatis -- Lacus Gaudii -- Lacus Hiemalis -- Lacus Lenitatis -- Lacus Luxuriae -- Lacus Mortis -- Lacus Oblivionis -- Lacus Odii -- Lacus Perseverantiae -- Lacus Solitudinis -- Lacus Somniorum -- Lacus Spei -- Lacus Temporis -- Lacus Timoris -- Lacus Veris -- Lagoon Nebula -- Lagrangian point -- Lagrange, Joseph Louis -- Langrange, Joseph-Louis de -- Lalande 21185 -- Lambert, Johann Heinrich -- Lanczos, Cornelius -- Langley, Samuel Pierpont -- Lansberg, Philip Van -- Lansberg's tables -- Laplace, Pierre-Simon -- Laplace's equation -- Large Binocular Telescope -- Large liquid mirror telescopes -- Large-scale structure of the cosmos -- Larissa -- Larson, Stephen -- Laser -- La Silla Observatory -- Lassell, William -- Late Nectarian -- Latitude -- Law of physics -- LBT -- Leap second -- Leap year -- Leavitt, Henrietta Swan -- Leda (moon) -- Lemaître, Georges-Henri -- Lens -- Lenticular galaxy -- Leo -- Leo Minor -- Leonids -- Lepus -- Le Verrier, Urbain -- Levy, David -- Libra -- Libration -- Lick Observatory -- Light -- Light curve -- Light pollution -- Light year -- Lippershey, Hans -- List of astronomers -- List of astronomical topics -- List of astrophysicists -- List of brightest stars -- List of constellations by area -- List of largest optical reflecting telescopes -- List of largest optical refracting telescopes -- List of meteor showers -- List of mnemonics for star classification -- List of nearest stars -- List of semiregular variable stars -- List of stars -- List of telescope types -- Little Dipper -- Little Ice Age -- Lobachevsky, Nikolai Ivanovich -- Local Group -- Local Supercluster -- Lomonosov Gold Medal -- Long Count -- Long period variable -- Longitude -- Longitude prize -- Loop quantum gravity -- Lord Rosse -- Lorentz, Hendrik -- Lorentz transformation equations -- Lorenz, Edward -- Lorenz attractor -- Low Earth orbiting satellite -- Low-mass X-ray binaries -- Lowell Observatory -- Lower Imbrian -- Lovell Radio Telescope -- Lowell, Percival -- Luminance -- Luminiferous aether -- Luminosity -- Luminosity distance -- Luna -- Lunar calendar -- Lunar eclipse -- Lunar geologic timescale -- Lunar mare -- Lunar meteorite -- Lunar phase -- Lunation -- Lunisolar calendar -- Lunisolar precession -- Lupus -- Lupus (constellation) -- Lyapunov, Aleksandr -- Lyman alpha forest -- Lynx (constellation) -- Lyot, Bernard-Ferdinand -- Lyot filter -- Lyra -- Lysithea

M

M13 -- M27 -- M31 -- M33 -- M41 -- M42 -- M45 -- M49 -- M57 -- M58 -- M59 -- M60 -- M61 -- M81 -- M81 Group -- M82 -- M84 -- M86 -- M87 -- M90 -- M100 -- M101 -- M104 -- M107 -- M-theory -- M-theory simplified -- M-type asteroid -- van Maanen, Adriaan -- Mädler, Johann Heinrich, von -- Maffei Group -- Magellanic Clouds -- Magnetar -- Magnetic field -- Magnetic flux tubes -- Magnetic mirror -- Magnetism -- Magnetohydrodynamics -- Magnetopause -- Magnetosphere -- Magnification -- Magnitude -- Magnitude comparison -- Main belt -- Main sequence -- Maksutov-Cassegrain telescope -- Maksutov-Cassegrain -- Malayalam calendar -- Many-worlds interpretation -- Marcy, Geoffrey -- Mare Anguis -- Mare Australe -- Mare Cognitum -- Mare Crisium -- Mare Fecunditatis -- Mare Frigoris -- Mare Humboldtianum -- Mare Humorum -- Mare Imbrium -- Mare Ingenii -- Mare Insularum -- Mare Marginis -- Mare Moscoviense -- Mare Nectaris -- Mare Nubium -- Mare Orientale -- Mare Serenitatis -- Mare Smythii -- Mare Spumans -- Mare Tranquillitatis -- Mare Undarum -- Mare Vaporum -- Manilius, Marcus -- Marius, Simon -- Mars (planet) -- Martian meteorite -- Maskelyne, Nevil -- Mass -- Mass-energy equivalence -- Mass transfer -- Massive compact halo object -- Mauna Loa Solar Observatory -- Maunder Minimum -- Maupertuis, Pierre Louis Moreau de -- Maxwell-Boltzmann distribution -- Maxwell's equations -- Mayan calendar -- Mayor, Michael -- McCormick Observatory -- McCrea, William -- Mean solar day -- Mean solar time -- Mean sun -- Méchain, Pierre -- Mechanics -- Megrez -- Mensa (constellation) -- Merak -- Mercator, Nicholas -- Mercury (planet) -- Meridian -- Messier marathon -- Messier object -- Messier, Charles -- Metal-rich -- Metal-poor -- Metallic hydrogen -- Meteor -- Meteor shower -- Meteorite -- Meteorites classification -- Metis (moon) -- Meton -- Metonic cycle -- Mexican calendar -- Miaplacidus -- Michelson-Morley experiment -- Microquasar -- Microscopium -- Microwave -- Milky Way -- Minkowski, Hermann -- Mimas (moon) -- Minor planet -- Mintaka -- Minute of arc -- Mira -- Mira variable -- Mirach -- Miranda (moon) -- Mirfak -- Mirror -- Mizar -- MMT -- MMT Observatory -- Modified Newtonian dynamics -- Möbius, August Ferdinand -- Molecular cloud -- Monoceros -- Mons Ida -- Mons Lyctas -- Montes Pyrenaeus -- Month -- Moon -- Moon phase -- Moore, Patrick - Mt. Olympus -- Mount Palomar observatory -- Mount Stromlo Observatory -- Mount Wilson Observatory -- Muliphem -- Müller, Johannes -- Multiple star -- Multiverse -- Murzim -- Musca --

N

N-body problem -- Nabu-rimanni -- Nadir -- Naiad -- Naiad (moon) -- Naked singularity -- Naos -- Napier, John -- NASA -- National Optical Astronomy Observatories -- National Optical Astronomy Observatory -- National Radio Astronomy Observatory -- Natural satellite -- NEAR Shoemaker -- Near-Earth asteroid -- Near-Earth object -- Nebula -- Nebular hypothesis -- Nectarian -- Nectarian System -- Nemesis (star) -- Nemontemi -- Neptune (planet) -- Nereid (moon) -- von Neumann, John -- Neutrino -- Neutrino mass -- Neutrino oscillation -- Neutron -- Neutron star -- Neutronium --

Nevanlinna, Rolf -- New General Catalogue -- Newcomb, Simon -- Newcomb's Tables of the Sun -- New moon -- Newton's laws of motion -- Newtonian physics -- Newtonian telescope -- Newton, Isaac -- Next Generation Space Telescope -- NGC 1068 -- NGC 2244 -- NGC 2264 -- NGC 3227 -- NGC 3516 -- NGC 4321 -- NGC 4486 -- NGC 4593 -- NGC 5128 -- NGC 6027 -- NGC 6171 -- NGC 6240 -- NGC 6751 -- NGC 7742 -- NGST -- Nice Observatory -- Nicholson, Seth Barnes -- Niels Bohr Institute -- Night -- Nilson, Peter -- NOAO -- Node -- Node (astronomy) -- Non-Euclidean geometry -- Non-standard cosmology -- Norma (constellation) -- North America Nebula -- North Pole -- North Star -- Nova -- Novara da Ferrara, Domenico Maria -- Novikov, Igor Dmitrievich -- Novikov, Petr Sergeevich -- Nuclear decay -- Nuclear fusion -- Nucleocosmochronology -- Nucleosynthesis -- Nutation

O

Oak Ridge Observatory -- Oberon (moon) -- Oberth, Hermann Julius -- Obliquity of the ecliptic -- Obruchev crater -- Observatory -- Observatory of Paris -- Occultation -- Oceanus Procellarum -- Octans -- Odysseus crater -- OH maser -- Olbers' paradox -- Olbers, Heinrich Wilhelm Mathias -- Olympus Mons -- Omega Centauri -- Oort cloud -- Oort, Jan -- Open cluster -- Ophelia -- Ophiuchus -- Oppenheimer-Volkoff limit -- Opposition (astronomy) -- Optical astronomy -- Optical axis -- Optical binary -- Optical depth -- Optical double -- Optical spectrum -- Optics -- Orbit -- Orbital elements -- Orbital period -- Orbital plane -- Orbital resonance -- Orbital revolution -- Orbital speed -- Orion -- Orion Nebula -- Orrery -- Oscillatory Universe -- Outer Rook Mountains -- Overwhelmingly Large Telescope -- Owl Nebula -- Ozone layer

P

P-process -- Palermo Technical Impact Hazard Scale -- Palimpsest -- Pallasite -- Palomar Observatory Sky Survey -- Pan (moon) -- Pandora (moon) -- Panspermia -- Panzano Observatory -- Parabolic mirror -- Parabolic reflector -- Parallax -- Parallel -- Paranal Observatory -- Paris Observatory -- Parsec -- Parsons, William -- Particle horizon -- Particle physics -- Pasiphae (moon) -- Pauli exclusion principle -- Pavo (constellation) -- Payne-Gaposchkin, Cecilia -- Pegasus -- Pegasus (constellation) -- Peirce crater -- Penrose, Roger -- Penumbra -- Periapsis -- Perpetual calendar -- Perrine, Charles Dillon -- Perseus (constellation) -- Perseids -- Persian calendar -- Phecda -- Philosophiae Naturalis Principia Mathematica -- Phoenix (constellation) -- Phoebe (moon) -- Phobos (moon) -- Photographic plate -- Photometry -- Photon -- Photon decoupling -- Photosphere -- Physical constant -- Physical geodesy -- Physical law -- Physical phenomenon -- Piazzi, Giuseppe -- Piazzi Smyth, Charles -- Picard crater -- Pickering, Edward -- Pickering, William Henry -- Pictor -- Pierre Auger Observatory -- Pinwheel Galaxy -- Pisces -- Piscis Austrinus -- Planck units -- Planck's law of black body radiation -- Planck, Max -- Planet -- Planet X -- Planetarium -- Planetary Hypothesis -- Planetary nebula -- Planetary motion -- Planetary nomenclature -- Planetary phase -- Planetary ring -- Planetesimal -- Planetoid -- Planetology -- Planisphaerium -- Plasma -- Plasma equilibria and stability -- Plasma physics -- Pleiades -- Plekhnaton -- Ptolemaic system -- Plutino -- Pluto (planet) -- Pogson, Norman Robert -- Poincaré, Henri -- Poisson, Siméon-Denis -- Polar Aurora -- Polar coordinates -- Polar coordinate system -- Polar distance -- Polarimetry -- Polaris -- Polarization -- Polarized light -- Pole -- Pollux -- Pond, John -- Pons, Jean-Louis -- Porrima -- Portia -- Portia (moon) -- Posidonius -- Positional astronomy -- Potočnik, Herman -- Potsdam Observatory -- Pre-Nectarian -- Precession -- Priestley, Joseph -- Primary mirror -- Prime meridian -- Primordial black hole -- Primordial material -- Procyon -- Procyon A -- Procyon B -- Prograde and retrograde motion -- Prograde orbit -- Proleptic Gregorian Calendar -- Proleptic Julian calendar -- Prometheus (moon) -- Promonitorium Agarum -- Proper motion -- Proper motion distance -- Proportional -- Propylid -- Prosen, Marjan Majo -- Prospero -- Proteus (moon) -- Proton -- Proton-antiproton imbalance -- Proton-proton chain -- Proto-star -- Protoplanetary disk -- Protostar -- Protostellar disk -- Proxima Centauri -- Prussian tables -- Prutenicae Tabulae -- Ptolemy -- Ptolemy Cluster -- Puck (moon) -- Pulsar -- Puppis -- Pyxis

Q

Quadrant -- Quadrivium -- Quantum chromodynamics -- Quantum electrodynamics -- Quantum field theory -- Quantum gravity -- Quantum mechanics -- Quaoar -- Quark -- Quark-antiquark epoch -- Quasar -- Quasar, Redshifts and Controversies -- Quetelet, Lambert Adolphe Jacques -- Queloz, Didier -- Quintessence

R

R-process -- R-type asteroid -- Radial velocity -- Radiant -- Radiation pressure -- Radio astronomy -- Radio galaxy -- Radio star -- Radio telescope -- Radio wave -- Rainbow -- Ranzinger, Pavla -- Rare Earth hypothesis -- Ras Algethi -- Rayleigh scattering -- Reber, Grote -- Red clump -- Red dwarf star -- Red giant -- Redshift -- Rees, Martin -- Reflection -- Reflection nebula -- Reflector telescope -- Refraction -- Refractor telescope -- Regiomontanus -- Regolith -- Regulus -- Reinhold, Erasmus -- Reitsema, Harold -- Research Consortium on Nearby Stars -- Resolution (optics) -- Resolving power -- Reticulum -- Retrograde motion -- Retrogade orbit -- Revised Julian calendar -- Reynolds, Alastair -- Rhea (moon) -- Rheticus, Georg Joachim -- Rho Coronae Borealis -- Rhyolite -- Riemannian geometry -- Rigel -- Right ascension -- Rijl al Awwa -- Rima Sirsalis -- Ring current -- Ring galaxy -- Ring Nebula -- Riphaeus Mountains -- Ritchey, George Willis -- Ritchey-Chrétien telescope -- Roche, Édouard Albert -- Roche limit -- Roche lobe -- Roman calendar -- Römer, Ole -- Rosalind -- Rosette Nebula -- Ross 128 -- Ross 154 -- Ross 248 -- Royal Astronomical Society -- Royal Greenwich Observatory -- Royal Society -- RR Lyrae -- RR Lyrae variable -- Rudbeckius, Olaus -- Russell, Henry Norris -- Ryle, Martin

S

S-process -- S-type asteroid -- Sabine, Edward -- Sagan, Carl -- Sagitta -- Sagittarius -- Sagittarius A -- Saiph -- Sandage, Allan -- Saros -- Satellite -- Saturn (planet) -- Saturn Nebula -- Savile, Henry -- Savilian chair of astronomy -- Scalar -- Scattered Disk Object -- Scattered disk object -- Schwabe, Samuel Heinrich -- Scheiner, Christoph -- Schmidt, Bernard -- Schmidt, Bernhard -- Schmidt, Bernhard Voldomar -- Schmidt camera -- Schmidt-Cassegrain -- Schmidt-Cassegrain telescope -- Schmidt, Maarten -- Schmidt survey -- Schwabe, Heinrich -- Schwarzschild, Karl -- Schwarzschild radius -- Schwassmann-Wachmann-3 -- Scientific journal -- Scientific paper -- Scintillation -- Scorpius -- Sculptor (constellation) -- Sculptor Group -- Scutum -- Season -- Second -- Second of arc -- Second Superstring Revolution -- Seeing -- Semidetached binary -- Semimajor axis -- Semiregular variable -- Serpens -- Serrurier trusses -- Setebos -- SETI -- Setting circle -- Setting circles -- Sextans -- Seyfert galaxy -- Seyfert's Sextet -- Seyfert, Carl Keenan -- Shape of the universe -- Shapley, Harlow -- Shaula -- Shedir -- Shepherd satellite -- Shklovsky, Iosif Samuilovich -- Shock wave -- Shoemaker, Carolyn -- Shoemaker, Eugene -- Short, James -- Sidereal day -- Sidereal time -- Sidereal year -- Siding Springs Observatory -- Sinope (moon) -- Sirius -- Sirius A -- Sirius B -- Sirona -- Sirrah -- Sirsalis crater -- Sitter, Willem, de -- Sky -- Small-angle formula -- Smith, Francis Graham -- Smithsonian Astrophysical Observatory -- Smyth, William Henry -- Snell's law -- Soft gamma repeater -- Soft X-ray transient -- Solar activity -- Solar and Heliospheric Observatory -- Solar calendar -- Solar cosmic ray -- Solar cycle -- Solar day -- Solar eclipse -- Solar flare -- Solar luminosity -- Solar mass -- Solar maximun -- Solar nebula -- Solar neutrino problem -- Solar prominence -- Solar radiation -- Solar system -- Solar terminator line -- Solar time -- Solar wind -- Solar year -- Solstice -- Sombrero Galaxy -- Sonneberg Observatory -- Sothic cycle -- Sothic period -- South Pole -- South Pole-Aitken basin -- Southern Pinwheel Galaxy -- Soviet revolutionary calendar -- Space -- Space observatory -- Space science -- Space weather -- Spacetime -- Special relativity -- Spectral density -- Spectral line -- Spectral type -- Spectrograph -- Spectroheliograph -- Spectrometry -- Spectroscopy -- Spectroscopic binary -- Speed of gravity -- Speed of light -- Spherical aberration -- Spherical coordinate system