260 relations: Accretion disk, Active galactic nucleus, Algol variable, Alinda asteroid, Alpha Cygni variable, Alpha2 Canum Venaticorum variable, Am star, Amor asteroid, Ap and Bp stars, Apollo asteroid, Arjuna asteroid, Asterism (astronomy), Asteroid, Asteroid belt, Asteroid family, Astronomy, Aten asteroid, Atira asteroid, Barium star, Barred spiral galaxy, Beta Cephei variable, Beta Lyrae, Binary asteroid, Binary star, Black dwarf, Black hole, Blazar, Blue giant, Blue straggler, Blue supergiant star, Bok globule, Bolide, Bright giant, Brightest cluster galaxy, Brown dwarf, Bulge (astronomy), Cambridge University Press, Carbon star, Cataclysmic variable star, Centaur (minor planet), Cepheid variable, Ceres (dwarf planet), Chemically peculiar star, Chthonian planet, Circumstellar disc, Classical Kuiper belt object, Co-orbital configuration, Coma (cometary), Comet, Comet nucleus, ..., Comet tail, Compact star, Constellation, Contact binary, Contact binary (small Solar System body), Cosmic dust, Cosmic microwave background, Cosmic string, Cosmology, Cybele asteroid, Damocloid, Dark galaxy, Dark matter, Dark nebula, Debris disk, Delta Scuti variable, Detached object, Disc galaxy, Domain wall (string theory), Double star, Dwarf galaxy, Dwarf nova, Dwarf planet, Dysnomia (moon), Earth, Earth analog, Earth trojan, Eccentric Jupiter, Elliptical galaxy, Emission nebula, Eos family, Eris (dwarf planet), Exoplanet, Flare star, Flora family, FU Orionis star, Galactic corona, Galactic halo, Galaxy, Galaxy filament, Galaxy groups and clusters, Galaxy merger, Galaxy morphological classification, Gamma-ray burst, Gas giant, Giant planet, Giant star, Globular cluster, H I region, H II region, Haumea, Heliosphere, Hertzsprung–Russell diagram, Hilda asteroid, Hot Jupiter, Hot Neptune, Hungaria asteroid, Hygiea family, Hypercompact stellar system, Hypergiant, Ice giant, Instability strip, Interacting galaxy, Intergalactic dust, Intermediate-mass black hole, International Astronomical Naming Commission, Interplanetary dust cloud, Interplanetary magnetic field, Interplanetary medium, Interstellar cloud, Interstellar medium, Irregular galaxy, Irregular variable, Jupiter, Jupiter trojan, Koronis family, Kuiper belt, Lenticular galaxy, List of light sources, List of Mars-crossing minor planets, List of natural satellites, List of possible dwarf planets, List of Solar System objects, Lists of astronomical objects, Luminous blue variable, Magnetar, Main sequence, Makemake, Maria family, Mars, Mars trojan, Massive compact halo object, Mercury (planet), Meteoroid, Micrometeoroid, Minor planet, Minor-planet moon, Mira variable, Molecular cloud, Moon, Moons of Haumea, Moons of Jupiter, Moons of Mars, Moons of Neptune, Moons of Pluto, Moons of Saturn, Moons of Uranus, Natural satellite, Near-Earth object, Nebula, Neptune, Neptune trojan, Neutron star, Nova, Nysa family, Observable universe, Ocean planet, Oort cloud, Open cluster, Outer space, Oxford University Press, P Cygni, Pallas family, Phocaea family, Physical body, Planet, Planetary nebula, Planetary system, Planetesimal, Plutino, Pluto, Potentially hazardous object, Pre-main-sequence star, Preon star, Proplyd, Protoplanetary disk, Protostar, Pulsar, Pulsar planet, Pulsar wind nebula, Quark star, Quasar, R Coronae Borealis variable, Radio galaxy, Red giant, Red supergiant star, Reflection nebula, Resonant trans-Neptunian object, Ring galaxy, Ring system, Rogue planet, Rotating ellipsoidal variable, RR Lyrae variable, RV Tauri variable, S-type star, Saturn, Scattered disc, Sednoid, Semiregular variable star, Seyfert galaxy, Shell star, Small Solar System body, Solar System, Spiral galaxy, Star, Star cluster, Star system, Starburst galaxy, Stellar association, Stellar black hole, Stellar classification, Stellar evolution, Stellar population, Sub-brown dwarf, Subdwarf, Subgiant, Sun, Super-Earth, Supercluster, Supergiant star, Superluminous supernova, Supermassive black hole, Supernova, Supernova remnant, Symbiotic binary, T Tauri star, Themis family, Thick disk, Thin disk, Trans-Neptunian object, Trojan (astronomy), Type Ib and Ic supernovae, Type II supernova, Universe, Uranus, Uranus trojan, Variable star, Venus, Vesta family, Visual binary, Void (astronomy), Vulcanoid, W Ursae Majoris, W Virginis variable, Weakly interacting massive particles, White dwarf, Wolf–Rayet star, X-ray binary, X-ray burster, Young stellar object. Expand index (210 more) » « Shrink index
An accretion disk is a structure (often a circumstellar disk) formed by diffused material in orbital motion around a massive central body.
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much higher than normal luminosity over at least some portion—and possibly all—of the electromagnetic spectrum, with characteristics indicating that the excess luminosity is not produced by stars.
Algol variables or Algol-type binaries are a class of eclipsing binary stars that are related to the prototype member of this class, β Persei (Beta Persei, Algol) from an evolutionary point of view.
The Alinda asteroids are a dynamical group of asteroids with a semi-major axis of about 2.5 AU and an orbital eccentricity approximately between 0.4 and 0.65.
Alpha Cygni variables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the same time others parts expand.
An Alpha2 Canum Venaticorum variable (or α2 CVn variable) is a type of variable star.
An Am star or metallic-line star is a type of chemically peculiar star of spectral type A whose spectrum has strong and often variable absorption lines of metals such as zinc, strontium, zirconium, and barium, and deficiencies of others, such as calcium and scandium.
The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor.
Ap and Bp stars are chemically peculiar stars (hence the "p") of types A and B which show overabundances of some metals, such as strontium, chromium and europium.
The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, discovered by German astronomer Karl Reinmuth in the 1930s.
The Arjuna asteroids (also known as "Arjunas") are a dynamical group of asteroids in the Solar System.
In observational astronomy, an asterism is a popular known pattern or group of stars that are recognised in the night sky.
Asteroids are minor planets, especially those of the inner Solar System.
The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter.
An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination.
Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.
The Aten asteroids are a dynamical group of asteroids whose orbits bring them into proximity with Earth.
Atira asteroids or Apohele asteroids, also known as Interior-Earth Objects (IEOs), are asteroids, whose orbits are entirely confined within Earth's orbit, that is, their orbit has an aphelion (farthest point from the Sun) smaller than Earth's perihelion (nearest point to the Sun), which is 0.983 astronomical units (AU).
Barium stars are spectral class G to K giants, whose spectra indicate an overabundance of s-process elements by the presence of singly ionized barium, Ba II, at λ 455.4 nm.
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars.
Beta Cephei variables, also known as Beta Canis Majoris stars, are variable stars that exhibit small rapid variations in their brightness due to pulsations of the stars' surfaces, thought due to the unusual properties of iron at temperatures of 200,000 K in their interiors.
Beta Lyrae (Latinized from β Lyrae, abbreviated Beta Lyr, β Lyr), also named Sheliak, is a binary star system approximately from the Sun in the constellation of Lyra.
A binary asteroid is a system of two asteroids orbiting their common barycenter.
A binary star is a star system consisting of two stars orbiting around their common barycenter.
A black dwarf is a theoretical stellar remnant, specifically a white dwarf that has cooled sufficiently that it no longer emits significant heat or light.
A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it.
A blazar is a very compact quasar (quasi-stellar radio source) associated with a presumed supermassive black hole at the center of an active, giant elliptical galaxy.
In astronomy, a blue giant is a hot star with a luminosity class of III (giant) or II (bright giant).
A blue straggler is a main-sequence star in an open or globular cluster that is more luminous and bluer than stars at the main-sequence turn-off point for the cluster.
Blue supergiant stars are hot luminous stars, referred to scientifically as OB supergiants.
In astronomy, Bok globules are isolated and relatively small dark nebulae, containing dense cosmic dust and gas from which star formation may take place.
A bolide (French via Latin from the Greek βολίς bolís, "missile") is an extremely bright meteor, especially one that explodes in the atmosphere.
The luminosity class II in the Yerkes spectral classification is given to bright giants.
A brightest cluster galaxy (BCG) is defined as the brightest galaxy in a cluster of galaxies.
Brown dwarfs are substellar objects that occupy the mass range between the heaviest gas giant planets and the lightest stars, having masses between approximately 13 to 75–80 times that of Jupiter, or approximately to about.
In astronomy, a bulge is a tightly packed group of stars within a larger formation.
Cambridge University Press (CUP) is the publishing business of the University of Cambridge.
A carbon star is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen; the two elements combine in the upper layers of the star, forming carbon monoxide, which consumes all the oxygen in the atmosphere, leaving carbon atoms free to form other carbon compounds, giving the star a "sooty" atmosphere and a strikingly ruby red appearance.
Cataclysmic variable stars (CV) are stars which irregularly increase in brightness by a large factor, then drop back down to a quiescent state.
Centaurs are small solar system bodies with a semi-major axis between those of the outer planets.
A Cepheid variable is a type of star that pulsates radially, varying in both diameter and temperature and producing changes in brightness with a well-defined stable period and amplitude.
Ceres (minor-planet designation: 1 Ceres) is the largest object in the asteroid belt that lies between the orbits of Mars and Jupiter, slightly closer to Mars' orbit.
In astrophysics, chemically peculiar stars (CP stars) are stars with distinctly unusual metal abundances, at least in their surface layers.
Chthonian planets (sometimes 'cthonian') are a hypothetical class of celestial objects resulting from the stripping away of a gas giant's hydrogen and helium atmosphere and outer layers, which is called hydrodynamic escape.
A circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accumulation of matter composed of gas, dust, planetesimals, asteroids or collision fragments in orbit around a star.
A classical Kuiper belt object, also called a cubewano ("QB1-o"), is a low-eccentricity Kuiper belt object (KBO) that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune.
In astronomy, a co-orbital configuration is a configuration of two or more astronomical objects (such as asteroids, moons, or planets) orbiting at the same, or very similar, distance from their primary, i.e. they are in a 1:1 mean-motion resonance.
The coma is the nebulous envelope around the nucleus of a comet, formed when the comet passes close to the Sun on its highly elliptical orbit; as the comet warms, parts of it sublime.
A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing.
The nucleus is the solid, central part of a comet, popularly termed a dirty snowball or an icy dirtball.
A comet tail—and coma—are features visible in comets when they are illuminated by the Sun and may become visible from Earth when a comet passes through the inner Solar System.
In astronomy, the term "compact star" (or "compact object") refers collectively to white dwarfs, neutron stars, and black holes.
A constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices.
In astronomy, a contact binary is a binary star system whose component stars are so close that they touch each other or have merged to share their gaseous envelopes.
A contact binary is a small Solar System body that is composed of two bodies that have gravitated toward each other until they touch.
Cosmic dust, also called extraterrestrial dust or space dust, is dust which exists in outer space, as well as all over planet Earth.
The cosmic microwave background (CMB, CMBR) is electromagnetic radiation as a remnant from an early stage of the universe in Big Bang cosmology.
Cosmic strings are hypothetical 1-dimensional topological defects which may have formed during a symmetry breaking phase transition in the early universe when the topology of the vacuum manifold associated to this symmetry breaking was not simply connected.
Cosmology (from the Greek κόσμος, kosmos "world" and -λογία, -logia "study of") is the study of the origin, evolution, and eventual fate of the universe.
Cybele asteroids (also known as the "Cybeles") are a dynamical group of asteroids, named after the asteroid 65 Cybele.
Damocloids are a class of minor planets such as 5335 Damocles and 1996 PW that have Halley-family or long-period highly eccentric orbits typical of periodic comets such as Halley's Comet, but without showing a cometary coma or tail.
A dark galaxy is a hypothesized galaxy with no, or very few, stars.
Dark matter is a theorized form of matter that is thought to account for approximately 80% of the matter in the universe, and about a quarter of its total energy density.
A dark nebula or absorption nebula is a type of interstellar cloud that is so dense that it obscures the light from objects behind it, such as background stars and emission or reflection nebulae.
A debris disk is a circumstellar disk of dust and debris in orbit around a star.
A Delta Scuti variable (sometimes termed dwarf cepheid) is a variable star which exhibits variations in its luminosity due to both radial and non-radial pulsations of the star's surface.
Detached objects are a dynamical class of minor planets in the outer reaches of the Solar System and belong to the broader family of trans-Neptunian objects (TNOs).
A disc galaxy is a galaxy characterized by a disc, a flattened circular volume of stars.
In physics, a domain wall is any of several similar things in string theory, magnetism, or optics.
In observational astronomy, a double star or visual double is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope.
A dwarf galaxy is a small galaxy composed of about 100 million up to several billion stars, a small number compared to the Milky Way's 200–400 billion stars.
A U Geminorum-type variable star, or dwarf nova (pl. novae) is a type of cataclysmic variable star consisting of a close binary star system in which one of the components is a white dwarf that accretes matter from its companion.
A dwarf planet is a planetary-mass object that is neither a planet nor a natural satellite.
Dysnomia (Greek: Δυσνομία)—officially (136199) Eris I Dysnomia—is the only known moon of the dwarf planet Eris (the most massive known dwarf planet in the Solar System).
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
An Earth analog (also referred to as an Earth twin or Earth-like planet, though this latter term may refer to any terrestrial planet) is a planet or moon with environmental conditions similar to those found on Earth.
An Earth trojan is an asteroid that orbits the Sun in the vicinity of the Earth–Sun Lagrangian points (leading 60°) or (trailing 60°), thus having an orbit similar to Earth's.
An eccentric Jupiter is a Jovian planet that orbits its star in an eccentric orbit.
An elliptical galaxy is a type of galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless image.
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths.
The Eos family (adj. Eoan; FIN: 606) is a very large asteroid family located in the outer region of the asteroid belt.
Eris (minor-planet designation 136199 Eris) is the most massive and second-largest (by volume) dwarf planet in the known Solar System.
An exoplanet or extrasolar planet is a planet outside our solar system.
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes.
The Flora or Florian '''family''' of asteroids is a large grouping of S-type asteroids in the inner main belt, whose origin and properties are relatively poorly understood at present.
In stellar evolution, an FU Orionis star (also FU Orionis object, or FUor) is a pre–main-sequence star which displays an extreme change in magnitude and spectral type.
The terms galactic corona and gaseous corona have been used in the first decade of the 21st century to describe a hot, ionised, gaseous component in the Galactic halo of the Milky Way.
A galactic halo is an extended, roughly spherical component of a galaxy which extends beyond the main, visible component.
A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter.
The distribution reveals fine, filamentary structures.
Galaxy groups and clusters are the largest known gravitationally bound objects to have arisen thus far in the process of cosmic structure formation.
Galaxy mergers can occur when two (or more) galaxies collide.
Galaxy morphological classification is a system used by astronomers to divide galaxies into groups based on their visual appearance.
In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic explosions that have been observed in distant galaxies.
A gas giant is a giant planet composed mainly of hydrogen and helium.
A giant planet is any massive planet.
A giant star is a star with substantially larger radius and luminosity than a main-sequence (or dwarf) star of the same surface temperature.
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite.
An HI region or H I region (read H one) is a cloud in the interstellar medium composed of neutral atomic hydrogen (HI), in addition to the local abundance of helium and other elements.
An H II region or HII region is a region of interstellar atomic hydrogen that is ionized.
Haumea, minor-planet designation 136108 Haumea, is a dwarf planet located beyond Neptune's orbit.
The heliosphere is the bubble-like region of space dominated by the Sun, which extends far beyond the orbit of Pluto.
The Hertzsprung–Russell diagram, abbreviated H–R diagram, HR diagram or HRD, is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their stellar classifications or effective temperatures.
The Hilda asteroids (adj. Hildian) are a dynamical group of asteroids in a 3:2 orbital resonance with Jupiter.
Hot Jupiters are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter but that have very short orbital period (P The close proximity to their stars and high surface-atmosphere temperatures resulted in the moniker "hot Jupiters". Hot Jupiters are the easiest extrasolar planets to detect via the radial-velocity method, because the oscillations they induce in their parent stars' motion are relatively large and rapid compared to those of other known types of planets. One of the best-known hot Jupiters is 51 Pegasi b. Discovered in 1995, it was the first extrasolar planet found orbiting a Sun-like star. 51 Pegasi b has an orbital period of about 4 days.
A hot Neptune or Hoptune is a type of giant planet with a mass similar to that of Uranus or Neptune orbiting close to its star, normally within less than 1 AU.
The Hungaria group is a dynamical group of asteroids in the asteroid belt.
The Hygiea or Hygiean '''family''' of asteroids is a grouping of dark, carbonaceous C-type and B-type asteroids in outer asteroid belt, the largest member of which is 10 Hygiea.
A hypercompact stellar system (HCSS) is a dense cluster of stars around a supermassive black hole that has been ejected from the center of its host galaxy.
A hypergiant (luminosity class 0 or Ia+) is among the very rare kinds of stars that typically show tremendous luminosities and very high rates of mass loss by stellar winds.
An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur.
The unqualified term instability strip usually refers to a region of the Hertzsprung–Russell diagram largely occupied by several related classes of pulsating variable stars: Delta Scuti variables, SX Phoenicis variables, and rapidly oscillating Ap stars (roAps) near the main sequence; RR Lyrae variables where it intersects the horizontal branch; and the Cepheid variables where it crosses the supergiants.
Interacting galaxies (colliding galaxies) are galaxies whose gravitational fields result in a disturbance of one another.
Intergalactic dust is cosmic dust in between galaxies in intergalactic space.
An intermediate-mass black hole (IMBH) is a class of black hole with mass in the range 102-105 solar masses: significantly more than stellar black holes but less than the 105-109 solar mass supermassive black holes.
The International Astronomical Naming Commission or IANC is a foundation with international ties set up to record, change, and document the naming of all known astronomical bodies.
The interplanetary dust cloud, or zodiacal cloud, consists of cosmic dust (small particles floating in outer space) that pervades the space between planets in the Solar System and other planetary systems.
The interplanetary magnetic field (IMF), now more commonly referred to as the heliospheric magnetic field (HMF), is the component of the solar magnetic field which is dragged out from the solar corona by the solar wind flow to fill the Solar System.
The interplanetary medium is the material which fills the Solar System, and through which all the larger Solar System bodies, such as planets, dwarf planets, asteroids, and comets, move.
An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies.
In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy.
An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy.
An irregular variable is a type of variable star in which variations in brightness show no regular periodicity.
Jupiter is the fifth planet from the Sun and the largest in the Solar System.
The Jupiter trojans, commonly called Trojan asteroids or just Trojans, are a large group of asteroids that share the planet Jupiter's orbit around the Sun.
The Koronis or Koronian family is a family of asteroids in the main belt between Mars and Jupiter.
The Kuiper belt, occasionally called the Edgeworth–Kuiper belt, is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun.
A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes.
This is a list of sources of light, including both natural and artificial processes that emit light.
A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars.
The Solar System's planets and officially recognized dwarf planets are known to be orbited by 184 natural satellites, or moons.
It is estimated that there may be 200 dwarf planets in the Kuiper belt of the outer Solar System and possibly more than 10,000 in the region beyond.
The following is a list of Solar System objects by orbit, ordered by increasing distance from the Sun.
This is a list of lists, grouped by type of astronomical object.
Luminous blue variables (LBVs) are massive evolved stars that show unpredictable and sometimes dramatic variations in both their spectra and brightness.
A magnetar is a type of neutron star with an extremely powerful inferred magnetic field (\sim 10^ - 10^ G).
In astronomy, the main sequence is a continuous and distinctive band of stars that appear on plots of stellar color versus brightness.
Makemake (minor-planet designation 136472 Makemake) is a dwarf planet and perhaps the largest Kuiper belt object in the classical population, with a diameter approximately two thirds that of Pluto.
The Maria family (adj. Marian; FIN: 506; also known as Roma family) is a collisional asteroid family located in the inner parts of the intermediate asteroid belt, near the 1:3 Kirkwood gap.
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System after Mercury.
The Mars trojans are a group of objects that share the orbit of the planet Mars around the Sun.
A massive astrophysical compact halo object (MACHO) is any kind of astronomical body that might explain the apparent presence of dark matter in galaxy halos.
Mercury is the smallest and innermost planet in the Solar System.
A meteoroid is a small rocky or metallic body in outer space.
A micrometeoroid is a tiny meteoroid; a small particle of rock in space, usually weighing less than a gram.
A minor planet is an astronomical object in direct orbit around the Sun (or more broadly, any star with a planetary system) that is neither a planet nor exclusively classified as a comet.
A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite.
Mira variables ("Mira", Latin, adj. - feminine form of adjective "wonderful"), named for the prototype star Mira, are a class of pulsating variable stars characterized by very red colours, pulsation periods longer than 100 days, and amplitudes greater than one magnitude in infrared and 2.5 magnitude at visual wavelengths.
A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit the formation of molecules, most commonly molecular hydrogen (H2).
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite.
The outer Solar System dwarf planet Haumea has two known moons, Hiʻiaka and Namaka, named after Hawaiian goddesses.
There are 69 known moons of Jupiter.
The two moons of Mars are Phobos and Deimos.
Neptune has 14 known moons, which are named for minor water deities in Greek mythology.
The dwarf planet Pluto has five moons down to a detection limit of about 1 km in diameter.
The moons of Saturn are numerous and diverse, ranging from tiny moonlets less than 1 kilometer across to the enormous Titan, which is larger than the planet Mercury.
Uranus is the seventh planet of the Solar System; it has 27 known moons, all of which are named after characters from the works of William Shakespeare and Alexander Pope.
A natural satellite or moon is, in the most common usage, an astronomical body that orbits a planet or minor planet (or sometimes another small Solar System body).
A near-Earth object (NEO) is any small Solar System body whose orbit can bring it into proximity with Earth.
A nebula (Latin for "cloud" or "fog"; pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases.
Neptune is the eighth and farthest known planet from the Sun in the Solar System.
Neptune trojans are bodies that orbit the Sun near one of the stable Lagrangian points of Neptune, similar to the trojans of other planets.
A neutron star is the collapsed core of a large star which before collapse had a total of between 10 and 29 solar masses.
A nova (plural novae or novas) or classical nova (CN, plural CNe) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star, that slowly fades over several weeks or many months.
The Nysa family (adj. Nysian; FIN: 405) is part of the Nysa–Polana complex, the largest cluster of asteroid families in the asteroid belt.
The observable universe is a spherical region of the Universe comprising all matter that can be observed from Earth at the present time, because electromagnetic radiation from these objects has had time to reach Earth since the beginning of the cosmological expansion.
An ocean planet, ocean world, water world, aquaplanet or panthalassic planet is a type of terrestrial planet that contains a substantial amount of water either at its surface or subsurface.
The Oort cloud, named after the Dutch astronomer Jan Oort, sometimes called the Öpik–Oort cloud, is a theoretical cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from.
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age.
Outer space, or just space, is the expanse that exists beyond the Earth and between celestial bodies.
Oxford University Press (OUP) is the largest university press in the world, and the second oldest after Cambridge University Press.
P Cygni (34 Cyg) is a variable star in the constellation Cygnus.
The Pallas or Palladian '''family''' of asteroids is a grouping of B-type asteroids at very high inclinations in the intermediate asteroid belt (Cellino et al. (2002)).
The Phocaea family (FIN: 701) is a collisional family of asteroids located between 2.25 and 2.5 AU in the inner region of the asteroid belt.
In physics, a physical body or physical object (or simply a body or object) is an identifiable collection of matter, which may be constrained by an identifiable boundary, and may move as a unit by translation or rotation, in 3-dimensional space.
A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.
A planetary nebula, abbreviated as PN or plural PNe, is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
A planetary system is a set of gravitationally bound non-stellar objects in or out of orbit around a star or star system.
Planetesimals are solid objects thought to exist in protoplanetary disks and in debris disks.
In astronomy, the plutinos are a dynamical group of trans-Neptunian objects in the outermost region of the Solar System that orbit in 2:3 mean-motion resonance with Neptune.
Pluto (minor planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond Neptune.
A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make exceptionally close approaches to the Earth and large enough to cause significant regional damage in the event of impact.
A pre-main-sequence star (also known as a PMS star and PMS object) is a star in the stage when it has not yet reached the main sequence.
A preon star is a theoretical type of compact star made of preons, which are "point-like" particles conceived to be subcomponents of quarks and leptons.
A proplyd, a syllabic abbreviation of an ionized protoplanetary disk, is an externally illuminated photoevaporating disk around a young star.
A protoplanetary disk is a rotating circumstellar disk of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star.
A protostar is a very young star that is still gathering mass from its parent molecular cloud.
A pulsar (from pulse and -ar as in quasar) is a highly magnetized rotating neutron star or white dwarf that emits a beam of electromagnetic radiation.
Pulsar planets are planets that are found orbiting pulsars, or rapidly rotating neutron stars.
A pulsar wind nebula (PWN, plural PWNe), sometimes called a plerion (derived from the Greek "πλήρης", pleres, meaning "full"), is a type of nebula found inside the shells of supernova remnants (SNRe) that is powered by pulsar winds generated by its central pulsar.
A quark star is a hypothetical type of compact exotic star, where extremely high temperature and pressure has forced nuclear particles to form a continuous state of matter that consists primarily of free quarks, which can be modeled using the Calabi–Yau manifold.
A quasar (also known as a QSO or quasi-stellar object) is an extremely luminous active galactic nucleus (AGN).
An R Coronae Borealis variable (abbreviated RCB, R CrB) is an eruptive variable star that varies in luminosity in two modes, one low amplitude pulsation (a few tenths of a magnitude), and one irregular, unpredictably-sudden fading by 1 to 9 magnitudes.
Radio galaxies and their relatives, radio-loud quasars and blazars, are types of active galaxy that are very luminous at radio wavelengths, with luminosities up to 1039 W between 10 MHz and 100 GHz.
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses) in a late phase of stellar evolution.
Red supergiants are stars with a supergiant luminosity class (Yerkes class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous.
In astronomy, reflection nebulae are clouds of interstellar dust which might reflect the light of a nearby star or stars.
In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object (TNO) in mean-motion orbital resonance with Neptune.
A ring galaxy is a galaxy with a circle-like appearance.
A ring system is a disc or ring orbiting an astronomical object that is composed of solid material such as dust and moonlets, and is a common component of satellite systems around giant planets.
A rogue planet (also termed an interstellar planet, nomad planet, free-floating planet, orphan planet, wandering planet, starless planet, or sunless planet) is a planetary-mass object that orbits a galactic center directly.
Rotating ellipsoidal variables are a class of variable star.
RR Lyrae variables are periodic variable stars, commonly found in globular clusters.
RV Tauri variables are luminous variable stars that have distinctive light variations with alternating deep and shallow minima.
An S-type star (or just S star) is a cool giant with approximately equal quantities of carbon and oxygen in its atmosphere.
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter.
The scattered disc (or scattered disk) is a distant circumstellar disc in the Solar System that is sparsely populated by icy small solar system bodies, and are a subset of the broader family of trans-Neptunian objects.
A sednoid is a trans-Neptunian object with a perihelion greater than and a semi-major axis greater than.
Semiregular variable stars are giants or supergiants of intermediate and late spectral type showing considerable periodicity in their light changes, accompanied or sometimes interrupted by various irregularities.
Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars.
A shell star is a star having a spectrum that exhibits features indicating a circumstellar disc of gas surrounding the star at the equator.
A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, nor a dwarf planet, nor a natural satellite.
The Solar SystemCapitalization of the name varies.
Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae(pp. 124–151) and, as such, form part of the Hubble sequence.
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.
Star clusters are groups of stars.
A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction.
A starburst galaxy is a galaxy undergoing an exceptionally high rate of star formation, as compared to the long-term average rate of star formation in the galaxy or the star formation rate observed in most other galaxies.
A stellar association is a very loose star cluster, looser than both open clusters and globular clusters.
A stellar black hole (or stellar-mass black hole) is a black hole formed by the gravitational collapse of a massive star.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics.
Stellar evolution is the process by which a star changes over the course of time.
During 1944, Walter Baade categorized groups of stars within the Milky Way into bluer stars associated with the spiral arms and the general position of yellow stars near the central galactic bulge or within globular star clusters.
A sub-brown dwarf or planetary-mass brown dwarf is an astronomical object that formed in the same manner as stars and brown dwarfs (i.e. through the collapse of a gas cloud) but that has a mass below the limiting mass for thermonuclear fusion of deuterium (about). Some researchers call them free-floating planets whereas others call them planetary-mass brown dwarfs.
A subdwarf, sometimes denoted by "sd", is a star with luminosity class VI under the Yerkes spectral classification system.
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as true giant stars.
The Sun is the star at the center of the Solar System.
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below the masses of the Solar System's ice giants, Uranus and Neptune, which have masses of 15 and 17 times Earth's, respectively.
A supercluster is a large group of smaller galaxy clusters or galaxy groups; it is among the largest-known structures of the cosmos.
Supergiants are among the most massive and most luminous stars.
A superluminous supernova (SLSN, plural superluminous supernovae or SLSNe; also known as hypernova) is a type of stellar explosion with a luminosity 10 or more times higher than that of standard supernovae.
A supermassive black hole (SMBH or SBH) is the largest type of black hole, on the order of hundreds of thousands to billions of solar masses, and is found in the centre of almost all currently known massive galaxies.
A supernova (plural: supernovae or supernovas, abbreviations: SN and SNe) is a transient astronomical event that occurs during the last stellar evolutionary stages of a star's life, either a massive star or a white dwarf, whose destruction is marked by one final, titanic explosion.
A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova.
A symbiotic binary is a type of binary star system, often simply called a symbiotic star.
T Tauri stars (TTS) are a class of variable stars associated with youth.
The Themis or Themistian asteroid family is a Hirayama family (having similar orbital elements) of asteroids found in the outer portion of the asteroid belt, between the orbits of Mars and Jupiter.
The thick disk is one of the structural components of about 2/3 of all disk galaxies, including the Milky Way.
The thin disk is a structural component of spiral and S0-type galaxies, composing of stars, gas and dust.
A trans-Neptunian object (TNO, also written transneptunian object) is any minor planet in the Solar System that orbits the Sun at a greater average distance (semi-major axis) than Neptune, 30 astronomical units (AU).
In astronomy, a trojan is a minor planet or moon that shares the orbit of a planet or larger moon, wherein the trojan remains in the same, stable position relative to the larger object.
Type Ib and Type Ic supernovae are categories of supernovae that are caused by the core collapse of massive stars.
A Type II supernova (plural: supernovae or supernovas) results from the rapid collapse and violent explosion of a massive star.
The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy.
Uranus is the seventh planet from the Sun.
There are two known Uranus trojans, or minor planets orbiting in the Lagrangian points of Uranus.
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) fluctuates.
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days.
The Vesta or Vestian family of asteroids is a large and prominent grouping of mostly V-type asteroids ("vestoids") in the inner asteroid belt in the vicinity of 4 Vesta.
A visual binary is a gravitationally bound system that can be resolved into two stars.
Cosmic voids are vast spaces between filaments (the largest-scale structures in the universe), which contain very few or no galaxies.
The vulcanoids are a hypothetical population of asteroids that orbit the Sun in a dynamically stable zone inside the orbit of the planet Mercury.
W Ursae Majoris (W UMa) is the variable star designation for a binary star system in the northern constellation of Ursa Major.
W Virginis variables are a subclass of Type II Cepheids which exhibit pulsation periods between 10–20 days,Wallerstein, G.,, Publications of the Astronomical Society of the Pacific, 114 p.689–699 (2002) and are of spectral class F6 – K2.
Weakly interacting massive particles (WIMPs) are hypothetical particles that are thought to constitute dark matter.
A white dwarf, also called a degenerate dwarf, is a stellar core remnant composed mostly of electron-degenerate matter.
Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of highly ionised helium and nitrogen or carbon.
X-ray binaries are a class of binary stars that are luminous in X-rays.
X-ray bursters are one class of X-ray binary stars exhibiting periodic and rapid increases in luminosity (typically a factor of 10 or greater) that peak in the X-ray regime of the electromagnetic spectrum.
Young stellar object (YSO) denotes a star in its early stage of evolution.
Astronomical Objects, Astronomical bodies, Astronomical body, Astronomical objects, Celestial bodes, Celestial bodies, Celestial body, Celestial object, Celestial objects, Cosmological object, Heavenly body.