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Astronomical object
 
 
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s are significant physical entities
Entity

An entity is something that has a distinct, separate existence, though it need not be a material existence. In particular, abstractions and legal fictions are usually regarded as entities....
, associations or structures which current science
Science

In its broadest sense, science refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research....
 has confirmed to exist in outer space
Outer space

Outer space comprises the relatively empty regions of the universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace and terrestrial locations....
. This does not necessarily mean that more current science will not disprove their existence. Some astronomical objects, such as Themis and Neith are, in light of more recent findings, considered not to exist at all. Others, like Pluto
Pluto

Pluto , Minor planet names Pluto, is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun....
 and Ceres, prove to be of an entirely different nature than first expected.






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s are significant physical entities
Entity

An entity is something that has a distinct, separate existence, though it need not be a material existence. In particular, abstractions and legal fictions are usually regarded as entities....
, associations or structures which current science
Science

In its broadest sense, science refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research....
 has confirmed to exist in outer space
Outer space

Outer space comprises the relatively empty regions of the universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace and terrestrial locations....
. This does not necessarily mean that more current science will not disprove their existence. Some astronomical objects, such as Themis and Neith are, in light of more recent findings, considered not to exist at all. Others, like Pluto
Pluto

Pluto , Minor planet names Pluto, is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun....
 and Ceres, prove to be of an entirely different nature than first expected. In these cases, the scientific community
Scientific community

The scientific community consists of the total body of scientists, its relationships and interactions. It is normally divided into "sub-communities" each working on a particular field within science....
 must come to a consensus as to the new status of these objects. Astronomical objects thought to exist based on indirect scientific evidence are considered hypothetical.

Astronomical objects can be easily confused with astronomical bodies. The term body indicates a simple object, such as a planet
Planet

A planet , as 2006 definition of planet by the International Astronomical Union , is a celestial body orbiting a star or Stellar evolution#Stellar remnants that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared the neighbourhood of planetesimals....
. On the other hand, an astronomical object could be an asteroid belt
Asteroid belt

The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets....
. These terms differ from celestial objects and celestial bodies only in that the latter terms do not include the Earth
Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
.

The table below lists the general categories of objects by their location or structure.

Solar System
Solar System

The Solar System consists of the Sun and those Astronomical object bound to it by gravity: the eight planets and five dwarf planets, their 173 known Natural satellite, and billions of Small Solar System body....
 Extrasolar objects
Simple objects Compound objects Extended objects
  • Sun
    Sun

    The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
  • Planetary system
    Planetary system

    A planetary system consists of the various non-stellar objects orbiting a star such as planets, natural satellites, asteroids, meteoroids, comets, and cosmic dust....
    • Planet
      Planet

      A planet , as 2006 definition of planet by the International Astronomical Union , is a celestial body orbiting a star or Stellar evolution#Stellar remnants that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared the neighbourhood of planetesimals....
      s
      • Mercury
        Mercury (planet)

        Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 88 days. The orbit of Mercury has the highest Orbital eccentricity of all the Solar System planets, and it has the smallest axial tilt....
      • Venus
        Venus

        Venus is the second-closest planet to the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus , the Roman mythology goddess of love....
      • Earth
        Earth

        Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
        • Moon
          Moon

          The Moon is Earth's only natural satellite and the List of natural satellites by diameter satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is km, about thirty times the diameter of the Earth....
        • 3753 Cruithne
          3753 Cruithne

          3753 Cruithne is an asteroid in orbit around the Sun in 1:1 orbital resonance with that of the Earth. Due to its unusual orbit relative to that of the Earth, it is a periodic inclusion planetoid and is sometimes incorrectly called "Earth's second moon", since it orbits the Sun, not the Earth....
      • Mars
        MARS

        In cryptography, MARS is a block cipher that was IBM's submission to the Advanced Encryption Standard process. MARS was selected as an AES finalist in August 1999, after the AES2 conference in March 1999, where it was voted as the fifth and last finalist algorithm....
        • satellites
          Mars' natural satellites

          Mars has two tiny Natural satellite, Phobos and Deimos , which are thought to be captured asteroids.Both satellites were discovered in 1877 by Asaph Hall, and are named after the characters Phobos and Deimos who, in Greek mythology, accompanied their father Ares, god of war, into battle....
      • Jupiter
        Jupiter

        Jupiter is the fifth planet from the Sun and the Solar system by size planet within the Solar System. It is two and a half times as massive as all of the other planets in our Solar System combined....
        • satellites
          Jupiter's natural satellites

          Jupiter has 63 confirmed natural satellite, giving it the largest retinue of moons with "reasonably secure" orbits of any planet in the Solar System....
      • Saturn
        Saturn

        Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn, along with Jupiter, Uranus and Neptune, is classified as a gas giant....
        • satellites
          Saturn's natural satellites

          Saturn has 61 natural satellite with confirmed orbits, 52 of which have names, and most of which are quite small. There are also hundreds of known "moonlets" embedded within Rings of Saturn....
      • Uranus
        Uranus

        Uranus is the seventh planet from the Sun and the third-largest and fourth most massive planet in the Solar System. It is named after the ancient Greek deity of the sky Uranus the father of Kronos and grandfather of Zeus ....
        • satellites
          Uranus' natural satellites

          File:Uranus_moons.jpgUranus, the seventh planet of the Solar System, has 27 known Natural satellite, all of which are named after characters from the works of William Shakespeare and Alexander Pope....
      • Neptune
        NEPTUNE

        =Overview=The project, along with sister project, VENUS, offers a unique approach to ocean science. Traditionally, ocean scientists have relied on infrequent ship cruises or space-based satellites to carry out their research....
        • satellites
          Neptune's natural satellites

          Neptune has thirteen known natural satellite. The largest by far is Triton , discovered by William Lassell just seventeen days after the discovery of Neptune itself....
    • Dwarf planet
      Dwarf planet

      A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but has not Clearing the neighbourhood of planetesimals and is not a natural satellite....
      s
      • Pluto
        Pluto

        Pluto , Minor planet names Pluto, is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun....
        • satellites
          Pluto's natural satellites

          Pluto has three known Natural satellite. The largest, Charon , is proportionally larger, compared to its primary, than any other satellite of a known planet or dwarf planet in the solar system....
      • Eris
        Eris (dwarf planet)

        'Eris' , Minor planet names '136199 Eris', is the largest known dwarf planet in the Solar System and the ninth-largest body known to orbit the Sun directly....
        • Dysnomia
          Dysnomia (moon)

          'Dysnomia' , officially ' Eris I Dysnomia', is the only known natural satellite of the dwarf planet Eris . It was discovered in 2005 by Michael E....
      • Ceres
      • Makemake
      • Haumea
        • satellites
    • Asteroid
      Asteroid

      Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, smaller than planets but larger than meteoroids....
      s
      • "Vulcanoids"
      • "Apoheles"
      • Near-Earth asteroids
        • "Arjuna
          Arjuna asteroid

          The Arjuna asteroids are a class of near-Earth asteroids whose orbits are very Earth-like in character, having low inclination, orbital periods close to one Earth year, and low eccentricity ....
          s"
        • Aten
          Aten asteroid

          The Aten asteroids are a group of near-Earth asteroids, named after the first of the group to be discovered . They are defined by having semi-major axis of less than one astronomical unit ....
          s
        • Apollo
          Apollo asteroid

          The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, the first asteroid of this group to be discovered by Karl Wilhelm Reinmuth....
          s
        • Amor
          Amor asteroid

          The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it....
          s
      • Mars-crossers
        Mars-crosser asteroid

        A Mars-crosser asteroid is an asteroid whose orbit crosses that of Mars. The known numbered Mars-crossers are listed here. They include the two numbered Martian Trojan asteroids: 5261 Eureka and ....
      • Asteroid belt
        Asteroid belt

        The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets....
        • Hungaria
          Hungaria family

          The Hungaria asteroids are a group of asteroids in the main belt that orbit the Sun between 1.78 and 2.00 astronomical unit. The asteroids typically have a low Orbital eccentricity and an inclination of 16 to 34 degrees....
          s
        • Phocaea
          Phocaea family

          The Phocaea asteroids are a group of asteroids that orbit the sun between 2.25 and 2.5 astronomical unit. Asteroids in this group have orbits with Orbital eccentricity greater than 0.1 and inclinations between 18 and 32....
          s
        • Nysa
          Nysa family

          The Nysa asteroids are a group of asteroids in the Main Belt orbiting the sun between 2.41 and 2.5 astronomical unit. Asteroids in this family have Orbital eccentricity between 0.12 and 0.21 and inclinations of 1.4 to 4.3....
          s
        • Alinda
          Alinda family

          The Alinda asteroids are a group of asteroids with a semi-major axis of about 2.5 Astronomical unit and an eccentricity approximately between 0.4 and 0.65....
          s
        • Hildas
        • Pallas
        • Marias
        • Koronis
          Koronis family

          The Koronis family is a family of asteroids in the Asteroid belt between Mars and Jupiter. They are thought to have have been formed at least two billion years ago in a catastrophic collision between two larger bodies....
        • Eos
          Eos family

          The Eos family is a prominent asteroid family of Asteroid belt asteroids that is believed to have formed as a result of an ancient catastrophic collision....
        • Themis
          Themis family

          The Themis Asteroid Family is a Hirayama family of asteroids found in the outer portion of the main asteroid belt, between the orbits of Mars and Jupiter....
        • Griquas
          Griqua family

          The Griqua asteroids are a group of asteroids in the Main Belt orbiting the sun between 3.1 and 3.27 astronomical unit. Asteroids in this group have Orbital eccentricity greater than 0.35....
        • Cybeles
          Cybele asteroid

          Cybele asteroids are a group of asteroids in the main belt with a mean orbital radius between 3.27 astronomical unit and 3.7 AU, an Orbital eccentricity less than 0.3, and an inclination less than 25?....
        • Thule
          279 Thule

          279 Thule is a very large Asteroid belt asteroid. It is classified as a D-type asteroid and is probably composed of organic rich silicates, carbon and anhydrous silicates....
        • Vesta
          4 Vesta

          4 Vesta is the second most massive object in the asteroid belt, with a mean diameter of about 530 km and an estimated mass of 9% of the mass of the entire asteroid belt....
      • Trojan asteroid
        Trojan asteroid

        The Jupiter Trojans, commonly called Trojans or Trojan asteroids, are a large group of objects that share the orbit of the planet Jupiter around the Sun....
        s
        • Mars trojan
          Trojan (astronomy)

          In astronomy, the adjective 'trojan' refers to a minor planet or natural satellite that shares an orbit with a larger planet or moon, but does not collide with it because it orbits around one of the two Lagrangian points of stability, L4 and L5, which lie 60? ahead of and behind the larger body....
          s
        • Jupiter trojans
        • Neptune trojan
          Neptune Trojan

          As of May 2008, there are six known Neptune trojans which have the same orbital period as Neptune. They lie in the elongated, curved region around the L4 Lagrangian point 60? ahead of Neptune....
          s
      • Outer planet crossers
      • Damocloid
        Damocloid asteroid

        Damocloids are asteroids such as 5335 Damocles and 1996 PW that have Halley family or long-period highly eccentricity orbits typical of periodic comets such as Comet Halley, but without showing a coma or tail....
        s
      • Centaur
        Centaur (planetoid)

        The centaurs are an unstable orbital class of minor planets named after the mythological race of centaurs. The name was chosen because they behave as half asteroid and half comet....
        s
    • Trans-Neptunian object
      Trans-Neptunian object

      A trans-Neptunian object is any object in the solar system that orbits the sun at a greater distance on average than Neptune . The Kuiper belt, scattered disk, and Oort cloud are three divisions of this volume of space....
      s
      • Kuiper Belt
        Kuiper belt

        The Kuiper belt , sometimes called the Edgeworth-Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 55 Astronomical unit from the Sun....
        • Plutino
          Plutino

          In astronomy, a plutino is a trans-Neptunian object in 2:3 orbital resonance with Neptune . For every 2 orbits that a Plutino makes, Neptune orbits 3 times....
          s
        • Cubewano
          Cubewano

          In astronomy a classical Kuiper Belt object, also called a cubewano , is a Kuiper belt object that orbits beyond Neptune and is not controlled by an orbital resonance with the giant planet....
          s
        • Twotinos
      • Scattered Disk Objects
        • Sedna
    • Comet
      Comet

      A comet is a Small Solar System body that orbits the Sun and, when close enough to the Sun, exhibits a visible coma or a tail?both primarily from the effects of solar radiation upon the Comet nucleus....
      s
    • Oort cloud
      Oort cloud

      The Oort cloud is a hypothetical spherical cloud of comets which may lie roughly 50 000 astronomical unit, or nearly a light-year, from the Sun....
    • Meteoroid
      Meteoroid

      A meteoroid is a small sand to boulder sized particle of debris in the Solar System. The visible path of a meteoroid that enters Earth Earth's atmosphere is called a meteor, or commonly a "shooting star" or "falling star"....
      s
      • Meteor
        METEOR

        METEOR is a Metrics for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision....
        s
      • Meteor shower
        Meteor shower

        Meteor showers, some of which are known as "meteor storms" , "meteor outbursts,"or "star storm are celestial events in which a number of meteors are observed to radiate from one point in the sky....
        s
  • Exoplanets
    • Hot Jupiter
      Hot Jupiter

      Hot Jupiters are a class of extrasolar planet whose mass is close to or exceeds that of Jupiter , but unlike in the Solar System, where Jupiter orbits at 5 Astronomical Unit, the planets referred to as hot Jupiters orbit within approximately 0.05 AU of their parent stars, about one eighth the distance that Mercury orbits the Sun....
      s
    • Eccentric Jupiter
      Eccentric Jupiter

      An Eccentric Jupiter is a Jovian planet that orbits its star in a highly Eccentricity orbit, much like a comet. Eccentric Jupiters, like Hot Jupiters, are likely to disqualify a planetary system from having earth-like planets in it because a planet as massive as Jupiter can, given sufficient time, throw all planets of earth-like mass out of...
      s
    • Pulsar planet
      Pulsar planet

      Pulsar planets are planets that are found orbiting pulsars, or rapidly rotating neutron stars. The first such planet to be discovered was around a millisecond pulsar and was the first extrasolar planet to be discovered....
      s
    • Hot Neptune
      Hot Neptune

      A hot Neptune is a hypothetical extrasolar planet in an orbit close to its star . The mass of a hot Neptune resembles the Planetary core and envelope mass of Uranus and Neptune....
      s / Super-Earth
      Super-Earth

      A Super-Earth is an extrasolar planet more massive than the Earth but less massive than a gas giant. The term "super-Earth" refers only to the mass of the planet and does not imply anything about the surface conditions or habitability: in particular it does not imply that the planet would have a similar temperature or environment to Earth....
      s
    • Transiting planets
    • Rogue
      Rogue Planet

      Rogue Planet may refer to:In literature:* Rogue Planet , a Dan Dare story that ran in the original Eagle comic from Volume 6, Issue 48 to Volume 8, Issue 7...
       / Interstellar planet
      Interstellar planet

      A rogue planet is an object which has equivalent mass to a planet and is not gravitationally bound to any star, and that therefore moves through outer space as an independent object....
      s
    • Hypothetical planet types
      • Chthonian planet
        Chthonian planet

        A Chthonian planet , is a hypothetical class of celestial objects resulting from the stripping away of a gas giant's hydrogen and helium celestial body atmosphere and outer layers....
        s
      • Ocean planet
        Ocean planet

        An ocean planet is a hypothetical type of planet whose surface is completely covered with an ocean of water.Planetary objects that form in the outer solar system begin as a comet-like mixture of roughly 50% water and 50% rock by weight....
        s
      • Trojan planet
        Trojan planet

        A Trojan planet is a planet orbiting in the Lagrangian point of a star and a massive orbiting body, a gas giant or potentially a smaller companion star....
        s
  • Brown dwarf
    Brown dwarf

    Brown dwarfs are sub-star objects with a mass below that necessary to maintain hydrogen-burning nuclear fusion reactions in their cores, as do stars on the main sequence, but which have fully convective surfaces and interiors, with no chemical differentiation by depth....
    s
    • L-type star
    • T-type star
    • Sub-brown dwarf
      Sub-brown dwarf

      A sub-brown dwarf is a planetary-mass object whose mass is smaller than the low-mass cut-off for brown dwarfs . Unlike proper brown dwarfs, they are not massive enough to nuclear fusion deuterium....
      s
  • Star
    Star

    A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
    s by spectral type
  • Blue stars
  • Blue-white stars
  • White stars
  • Yellow-white stars
  • Yellow stars
  • Orange stars
  • Red stars
    • Peculiar star
      Peculiar star

      In astrophysics, peculiar stars have distinctly unusual metal abundances, at least in their surface layers.Chemically peculiar stars are common among hot main sequence stars....
      s
      • Carbon star
        Carbon star

        A carbon star is a late type giant star similar to a 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 an...
        s
      • S-type star
        S-type star

        A star with stellar classification S is a late-type giant star whose spectrum displays bands from zirconium oxide in addition to titanium oxide which is characteristically exhibited by K and M class giant stars....
        s
      • Shell star
        Shell star

        A shell star is a star having a spectrum that exhibits features indicating a circumstellar disc of gas surrounding the star at the equator. The shell stars are fast rotators, giving a partial explanation on the mechanism, but shell stars are still considered enigmatic....
        s
      • Wolf-Rayet star
        Wolf-Rayet star

        Wolf-Rayet stars are evolved, massive stars , which are losing mass rapidly by means of a very strong solar wind, with speeds up to 2000 km/s....
        s
      • Peculiar A-type stars
      • Metallic A-type stars
      • Barium star
        Barium star

        Barium stars are G to K class giant star, whose Star classification indicate an overabundance of s-process elements by the presence of singly ionized barium, Ba II, at wavelength 455.4nm....
        s
      • P Cygni stars
      • Blue straggler
        Blue straggler

        Blue stragglers are stars in open cluster or globular clusters that are stellar classification than other cluster stars having the same luminosity....
        s
  • Star
    Star

    A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
    s by luminosity class
    • Subdwarf star
      Subdwarf star

      A subdwarf star, sometimes denoted by "sd", is luminosity class VI under the stellar classification#Yerkes spectral classification system. They are defined as stars with luminosity 1.5 to 2 Absolute magnitude lower than that of main-sequence stars of the same spectral type....
      s
    • Dwarf
      Dwarf star

      The term dwarf star refers to a variety of distinct classes of stars.* Dwarf star alone generally refers to any main sequence star, a star of Stellar classification#Yerkes spectral classification V....
       (Main sequence
      Main sequence

      The main sequence is a continuous and distinctive band of stars that appear on plots of stellar Color index versus brightness. These color-absolute magnitude plots are known as Hertzsprung-Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell....
      ) star
      Star

      A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
      s
    • Subgiant stars
    • Giant star
      Giant star

      A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same effective temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun....
      s
    • Bright giant stars
    • Supergiant star
      Supergiant

      Supergiants are among the most massive stars. In the Hertzsprung-Russell diagram they occupy the top region of the diagram. In the spectral classification supergiants are class Ia or Ib ....
      s
    • Hypergiant stars
  • Star
    Star

    A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
    s by population
    • Population III stars
    • Population II stars
      • Halo stars
      • Thick disk stars
    • Population I stars
  • Star
    Star

    A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
    s by stellar evolution
    Stellar evolution

    Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only few millions of years to trillions of years , considerably more than the age of the universe....
    • Protostar
      Protostar

      A protostar is a large star that forms by contraction out of the gas of a giant molecular cloud in the interstellar medium. The protostellar phase is an early stage in the process of star formation....
      s
    • Young stellar object
      Young stellar object

      Young stellar object denotes a star in its early stage of evolution.This class consists of two groups of objects: protostars and pre-main sequence stars....
      s
    • Main sequence star
      Main sequence

      The main sequence is a continuous and distinctive band of stars that appear on plots of stellar Color index versus brightness. These color-absolute magnitude plots are known as Hertzsprung-Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell....
      s
    • Red giant star
      Red giant

      A red giant is a luminous giant star of low or intermediate mass that is in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower....
      s
    • Red supergiant
      Red supergiant

      Red supergiants are supergiant stars of spectral classification K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive....
       stars
    • Blue supergiant
      Blue supergiant

      Blue supergiants are supergiant stars of spectral classification O or B.They are extremely hot and bright, with surface temperatures of 20,000-50,000 K....
       stars
    • Wolf-Rayet star
      Wolf-Rayet star

      Wolf-Rayet stars are evolved, massive stars , which are losing mass rapidly by means of a very strong solar wind, with speeds up to 2000 km/s....
      s
    • White dwarf star
      White dwarf

      A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. Because a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth, it is very density....
      s
    • Neutron star
      Neutron star

      A neutron star is a type of compact star that can result from the gravitational collapse of a massive star during a Type II supernova, Type Ib and Ic supernovae supernova event....
      s
  • Variable star
    Variable star

    A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth....
    s
    • Intrinsic variables
      • Pulsating variables
        • Cepheid variable
          Cepheid variable

          A Cepheid variable or Cepheid is a member of a particular class of variable stars, notable for a fairly tight correlation between their period of Radial pulsations and absolute luminosity....
          s
        • W Virginis variable
          W Virginis variable

          A W Virginis variable is a variable star similar to a Cepheid variable. However, using the formula for W Virginis variables to calculate distance of a Cepheid variable will yield a value that is too small, a mistake that Edwin Hubble made while observing Andromeda Galaxy....
          s
        • Delta Scuti variable
          Delta Scuti variable

          A Delta Scuti variable is a variable star which exhibits variations in its luminosity due to both radial and non-radial pulsations of the star's surface....
          s
        • RR Lyrae variable
          RR Lyrae variable

          RR Lyrae variables are variable stars often used as standard candles.RR Lyrae are pulsating horizontal branch stars, with a mass of around half the Sun's....
          s
        • Mira variable
          Mira variable

          Mira variables, named after the star Mira , are a class of pulsating variable stars characterized by very red colors, pulsation periods longer than 100 days, and light amplitudes greater than one Apparent magnitude....
          s
        • Semiregular variables
        • Irregular variable
          Irregular variable

          An irregular variable is a type of variable star in which variations in brightness show no regular periodicity. There are two main sub-types of irregular variable: eruptive and pulsating....
          s
        • Beta Cephei variable
          Beta Cephei variable

          Beta Cephei variables are variable stars which exhibit variations in their brightness due to pulsations of the stars' surfaces. The point of maximum brightness roughly corresponds to the maximum contraction of the star....
          s
        • Alpha Cygni variable
          Alpha Cygni variable

          Alpha Cygni variables are Variable star which exhibit non-radial pulsations. They are supergiant stars of Stellar classification B or A. Variations in brightness on the order of 0.1 apparent magnitude are associated with the radial pulsations, which often seem irregular variable, due to Beat ing of multiple pulsation periods....
          s
        • RV Tauri variable
          RV Tauri variable

          RV Tauri variables are supergiant variable stars. They exhibit changes in luminosity which are tied to radial pulsations of their surfaces. Their changes in brightness are also correlated with changes in their stellar classification....
          s
      • Eruptive variables
        • Flare star
          Flare star

          A flare star is a variable star which can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to magnetic reconnection in the atmospheres of the stars....
          s
        • T Tauri variables
        • FU Orionis variables
        • R Coronae Borealis variable
          R Coronae Borealis variable

          A R Coronae Borealis variable is an eruptive variable star that varies in luminosity in two modes, one low amplitude pulsation , and one irregular unpredictably sudden fading by 1 to 9 magnitudes....
          s
        • Luminous blue variable
          Luminous blue variable

          Luminous blue variables, also known as S Doradus variables, are very bright, blue, hypergiant variable stars, named after S Doradus the brightest star of the Large Magellanic Cloud....
          s
      • Cataclysmic variables
        • Symbiotic variables
        • Dwarf nova
          Dwarf nova

          A dwarf nova is a type of cataclysmic variable, consisting of a close binary star system in which one of the components is a white dwarf, which accretion disk matter from its companion....
          e
        • Nova
          Nova

          A nova is a cataclysmic nuclear explosion caused by the Accretion of hydrogen onto the surface of a white dwarf star. Novae are not to be confused with Type Ia supernovae, or another form of stellar explosion first announced by Caltech in May 2007, Luminous Red Novae....
          e
        • Supernova
          Supernova

          A supernova is a Astronomy#Stellar astronomy explosion. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months....
          e
          • Type I supernovae
          • Type II supernova
            Type II supernova

            File:HST SN 1987A 20th anniversary.jpgType II supernova, or core-collapse supernova, is a sub-category of cataclysmic variable stars that results from the internal collapse and violent explosion of a massive star....
            e
        • Hypothetical
          • Collapsars or Hypernova
            Hypernova

            Hypernova refers to an exceptionally large star that collapses at the end of its lifespan?for example, a collapsar, or a large supernova....
            e
    • Extrinsic variables
      • Rotating variables
        • Alpha2 CVn stars
        • Rotating ellipsoidal variable
          Rotating ellipsoidal variable

          Rotating ellipsoidal variables are a class of variable star. They are close binary star systems whose components are ellipsoid. They are not eclipsing, but fluctuations in apparent magnitude occur due to changes in the amount of light emitting area visible to the observer....
          s
      • Eclipsing binaries
        • Algol star
          Algol variable

          Algol variables or Algol type binaries are a class of eclipse binary stars. When the cooler component passes in front of the hotter one, part of the latter's light is blocked, and the total brightness of the binary, as viewed from Earth, temporarily decreases....
          s, Algol
          Algol

          Algol , known colloquially as the Demon Star, is a bright star in the constellation Perseus . It is one of the best known eclipsing binary, the first such star to be discovered, and also one of the first variable stars to be discovered....
        • Beta Lyrae stars
        • W Ursae Majoris stars
  • Compact star
    Compact star

    In astronomy, the term compact star is used to refer collectively to white dwarfs, neutron stars, other exotic star, and black holes. These objects are all small for their mass....
    s
    • White dwarf
      White dwarf

      A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. Because a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth, it is very density....
      s
      • Black dwarf
        Black dwarf

        A black dwarf is a List of hypothetical astronomical objects, created when a white dwarf becomes sufficiently cool to no longer emit significant heat or light....
        s
    • Neutron star
      Neutron star

      A neutron star is a type of compact star that can result from the gravitational collapse of a massive star during a Type II supernova, Type Ib and Ic supernovae supernova event....
      s
      • Magnetar
        Magnetar

        A magnetar is a neutron star with an extremely powerful magnetic field, the decay of which powers the emission of copious amounts of high-energy electromagnetic radiation, particularly X-rays and gamma-rays....
        s
      • Pulsar
        Pulsar

        Pulsars are highly magnetized, rotating neutron stars that emit a beam of electromagnetic radiation. The observed periods of their pulses range from 1.4 milliseconds to 8.5 seconds....
        s
    • Hypothetical stars
      • Quark star
        Quark star

        A quark star or strange star is a hypothetical type of exotic star composed of quark matter, or strange matter. These are ultra-dense Phase s of degenerate matter theorized to form inside particularly massive neutron stars....
        s
      • Preon star
        Preon star

        A preon star is a List of hypothetical astronomical objects compact star made of preons, a group of theoretical subatomic particles that may compose quarks and leptons....
        s
    • Black hole
      Black hole

      In general relativity, a black hole is a region of space in which the gravitational field is so powerful that nothing, including electromagnetic radiation , can escape its pull after having fallen past its event horizon....
      s
      • Intermediate-mass black hole
        Intermediate-mass black hole

        An Intermediate-mass black hole is a black hole whose mass is significantly more than stellar black holes yet far less than supermassive black holes ....
        s
      • Supermassive black hole
        Supermassive black hole

        A supermassive black hole is a black hole with a mass of an order of magnitude between 105 and 1010 solar masses. Most, if not all, galaxy, including the Milky Way, are believed to contain supermassive black holes at their centers....
        s
  • Gamma ray burst
    Gamma ray burst

    Gamma-ray bursts are the most Luminosity Electromagnetism events occurring in the universe since the Big Bang. They are flashes of gamma rays emanating from seemingly random places in deep space at random times....
    s
  • Planetary system
    Planetary system

    A planetary system consists of the various non-stellar objects orbiting a star such as planets, natural satellites, asteroids, meteoroids, comets, and cosmic dust....
    s
  • Star system
    Star system

    A star system or stellar system is a small number of stars which orbit each other, bound by gravitation. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems....
    s
    • Single star systems
      Star

      A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
      • Solar system
        Solar System

        The Solar System consists of the Sun and those Astronomical object bound to it by gravity: the eight planets and five dwarf planets, their 173 known Natural satellite, and billions of Small Solar System body....
    • Multiple star systems
      Star system

      A star system or stellar system is a small number of stars which orbit each other, bound by gravitation. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems....
      • Binary star
        Binary star

        A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star or secondary....
        s
        • Optical binaries
        • Visual binaries
        • Astrometric binaries
        • Spectroscopic binaries
        • Eclipsing binaries
        • Close binaries
          • Detached binaries
          • Semidetached binaries
          • Contact binaries
            Contact binary

            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 a common gaseous envelope....
          • Unresolved binaries
        • X-ray binaries
          X-ray binary

          X-ray binaries are a class of binary stars that are luminous in X-rays.The X-rays are produced by matter falling from one component to the other component, which is compact: a white dwarf, neutron star, or black hole....
        • X-ray burster
          X-ray burster

          X-ray bursters are one class of X-ray binary exhibiting periodic and rapid increases in Luminosity peaked in the X-ray regime of the Electromagnetic spectrum....
          s
      • Triple star systems
  • Stellar groupings
    • Star cluster
      Star cluster

      Star clusters or star clouds are groups of stars which are gravity bound. Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars, while open clusters generally contain less than a few hundred members, and are often very young....
      s
      • Stellar association
        Stellar association

        A stellar association is a very loose star cluster, looser than both open clusters and globular clusters. Stellar associations will normally contain from 10 to 100 or more stars....
        s
      • Open cluster
        Open cluster

        An open cluster is a star cluster of up to a few thousand stars that were formed from the same giant molecular cloud, and are still loosely gravity to each other....
        s
      • Globular cluster
        Globular cluster

        A globular cluster is a sphere collection of stars that orbits a Galactic Center as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers....
        s
    • Constellation
      Constellation

      A constellation is a group of stars that appear to have a physical proximity in the sky. The stars in a constellation are often vastly distant from each other, but they appear close to each other from the perspective of Earth....
      s
    • Asterisms
      Asterism (astronomy)

      In astronomy, an asterism is a pattern of stars seen in Earth's sky which is not an official constellation. Like constellations, they are composed of stars which, while they are in the same general direction, are not physically related, often being at significantly different distances from Earth....
  • Galaxy
    Galaxy

    A galaxy is a massive, gravitation system that consists of stars and stellar remnants, an interstellar medium of gas and cosmic dust, and an important but poorly-understood component tentatively dubbed dark matter....
     components
    • Galactic bulges
      • Galactic bars
    • Galactic rings
    • Spiral arms
    • Thin disks
    • Thick disks
    • Galactic halo
      Galactic halo

      The term galactic halo is used to denote an extended, roughly spherical component of a galaxy, which extends beyond the main, visible component....
      s
    • Galactic corona
      Galactic corona

      The terms galactic corona and gaseous corona have been used in the first decade of the twenty-first century to describe a hot, ionised, gaseous component in the Galactic halo of the Milky Way....
      e
  • Galaxies
    Galaxy

    A galaxy is a massive, gravitation system that consists of stars and stellar remnants, an interstellar medium of gas and cosmic dust, and an important but poorly-understood component tentatively dubbed dark matter....
    • Galaxies
      Galaxy

      A galaxy is a massive, gravitation system that consists of stars and stellar remnants, an interstellar medium of gas and cosmic dust, and an important but poorly-understood component tentatively dubbed dark matter....
       by morphology
      • Spiral galaxies
        Spiral galaxy

        A spiral galaxy is a galaxy belonging to one of the three main galaxy morphological classification originally described by Edwin Hubble in his 1936 work ?The Realm of the Nebulae? and, as such, forms part of the Hubble sequence....
      • Barred spiral galaxies
        Barred spiral galaxy

        A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in approximately half of all spiral galaxies....
      • Lenticular galaxies
        Lenticular galaxy

        File:File-Ngc5866 hst big.pngA lenticular galaxy is a type of galaxy which is intermediate between an elliptical galaxy and a spiral galaxy in galaxy morphological classification schemes....
      • Elliptical galaxies
        Elliptical galaxy

        An elliptical galaxy is a galaxy having an approximately ellipsoid shape and a smooth, nearly featureless brightness profile. They range in shape from nearly spherical to highly flattened and in size from hundreds of millions to over one trillion stars....
      • Ring galaxies
        Ring galaxy

        A ring galaxy is a galaxy with a ring-like appearance. The ring consists of massive, relatively young blue stars, which are extremely bright. The central region contains relatively little luminous matter....
      • Irregular galaxies
        Irregular galaxy

        Some galaxies do not have a regular shape, like a spiral galaxy or an elliptical galaxy. Those galaxies are known as irregular galaxies. Their shape is uncommon....
    • Galaxies
      Galaxy

      A galaxy is a massive, gravitation system that consists of stars and stellar remnants, an interstellar medium of gas and cosmic dust, and an important but poorly-understood component tentatively dubbed dark matter....
       by size
      • Brightest cluster galaxies
        Brightest cluster galaxy

        Brightest cluster galaxy is defined as the brightest galaxy in a cluster of galaxies. BCGs include the most massive galaxies in the universe....
      • Giant ellipticals
      • Dwarf galaxies
        Dwarf galaxy

        A dwarf galaxy is a small galaxy composed of up to several billion stars, a small number compared to our own Milky Way's 200-400 billion stars....
    • Active galaxies
      • Quasar
        Quasar

        A Quasi-stellar radio source is a powerfully energetic and distant active galactic nucleus. Quasars were first identified as being high redshift sources of electromagnetic energy, including radio frequency and visible spectrum, that were point-like, similar to stars, rather than extended sources similar to galaxy....
        s
        • Blazar
          Blazar

          A blazar is a very compact and highly variable energy source associated with a presumed supermassive black hole at the center of a host galaxy. Blazars are among the most violent phenomena in the universe and are an important topic in extragalactic astronomy....
          s
      • Radio galaxies
        Radio galaxy

        Radio galaxies and their relatives, radio-loud quasars and blazars, are types of active galaxy that are very luminous at radio waves . The radio emission is due to the synchrotron radiation....
      • Seyfert galaxies
        Seyfert galaxy

        Seyfert galaxies are a class of galaxy with nuclei that produce spectral line emission from highly ionized gas, named after Carl Keenan Seyfert, the astronomer who first identified the class in 1943....
      • Starburst galaxies
        Starburst galaxy

        A starburst galaxy is a galaxy in the process of an exceptionally high rate of star formation, compared to the usual star formation rate seen in most galaxies....
    • Dark galaxies
  • Galaxy group
    Galaxy groups and clusters

    Galaxy groups and clusters are the largest gravitationally-bound objects to have arisen thus far in the process of cosmic structure formation....
    s
  • Galaxy cluster
    Galaxy groups and clusters

    Galaxy groups and clusters are the largest gravitationally-bound objects to have arisen thus far in the process of cosmic structure formation....
    s
  • Supercluster
    Supercluster

    Superclusters are large groups of smaller galaxy groups and clusters and are among the Large-scale structure of the cosmos of the cosmos....
    s
  • Filaments
    Galaxy filament

    In physical cosmology, filaments are the largest known structures in the universe, thread-like structures with a typical length of 50 to 80 parsec#Megaparsecs_and_gigaparsecss that form the boundaries between large void in the universe....
     / Voids
    Void (astronomy)

    In astronomy, voids are the empty spaces between galaxy filament, the largest-scale structures in the Universe, that contain very few, or no, galaxies....
  • Circumstellar matter
    • Debris disk
      Debris disk

      A debris disk is a ring-shaped circumstellar disk of dust and debris in orbit around a star. Debris disks have been found around both evolved and young stars, as well as at least one debris disk in orbit around a neutron star....
      s
    • Interplanetary medium
      Interplanetary medium

      The interplanetary medium is the material which fills the solar systems and through which all the larger solar system bodies such as planets, asteroids and comets move....
    • Protoplanetary disk
      Protoplanetary disk

      A protoplanetary disk is a rotating circumstellar disk of dense gas surrounding a young newly formed star, a T Tauri star or Herbig Ae/Be stars....
      s
  • Interstellar medium
    Interstellar medium

    In astronomy, the interstellar medium is the gas and cosmic dust that pervade interstellar space: the matter that exists between the stars within a galaxy....
  • Nebula
    Nebula

    A nebula is an interstellar cloud of cosmic dust, hydrogen gas and Plasma . Originally nebula was a general name for any extended astronomy astronomical object, including galaxy beyond the Milky Way ....
    e
    • Emission nebula
      Emission nebula

      An emission nebula is a cloud of ionized gas emitting light of various colors. The most common source for ionization are high-energy photons emitted from a nearby hot star....
      e
      • Planetary nebula
        Planetary nebula

        A planetary nebula is an emission nebula consisting of a glowing shell of gas and Plasma formed by certain types of stars when they die. The name originated in the 18th century because of their similarity in appearance to gas giants when viewed through small optical telescopes, and is unrelated to the planets of the solar system....
        e
      • Supernova remnant
        Supernova remnant

        A supernova remnant is the structure resulting from the gigantic explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way....
        s
      • Plerions
      • H II region
        H II region

        An H II region is a cloud of glowing gas and Plasma , sometimes several hundred light-years across, in which star formation is taking place....
        s
    • Reflection nebula
      Reflection nebula

      In Astronomy, reflection nebulae are interstellar cloud of dust which are simply reflecting the light of a nearby star or stars. The energy from the nearby star, or stars, is insufficient to ionize the gas of the nebula to create an emission nebula, but is enough to give sufficient scattering to make the dust visible....
      e
    • Dark nebula
      Dark nebula

      A dark nebula is a type of interstellar cloud that is so dense that it obscures the light from the background emission nebula or reflection nebula or that it blocks out background stars ....
      e
      • Molecular cloud
        Molecular cloud

        A molecular cloud, sometimes called a stellar nursery if star formation is occurring within, is a type of interstellar cloud whose density and size permits the formation of molecules, most commonly molecular hydrogen ....
        s
      • Bok globule
        Bok globule

        A Bok globule is a dark cloud of dense dust and gas in which star formation sometimes takes place. Bok globules are found within H II regions, and typically have a mass of about 2 to 50 solar masses contained within a region about a light year or so across ....
        s
      • Proplyds
    • H I region
      H I region

      An H I region is an interstellar cloud composed of neutral atomic hydrogen . These regions are non-luminous, save for emission of the hydrogen line spectral line....
      s
  • Intergalactic medium
  • Cosmic microwave background radiation
    Cosmic microwave background radiation

    In physical cosmology, the cosmic microwave background radiation CMB is a form of electromagnetic radiation filling the universe. With a traditional optical telescope, the space between stars and galaxies is pitch black....
  • Dark matter
    Dark matter

    In astronomy and physical cosmology, dark matter is Hypothesis matter that is undetectable by its emitted electromagnetic radiation, but whose presence can be inferred from gravity effects on visible matter....
    • MACHO
      Massive compact halo object

      Massive astrophysical compact halo object, or MACHO, is a general name for any kind of astronomy body that might explain the apparent presence of dark matter in galaxy galactic halo....
      s
    • WIMPs
  • Hypothetical
    • Cosmic string
      Cosmic string

      A cosmic string is a hypothetical 1-dimensional topological defect in various fields. Cosmic strings are hypothesized to form when the field undergoes a phase change in different regions of spacetime, resulting in condensations of energy density at the boundaries between regions....
    • Domain wall
      Domain wall

      A domain wall is a term used in physics which can have one of two distinct but similar meanings in either magnetism or string theory. It is also used as technobabble in science fiction....


    See also


    • List of solar system objects
      List of solar system objects

      The following is a list of Solar System objects by orbit, ordered by increasing distance from the Sun. Most named objects in this list have a diameter of 500 km or more....
    • Lists of astronomical objects
      Lists of astronomical objects

      This is a partial list of the various lists of astronomical objects.* Geological features of the solar system* List of planets** List of natural satellites...
    • List of light sources
      List of light sources

      This is a list of sources of light, including both natural and artificial sources, and both processes and devices....