344 relations: Absolute magnitude, Active galactic nucleus, Age of the universe, Al-Andalus, Al-Biruni, Alpha Sculptoris, Anaxagoras, Ancient Greek, Ancient Greek philosophy, Andromeda (constellation), Andromeda Galaxy, Andromeda–Milky Way collision, Angular momentum, Angular resolution, Antarctic Circle, Anthropogeny, Apparent magnitude, Apsis, Aquila (constellation), Ara (constellation), Arctic Circle, Arianrhod, Aristotle, Associated Press, Asteroid, Astronomical unit, Astrophotography, Athena, Atmosphere, Atmosphere of Earth, Auriga (constellation), Avempace, Baade's Window, Babylonia, Barred spiral galaxy, Baryon, BBC, BD +17° 3248, Beta Comae Berenices, Big Bang, Billion years, Binary system, Black hole, Boötes void, Bortle scale, Brown dwarf, Bulge (astronomy), Canis Major, Canis Major Overdensity, Carina (constellation), ..., Carina Dwarf Spheroidal Galaxy, Carina–Sagittarius Arm, Cassiopeia (constellation), Cayrel's Star, Celestial equator, Celestial sphere, Centaurus, Cepheid variable, Cepheus (constellation), Chandra X-ray Observatory, Chemical element, Circinus, Circle of latitude, Circumstellar habitable zone, Classical Latin, Coalsack Nebula, Color index, Colure, Comet, Conjunction (astronomy), Constellation, Contiguous United States, Corona Borealis, Cosmic Background Explorer, Cosmic distance ladder, Cosmic dust, Cosmic microwave background, Crux, Cygnus (constellation), Dark matter, Dark matter halo, Dôn, Declination, Degree (angle), Democritus, Density wave theory, Diameter, Differential rotation, Disc galaxy, Doppler effect, Draco Dwarf, Dragon, Dwarf galaxy, Earth's orbit, Ecliptic, Edwin Hubble, Electromagnetic radiation, Elise Otté, Elliptic orbit, Elliptical galaxy, Enûma Eliš, Enlil, Epoch (astronomy), Equator, European Southern Observatory, European Space Agency, Exocomet, Exoplanet, Expansion of the universe, Extinction event, Fermi Gamma-ray Space Telescope, Fornax Dwarf, Frame of reference, Gaia (spacecraft), Galactic anticenter, Galactic astronomy, Galactic Center, Galactic coordinate system, Galactic habitable zone, Galactic halo, Galactic plane, Galactic ridge, Galactic year, Galaxy, Galaxy cluster, Galaxy color–magnitude diagram, Galaxy merger, Galaxy morphological classification, Galaxy rotation curve, Galileo Galilei, Gemini (constellation), Geometry, Globular cluster, Gould Belt, Gravitational microlensing, Gravity, Great Attractor, Great Debate (astronomy), Great Rift (astronomy), Greek mythology, Grus (constellation), Gwydion, H II region, Harlow Shapley, HD 140283, HE 1523-0901, Heber Doust Curtis, Helium, Hera, Heracles, Hercules (constellation), Hermes, High-velocity cloud, Horizon, Hubble sequence, Hubble's law, Hydra (constellation), Hydrogen, Hydrogen atom, Hydrogen line, Ibn Qayyim al-Jawziyya, Immanuel Kant, Inertial frame of reference, Interstellar medium, Isotope, Isotopes of thorium, Journal of the Royal Astronomical Society of Canada, Kepler (spacecraft), Kepler's laws of planetary motion, Kepler-32, Klemperer rosette, Koine Greek, Lacerta, Laniakea Supercluster, Large Magellanic Cloud, Laser guide star, Latin, Leo I (dwarf galaxy), Leo II (dwarf galaxy), Light pollution, Light-year, Limiting magnitude, Line (geometry), List of galaxies, List of nearest bright stars, List of nearest stars and brown dwarfs, Local Bubble, Local Group, Local Interstellar Cloud, Los Angeles Times, Magellanic Clouds, Magellanic Stream, Magnetic field, Magnitude (astronomy), Marduk, Mass, Measurement, Meridian (astronomy), Messier object, Metallicity, Meteorology (Aristotle), Metre per second, Modified Newtonian dynamics, Molecular cloud, Monoceros, Monoceros Ring, Monthly Notices of the Royal Astronomical Society, Moonlight, Mount Wilson Observatory, Musca, Muslim world, Myr, Naked eye, NASA, Nasir al-Din al-Tusi, National god, Near 3 kpc Arm, Nebula, Neoplatonism, Neptune, Neutron star, Night sky, Nippur, Norma (constellation), Norma Arm, Nova, Nucleocosmochronology, Olympiodorus the Younger, Omega Centauri, Online Etymology Dictionary, Oort constants, Open cluster, Ophiuchus, Optical telescope, Orbital period, Orbital speed, Ordinal number (linguistics), Orion (constellation), Orion Arm, Parallax, Paranal Observatory, Parkes Observatory, Parsec, Peculiar velocity, Perseus (constellation), Perseus Arm, Persian people, Phys.org, Planck (spacecraft), Planet, Polar coordinate system, Proceedings of the National Academy of Sciences of the United States of America, Puppis, Quarter (United States coin), R-process, Radio astronomy, Radionuclide, Red dwarf, Red giant, Redshift, Refraction, Rensselaer Polytechnic Institute, Rest frame, Retrograde and prograde motion, Right ascension, Rogue planet, RR Lyrae variable, Rural area, Sagitta, Sagittarius (constellation), Sagittarius A*, Sagittarius Dwarf Spheroidal Galaxy, Satellite galaxies of the Milky Way, Scorpius, Sculptor Dwarf Galaxy, Scutum (constellation), Scutum–Centaurus Arm, Sextans Dwarf Spheroidal, Shapley Supercluster, Simple harmonic motion, Sloan Digital Sky Survey, Small Magellanic Cloud, Smith's Cloud, SN 1885A, Solar analog, Solar apex, Solar mass, Solar System, Space.com, Special relativity, Spectral line, Speed of light, Spiral galaxy, Spitzer Space Telescope, Stanford Encyclopedia of Philosophy, Star, Star formation, Stellar collision, Sublunary sphere, Sumer, Sun, Supercluster, Supermassive black hole, Surface brightness, Suzaku (satellite), Swinburne University of Technology, Taurus (constellation), Terrestrial planet, The Astrophysical Journal, The New York Times, The Washington Post, Thick disk, Thin disk, Thomas Wright (astronomer), Thorium, Tiamat, Triangulum Australe, Trickster, Universe, Universe Today, University of California, Berkeley, University of Cambridge, Uranium-238, Ursa Minor Dwarf, Vega, Vela (constellation), Very Large Telescope, Very Long Baseline Array, Virgo (constellation), Virgo Cluster, Virgo Stellar Stream, Virgo Supercluster, VRML, Vulpecula, Welsh language, White dwarf, Wilkinson Microwave Anisotropy Probe, William Herschel, William Parsons, 3rd Earl of Rosse, X-ray, XMM-Newton, Zenith, Zodiac, Zone of Avoidance. 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Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale.
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.
In physical cosmology, the age of the universe is the time elapsed since the Big Bang.
Al-Andalus (الأنْدَلُس, trans.; al-Ándalus; al-Ândalus; al-Àndalus; Berber: Andalus), also known as Muslim Spain, Muslim Iberia, or Islamic Iberia, was a medieval Muslim territory and cultural domain occupying at its peak most of what are today Spain and Portugal.
Abū Rayḥān Muḥammad ibn Aḥmad Al-Bīrūnī (Chorasmian/ابوریحان بیرونی Abū Rayḥān Bērōnī; New Persian: Abū Rayḥān Bīrūnī) (973–1050), known as Al-Biruni (البيروني) in English, was an IranianD.J. Boilot, "Al-Biruni (Beruni), Abu'l Rayhan Muhammad b. Ahmad", in Encyclopaedia of Islam (Leiden), New Ed., vol.1:1236–1238.
Alpha Sculptoris, Latinized from α Sculptoris, is the Bayer designation for a blue-white star in the southern constellation of Sculptor.
Anaxagoras (Ἀναξαγόρας, Anaxagoras, "lord of the assembly"; BC) was a Pre-Socratic Greek philosopher.
The Ancient Greek language includes the forms of Greek used in ancient Greece and the ancient world from around the 9th century BC to the 6th century AD.
Ancient Greek philosophy arose in the 6th century BC and continued throughout the Hellenistic period and the period in which Ancient Greece was part of the Roman Empire.
Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy and remains one of the 88 modern constellations.
The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224, is a spiral galaxy approximately 780 kiloparsecs (2.5 million light-years) from Earth, and the nearest major galaxy to the Milky Way.
The Andromeda–Milky Way collision is a galactic collision predicted to occur in about 4 billion years between two galaxies in the Local Group—the Milky Way (which contains the Solar System and Earth) and the Andromeda Galaxy.
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational equivalent of linear momentum.
Angular resolution or spatial resolution describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object, thereby making it a major determinant of image resolution.
The Antarctic Circle is the most southerly of the five major circles of latitude that mark maps of the Earth.
Anthropogeny is the study of human origins.
The apparent magnitude of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth.
An apsis (ἁψίς; plural apsides, Greek: ἁψῖδες) is an extreme point in the orbit of an object.
Aquila is a constellation on the celestial equator.
Ara (Latin: "The Altar") is a southern constellation situated between Scorpius and Triangulum Australe.
The Arctic Circle is the most northerly of the five major circles of latitude as shown on maps of Earth.
Arianrhod is a figure in Welsh mythology who plays her most important role in the Fourth Branch of the Mabinogi.
Aristotle (Ἀριστοτέλης Aristotélēs,; 384–322 BC) was an ancient Greek philosopher and scientist born in the city of Stagira, Chalkidiki, in the north of Classical Greece.
The Associated Press (AP) is a U.S.-based not-for-profit news agency headquartered in New York City.
Asteroids are minor planets, especially those of the inner Solar System.
The astronomical unit (symbol: au, ua, or AU) is a unit of length, roughly the distance from Earth to the Sun.
Astrophotography is a specialized type of photography for recording photos of astronomical objects, celestial events, and areas of the night sky.
Athena; Attic Greek: Ἀθηνᾶ, Athēnā, or Ἀθηναία, Athēnaia; Epic: Ἀθηναίη, Athēnaiē; Doric: Ἀθάνα, Athānā or Athene,; Ionic: Ἀθήνη, Athēnē often given the epithet Pallas,; Παλλὰς is the ancient Greek goddess of wisdom, handicraft, and warfare, who was later syncretized with the Roman goddess Minerva.
An atmosphere is a layer or a set of layers of gases surrounding a planet or other material body, that is held in place by the gravity of that body.
The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity.
Auriga is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century astronomer Ptolemy.
Avempace (– 1138) is the Latinate form of Ibn Bâjja (ابن باجه), full name Abû Bakr Muḥammad Ibn Yaḥyà ibn aṣ-Ṣâ’igh at-Tûjîbî Ibn Bâjja al-Tujibi (أبو بكر محمد بن يحيى بن الصائغ), was an Arab Andalusian polymath: his writings include works regarding astronomy, physics, and music, as well as philosophy, medicine, botany, and poetry.
Baade's Window is an area of the sky with relatively low amounts of interstellar "dust" along the line of sight from the Earth.
Babylonia was an ancient Akkadian-speaking state and cultural area based in central-southern Mesopotamia (present-day Iraq).
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars.
A baryon is a composite subatomic particle made up of three quarks (a triquark, as distinct from mesons, which are composed of one quark and one antiquark).
The British Broadcasting Corporation (BBC) is a British public service broadcaster.
BD +17° 3248 is an old Population II star located at a distance of roughly in the Galactic Halo.
Beta Comae Berenices (β Comae Berenices, β Com) is a main sequence dwarf star in the northern constellation of Coma Berenices.
The Big Bang theory is the prevailing cosmological model for the universe from the earliest known periods through its subsequent large-scale evolution.
A billion years (109 years) is a unit of time on the petasecond scale, more precisely equal to seconds.
A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter (also see animated examples).
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.
The Boötes void (or the Great Void) is an enormous, approximately spherically-shaped region of space, containing very few galaxies.
The Bortle scale is a nine-level numeric scale that measures the night sky's brightness of a particular location.
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.
Canis Major is a constellation in the southern celestial hemisphere.
The Canis Major Dwarf Galaxy (CMa Dwarf) or Canis Major Overdensity (CMa Overdensity) is a disputed dwarf irregular galaxy in the Local Group, located in the same part of the sky as the constellation Canis Major.
Carina is a constellation in the southern sky.
The Carina Dwarf Spheroidal Galaxy is a dwarf galaxy in the Carina constellation.
The Carina–Sagittarius Arm (also known as Sagittarius Arm or Sagittarius–Carina Arm, labeled -I) is generally thought to be a minor spiral arm of the Milky Way galaxy.
Cassiopeia is a constellation in the northern sky, named after the vain queen Cassiopeia in Greek mythology, who boasted about her unrivalled beauty.
BPS CS31082-0001, named Cayrel's Star, is an old Population II star located in a distance of 4 kpc in the Galactic Halo.
The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth.
In astronomy and navigation, the celestial sphere is an abstract sphere with an arbitrarily large radius concentric to Earth.
Centaurus is a bright constellation in the southern sky.
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.
Cepheus is a constellation in the northern sky, which is named after Cepheus (a King in the Greek mythology).
The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space observatory launched on STS-93 by NASA on July 23, 1999.
A chemical element is a species of atoms having the same number of protons in their atomic nuclei (that is, the same atomic number, or Z).
Circinus is a small, faint constellation in the southern sky, first defined in 1756 by the French astronomer Nicolas-Louis de Lacaille.
A circle of latitude on Earth is an abstract east–west circle connecting all locations around Earth (ignoring elevation) at a given latitude.
In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.
Classical Latin is the modern term used to describe the form of the Latin language recognized as standard by writers of the late Roman Republic and the Roman Empire.
The Coalsack Dark Nebula (or simply the Coalsack) is the most prominent dark nebula in the skies, easily visible to the naked eye as a dark patch silhouetted against the southern Milky Way.
In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature.
Colure, in astronomy, is either of the two principal meridians of the celestial sphere.
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.
In astronomy, a conjunction occurs when two astronomical objects or spacecraft have either the same right ascension or the same ecliptic longitude, usually as observed from Earth.
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.
The contiguous United States or officially the conterminous United States consists of the 48 adjoining U.S. states plus Washington, D.C. on the continent of North America.
Corona Borealis is a small constellation in the Northern Celestial Hemisphere.
The Cosmic Background Explorer (COBE), also referred to as Explorer 66, was a satellite dedicated to cosmology, which operated from 1989 to 1993.
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects.
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.
Crux is a constellation located in the southern sky in a bright portion of the Milky Way.
Cygnus is a northern constellation lying on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan.
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 matter halo is a hypothetical component of a galaxy that envelops the galactic disc and extends well beyond the edge of the visible galaxy.
Dôn is an ancestor figure in Welsh legend and literature.
In astronomy, declination (abbreviated dec; symbol δ) is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle.
A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a measurement of a plane angle, defined so that a full rotation is 360 degrees.
Democritus (Δημόκριτος, Dēmókritos, meaning "chosen of the people") was an Ancient Greek pre-Socratic philosopher primarily remembered today for his formulation of an atomic theory of the universe.
Density wave theory or the Lin-Shu density wave theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain the spiral arm structure of spiral galaxies.
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle.
Differential rotation is seen when different parts of a rotating object move with different angular velocities (rates of rotation) at different latitudes and/or depths of the body and/or in time.
A disc galaxy is a galaxy characterized by a disc, a flattened circular volume of stars.
The Doppler effect (or the Doppler shift) is the change in frequency or wavelength of a wave in relation to observer who is moving relative to the wave source.
The Draco Dwarf is a spheroidal galaxy which was discovered by Albert George Wilson of Lowell Observatory in 1954 on photographic plates of the National Geographic Society's Palomar Observatory Sky Survey (POSS).
A dragon is a large, serpent-like legendary creature that appears in the folklore of many cultures around the world.
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.
Earth's orbit is the trajectory along which Earth travels around the Sun.
The ecliptic is the circular path on the celestial sphere that the Sun follows over the course of a year; it is the basis of the ecliptic coordinate system.
Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer.
In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.
Elise Otté (30 September 1818 – 20 December 1903) was an Anglo-Danish linguist, scholar and historian.
In astrodynamics or celestial mechanics, an elliptic orbit or elliptical orbit is a Kepler orbit with an eccentricity of less than 1; this includes the special case of a circular orbit, with eccentricity equal to 0.
An elliptical galaxy is a type of galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless image.
The (Akkadian Cuneiform:, also spelled "Enuma Elish"), is the Babylonian creation myth (named after its opening words).
Enlil, later known as Elil, was the ancient Mesopotamian god of wind, air, earth, and storms.
In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time.
An equator of a rotating spheroid (such as a planet) is its zeroth circle of latitude (parallel).
The European Southern Observatory (ESO) is a 15-nation intergovernmental research organization for ground-based astronomy.
The European Space Agency (ESA; Agence spatiale européenne, ASE; Europäische Weltraumorganisation) is an intergovernmental organisation of 22 member states dedicated to the exploration of space.
An exocomet, or extrasolar comet, is a comet outside the Solar System, which includes interstellar comets and those that orbit stars other than the Sun.
An exoplanet or extrasolar planet is a planet outside our solar system.
The expansion of the universe is the increase of the distance between two distant parts of the universe with time.
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth.
The Fermi Gamma-ray Space Telescope (FGST), formerly called the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit.
The Fornax Dwarf Spheroidal is an elliptical dwarf galaxy in the constellation Fornax that was discovered in 1938 by Harlow Shapley.
In physics, a frame of reference (or reference frame) consists of an abstract coordinate system and the set of physical reference points that uniquely fix (locate and orient) the coordinate system and standardize measurements.
Gaia is a space observatory of the European Space Agency (ESA) designed for astrometry: measuring the positions and distances of stars with unprecedented precision.
The galactic anticenter is a direction in space directly opposite to the Galactic Center, as viewed from Earth.
Galactic astronomy is the study of the Milky Way galaxy and all its contents.
The Galactic Center is the rotational center of the Milky Way.
The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way galaxy, and the fundamental plane parallel to an approximation of the galactic plane but offset to its north.
In astrobiology and planetary astrophysics, the galactic habitable zone is the region of a galaxy in which life might most likely develop.
A galactic halo is an extended, roughly spherical component of a galaxy which extends beyond the main, visible component.
The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies.
The galactic ridge is a region of the inner galaxy that is coincident with the galactic plane of the Milky Way.
The galactic year, also known as a cosmic year, is the duration of time required for the Sun to orbit once around the center of the Milky Way Galaxy.
A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter.
A galaxy cluster, or cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity with typical masses ranging from 1014–1015 solar masses.
The galaxy color–magnitude diagram shows the relationship between absolute magnitude (a measure of luminosity) and mass of galaxies.
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.
The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre.
Galileo Galilei (15 February 1564Drake (1978, p. 1). The date of Galileo's birth is given according to the Julian calendar, which was then in force throughout Christendom. In 1582 it was replaced in Italy and several other Catholic countries with the Gregorian calendar. Unless otherwise indicated, dates in this article are given according to the Gregorian calendar. – 8 January 1642) was an Italian polymath.
Gemini is one of the constellations of the zodiac.
Geometry (from the γεωμετρία; geo- "earth", -metron "measurement") is a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space.
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite.
The Gould Belt is a partial ring of stars in the Milky Way, about 3000 light years across, tilted toward the galactic plane by about 16 to 20 degrees.
Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect.
Gravity, or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are brought toward (or gravitate toward) one another.
The Great Attractor is an apparent gravitational anomaly in intergalactic space at the center of the local Laniakea Supercluster, in which the Milky Way is located, in the so-called Zone of Avoidance that is notoriously difficult to observe in visible wavelengths due to the obscuring effects of our own galactic plane.
The Great Debate, also called the Shapley–Curtis Debate, was held on 26 April 1920 at the Smithsonian Museum of Natural History, between the astronomers Harlow Shapley and Heber Curtis.
In astronomy, the Great Rift (sometimes called the Dark Rift or, less commonly, the Dark River) is an aggregation of overlapping, non-luminous, molecular dust clouds that lie between the Solar System and the Sagittarius Arm of the Milky Way galaxy.
Greek mythology is the body of myths and teachings that belong to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices.
Grus (or colloquially) is a constellation in the southern sky.
Gwydion fab Dôn is a magician, hero and trickster of Welsh mythology, appearing most prominently in the Fourth Branch of the Mabinogi, which focuses largely on his relationship with his young nephew, Lleu Llaw Gyffes.
An H II region or HII region is a region of interstellar atomic hydrogen that is ionized.
Harlow Shapley (November 2, 1885 – October 20, 1972) was a 20th-century American scientist, head of the Harvard College Observatory (1921–1952), and political activist during the latter New Deal and Fair Deal.
HD 140283, informally nicknamed the Methuselah star, is a metal-poor subgiant star about 200 light years away from the Earth in the constellation Libra, specifically toward Ophiuchus.
HE 1523-0901 is the designation given to a red giant star in the Milky Way galaxy approximately 7500 light years from Earth.
Heber Doust Curtis (June 27, 1872 – January 9, 1942) was an American astronomer.
Helium (from lit) is a chemical element with symbol He and atomic number 2.
Hera (Ἥρᾱ, Hērā; Ἥρη, Hērē in Ionic and Homeric Greek) is the goddess of women, marriage, family, and childbirth in Ancient Greek religion and myth, one of the Twelve Olympians and the sister-wife of Zeus.
Heracles (Ἡρακλῆς, Hēraklês, Glory/Pride of Hēra, "Hera"), born Alcaeus (Ἀλκαῖος, Alkaios) or Alcides (Ἀλκείδης, Alkeidēs), was a divine hero in Greek mythology, the son of Zeus and Alcmene, foster son of AmphitryonBy his adoptive descent through Amphitryon, Heracles receives the epithet Alcides, as "of the line of Alcaeus", father of Amphitryon.
Hercules is a constellation named after Hercules, the Roman mythological hero adapted from the Greek hero Heracles.
Hermes (Ἑρμῆς) is an Olympian god in Greek religion and mythology, the son of Zeus and the Pleiad Maia, and the second youngest of the Olympian gods (Dionysus being the youngest).
High-velocity clouds (HVCs) are large collections of gas found throughout the galactic halo of the Milky Way.
The horizon or skyline is the apparent line that separates earth from sky, the line that divides all visible directions into two categories: those that intersect the Earth's surface, and those that do not.
The Hubble sequence is a morphological classification scheme for galaxies invented by Edwin Hubble in 1926.
Hubble's law is the name for the observation in physical cosmology that.
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees.
Hydrogen is a chemical element with symbol H and atomic number 1.
A hydrogen atom is an atom of the chemical element hydrogen.
The hydrogen line, 21-centimeter line or H I line refers to the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms.
Shams al-Dīn Abū ʿAbd Allāh Muḥammad ibn Abī Bakr ibn Ayyūb al-Zurʿī l-Dimashqī l-Ḥanbalī (1292–1350 CE / 691 AH–751 AH), commonly known as Ibn Qayyim al-Jawziyya ("The son of the principal of Jawziyyah") or Ibn al-Qayyim ("Son of the principal"; ابن قيم الجوزية) for short, or reverentially as Imam Ibn al-Qayyim in Sunni tradition, was an important medieval Islamic jurisconsult, theologian, and spiritual writer.
Immanuel Kant (22 April 1724 – 12 February 1804) was a German philosopher who is a central figure in modern philosophy.
An inertial frame of reference in classical physics and special relativity is a frame of reference in which a body with zero net force acting upon it is not accelerating; that is, such a body is at rest or it is moving at a constant speed in a straight line.
In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy.
Isotopes are variants of a particular chemical element which differ in neutron number.
Although thorium (90Th) has 6 naturally occurring isotopes, none of these isotopes are stable; however, one isotope, 232Th, is relatively stable, with a half-life of 1.405×1010 years, considerably longer than the age of the Earth, and even slightly longer than the generally accepted age of the universe.
The Journal of the Royal Astronomical Society of Canada is a bimonthly peer-reviewed scientific journal published by the Royal Astronomical Society of Canada since 1907.
Kepler is a space observatory launched by NASA to discover Earth-size planets orbiting other stars.
In astronomy, Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun.
Kepler-32 is an M-type main sequence star located about 1070 light years from Earth, in the constellation of Cygnus.
A Klemperer rosette is a gravitational system of heavier and lighter bodies orbiting in a regular repeating pattern around a common barycenter.
Lacerta is one of the 88 modern constellations defined by the International Astronomical Union.
The Laniakea Supercluster (Laniakea; also called Local Supercluster or Local SCl or sometimes Lenakaeia) is the galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies.
The Large Magellanic Cloud (LMC) is a satellite galaxy of the Milky Way.
A laser guide star is an artificial star image created for use in astronomical adaptive optics systems, which are employed in large telescopes in order to correct atmospheric distortion of light (called astronomical seeing).
Latin (Latin: lingua latīna) is a classical language belonging to the Italic branch of the Indo-European languages.
Leo I is a dwarf spheroidal galaxy in the constellation Leo.
Leo II (or Leo B) is a dwarf spheroidal galaxy about 690,000 light-years away in the constellation Leo.
Light pollution, also known as photopollution, is the presence of anthropogenic light in the night environment.
The light-year is a unit of length used to express astronomical distances and measures about 9.5 trillion kilometres or 5.9 trillion miles.
In astronomy, limiting magnitude is the faintest apparent magnitude of a celestial body that is detectable or detected by a given instrument.
The notion of line or straight line was introduced by ancient mathematicians to represent straight objects (i.e., having no curvature) with negligible width and depth.
The following is a list of notable galaxies.
This list of nearest bright stars is a table of stars found within 15 parsecs (48.9 light-years) of the Sun that have an absolute magnitude of +8.5 or brighter, which is approximately comparable to a listing of stars more luminous than a red dwarf.
The following two lists include all the known stars and brown dwarfs that are within of the Sun, or were/will be within in the astronomically near past or future.
The Local Bubble, or Local Cavity, is a relative cavity in the interstellar medium (ISM) in the Orion Arm of the Milky Way.
The Local Group is the galaxy group that includes the Milky Way.
The Local Interstellar Cloud (LIC), also known as the Local Fluff, is the interstellar cloud roughly across through which the Solar System is currently moving.
The Los Angeles Times is a daily newspaper which has been published in Los Angeles, California since 1881.
The Magellanic Clouds (or Nubeculae Magellani) are two irregular dwarf galaxies visible in the Southern Celestial Hemisphere; they are members of the Local Group and are orbiting the Milky Way galaxy.
The Magellanic Stream, which contains a gaseous feature dubbed the leading arm, is a stream of high-velocity clouds of gas extending from the Large and Small Magellanic Clouds over 100° through the Galactic south pole of the Milky Way.
A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials.
In astronomy, magnitude is a logarithmic measure of the brightness of an object in a defined passband, often in the visible or infrared spectrum, but sometimes across all wavelengths.
Marduk (cuneiform: dAMAR.UTU; Sumerian: amar utu.k "calf of the sun; solar calf"; Greek Μαρδοχαῖος, Mardochaios) was a late-generation god from ancient Mesopotamia and patron deity of the city of Babylon.
Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied.
Measurement is the assignment of a number to a characteristic of an object or event, which can be compared with other objects or events.
In astronomy, the meridian is the great circle passing through the celestial poles, the zenith, and the nadir of an observer's location.
The Messier objects are a set of 110 astronomical objects, of which 103 were included in lists published by French astronomer Charles Messier in 1771 and 1781.
In astronomy, metallicity is used to describe the abundance of elements present in an object that are heavier than hydrogen or helium.
Meteorology (Greek: Μετεωρολογικά; Latin: Meteorologica or Meteora) is a treatise by Aristotle.
Metre per second (American English: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector quantity which specifies both magnitude and a specific direction), defined by distance in metres divided by time in seconds.
Modified Newtonian dynamics (MOND) is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies.
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).
Monoceros (Greek: Μονόκερως) is a faint constellation on the celestial equator.
The Monoceros Ring is a long, complex, ringlike filament of stars that wraps around the Milky Way three times.
Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.
Moonlight consists of mostly sunlight (with little earthlight) reflected from the parts of the Moon's surface where the Sun's light strikes.
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States.
Musca is a small constellation in the deep southern sky.
The terms Muslim world and Islamic world commonly refer to the unified Islamic community (Ummah), consisting of all those who adhere to the religion of Islam, or to societies where Islam is practiced.
The abbreviation myr, "million years", is a unit of a quantity of (i.e.) years, or 31.6 teraseconds.
Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying or light-collecting optical instrument, such as a telescope or microscope.
The National Aeronautics and Space Administration (NASA) is an independent agency of the executive branch of the United States federal government responsible for the civilian space program, as well as aeronautics and aerospace research.
Muhammad ibn Muhammad ibn al-Hasan al-Tūsī (محمد بن محمد بن حسن طوسی‎ 18 February 1201 – 26 June 1274), better known as Nasir al-Din Tusi (نصیر الدین طوسی; or simply Tusi in the West), was a Persian polymath, architect, philosopher, physician, scientist, and theologian.
National gods are a class of guardian divinities or deities whose special concern is the safety and well-being of an ethnic group (nation), and of that group's leaders.
The Near 3 kpc Arm (also called Expanding 3 kpc Arm or simply 3 kpc Arm) was discovered in the 1950s by astronomer van Woerden and collaborators through 21-centimeter radio measurements of HI (atomic hydrogen).
A nebula (Latin for "cloud" or "fog"; pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases.
Neoplatonism is a term used to designate a strand of Platonic philosophy that began with Plotinus in the third century AD against the background of Hellenistic philosophy and religion.
Neptune is the eighth and farthest known planet from the Sun in the Solar System.
A neutron star is the collapsed core of a large star which before collapse had a total of between 10 and 29 solar masses.
The term night sky, usually associated with astronomy from Earth, refers to the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon.
Nippur (Sumerian: Nibru, often logographically recorded as, EN.LÍLKI, "Enlil City;": Vol. 1, Part 1. Accessed 15 Dec 2010. Akkadian: Nibbur) was among the most ancient of Sumerian cities.
Norma is a small constellation in the Southern Celestial Hemisphere between Ara and Lupus, one of twelve drawn up in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments.
The Norma Arm is a minor spiral arm of the Milky Way extending from and around its central hub region.
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.
Nucleocosmochronology or nuclear cosmochronology is a technique used to determine timescales for astrophysical objects and events.
Olympiodorus the Younger (Ὀλυμπιόδωρος ὁ Νεώτερος; c. 495 – 570) was a Neoplatonist philosopher, astrologer and teacher who lived in the early years of the Byzantine Empire, after Justinian's Decree of 529 AD which closed Plato's Academy in Athens and other pagan schools.
Omega Centauri (ω Cen or NGC 5139) is a globular cluster in the constellation of Centaurus that was first identified as a non-stellar object by Edmond Halley in 1677.
The Online Etymology Dictionary is a free online dictionary written and compiled by Douglas Harper that describes the origins of English-language words.
The Oort constants (discovered by Jan Oort) A and B are empirically derived parameters that characterize the local rotational properties of our galaxy, the Milky Way, in the following manner: \begin & A.
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.
Ophiuchus is a large constellation straddling the celestial equator.
An optical telescope is a telescope that gathers and focuses light, mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct view, or to make a photograph, or to collect data through electronic image sensors.
The orbital period is the time a given astronomical object takes to complete one orbit around another object, and applies in astronomy usually to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars.
In gravitationally bound systems, the orbital speed of an astronomical body or object (e.g. planet, moon, artificial satellite, spacecraft, or star) is the speed at which it orbits around either the barycenter or, if the object is much less massive than the largest body in the system, its speed relative to that largest body.
In linguistics, ordinal numbers (or ordinal numerals) are words representing position or rank in a sequential order; the order may be of size, importance, chronology, and so on (e.g., "third", "tertiary").
Orion is a prominent constellation located on the celestial equator and visible throughout the world.
The Orion Arm is a minor spiral arm of the Milky Way some across and approximately in length, containing the Solar System, including the Earth.
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.
Paranal Observatory is an astronomical observatory operated by the European Southern Observatory (ESO); it is located in the Atacama Desert of northern Chile on Cerro Paranal at altitude, south of Antofagasta.
The Parkes Observatory (also known informally as "The Dish") is a radio telescope observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia.
The parsec (symbol: pc) is a unit of length used to measure large distances to astronomical objects outside the Solar System.
Peculiar motion or peculiar velocity refers to the velocity of an object relative to a rest frame — usually a frame in which the average velocity of some objects is zero.
Perseus is a constellation in the northern sky, being named after the Greek mythological hero Perseus.
The Perseus Arm is one of two major spiral arms of the Milky Way galaxy.
The Persians--> are an Iranian ethnic group that make up over half the population of Iran.
Phys.org is a science, research and technology news aggregator where much of the content is republished directly from press releases and news agencies-in a practice known as churnalism.
Planck was a space observatory operated by the European Space Agency (ESA) from 2009 to 2013, which mapped the anisotropies of the cosmic microwave background (CMB) at microwave and infra-red frequencies, with high sensitivity and small angular resolution.
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.
In mathematics, the polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a reference point and an angle from a reference direction.
Proceedings of the National Academy of Sciences of the United States of America (PNAS) is the official scientific journal of the National Academy of Sciences, published since 1915.
Puppis is a constellation in the southern sky.
The quarter, short for quarter dollar, is a United States coin worth 25 cents, one-fourth of a dollar.
The rapid neutron-capture process, or so-called r-process, is a set of nuclear reactions that in nuclear astrophysics is responsible for the creation (nucleosynthesis) of approximately half the abundances of the atomic nuclei heavier than iron, usually synthesizing the entire abundance of the two most neutron-rich stable isotopes of each heavy element.
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies.
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is an atom that has excess nuclear energy, making it unstable.
A red dwarf (or M dwarf) is a small and relatively cool star on the main sequence, of M spectral type.
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.
In physics, redshift happens when light or other electromagnetic radiation from an object is increased in wavelength, or shifted to the red end of the spectrum.
Refraction is the change in direction of wave propagation due to a change in its transmission medium.
Rensselaer Polytechnic Institute, or RPI, is a private research university and space-grant institution located in Troy, New York, with two additional campuses in Hartford and Groton, Connecticut.
In special relativity the rest frame of a particle is the coordinate system (frame of reference) in which the particle is at rest.
Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is the central object (right figure).
Right ascension (abbreviated RA; symbol) is the angular distance measured only eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point above the earth in question.
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.
RR Lyrae variables are periodic variable stars, commonly found in globular clusters.
In general, a rural area or countryside is a geographic area that is located outside towns and cities.
Sagitta is a dim but distinctive constellation in the northern sky.
Sagittarius is one of the constellations of the zodiac.
Sagittarius A* (pronounced "Sagittarius A-star", standard abbreviation Sgr A*) is a bright and very compact astronomical radio source at the center of the Milky Way, near the border of the constellations Sagittarius and Scorpius.
The Sagittarius Dwarf Spheroidal Galaxy (Sgr dSph), also known as the Sagittarius Dwarf Elliptical Galaxy (Sgr dE or Sag DEG), is an elliptical loop-shaped satellite galaxy of the Milky Way.
The Milky Way has several smaller galaxies gravitationally bound to it, as part of the Milky Way subgroup, which is part of the local galaxy cluster, the Local Group.
Scorpius is one of the constellations of the zodiac.
The Sculptor Dwarf Galaxy (also known as Sculptor Dwarf Elliptical Galaxy or the Sculptor Dwarf Spheroidal Galaxy) is a dwarf spheroidal galaxy that is a satellite of the Milky Way.
Scutum is a small constellation introduced in the seventeenth century.
The Scutum–Centaurus Arm, also known as Scutum-Crux arm, is a long, diffuse curving streamer of stars, gas and dust that spirals outward from the proximate end of the Milky Way's central bar.
The Sextans Dwarf Spheroidal is a dwarf spheroidal galaxy that was discovered in 1990 by Mike Irwin as the 8th satellite of the Milky Way, located in the constellation of Sextans.
The Shapley Supercluster or Shapley Concentration (SCl 124) is the largest concentration of galaxies in our nearby universe that forms a gravitationally interacting unit, thereby pulling itself together instead of expanding with the universe.
In mechanics and physics, simple harmonic motion is a special type of periodic motion or oscillation motion where the restoring force is directly proportional to the displacement and acts in the direction opposite to that of displacement.
The Sloan Digital Sky Survey or SDSS is a major multi-spectral imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States.
The Small Magellanic Cloud (SMC), or Nubecula Minor, is a dwarf galaxy near the Milky Way.
Smith's Cloud is a high-velocity cloud of hydrogen gas located in the constellation Aquila at Galactic coordinates l.
Solar-type star, solar analogs (also analogues), and solar twins are stars that are particularly similar to the Sun.
The solar apex, or the Apex of the Sun's Way, refers to the direction that the Sun travels with respect to the Local Standard of Rest.
The solar mass is a standard unit of mass in astronomy, equal to approximately.
The Solar SystemCapitalization of the name varies.
Space.com is a space and astronomy news website.
In physics, special relativity (SR, also known as the special theory of relativity or STR) is the generally accepted and experimentally well-confirmed physical theory regarding the relationship between space and time.
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies.
The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.
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.
The Spitzer Space Telescope (SST), formerly the Space Infrared Telescope Facility (SIRTF), is an infrared space telescope launched in 2003 and still operating as of 2018.
The Stanford Encyclopedia of Philosophy (SEP) combines an online encyclopedia of philosophy with peer-reviewed publication of original papers in philosophy, freely accessible to Internet users.
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming regions", collapse and form stars.
A stellar collision is the coming together of two stars caused by gravity, gravitational radiation, or other mechanisms not well understood.
In Aristotelian physics and Greek astronomy, the sublunary sphere is the region of the geocentric cosmos below the Moon, consisting of the four classical elements: earth, water, air, and fire.
SumerThe name is from Akkadian Šumeru; Sumerian en-ĝir15, approximately "land of the civilized kings" or "native land".
The Sun is the star at the center of the Solar System.
A supercluster is a large group of smaller galaxy clusters or galaxy groups; it is among the largest-known structures of the cosmos.
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.
In astronomy, surface brightness quantifies the apparent brightness or flux density per unit angular area of a spatially extended object such as a galaxy or nebula, or of the night sky background.
Suzaku (formerly ASTRO-EII) was an X-ray astronomy satellite developed jointly by NASA's Goddard Space Flight Center and the Institute of Space and Aeronautical Science at JAXA to probe high energy X-ray sources, such as supernova explosions, black holes and galactic clusters.
Swinburne University of Technology (often simply called Swinburne) is an Australian public university based in Melbourne, Victoria.
Taurus (Latin for "the Bull") is one of the constellations of the zodiac, which means it is crossed by the plane of the ecliptic.
A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals.
The Astrophysical Journal, often abbreviated ApJ (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler.
The New York Times (sometimes abbreviated as The NYT or The Times) is an American newspaper based in New York City with worldwide influence and readership.
The Washington Post is a major American daily newspaper founded on December 6, 1877.
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.
Thomas Wright (22 September 171125 February 1786) was an English astronomer, mathematician, instrument maker, architect and garden designer.
Thorium is a weakly radioactive metallic chemical element with symbol Th and atomic number 90.
In the religion of ancient Babylon, Tiamat (𒀭𒋾𒊩𒆳 or, Greek: Θαλάττη Thaláttē) is a primordial goddess of the salt sea, mating with Abzû, the god of fresh water, to produce younger gods.
Triangulum Australe is a small constellation in the far Southern Celestial Hemisphere.
In mythology, and in the study of folklore and religion, a trickster is a character in a story (god, goddess, spirit, man, woman, or anthropomorphisation), which exhibits a great degree of intellect or secret knowledge, and uses it to play tricks or otherwise disobey normal rules and conventional behaviour.
The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy.
Universe Today (UT) is a popular North American-based non-commercial space and astronomy news website.
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public research university in Berkeley, California.
The University of Cambridge (informally Cambridge University)The corporate title of the university is The Chancellor, Masters, and Scholars of the University of Cambridge.
Uranium-238 (238U or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%.
The Ursa Minor Dwarf is a dwarf spheroidal galaxy, discovered by A.G. Wilson of the Lowell Observatory, in the United States, during the Palomar Sky Survey in 1955.
Vega, also designated Alpha Lyrae (α Lyrae, abbreviated Alpha Lyr or α Lyr), is the brightest star in the constellation of Lyra, the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus.
Vela is a constellation in the southern sky.
The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile.
The Very Long Baseline Array (VLBA) is a system of ten radio telescopes which are operated remotely from their Array Operations Center located in Socorro, New Mexico, as a part of the (LBO).
Virgo is one of the constellations of the zodiac.
The Virgo Cluster is a cluster of galaxies whose center is 53.8 ± 0.3 Mly (16.5 ± 0.1 Mpc) away in the constellation Virgo.
The Virgo Stellar Stream, also known as Virgo Overdensity, is the proposed name for a stellar stream in the constellation of Virgo which was discovered in 2005.
The Virgo Supercluster (Virgo SC) or the Local Supercluster (LSC or LS) is a mass concentration of galaxies containing the Virgo Cluster and Local Group, which in turn contains the Milky Way and Andromeda galaxies.
VRML (Virtual Reality Modeling Language, pronounced vermal or by its initials, originally—before 1995—known as the Virtual Reality Markup Language) is a standard file format for representing 3-dimensional (3D) interactive vector graphics, designed particularly with the World Wide Web in mind.
Vulpecula is a faint constellation in the northern sky.
Welsh (Cymraeg or y Gymraeg) is a member of the Brittonic branch of the Celtic languages.
A white dwarf, also called a degenerate dwarf, is a stellar core remnant composed mostly of electron-degenerate matter.
The Wilkinson Microwave Anisotropy Probe (WMAP), originally known as the Microwave Anisotropy Probe (MAP), was a spacecraft operating from 2001 to 2010 which measured temperature differences across the sky in the cosmic microwave background (CMB) – the radiant heat remaining from the Big Bang.
Frederick William Herschel, (Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer, composer and brother of fellow astronomer Caroline Herschel, with whom he worked.
William Parsons, 3rd Earl of Rosse HFRSE (17 June 1800 – 31 October 1867) was an Anglo-Irish astronomer who had several telescopes built.
X-rays make up X-radiation, a form of electromagnetic radiation.
XMM-Newton, also known as the High Throughput X-ray Spectroscopy Mission and the X-ray Multi-Mirror Mission, is an X-ray space observatory launched by the European Space Agency in December 1999 on an Ariane 5 rocket.
The zenith is an imaginary point directly "above" a particular location, on the imaginary celestial sphere.
The zodiac is an area of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year.
The Zone of Avoidance (ZOA) is the area of the sky that is obscured by the Milky Way.
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