105 relations: Absolute magnitude, Andromeda Galaxy, Angular diameter, Angular distance, Approximation, Astrometry, Astronomer, Astronomer Royal, Astronomical object, Astronomical system of units, Astronomical unit, Astronomische Nachrichten, Astronomy, Astrophysics, Boötes void, Brady Haran, Carl Charlier, Celestial sphere, CfA2 Great Wall, Constellation, Cosmic background radiation, Cosmic distance ladder, Diameter, Distance, Distance measures (cosmology), Earth, European Space Agency, Frank Watson Dyson, Friedrich Bessel, Full-sky Astrometric Mapping Explorer, Gaia (spacecraft), Galactic Center, Galaxy, Galaxy cluster, Galaxy filament, Galaxy group, Giga-, Globular cluster, Goddard Space Flight Center, Herbert Hall Turner, Hercules–Corona Borealis Great Wall, Hipparcos, Hubble Space Telescope, Hubble's law, Imperial units, International Astronomical Union, International System of Units, Kilo-, Kilometre, Length, ..., Light-year, List of largest cosmic structures, Mega-, Messier 87, Messier object, Metre, Metric system, Mile, Milky Way, Monthly Notices of the Royal Astronomical Society, Multiplicative inverse, Naked eye, NASA, Night sky, Observable universe, Oort cloud, Open cluster, Orders of magnitude (length), Parallax, Particle horizon, Physical cosmology, Pleiades, Popular science, Portmanteau, Proxima Centauri, Quasar, Redshift, Right triangle, RX J1242-11, Sagittarius (constellation), Semi-major and semi-minor axes, Significant figures, Siriometer, Skinny triangle, Solar System, Space probe, Speed of light, Spiral galaxy, Star, Subtended angle, Sun, Supercluster, Supermassive black hole, Tangent, Telescope, Trigonometric functions, Trigonometry, Unit of length, United States customary units, University of Nottingham, Usage, Virgo Cluster, Voyager 1, 1,000,000,000, 61 Cygni. Expand index (55 more) » « Shrink index
Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale.
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 angular diameter, angular size, apparent diameter, or apparent size is an angular measurement describing how large a sphere or circle appears from a given point of view.
In mathematics (in particular geometry and trigonometry) and all natural sciences (e.g. astronomy and geophysics), the angular distance (angular separation, apparent distance, or apparent separation) between two point objects, as viewed from a location different from either of these objects, is the angle of length between the two directions originating from the observer and pointing toward these two objects.
An approximation is anything that is similar but not exactly equal to something else.
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies.
An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside the scope of Earth.
Astronomer Royal is a senior post in the Royal Households of the United Kingdom.
An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.
The astronomical system of units, formally called the IAU (1976) System of Astronomical Constants, is a system of measurement developed for use in astronomy.
The astronomical unit (symbol: au, ua, or AU) is a unit of length, roughly the distance from Earth to the Sun.
Astronomische Nachrichten (Astronomical Notes), one of the first international journals in the field of astronomy, was founded in 1821 by the German astronomer Heinrich Christian Schumacher.
Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.
Astrophysics is the branch of astronomy that employs the principles of physics and chemistry "to ascertain the nature of the astronomical objects, rather than their positions or motions in space".
The Boötes void (or the Great Void) is an enormous, approximately spherically-shaped region of space, containing very few galaxies.
Brady John Haran (born 18 June 1976) is an Australian-born British independent filmmaker and video journalist who is known for his educational videos and documentary films produced for BBC News and his YouTube channels, the most notable being Periodic Videos and Numberphile.
Carl Vilhelm Ludwig Charlier (1 April 1862 – 4 November 1934) was a Swedish astronomer.
In astronomy and navigation, the celestial sphere is an abstract sphere with an arbitrarily large radius concentric to Earth.
The Great Wall (also called Coma Wall), sometimes specifically referred to as the CfA2 Great Wall, is an immense galaxy filament.
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.
Cosmic background radiation is electromagnetic radiation from the big bang.
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.
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.
Distance is a numerical measurement of how far apart objects are.
Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
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.
Sir Frank Watson Dyson, KBE, FRS, FRSE (8 January 1868 – 25 May 1939) was an English astronomer and Astronomer Royal who is remembered today largely for introducing time signals ("pips") from Greenwich, England, and for the role he played in proving Einstein's theory of general relativity.
Friedrich Wilhelm Bessel (22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist and geodesist.
Full-sky Astrometric Mapping Explorer (or FAME) was a proposed astrometric satellite designed to determine with unprecedented accuracy the positions, distances, and motions of 40 million stars within our galactic neighborhood (distances by stellar parallax possible).
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 Center is the rotational center of the Milky Way.
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 distribution reveals fine, filamentary structures.
A galaxy group or group of galaxies (GrG) is an aggregation of galaxies comprising about 50 or fewer gravitationally bound members, each at least as luminous as the Milky Way (about 1010 times the luminosity of the Sun); collections of galaxies larger than groups that are first-order clustering are called galaxy clusters.
Giga is a unit prefix in the metric system denoting a factor of a (short-form) billion (109 or 000).
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite.
The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States.
Herbert Hall Turner FRS (13 August 1861, Leeds – 20 August 1930, Stockholm) was a British astronomer and seismologist.
Hercules–Corona Borealis Great Wall or the Great GRB Wall.
Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993.
The Hubble Space Telescope (HST) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation.
Hubble's law is the name for the observation in physical cosmology that.
The system of imperial units or the imperial system (also known as British Imperial or Exchequer Standards of 1825) is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced.
The International Astronomical Union (IAU; Union astronomique internationale, UAI) is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy.
The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.
Kilo is a decimal unit prefix in the metric system denoting multiplication by one thousand (103).
The kilometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: km; or) or kilometer (American spelling) is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for). It is now the measurement unit used officially for expressing distances between geographical places on land in most of the world; notable exceptions are the United States and the road network of the United Kingdom where the statute mile is the official unit used.
In geometric measurements, length is the most extended dimension of an object.
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.
This is a list of the largest cosmic structures so far discovered.
Mega is a unit prefix in metric systems of units denoting a factor of one million (106 or 000).
Messier 87 (also known as Virgo A or NGC 4486, generally abbreviated to M87) is a supergiant elliptical galaxy in the constellation Virgo.
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.
The metre (British spelling and BIPM spelling) or meter (American spelling) (from the French unit mètre, from the Greek noun μέτρον, "measure") is the base unit of length in some metric systems, including the International System of Units (SI).
The metric system is an internationally adopted decimal system of measurement.
The mile is an English unit of length of linear measure equal to 5,280 feet, or 1,760 yards, and standardised as exactly 1,609.344 metres by international agreement in 1959.
The Milky Way is the galaxy that contains our Solar System.
Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.
In mathematics, a multiplicative inverse or reciprocal for a number x, denoted by 1/x or x−1, is a number which when multiplied by x yields the multiplicative identity, 1.
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.
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.
The observable universe is a spherical region of the Universe comprising all matter that can be observed from Earth at the present time, because electromagnetic radiation from these objects has had time to reach Earth since the beginning of the cosmological expansion.
The Oort cloud, named after the Dutch astronomer Jan Oort, sometimes called the Öpik–Oort cloud, is a theoretical cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from.
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age.
The following are examples of orders of magnitude for different lengths.
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.
The particle horizon (also called the cosmological horizon, the comoving horizon (in Dodelson's text), or the cosmic light horizon) is the maximum distance from which particles could have traveled to the observer in the age of the universe.
Physical cosmology is the study of the largest-scale structures and dynamics of the Universe and is concerned with fundamental questions about its origin, structure, evolution, and ultimate fate.
The Pleiades (also known as the Seven Sisters and Messier 45), are an open star cluster containing middle-aged, hot B-type stars located in the constellation of Taurus.
Popular science (also called pop-science or popsci) is an interpretation of science intended for a general audience.
A portmanteau or portmanteau word is a linguistic blend of words,, p. 644 in which parts of multiple words or their phones (sounds) are combined into a new word, as in smog, coined by blending smoke and fog, or motel, from motor and hotel.
Proxima Centauri, or Alpha Centauri C, is a red dwarf, a small low-mass star, about from the Sun in the constellation of Centaurus.
A quasar (also known as a QSO or quasi-stellar object) is an extremely luminous active galactic nucleus (AGN).
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.
A right triangle (American English) or right-angled triangle (British English) is a triangle in which one angle is a right angle (that is, a 90-degree angle).
RX J1242.6-1119A (often abbreviated RX J1242-11) is an elliptical galaxy located approximately 200 megaparsecs (about 650 million light-years) from Earth.
Sagittarius is one of the constellations of the zodiac.
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the widest points of the perimeter.
The significant figures (also known as the significant digits) of a number are digits that carry meaning contributing to its measurement resolution.
The siriometer is an obsolete astronomical unit of length, defined to be equal to one million astronomical units (au).
A skinny triangle in trigonometry is a triangle whose height is much greater than its base.
The Solar SystemCapitalization of the name varies.
A space probe is a robotic spacecraft that does not orbit the Earth, but, instead, explores further into outer space.
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.
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.
In geometry, an angle subtended by an arc, line segment, or other curve is one whose two rays pass through the endpoints of the arc.
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 geometry, the tangent line (or simply tangent) to a plane curve at a given point is the straight line that "just touches" the curve at that point.
A telescope is an optical instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light).
In mathematics, the trigonometric functions (also called circular functions, angle functions or goniometric functions) are functions of an angle.
Trigonometry (from Greek trigōnon, "triangle" and metron, "measure") is a branch of mathematics that studies relationships involving lengths and angles of triangles.
A unit of length refers to any discrete, pre-established length or distance having a constant magnitude which is used as a reference or convention to express linear dimension.
United States customary units are a system of measurements commonly used in the United States.
The University of Nottingham is a public research university in Nottingham, United Kingdom.
Usage is the manner in which written and spoken language is used, the "points of grammar, syntax, style, and the choice of words", and "the way in which a word or phrase is normally and correctly used".
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.
Voyager 1 is a space probe launched by NASA on September 5, 1977.
1,000,000,000 (one billion, short scale; one thousand million or milliard, yard, long scale) is the natural number following 999,999,999 and preceding 1,000,000,001.
61 Cygni Not to be confused with 16 Cygni, a more distant system containing two G-type stars harboring the gas giant planet 16 Cygni Bb.