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WMAP Cold Spot
The CMB Cold Spot or WMAP Cold Spot is a region of the sky seen in microwaves that has been found to be unusually large and cold relative to the expected properties of the cosmic microwave background radiation (CMBR). The "Cold Spot" is approximately 70 µK (0.00007 K) colder than the average CMB temperature (approximately 2.7 K), whereas the root mean square of typical temperature variations is only 18 µK.After the dipole anisotropy, which is due to the Doppler shift of the microwave background radiation due to our peculiar velocity relative to the comoving cosmic rest frame, has been subtracted out. This feature is consistent with the Earth moving at some 627 km/s towards the constellation Virgo. At some points, the "cold spot" is 140 µK colder than the average CMB temperature. The radius of the "cold spot" subtends about 5°; it is centered at the galactic coordinate , (equatorial: ''α'' = , ''δ'' = ). It is, therefore, in the South ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eridanus Supervoid In Celestial Sphere
Eridanus can refer to: Rivers *Eridanos (mythology) (or Eridanus), a river in Greek mythology, somewhere in Central Europe, which was territory that Ancient Greeks knew only vaguely *The Po River, according to Roman word usage *Eridanos (Athens), a former river near Athens, now subterranean * Eridanos (geology), a former large river that flowed between forty million and seven hundred thousand years ago from Lapland to the North Sea through where the Baltic Sea is now Astronomy *Eridanus (constellation), a southern constellation *Eridanus Cluster of galaxies in the constellation Eridanus *Eridanus II, a low-surface brightness dwarf galaxy in the constellation Eridanus *List of stars in Eridanus *Delta Eridani, a star *Eta Eridani, a star *Gamma Eridani, a star *Eridanus Supervoid, a large-scale cosmic underdensity Miscellaneous *Éridan (rocket), a French rocket * ''Éridan''-class minehunter, a class of French naval minehunters *''Eridanosaurus'', a rhinocerotid originally describ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Celestial Hemisphere
The southern celestial hemisphere, also called the Southern Sky, is the southern half of the celestial sphere; that is, it lies south of the celestial equator. This arbitrary sphere, on which seemingly fixed stars form constellations, appears to rotate westward around a polar axis due to Earth's rotation. At any given time, the entire Southern Sky is visible from the geographic South Pole, while less of this hemisphere is visible the further north the observer is located. The northern counterpart is the northern celestial hemisphere. Astronomy In the context of astronomical discussions or writing about celestial mapping, it may also simply then be referred to as the Southern Hemisphere. For the purpose of celestial mapping, the sky is considered by astronomers as the inside of a sphere divided in two halves by the celestial equator. The Southern Sky or Southern Hemisphere is, therefore, that half of the celestial sphere that is south of the celestial equator. Even if ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmological Inflation
In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from seconds after the conjectured Big Bang singularity to some time between and seconds after the singularity. Following the inflationary period, the universe continued to expand, but at a slower rate. The acceleration of this expansion due to dark energy began after the universe was already over 7.7 billion years old (5.4 billion years ago). Inflation theory was developed in the late 1970s and early 80s, with notable contributions by several theoretical physicists, including Alexei Starobinsky at Landau Institute for Theoretical Physics, Alan Guth at Cornell University, and Andrei Linde at Lebedev Physical Institute. Alexei Starobinsky, Alan Guth, and Andrei Linde won the 2014 Kavli Prize "for pioneering the theory of cosmic inflation." It was developed further in the ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Fluctuation
In quantum physics, a quantum fluctuation (also known as a vacuum state fluctuation or vacuum fluctuation) is the temporary random change in the amount of energy in a point in space, as prescribed by Werner Heisenberg's uncertainty principle. They are minute random fluctuations in the values of the fields which represent elementary particles, such as electric and magnetic fields which represent the electromagnetic force carried by photons, W and Z fields which carry the weak force, and gluon fields which carry the strong force. Vacuum fluctuations appear as virtual particles, which are always created in particle-antiparticle pairs. Since they are created spontaneously without a source of energy, vacuum fluctuations and virtual particles are said to violate the conservation of energy. This is theoretically allowable because the particles annihilate each other within a time limit determined by the uncertainty principle so they are not directly observable. The uncertainty prin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gaussian Random Field
A Gaussian random field (GRF) within statistics, is a random field involving Gaussian probability density functions of the variables. A one-dimensional GRF is also called a Gaussian process. An important special case of a GRF is the Gaussian free field. With regard to applications of GRFs, the initial conditions of physical cosmology generated by quantum mechanical fluctuations during cosmic inflation are thought to be a GRF with a nearly scale invariant spectrum. Construction One way of constructing a GRF is by assuming that the field is the sum of a large number of plane, cylindrical or spherical waves with uniformly distributed random phase. Where applicable, the central limit theorem dictates that at any point, the sum of these individual plane-wave contributions will exhibit a Gaussian distribution. This type of GRF is completely described by its power spectral density, and hence, through the Wiener–Khinchin theorem, by its two-point autocorrelation function Auto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilkinson Microwave Anisotropy Probe
The Wilkinson Microwave Anisotropy Probe (WMAP), originally known as the Microwave Anisotropy Probe (MAP and Explorer 80), was a NASA 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. Headed by Professor Charles L. Bennett of Johns Hopkins University, the mission was developed in a joint partnership between the NASA Goddard Space Flight Center and Princeton University. The WMAP spacecraft was launched on 30 June 2001 from Florida. The WMAP mission succeeded the COBE space mission and was the second medium-class (MIDEX) spacecraft in the NASA Explorer program. In 2003, MAP was renamed WMAP in honor of cosmologist David Todd Wilkinson (1935–2002), who had been a member of the mission's science team. After nine years of operations, WMAP was switched off in 2010, following the launch of the more advanced Planck spacecraft by European Space Agency ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eridanus Supervoid
Eridanus can refer to: Rivers *Eridanos (mythology) (or Eridanus), a river in Greek mythology, somewhere in Central Europe, which was territory that Ancient Greeks knew only vaguely *The Po River, according to Roman word usage *Eridanos (Athens), a former river near Athens, now subterranean * Eridanos (geology), a former large river that flowed between forty million and seven hundred thousand years ago from Lapland to the North Sea through where the Baltic Sea is now Astronomy *Eridanus (constellation), a southern constellation *Eridanus Cluster of galaxies in the constellation Eridanus * Eridanus II, a low-surface brightness dwarf galaxy in the constellation Eridanus *List of stars in Eridanus *Delta Eridani, a star * Eta Eridani, a star *Gamma Eridani, a star * Eridanus Supervoid, a large-scale cosmic underdensity Miscellaneous *Éridan (rocket), a French rocket * ''Éridan''-class minehunter, a class of French naval minehunters *'' Eridanosaurus'', a rhinocerotid originally des ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Scientist
''New Scientist'' is a magazine covering all aspects of science and technology. Based in London, it publishes weekly English-language editions in the United Kingdom, the United States and Australia. An editorially separate organisation publishes a monthly Dutch-language edition. First published on 22 November 1956, ''New Scientist'' has been available in online form since 1996. Sold in retail outlets (paper edition) and on subscription (paper and/or online), the magazine covers news, features, reviews and commentary on science, technology and their implications. ''New Scientist'' also publishes speculative articles, ranging from the technical to the philosophical. ''New Scientist'' was acquired by Daily Mail and General Trust (DMGT) in March 2021. History Ownership The magazine was founded in 1956 by Tom Margerison, Max Raison and Nicholas Harrison as ''The New Scientist'', with Issue 1 on 22 November 1956, priced at one shilling (a twentieth of a pound in pre-decimal UK cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light-year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 (one million million, or billion in long scale). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word "year", the term ''light-year'' is sometimes misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years) which derives from astrometry; it is the distance at which one astronomical unit subtends an angle of one second of arc. Defini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megaparsec
The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 au subtends an angle of one arcsecond ( of a degree). This corresponds to astronomical units, i.e. 1\, \mathrm = 1/\tan \left( \ \mathrm \right)\, \mathrm. The nearest star, Proxima Centauri, is about from the Sun. Most stars visible to the naked eye are within a few hundred parsecs of the Sun, with the most distant at a few thousand. The word ''parsec'' is a portmanteau of "parallax of one second" and was coined by the British astronomer Herbert Hall Turner in 1913 to make calculations of astronomical distances from only raw observational data easy for astronomers. Partly for this reason, it is the unit preferred in astronomy and astrophysics, though the light-year remains prominent in popular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observable Universe
The observable universe is a ball-shaped region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion. There may be 2 trillion galaxies in the observable universe, although that number was reduced in 2021 to only several hundred billion based on data from '' New Horizons''. Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe is a spherical region centered on the observer and is unique for every unique observational position. The word ''observable'' in this sense does not refer to the capability of modern technology to detect light or other information from an object, or whether there is anything to be detected. It refers to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Largest Known Cosmic Structures
This is a list of the largest cosmic structures so far discovered. The unit of measurement used is the light-year (distance traveled by light in one Julian year; approximately 9.46 trillion kilometres). This list includes superclusters, galaxy filaments and large quasar groups (LQGs). The list characterizes each structure based on its longest dimension. Note that this list refers only to coupling of matter with defined limits, and not the coupling of matter in general (as per example the cosmic microwave background, which fills the entire universe). All structures in this list are defined as to whether their presiding limits have been identified. There are some speculations about this list: *The Zone of Avoidance, or the part of the sky occupied by the Milky Way, blocks out light to several structures, making their limits imprecisely identified. *Some structures are far too distant to be seen even with the most powerful telescopes. Some factors are included to explain the st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
