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Robert D'Escourt Atkinson
Robert d'Escourt Atkinson (born 11 April 1898, Rhayader, Wales – died 28 October 1982, Bloomington, Indiana) was a British astronomer, physicist and inventor. Biography Robert d'Escourt Atkinson was born in Wales on April 11, 1898. He went to Manchester Grammar School and received a degree in physics from Oxford in 1922. He worked in the Clarendon Laboratory and then went to Göttingen, where he received a Ph.D. in physics in 1928."Atkinson, Robert d’Escourt", by Wayne Orchiston, pp. 68-69 in ''The Biographical Dictionary of Astronomers'', eds. Thomas Hockey et al., Springer: New York, 2007, , . After teaching physics at the Berlin Technische Hochscule for a year, Atkinson was appointed Assistant Professor of Physics at Rutgers University. He taught at Rutgers University in New Jersey from 1929 to 1937, when he became Chief Assistant at the Royal Greenwich Observatory. During World War II, Atkinson was called away from this position to do anti-magnetic mine work. In 1944 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhayader
Rhayader (; cy, Rhaeadr Gwy; ) is a market town and community in Powys, Wales, within the historic county of Radnorshire. The town is from the source of the River Wye on Plynlimon, the highest point of the Cambrian Mountains, and is located at the junction of the A470 road and the A44 road north of Builth Wells and east of Aberystwyth. The population was 2,088, with 55% of the community having some form of Welsh identity, according to the 2011 census. The community is the largest in Wales by area, with . It includes the Elan Valley. Rhayader holds the record for the lowest-ever temperature recorded in Wales, -23.3 °C on 21 January 1940. Etymology The name, Rhayader, is a partly-Anglicised form of its Welsh name, ''Y Rhaeadr'' (the waterfall), or, to distinguish it from other places named after waterfalls, "Rhaeadr Gwy" (waterfall n theWye). Strictly speaking, according to place-name spelling conventions in Welsh, the name of the town would be 'Rhaeadr-gwy', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herstmonceux Castle
Herstmonceux Castle is a brick-built castle, dating from the 15th century, near Herstmonceux, East Sussex, England. It is one of the oldest significant brick buildings still standing in England. The castle was renowned for being one of the first buildings to use that material in England, and was built using bricks taken from the local clay, by builders from Flanders. It dates from 1441. Construction began under the then-owner, Sir Roger Fiennes, and was continued after his death in 1449 by his son, Lord Dacre. The parks and gardens of Herstmonceux Castle and Place are Grade II* listed on the Register of Historic Parks and Gardens. Other listed structures on the Herstmonceux estate include the Grade II listed walled garden to the north of the castle, and the Grade II* listed telescopes and workshops of the Herstmonceux Science Centre. History Early history The first written evidence of the existence of the Herst settlement appears in William the Conqueror's Domesday Book wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Clock
An astronomical clock, horologium, or orloj is a clock with special mechanisms and dials to display astronomical information, such as the relative positions of the Sun, Moon, zodiacal constellations, and sometimes major planets. Definition The term is loosely used to refer to any clock that shows, in addition to the time of day, astronomical information. This could include the location of the Sun and Moon in the sky, the age and Lunar phases, the position of the Sun on the ecliptic and the current zodiac sign, the sidereal time, and other astronomical data such as the Moon's nodes (for indicating eclipses) or a rotating star map. The term should not be confused with ''astronomical regulator'', a high precision but otherwise ordinary pendulum clock used in observatories. Astronomical clocks usually represent the Solar System using the geocentric model. The center of the dial is often marked with a disc or sphere representing the Earth, located at the center of the Solar Sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Dwarf Star
A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes from the emission of residual thermal energy; no fusion takes place in a white dwarf. The nearest known white dwarf is at 8.6 light years, the smaller component of the Sirius binary star. There are currently thought to be eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910. The name ''white dwarf'' was coined by Willem Luyten in 1922. White dwarfs are thought to be the final evolutionary state of stars whose mass is not high enough to become a neutron star or black hole. This includes over 97% of the other stars in the Milky Way. After the hydrogen- fusing period of a main-sequence star of low or medium mass ends, such a star will expand to a red g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Nucleosynthesis
Stellar nucleosynthesis is the creation (nucleosynthesis) of chemical elements by nuclear fusion reactions within stars. Stellar nucleosynthesis has occurred since the original creation of hydrogen, helium and lithium during the Big Bang. As a predictive theory, it yields accurate estimates of the observed abundances of the elements. It explains why the observed abundances of elements change over time and why some elements and their isotopes are much more abundant than others. The theory was initially proposed by Fred Hoyle in 1946, who later refined it in 1954. Further advances were made, especially to nucleosynthesis by neutron capture of the elements heavier than iron, by Margaret and Geoffrey Burbidge, William Alfred Fowler and Hoyle in their famous 1957 B2FH paper, which became one of the most heavily cited papers in astrophysics history. Stars evolve because of changes in their composition (the abundance of their constituent elements) over their lifespans, first by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter.However, most of the universe's mass is not in the form of baryons or chemical elements. See dark matter and dark energy. Stars such as the Sun are mainly composed of hydrogen in the plasma state. Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds. For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons. In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CNO Cycle
The CNO cycle (for carbon–nitrogen–oxygen; sometimes called Bethe–Weizsäcker cycle after Hans Albrecht Bethe and Carl Friedrich von Weizsäcker) is one of the two known sets of fusion reactions by which stars convert hydrogen to helium, the other being the proton–proton chain reaction (p–p cycle), which is more efficient at the Sun's core temperature. The CNO cycle is hypothesized to be dominant in stars that are more than 1.3 times as massive as the Sun. Unlike the proton-proton reaction, which consumes all its constituents, the CNO cycle is a catalytic cycle. In the CNO cycle, four protons fuse, using carbon, nitrogen, and oxygen isotopes as catalysts, each of which is consumed at one step of the CNO cycle, but re-generated in a later step. The end product is one alpha particle (a stable helium nucleus), two positrons, and two electron neutrinos. There are various alternative paths and catalysts involved in the CNO cycles, all these cycles have the same ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Fusion
Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles ( neutrons or protons). The difference in mass between the reactants and products is manifested as either the release or absorption of energy. This difference in mass arises due to the difference in nuclear binding energy between the atomic nuclei before and after the reaction. Nuclear fusion is the process that powers active or main-sequence stars and other high-magnitude stars, where large amounts of energy are released. A nuclear fusion process that produces atomic nuclei lighter than iron-56 or nickel-62 will generally release energy. These elements have a relatively small mass and a relatively large binding energy per nucleon. Fusion of nuclei lighter than these releases energy (an exothermic process), while the fusion of heavier nuclei results in energy retained by the product nucleons, and the resulting reaction is endo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Tunnelling
Quantum tunnelling, also known as tunneling ( US) is a quantum mechanical phenomenon whereby a wavefunction can propagate through a potential barrier. The transmission through the barrier can be finite and depends exponentially on the barrier height and barrier width. The wavefunction may disappear on one side and reappear on the other side. The wavefunction and its first derivative are continuous. In steady-state, the probability flux in the forward direction is spatially uniform. No particle or wave is lost. Tunneling occurs with barriers of thickness around 1–3 nm and smaller. Some authors also identify the mere penetration of the wavefunction into the barrier, without transmission on the other side as a tunneling effect. Quantum tunneling is not predicted by the laws of classical mechanics where surmounting a potential barrier requires sufficient kinetic energy. Quantum tunneling plays an essential role in physical phenomena such as nuclear fusion and alpha radioact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Gamow
George Gamow (March 4, 1904 – August 19, 1968), born Georgiy Antonovich Gamov ( uk, Георгій Антонович Гамов, russian: Георгий Антонович Гамов), was a Russian-born Soviet and American polymath, theoretical physicist and cosmologist. He was an early advocate and developer of Lemaître's Big Bang theory. He discovered a theoretical explanation of alpha decay by quantum tunneling, invented the liquid drop model and the first mathematical model of the atomic nucleus, and worked on radioactive decay, star formation, stellar nucleosynthesis and Big Bang nucleosynthesis (which he collectively called nucleocosmogenesis), and molecular genetics. In his middle and late career, Gamow directed much of his attention to teaching and wrote popular books on science, including '' One Two Three... Infinity'' and the ''Mr Tompkins'' series of books (1939–1967). Some of his books are still in print more than a half-century after their original publicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fritz Houtermans
Friedrich Georg "Fritz" Houtermans (January 22, 1903 – March 1, 1966) was a Dutch-Austrian-German atomic and nuclear physicist and Communist born in Zoppot near Danzig, West Prussia to a Dutch father, who was a wealthy banker. He was brought up in Vienna, where he was educated, and moved to Göttingen when he was 18 to study. It was in Göttingen where he obtained his Ph.D. under James Franck. Education Houtermans began his studies at the University of Göttingen in 1921, and he received his doctorate under James Franck in 1927, the same year Robert Oppenheimer received his doctorate under Max Born. He completed his Habilitation under Gustav Hertz at the Technical University of Berlin, in 1932. Hertz and Franck were Nobel Prize laureates; they shared the 1925 Nobel Prize in Physics.Hentschel, 1996, Appendix F; see the entry for Houtermans. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Astronomical Association
The British Astronomical Association (BAA) was formed in 1890 as a national body to support the UK's amateur astronomers. Throughout its history, the BAA has encouraged observers to make scientifically valuable observations, often in collaboration with professional colleagues. Among the BAA's first presidents was Walter Maunder, discoverer of the seventeenth century dearth in sunspots now known as the Maunder Minimum which he achieved by analysing historical observations. Later, this spirit of observing the night sky scientifically was championed by George Alcock, who discovered five comets and five novae using nothing more than a pair of binoculars. The BAA continues to contribute to the science of astronomy, even despite modern competition from space-based telescopes and highly automated professional observatories. Modern digital sensors, coupled with techniques such as lucky imaging, mean that even modest amateur equipment can rival what professional observatories could hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
