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Murchison Meteorite
The Murchison meteorite is a meteorite that fell in Australia in 1969 near Murchison, Victoria. It belongs to the carbonaceous chondrite class, a group of meteorites rich in organic compounds. Due to its mass (over ) and the fact that it was an observed fall, the Murchison meteorite is one of the most studied of all meteorites. In January 2020, cosmochemists reported that the oldest material found on Earth to date are the silicon carbide particles from the Murchison meteorite, which have been determined to be 7 billion years old, about 2.5 billion years older than the 4.54-billion-year age of the Earth and the Solar System. The published study noted that "dust lifetime estimates mainly rely on sophisticated theoretical models. These models, however, focus on the more common small dust grains and are based on assumptions with large uncertainties." History On 28 September 1969 at approximately 10:58 a.m. local time, near Murchison, Victoria, in Australia, a bright ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Museum Of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7.1 million visitors, it was the eighteenth most visited museum in the world and the second most visited natural history museum in the world after the Natural History Museum in London."The World's most popular museums", CNN.com, 22 June 2017. Opened in 1910, the museum on the National Mall was one of the first Smithsonian buildings constructed exclusively to hold the national collections and research facilities. The main building has an overall area of with of exhibition and public space and houses over 1,000 employees. The museum's collections contain over 145 million specimens of plants, animals, fossils, minerals, rocks, meteorites, human remains, and human cultural artifacts, the largest natural history collection in the world. It i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation And Evolution Of The Solar System
The formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed. This model, known as the nebular hypothesis, was first developed in the 18th century by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace. Its subsequent development has interwoven a variety of scientific disciplines including astronomy, chemistry, geology, physics, and planetary science. Since the dawn of the space age in the 1950s and the discovery of extrasolar planets in the 1990s, the model has been both challenged and refined to account for new observations. The Solar System has evolved considerably since its initial formation. Many moons have formed from circling discs of gas and dust around their parent planets ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alanine
Alanine (symbol Ala or A), or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group side chain. Consequently, its IUPAC systematic name is 2-aminopropanoic acid, and it is classified as a nonpolar, aliphatic α-amino acid. Under biological conditions, it exists in its zwitterionic form with its amine group protonated (as −NH3+) and its carboxyl group deprotonated (as −CO2−). It is non-essential to humans as it can be synthesised metabolically and does not need to be present in the diet. It is encoded by all codons starting with GC (GCU, GCC, GCA, and GCG). The L-isomer of alanine (left-handed) is the one that is incorporated into proteins. L-alanine is second only to leucine in rate of occurrence, accounting for 7.8% of the primary structure in a sample of 1,150 proteins. The right-handed form, D-alanine, occurs in p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycine
Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid (carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (GGU, GGC, GGA, GGG). Glycine is integral to the formation of alpha-helices in secondary protein structure due to its compact form. For the same reason, it is the most abundant amino acid in collagen triple-helices. Glycine is also an inhibitory neurotransmitter – interference with its release within the spinal cord (such as during a ''Clostridium tetani'' infection) can cause spastic paralysis due to uninhibited muscle contraction. It is the only achiral proteinogenic amino acid. It can fit into hydrophilic or hydrophobic environments, due to its minimal side chain of only one hydrogen atom. History and etymology Glycine was discovered in 1820 by the French chemist He ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Live Science
Live Science is a science news website run by Future via Purch, which it purchased from Imaginova in 2009. Stories and editorial commentary are typically syndicated to major news outlets, such as Yahoo!, MSNBC, AOL, and Fox News.{{fact, date=March 2020 Live Science was originally launched in 2004, but was subsequently shut down and re-launched in 2007. Live Science covers scientific breakthroughs, research ventures and odd facts from around the world in an online newsmagazine format. Purch consumer brands (including Live Science) were acquired by Future in 2018.{{Cite web , url=https://www.futureplc.com/brand/live-science/ , title=Live Science , work=Future plc Future plc is an international multimedia company established in the United Kingdom in 1985. The company has over 220 brands that span magazines, newsletters, websites, and events in fields such as video games, technology, films, music, photogr ... , access-date=18 December 2018 References {{reflist External links ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha amino acids appear in the genetic code. Amino acids can be classified according to the locations of the core structural functional groups, as Alpha and beta carbon, alpha- , beta- , gamma- or delta- amino acids; other categories relate to Chemical polarity, polarity, ionization, and side chain group type (aliphatic, Open-chain compound, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Description The combining capacity, or affinity of an ...—its atom making four electrons available to form covalent bond, covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025 percent of Earth's crust. Three Isotopes of carbon, isotopes occur naturally, Carbon-12, C and Carbon-13, C being stable, while Carbon-14, C is a radionuclide, decaying with a half-life of about 5,730 years. Carbon is one of the Timeline of chemical element discoveries#Ancient discoveries, few elements known since antiquity. Carbon is the 15th Abundance of elements in Earth's crust, most abundant element in the Earth's crust, and the Abundance of the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parent Body
In meteoritics, a parent body is the celestial body from which originates a meteorite or a class of meteorites. Identification The easiest way to correlate a meteorite with a parent body is when the parent body still exists. This is the case for Lunar and Martian meteorites. Samples from Lunar meteorites can be compared with samples from the Apollo program. Martian meteorites can be compared to analysis carried out by rovers (e.g. Curiosity). Meteorites can also be compared to spectral classes of asteroids. In order to identify the parent body of a class of meteorites, scientists compare their albedo and spectra with other known bodies. These studies show that some meteorite classes are closely related to some asteroids. The HED meteorites for example are correlated with 4 Vesta.Gunter Faure, Teresa M. Mensing. ''Introduction to Planetary Science: The Geological Perspective''Page 175 Another, perhaps most useful way to classify meteorites by parent bodies is by grouping t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorite Classification
In meteoritics, a meteorite classification system attempts to group similar meteorite, meteorites and allows scientists to communicate with a standardized terminology when discussing them. Meteorites are classified according to a variety of characteristics, especially mineralogy, mineralogical, petrology, petrological, chemistry, chemical, and isotope, isotopic properties. Terminology There is no single, standardized terminology used in meteorite classification; however, commonly used terms for categories include ''types'', ''classes'', ''clans'', ''groups'', and ''subgroups''. Some researchers hierarchize these terms, but there is no consensus as to which hierarchy is most appropriate. Meteorites that do not fit any known group (though they may fit somewhere within a higher level of classification) are ''ungrouped''. Genetic relationships Meteorite classification may indicate that a "genetic" relationship exists between similar meteorite specimens. Similarly classified meteorit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ABC News (Australia)
ABC News, or ABC News and Current Affairs, is a public news service produced by the Australian Broadcasting Corporation. Broadcasting within Australia and the rest of the world, the service covers both local and world affairs. The division of the organisation, which is called ABC News, Analysis and Investigations. is responsible for all news-gathering and coverage across the Australian Broadcasting Corporation's various television, radio, and online platforms. Some of the services included under the auspices of the division are the ABC News TV channel (formerly ABC News 24); the long-running radio news programs, '' AM'', '' The World Today'', and '' PM''; ABC NewsRadio, a 24-hour continuous news radio channel; and radio news bulletins and programs on ABC Local Radio, ABC Radio National, ABC Classic FM, and Triple J. ABC News Online has an extensive online presence which includes many written news reports and videos available via ABC Online, an ABC News mobile app (ABC Liste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
