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148-545: The primary source of contamination at the locations stems from the processing of uranium ores and the disposal of the byproducts. The major sources of site contamination are uranium , thorium , and radium . In addition to the radiological contaminants there are semi-volatile organic compounds, volatile organic compounds , and heavy metals comingled at the sites. Data from multiple sources EPA summary page Ohio River Pittsburgh District Ohio River Division Ohio River Division Ohio River Uranium Uranium

296-404: A bright spot at the north pole, indicating the presence of a polar vortex . In the 1990s, the number of the observed bright cloud features grew considerably, partly because new high-resolution imaging techniques became available. Most were found in the northern hemisphere as it started to become visible. An early explanation—that bright clouds are easier to identify in its dark part, whereas in

444-597: A comet." On 17 March he noted: "I looked for the Comet or Nebulous Star and found that it is a Comet, for it has changed its place." When he presented his discovery to the Royal Society , he continued to assert that he had found a comet, but also implicitly compared it to a planet: The power I had on when I first saw the comet was 227. From experience I know that the diameters of the fixed stars are not proportionally magnified with higher powers, as planets are; therefore I now put

592-524: A description of this process of reactor control). As little as 15 lb (6.8 kg) of uranium-235 can be used to make an atomic bomb. The nuclear weapon detonated over Hiroshima , called Little Boy , relied on uranium fission. However, the first nuclear bomb (the Gadget used at Trinity ) and the bomb that was detonated over Nagasaki ( Fat Man ) were both plutonium bombs. Uranium metal has three allotropic forms: The major application of uranium in

740-471: A distribution of uranium oxidation species in various forms ranging from most oxidized to least oxidized. Particles with short residence times in a calciner will generally be less oxidized than those with long retention times or particles recovered in the stack scrubber. Uranium content is usually referenced to U 3 O 8 , which dates to the days of the Manhattan Project when U 3 O 8

888-505: A few Earth masses of nebular gas, never reached that critical point. Recent simulations of planetary migration have suggested that both ice giants formed closer to the Sun than their present positions, and moved outwards after formation (the Nice model ). Uranus orbits the Sun once every 84 years. As viewed against the background of stars, since being discovered in 1781, the planet has returned to

1036-539: A few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite . Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 is the only naturally occurring fissile isotope , which makes it widely used in nuclear power plants and nuclear weapons . However, because of the low abundance of uranium-235 in natural uranium (which is, overwhelmingly, mostly uranium-238), uranium needs to undergo enrichment so that enough uranium-235

1184-556: A form of invisible light or rays emitted by uranium had exposed the plate. During World War I when the Central Powers suffered a shortage of molybdenum to make artillery gun barrels and high speed tool steels, they routinely used ferrouranium alloy as a substitute, as it presents many of the same physical characteristics as molybdenum. When this practice became known in 1916 the US government requested several prominent universities to research

1332-717: A fuel in the nuclear power industry and in Little Boy , the first nuclear weapon used in war . An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of nuclear weapons that used uranium metal and uranium-derived plutonium-239 . Dismantling of these weapons and related nuclear facilities is carried out within various nuclear disarmament programs and costs billions of dollars. Weapon-grade uranium obtained from nuclear weapons

1480-677: A higher incidence of cancer . An excess risk of lung cancer among Navajo uranium miners, for example, has been documented and linked to their occupation. The Radiation Exposure Compensation Act , a 1990 law in the US, required $ 100,000 in "compassion payments" to uranium miners diagnosed with cancer or other respiratory ailments. During the Cold War between the Soviet Union and the United States, huge stockpiles of uranium were amassed and tens of thousands of nuclear weapons were created using enriched uranium and plutonium made from uranium. After

1628-497: A lesser degree uranium-233, have a much higher fission cross-section for slow neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction . This generates the heat in nuclear power reactors and produces the fissile material for nuclear weapons. The primary civilian use for uranium harnesses the heat energy to produce electricity. Depleted uranium ( U) is used in kinetic energy penetrators and armor plating . The 1789 discovery of uranium in

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1776-423: A much greater distance from Uranus are the ten known irregular moons . The planet's magnetosphere is highly asymmetric and has many charged particles , which may be the cause of the darkening of its rings and moons. Uranus is visible to the naked eye, but it is very dim and was not classified as a planet until 1781, when it was first observed by William Herschel . About seven decades after its discovery, consensus

1924-448: A much more complicated and far more powerful type of fission/fusion bomb ( thermonuclear weapon ) was built, that uses a plutonium-based device to cause a mixture of tritium and deuterium to undergo nuclear fusion . Such bombs are jacketed in a non-fissile (unenriched) uranium case, and they derive more than half their power from the fission of this material by fast neutrons from the nuclear fusion process. The main use of uranium in

2072-516: A planet, expanding the known boundaries of the Solar System for the first time in history and making Uranus the first planet classified as such with the aid of a telescope . The discovery of Uranus also effectively doubled the size of the known Solar System because Uranus is around twice the distance from the Sun as the planet Saturn . Before its recognition as a planet, Uranus had been observed on numerous occasions, albeit generally misidentified as

2220-459: A plutonium-based device (see Trinity test and " Fat Man ") whose plutonium was derived from uranium-238. Little Boy became the first nuclear weapon used in war when it was detonated over Hiroshima , Japan , on 6 August 1945. Exploding with a yield equivalent to 12,500 tonnes of TNT , the blast and thermal wave of the bomb destroyed nearly 50,000 buildings and killed about 75,000 people (see Atomic bombings of Hiroshima and Nagasaki ). Initially it

2368-459: A polar cap in the northern hemisphere. So Uranus appeared to be asymmetric: bright near the south pole and uniformly dark in the region north of the southern collar. In 2007, when Uranus passed its equinox, the southern collar almost disappeared, and a faint northern collar emerged near 45° of latitude. In 2023, a team employing the Very Large Array observed a dark collar at 80° latitude, and

2516-405: A reaction by piling together 360 tonnes of graphite , 53 tonnes of uranium oxide , and 5.5 tonnes of uranium metal, most of which was supplied by Westinghouse Lamp Plant in a makeshift production process. Two types of atomic bomb were developed by the United States during World War II : a uranium-based device (codenamed " Little Boy ") whose fissile material was highly enriched uranium , and

2664-493: A regular planet moving in an orbit nearly circular to the sun as a Comet moving in a very eccentric ellipsis. I have not yet seen any coma or tail to it." Although Herschel continued to describe his new object as a comet, other astronomers had already begun to suspect otherwise. Finnish-Swedish astronomer Anders Johan Lexell , working in Russia, was the first to compute the orbit of the new object. Its nearly circular orbit led him to

2812-477: A revolving oblate spheroid set at the point at which atmospheric pressure equals 1 bar (100 kPa) is conditionally designated as a "surface". It has equatorial and polar radii of 25,559 ± 4 km (15,881.6 ± 2.5 mi) and 24,973 ± 20 km (15,518 ± 12 mi), respectively. This surface is used throughout this article as a zero point for altitudes. Uranus's internal heat appears markedly lower than that of

2960-413: A shielding material. Due to its high density, this material is found in inertial guidance systems and in gyroscopic compasses . Depleted uranium is preferred over similarly dense metals due to its ability to be easily machined and cast as well as its relatively low cost. The main risk of exposure to depleted uranium is chemical poisoning by uranium oxide rather than radioactivity (uranium being only

3108-525: A shorter half-life and so is an extinct radionuclide , having long since decayed completely to Th. Further uranium-236 was produced by the decay of Pu , accounting for the observed higher-than-expected abundance of thorium and lower-than-expected abundance of uranium. While the natural abundance of uranium has been supplemented by the decay of extinct Pu (half-life 375,000 years) and Cm (half-life 16 million years), producing U and U respectively, this occurred to an almost negligible extent due to

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3256-537: A star. The earliest possible known observation was by Hipparchus , who in 128 BC might have recorded it as a star for his star catalogue that was later incorporated into Ptolemy 's Almagest . The earliest definite sighting was in 1690, when John Flamsteed observed it at least six times, cataloguing it as 34 Tauri . The French astronomer Pierre Charles Le Monnier observed Uranus at least twelve times between 1750 and 1769, including on four consecutive nights. William Herschel observed Uranus on 13 March 1781 from

3404-482: A total of 10 cloud features across the entire planet. One proposed explanation for this dearth of features is that Uranus's internal heat is markedly lower than that of the other giant planets, being the coldest planet in the Solar System. In 1986, Voyager 2 found that the visible southern hemisphere of Uranus can be subdivided into two regions: a bright polar cap and dark equatorial bands. Their boundary

3552-412: A weak alpha emitter ). During the later stages of World War II , the entire Cold War , and to a lesser extent afterwards, uranium-235 has been used as the fissile explosive material to produce nuclear weapons. Initially, two major types of fission bombs were built: a relatively simple device that uses uranium-235 and a more complicated mechanism that uses plutonium-239 derived from uranium-238. Later,

3700-530: A world total production of 48,332 tonnes. Most uranium was produced not by conventional underground mining of ores (29% of production), but by in situ leaching (66%). In the late 1960s, UN geologists discovered major uranium deposits and other rare mineral reserves in Somalia . The find was the largest of its kind, with industry experts estimating the deposits at over 25% of the world's then known uranium reserves of 800,000 tons. The ultimate available supply

3848-639: Is Dao Yurenat ( ดาวยูเรนัส ), as in English. Its other name in Thai is Dao Maruettayu ( ดาวมฤตยู , Star of Mṛtyu), after the Sanskrit word for 'death', Mrtyu ( मृत्यु ). In Mongolian , its name is Tengeriin Van ( Тэнгэрийн ван ), translated as 'King of the Sky', reflecting its namesake god's role as the ruler of the heavens. In Hawaiian , its name is Heleʻekala ,

3996-552: Is malleable , ductile , slightly paramagnetic , strongly electropositive and a poor electrical conductor . Uranium metal has a very high density of 19.1 g/cm , denser than lead (11.3 g/cm ), but slightly less dense than tungsten and gold (19.3 g/cm ). Uranium metal reacts with almost all non-metallic elements (except noble gases ) and their compounds , with reactivity increasing with temperature. Hydrochloric and nitric acids dissolve uranium, but non-oxidizing acids other than hydrochloric acid attack

4144-504: Is 5.68 with a standard deviation of 0.17, while the extremes are 5.38 and 6.03. This range of brightness is near the limit of naked eye visibility. Much of the variability is dependent upon the planetary latitudes being illuminated from the Sun and viewed from the Earth. Its angular diameter is between 3.4 and 3.7 arcseconds, compared with 16 to 20 arcseconds for Saturn and 32 to 45 arcseconds for Jupiter. At opposition , Uranus

4292-445: Is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table . A uranium atom has 92 protons and 92 electrons , of which 6 are valence electrons . Uranium radioactively decays , usually by emitting an alpha particle . The half-life of this decay varies between 159,200 and 4.5 billion years for different isotopes , making them useful for dating

4440-471: Is a naturally occurring element found in low levels in all rock, soil, and water. It is the highest-numbered element found naturally in significant quantities on Earth and is almost always found combined with other elements. Uranium is the 48th most abundant element in the Earth’s crust. The decay of uranium, thorium , and potassium-40 in Earth's mantle is thought to be the main source of heat that keeps

4588-457: Is a dynamic part of the atmosphere, exhibiting strong winds, bright clouds, and seasonal changes. The middle layer of the Uranian atmosphere is the stratosphere , where temperature generally increases with altitude from 53 K (−220 °C; −364 °F) in the tropopause to between 800 and 850 K (527 and 577 °C; 980 and 1,070 °F) at the base of the thermosphere. The heating of

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4736-412: Is a limiting factor. In a 2021 study, the ice giants' interior conditions were mimicked by compressing water that contained minerals such as olivine and ferropericlase , thus showing that large amounts of magnesium could be dissolved in the liquid interiors of Uranus and Neptune. If Uranus has more of this magnesium than Neptune, it could form a thermal insulation layer, thus potentially explaining

4884-620: Is a rocky core, and surrounding it is a thick hydrogen and helium atmosphere. Trace amounts of hydrocarbons (thought to be produced via hydrolysis ) and carbon monoxide along with carbon dioxide (thought to have been originated from comets ) have been detected in the upper atmosphere. There are many unexplained climate phenomena in Uranus's atmosphere , such as its peak wind speed of 900 km/h (560 mph), variations in its polar cap, and its erratic cloud formation. The planet also has very low internal heat compared to other giant planets,

5032-411: Is a unique feature of Uranus. Its effects include a drag on small particles orbiting Uranus, causing a general depletion of dust in the Uranian rings. The Uranian thermosphere, together with the upper part of the stratosphere, corresponds to the ionosphere of Uranus. Observations show that the ionosphere occupies altitudes from 2,000 to 10,000 km (1,200 to 6,200 mi). The Uranian ionosphere

5180-519: Is also fissile by thermal neutrons. These discoveries led numerous countries to begin working on the development of nuclear weapons and nuclear power . Despite fission having been discovered in Germany, the Uranverein ("uranium club") Germany's wartime project to research nuclear power and/or weapons was hampered by limited resources, infighting, the exile or non-involvement of several prominent scientists in

5328-520: Is believed to be sufficient for at least the next 85 years, though some studies indicate underinvestment in the late twentieth century may produce supply problems in the 21st century. Uranium deposits seem to be log-normal distributed. There is a 300-fold increase in the amount of uranium recoverable for each tenfold decrease in ore grade. In other words, there is little high grade ore and proportionately much more low grade ore available. Calcined uranium yellowcake, as produced in many large mills, contains

5476-404: Is close to the protosolar helium mass fraction of 0.275 ± 0.01 , indicating that helium has not settled in its centre as it has in the gas giants. The third-most-abundant component of Uranus's atmosphere is methane ( CH 4 ). Methane has prominent absorption bands in the visible and near-infrared (IR), making Uranus aquamarine or cyan in colour. Methane molecules account for 2.3% of

5624-399: Is considered north and which is considered south and giving the planet prograde rotation. This gives it seasonal changes completely unlike those of the other planets. Pluto and asteroid 2 Pallas also have extreme axial tilts. Near the solstice , one pole faces the Sun continuously and the other faces away, with only a narrow strip around the equator experiencing a rapid day–night cycle, with

5772-537: Is denser than that of either Saturn or Neptune, which may arise from the low concentration of hydrocarbons in the stratosphere. The ionosphere is mainly sustained by solar UV radiation and its density depends on the solar activity . Auroral activity is insignificant as compared to Jupiter and Saturn. At ultraviolet and visible wavelengths, Uranus's atmosphere is bland in comparison to the other giant planets, even to Neptune, which it otherwise closely resembles. When Voyager 2 flew by Uranus in 1986, it observed

5920-781: Is difficult to precipitate uranium as phosphate in the presence of excess carbonate at alkaline pH. A Sphingomonas sp. strain BSAR-1 has been found to express a high activity alkaline phosphatase (PhoK) that has been applied for bioprecipitation of uranium as uranyl phosphate species from alkaline solutions. The precipitation ability was enhanced by overexpressing PhoK protein in E. coli . Plants absorb some uranium from soil. Dry weight concentrations of uranium in plants range from 5 to 60 parts per billion, and ash from burnt wood can have concentrations up to 4 parts per million. Dry weight concentrations of uranium in food plants are typically lower with one to two micrograms per day ingested through

6068-418: Is diluted with uranium-238 and reused as fuel for nuclear reactors. Spent nuclear fuel forms radioactive waste , which mostly consists of uranium-238 and poses a significant health threat and environmental impact . Uranium is a silvery white, weakly radioactive metal . It has a Mohs hardness of 6, sufficient to scratch glass and roughly equal to that of titanium , rhodium , manganese and niobium . It

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6216-485: Is found in hundreds of minerals, including uraninite (the most common uranium ore ), carnotite , autunite , uranophane , torbernite , and coffinite . Significant concentrations of uranium occur in some substances such as phosphate rock deposits, and minerals such as lignite , and monazite sands in uranium-rich ores (it is recovered commercially from sources with as little as 0.1% uranium ). Like all elements with atomic weights higher than that of iron , uranium

6364-444: Is located at about −45° of latitude . A narrow band straddling the latitudinal range from −45 to −50° is the brightest large feature on its visible surface. It is called a southern "collar". The cap and collar are thought to be a dense region of methane clouds located within the pressure range of 1.3 to 2 bar. Besides the large-scale banded structure, Voyager 2 observed ten small bright clouds, most lying several degrees to

6512-515: Is nearly universal in astrology. In English-language popular culture , humour is often derived from the common pronunciation of Uranus's name, which resembles that of the phrase "your anus ". Uranus is called by a variety of names in other languages. Uranus's name is literally translated as the "sky king star" in Chinese ( 天王星 ; Tiānwángxīng ), Japanese (天王星), Korean (천왕성), and Vietnamese ( sao Thiên Vương ). In Thai , its official name

6660-404: Is not precisely known, because different figures emerge depending on the model chosen; it must be between 9.3 and 13.5 Earth masses. Hydrogen and helium constitute only a small part of the total, with between 0.5 and 1.5 Earth masses. The remainder of the non-ice mass (0.5 to 3.7 Earth masses) is accounted for by rocky material . The standard model of Uranus's structure

6808-427: Is only naturally formed by the r-process (rapid neutron capture) in supernovae and neutron star mergers . Primordial thorium and uranium are only produced in the r-process, because the s-process (slow neutron capture) is too slow and cannot pass the gap of instability after bismuth. Besides the two extant primordial uranium isotopes, U and U, the r-process also produced significant quantities of U , which has

6956-424: Is present. Uranium-238 is fissionable by fast neutrons and is fertile , meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor . Another fissile isotope, uranium-233 , can be produced from natural thorium and is studied for future industrial use in nuclear technology. Uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons; uranium-235, and to

7104-407: Is produced through the thermal decomposition of uranium halides on a hot filament. It is estimated that 6.1 million tonnes of uranium exists in ores that are economically viable at US$ 130 per kg of uranium, while 35 million tonnes are classed as mineral resources (reasonable prospects for eventual economic extraction). Australia has 28% of the world's known uranium ore reserves and

7252-414: Is roughly 14.5 times that of Earth, making it the least massive of the giant planets. Its diameter is slightly larger than Neptune's at roughly four times that of Earth. A resulting density of 1.27 g/cm makes Uranus the second least dense planet, after Saturn. This value indicates that it is made primarily of various ices, such as water, ammonia, and methane. The total mass of ice in Uranus's interior

7400-429: Is similar at these altitudes. Heavier hydrocarbons and carbon dioxide have mixing ratios three orders of magnitude lower. The abundance ratio of water is around 7 × 10 . Ethane and acetylene tend to condense in the colder lower part of the stratosphere and tropopause (below 10 mBar level) forming haze layers, which may be partly responsible for the bland appearance of Uranus. The concentration of hydrocarbons in

7548-411: Is sometimes called a water–ammonia ocean. The extreme pressure and temperature deep within Uranus may break up the methane molecules, with the carbon atoms condensing into crystals of diamond that rain down through the mantle like hailstones. This phenomenon is similar to diamond rains that are theorised by scientists to exist on Jupiter , Saturn , and Neptune . Very-high-pressure experiments at

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7696-464: Is that it consists of three layers: a rocky ( silicate / iron–nickel ) core in the centre, an icy mantle in the middle, and an outer gaseous hydrogen/helium envelope. The core is relatively small, with a mass of only 0.55 Earth masses and a radius less than 20% of the planet; the mantle comprises its bulk, with around 13.4 Earth masses, and the upper atmosphere is relatively insubstantial, weighing about 0.5 Earth masses and extending for

7844-400: Is that, averaged over the Uranian year, the near-polar regions of Uranus receive a greater energy input from the Sun than its equatorial regions. Nevertheless, Uranus is hotter at its equator than at its poles. The underlying mechanism that causes this is unknown. The reason for Uranus's unusual axial tilt is also not known with certainty, but the usual speculation is that during the formation of

7992-441: Is then calcined to remove impurities from the milling process before refining and conversion. Commercial-grade uranium can be produced through the reduction of uranium halides with alkali or alkaline earth metals . Uranium metal can also be prepared through electrolysis of KUF 5 or UF 4 , dissolved in molten calcium chloride ( CaCl 2 ) and sodium chloride ( Na Cl) solution. Very pure uranium

8140-436: Is thought to have a highly complex cloud structure; water clouds are hypothesised to lie in the pressure range of 50 to 100 bar (5 to 10 MPa), ammonium hydrosulfide clouds in the range of 20 to 40 bar (2 to 4 MPa), ammonia or hydrogen sulfide clouds at between 3 and 10 bar (0.3 and 1 MPa) and finally directly detected thin methane clouds at 1 to 2 bar (0.1 to 0.2 MPa). The troposphere

8288-585: Is used for X-ray targets in the making of high-energy X-rays. The use of pitchblende , uranium in its natural oxide form, dates back to at least the year 79 AD, when it was used in the Roman Empire to add a yellow color to ceramic glazes. Yellow glass with 1% uranium oxide was found in a Roman villa on Cape Posillipo in the Bay of Naples , Italy, by R. T. Gunther of the University of Oxford in 1912. Starting in

8436-435: Is visible to the naked eye in dark skies, and becomes an easy target even in urban conditions with binoculars. On larger amateur telescopes with an objective diameter of between 15 and 23 cm, Uranus appears as a pale cyan disk with distinct limb darkening . With a large telescope of 25 cm or wider, cloud patterns, as well as some of the larger satellites, such as Titania and Oberon , may be visible. Uranus's mass

8584-533: The International Astronomical Union definition that the north pole is the pole which lies on Earth's North's side of the invariable plane of the Solar System . Uranus has retrograde rotation when defined this way. Alternatively, the convention in which a body's north and south poles are defined according to the right-hand rule in relation to the direction of rotation, Uranus's axial tilt may be given instead as 97.8°, which reverses which pole

8732-492: The Lawrence Livermore National Laboratory suggest that an ocean of metallic liquid carbon, perhaps with floating solid 'diamond-bergs', may comprise the base of the mantle. The bulk compositions of Uranus and Neptune are different from those of Jupiter and Saturn , with ice dominating over gases, hence justifying their separate classification as ice giants . There may be a layer of ionic water where

8880-402: The Manhattan Project , another team led by Enrico Fermi was able to initiate the first artificial self-sustained nuclear chain reaction , Chicago Pile-1 . An initial plan using enriched uranium-235 was abandoned as it was as yet unavailable in sufficient quantities. Working in a lab below the stands of Stagg Field at the University of Chicago , the team created the conditions needed for such

9028-492: The Megatons to Megawatts Program . An additional 4.6 billion tonnes of uranium are estimated to be dissolved in sea water ( Japanese scientists in the 1980s showed that extraction of uranium from sea water using ion exchangers was technically feasible). There have been experiments to extract uranium from sea water, but the yield has been low due to the carbonate present in the water. In 2012, ORNL researchers announced

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9176-466: The Oklo Fossil Reactors . The ore deposit is 1.7 billion years old; then, uranium-235 constituted about 3% of uranium on Earth. This is high enough to permit a sustained chain reaction, if other supporting conditions exist. The capacity of the surrounding sediment to contain the health-threatening nuclear waste products has been cited by the U.S. federal government as supporting evidence for

9324-688: The Shippingport Atomic Power Station in Pennsylvania , which began on 26 May 1958. Nuclear power was used for the first time for propulsion by a submarine , the USS Nautilus , in 1954. In 1972, French physicist Francis Perrin discovered fifteen ancient and no longer active natural nuclear fission reactors in three separate ore deposits at the Oklo mine in Gabon , Africa, collectively known as

9472-459: The Solar System 's planets. It has a marked axial tilt of 82.23° with a retrograde rotation period of 17 hours and 14 minutes. This means that in an 84-Earth-year orbital period around the Sun, its poles get around 42 years of continuous sunlight, followed by 42 years of continuous darkness. Uranus has the third-largest diameter and fourth-largest mass among the Solar System's planets. Based on current models, inside its volatile mantle layer

9620-465: The United States (2.5%), Argentina (2.1%) and Ukraine (1.9%). In 2008, Kazakhstan was forecast to increase production and become the world's largest supplier of uranium by 2009; Kazakhstan has dominated the world's uranium market since 2010. In 2021, its share was 45.1%, followed by Namibia (11.9%), Canada (9.7%), Australia (8.7%), Uzbekistan (7.2%), Niger (4.7%), Russia (5.5%), China (3.9%), India (1.3%), Ukraine (0.9%), and South Africa (0.8%), with

9768-439: The age of the Earth . The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99% of uranium on Earth) and uranium-235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead and slightly lower than that of gold or tungsten . It occurs naturally in low concentrations of

9916-497: The auroral activity can provide the necessary energy to maintain these temperatures. The weak cooling efficiency due to the lack of hydrocarbons in the stratosphere above 0.1 mBar pressure levels may contribute too. In addition to molecular hydrogen, the thermosphere-corona contains many free hydrogen atoms. Their small mass and high temperatures explain why the corona extends as far as 50,000 km (31,000 mi), or two Uranian radii, from its surface. This extended corona

10064-592: The break-up of the Soviet Union in 1991, an estimated 600 short tons (540 metric tons) of highly enriched weapons grade uranium (enough to make 40,000 nuclear warheads) had been stored in often inadequately guarded facilities in the Russian Federation and several other former Soviet states. Police in Asia , Europe , and South America on at least 16 occasions from 1993 to 2005 have intercepted shipments of smuggled bomb-grade uranium or plutonium, most of which

10212-432: The oceans may contain 10  kg (2 × 10  lb). The concentration of uranium in soil ranges from 0.7 to 11 parts per million (up to 15 parts per million in farmland soil due to use of phosphate fertilizers ), and its concentration in sea water is 3 parts per billion. Uranium is more plentiful than antimony , tin , cadmium , mercury , or silver, and it is about as abundant as arsenic or molybdenum . Uranium

10360-451: The "Georgian Planet" in honour of his new patron, King George III. He explained this decision in a letter to Joseph Banks: In the fabulous ages of ancient times the appellations of Mercury, Venus, Mars, Jupiter and Saturn were given to the Planets, as being the names of their principal heroes and divinities. In the present more philosophical era it would hardly be allowable to have recourse to

10508-619: The Dean of the Sapienza University of Rome , Orso Mario Corbino , named ausenium and hesperium , respectively. The experiments leading to the discovery of uranium's ability to fission (break apart) into lighter elements and release binding energy were conducted by Otto Hahn and Fritz Strassmann in Hahn's laboratory in Berlin. Lise Meitner and her nephew, physicist Otto Robert Frisch , published

10656-408: The Earth's outer core in the liquid state and drives mantle convection , which in turn drives plate tectonics . Uranium's concentration in the Earth's crust is (depending on the reference) 2 to 4 parts per million, or about 40 times as abundant as silver . The Earth's crust from the surface to 25 km (15 mi) down is calculated to contain 10  kg (2 × 10  lb) of uranium while

10804-545: The Earth-sized impactor theorised to be behind Uranus's axial tilt left the planet with a depleted core temperature, as the impact caused Uranus to expel most of its primordial heat. Another hypothesis is that some form of barrier exists in Uranus's upper layers that prevents the core's heat from reaching the surface. For example, convection may take place in a set of compositionally different layers, which may inhibit upward heat transport ; perhaps double diffusive convection

10952-450: The Hawaiian rendering of the name 'Herschel'. In Māori , its name is Whērangi . It is argued that the differences between the ice giants and the gas giants arise from their formation history. The Solar System is hypothesised to have formed from a rotating disk of gas and dust known as the presolar nebula . Much of the nebula's gas, primarily hydrogen and helium, formed the Sun, and

11100-640: The Latinised form of the deity's name, and the Roman equivalent was Caelus. In 1789, Bode's Royal Academy colleague Martin Klaproth named his newly discovered element uranium in support of Bode's choice. Ultimately, Bode's suggestion became the most widely used, and became universal in 1850 when HM Nautical Almanac Office , the final holdout, switched from using Georgium Sidus to Uranus . Uranus has two astronomical symbols . The first to be proposed, [REDACTED] ,

11248-686: The Russian government approved a federal program for nuclear and radiation safety for 2016 to 2030 with a budget of 562 billion rubles (ca. 8 billion USD ). Its key issue is "the deferred liabilities accumulated during the 70 years of the nuclear industry, particularly during the time of the Soviet Union". About 73% of the budget will be spent on decommissioning aged and obsolete nuclear reactors and nuclear facilities, especially those involved in state defense programs; 20% will go in processing and disposal of nuclear fuel and radioactive waste, and 5% into monitoring and ensuring of nuclear and radiation safety. Uranium

11396-429: The Solar System, an Earth-sized protoplanet collided with Uranus, causing the skewed orientation. Research by Jacob Kegerreis of Durham University suggests that the tilt resulted from a rock larger than Earth crashing into the planet 3 to 4 billion years ago. Uranus's south pole was pointed almost directly at the Sun at the time of Voyager 2 's flyby in 1986. The mean apparent magnitude of Uranus

11544-421: The Sun low over the horizon. On the other side of Uranus's orbit, the orientation of the poles towards the Sun is reversed. Each pole gets around 42 years of continuous sunlight, followed by 42 years of darkness. Near the time of the equinoxes , the Sun faces the equator of Uranus, giving a period of day–night cycles similar to those seen on most of the other planets. One result of this axis orientation

11692-400: The Uranian stratosphere above the haze is significantly lower than in the stratospheres of the other giant planets. The outermost layer of the Uranian atmosphere is the thermosphere and corona, which has a uniform temperature of around 800 K (527 °C) to 850 K (577 °C). The heat sources necessary to sustain such a high level are not understood, as neither the solar UV nor

11840-478: The ancient Greek deity of the sky Uranus ( Ancient Greek : Οὐρανός ), known as Caelus in Roman mythology, the father of Cronus ( Saturn ), grandfather of Zeus ( Jupiter ) and the great-grandfather of Ares ( Mars ), which was rendered as Uranus in Latin ( IPA: [ˈuːranʊs] ). It is the only one of the eight planets whose English name derives from a figure of Greek mythology . The pronunciation of

11988-463: The atmosphere by molar fraction below the methane cloud deck at the pressure level of 1.3 bar (130 kPa); this represents about 20 to 30 times the carbon abundance found in the Sun. The mixing ratio is much lower in the upper atmosphere due to its extremely low temperature, which lowers the saturation level and causes excess methane to freeze out. The abundances of less volatile compounds such as ammonia, water, and hydrogen sulfide in

12136-566: The bulk of the use, including common bathroom and kitchen tiles which can be produced in green, yellow, mauve , black, blue, red and other colors. Uranium was also used in photographic chemicals (especially uranium nitrate as a toner ), in lamp filaments for stage lighting bulbs, to improve the appearance of dentures , and in the leather and wood industries for stains and dyes. Uranium salts are mordants of silk or wool. Uranyl acetate and uranyl formate are used as electron-dense "stains" in transmission electron microscopy , to increase

12284-453: The cause of which remains unclear. Like the other giant planets, Uranus has a ring system , a magnetosphere , and many natural satellites . The extremely dark ring system reflects only about 2% of the incoming light. Uranus's 28 natural satellites include 18 known regular moons , of which 13 are small inner moons . Further out are the larger five major moons of the planet: Miranda , Ariel , Umbriel , Titania , and Oberon . Orbiting at

12432-409: The civilian sector is to fuel nuclear power plants . One kilogram of uranium-235 can theoretically produce about 20  terajoules of energy (2 × 10   joules ), assuming complete fission; as much energy as 1.5 million kilograms (1,500 tonnes ) of coal . Commercial nuclear power plants use fuel that is typically enriched to around 3% uranium-235. The CANDU and Magnox designs are

12580-463: The coldest upper region of the troposphere (the tropopause ) actually vary in the range between 49 and 57 K (−224 and −216 °C; −371 and −357 °F) depending on planetary latitude. The tropopause region is responsible for the vast majority of Uranus's thermal far infrared emissions, thus determining its effective temperature of 59.1 ± 0.3 K (−214.1 ± 0.3 °C; −353.3 ± 0.5 °F). The troposphere

12728-471: The conclusion that it was a planet rather than a comet. Berlin astronomer Johann Elert Bode described Herschel's discovery as "a moving star that can be deemed a hitherto unknown planet-like object circulating beyond the orbit of Saturn". Bode concluded that its near-circular orbit was more like a planet's than a comet's. The object was soon universally accepted as a new planet. By 1783, Herschel acknowledged this to Royal Society president Joseph Banks : "By

12876-549: The contrast of biological specimens in ultrathin sections and in negative staining of viruses , isolated cell organelles and macromolecules . The discovery of the radioactivity of uranium ushered in additional scientific and practical uses of the element. The long half-life of uranium-238 (4.47 × 10 years) makes it well-suited for use in estimating the age of the earliest igneous rocks and for other types of radiometric dating , including uranium–thorium dating , uranium–lead dating and uranium–uranium dating . Uranium metal

13024-529: The course of the American Revolutionary War by calling the new planet either Neptune George III or Neptune Great Britain , a compromise Lexell suggested as well. Daniel Bernoulli suggested Hypercronius and Transaturnis . Minerva was also proposed. In a March 1782 treatise, Johann Elert Bode proposed Uranus , the Latinised version of the Greek god of the sky, Ouranos . Bode argued that

13172-559: The deep atmosphere are poorly known. They are probably also higher than solar values. Along with methane, trace amounts of various hydrocarbons are found in the stratosphere of Uranus, which are thought to be produced from methane by photolysis induced by the solar ultraviolet (UV) radiation. They include ethane ( C 2 H 6 ), acetylene ( C 2 H 2 ), methylacetylene ( CH 3 C 2 H ), and diacetylene ( C 2 HC 2 H ). Spectroscopy has also uncovered traces of water vapour, carbon monoxide , and carbon dioxide in

13320-442: The development of uranium mining to extract the radium, which was used to make glow-in-the-dark paints for clock and aircraft dials. This left a prodigious quantity of uranium as a waste product, since it takes three tonnes of uranium to extract one gram of radium. This waste product was diverted to the glazing industry, making uranium glazes very inexpensive and abundant. Besides the pottery glazes, uranium tile glazes accounted for

13468-423: The direction of rotation. At some latitudes, such as about 60 degrees south, visible features of the atmosphere move much faster, making a full rotation in as little as 14 hours. The Uranian axis of rotation is approximately parallel to the plane of the Solar System, with an axial tilt of 82.23°. Depending on which pole is considered north, the tilt can be described either as 82.23° or as 97.8°. The former follows

13616-412: The dust grains collected together to form the first protoplanets. As the planets grew, some of them eventually accreted enough matter for their gravity to hold on to the nebula's leftover gas. The more gas they held onto, the larger they became; the larger they became, the more gas they held onto until a critical point was reached, and their size began to increase exponentially. The ice giants, with only

13764-465: The element very slowly. When finely divided, it can react with cold water; in air, uranium metal becomes coated with a dark layer of uranium oxide . Uranium in ores is extracted chemically and converted into uranium dioxide or other chemical forms usable in industry. Uranium-235 was the first isotope that was found to be fissile . Other naturally occurring isotopes are fissionable, but not fissile. On bombardment with slow neutrons, uranium-235 most of

13912-486: The feasibility to store spent nuclear fuel at the Yucca Mountain nuclear waste repository . Above-ground nuclear tests by the Soviet Union and the United States in the 1950s and early 1960s and by France into the 1970s and 1980s spread a significant amount of fallout from uranium daughter isotopes around the world. Additional fallout and pollution occurred from several nuclear accidents . Uranium miners have

14060-498: The field and several crucial mistakes such as failing to account for impurities in available graphite samples which made it appear less suitable as a neutron moderator than it is in reality. Germany's attempts to build a natural uranium / heavy water reactor had not come close to reaching criticality by the time the Americans reached Haigerloch , the site of the last German wartime reactor experiment. On 2 December 1942, as part of

14208-464: The first sample of uranium metal by heating uranium tetrachloride with potassium . Henri Becquerel discovered radioactivity by using uranium in 1896. Becquerel made the discovery in Paris by leaving a sample of a uranium salt, K 2 UO 2 (SO 4 ) 2 (potassium uranyl sulfate), on top of an unexposed photographic plate in a drawer and noting that the plate had become "fogged". He determined that

14356-499: The fissile component, and on 29 February 1940, Nier used an instrument he built at the University of Minnesota to separate the world's first uranium-235 sample in the Tate Laboratory. Using Columbia University 's cyclotron , John Dunning confirmed the sample to be the isolated fissile material on 1 March. Further work found that the far more common uranium-238 isotope can be transmuted into plutonium, which, like uranium-235,

14504-605: The food people eat. Worldwide production of uranium in 2021 was 48,332 tonnes , of which 21,819 t (45%) was mined in Kazakhstan . Other important uranium mining countries are Namibia (5,753 t), Canada (4,693 t), Australia (4,192 t), Uzbekistan (3,500 t), and Russia (2,635 t). Uranium ore is mined in several ways: open pit , underground , in-situ leaching , and borehole mining . Low-grade uranium ore mined typically contains 0.01 to 0.25% uranium oxides. Extensive measures must be employed to extract

14652-527: The garden of his house at 19 New King Street in Bath, Somerset , England (now the Herschel Museum of Astronomy ), and initially reported it (on 26 April 1781) as a comet . With a homemade 6.2-inch reflecting telescope, Herschel "engaged in a series of observations on the parallax of the fixed stars." Herschel recorded in his journal: "In the quartile near ζ Tauri  ... either [a] Nebulous star or perhaps

14800-482: The gravitational tug of an unseen planet. In 1845, Urbain Le Verrier began his own independent research into Uranus's orbit. On 23 September 1846, Johann Gottfried Galle located a new planet, later named Neptune , at nearly the position predicted by Le Verrier. The rotational period of the interior of Uranus is 17 hours, 14 minutes. As on all giant planets , its upper atmosphere experiences strong winds in

14948-422: The ice mantle, the total mass of ices in the interior will be lower, and, correspondingly, the total mass of rocks and hydrogen will be higher. Presently available data does not allow a scientific determination of which model is correct. The fluid interior structure of Uranus means that it has no solid surface. The gaseous atmosphere gradually transitions into the internal liquid layers. For the sake of convenience,

15096-410: The last 20% of Uranus's radius. Uranus's core density is around 9 g/cm , with a pressure in the centre of 8 million  bars (800 GPa ) and a temperature of about 5000  K . The ice mantle is not in fact composed of ice in the conventional sense, but of a hot and dense fluid consisting of water, ammonia and other volatiles . This fluid, which has a high electrical conductivity,

15244-763: The late Middle Ages , pitchblende was extracted from the Habsburg silver mines in Joachimsthal , Bohemia (now Jáchymov in the Czech Republic) in the Ore Mountains , and was used as a coloring agent in the local glassmaking industry. In the early 19th century, the world's only known sources of uranium ore were these mines. The discovery of the element is credited to the German chemist Martin Heinrich Klaproth . While he

15392-588: The metal from its ore. High-grade ores found in Athabasca Basin deposits in Saskatchewan , Canada can contain up to 23% uranium oxides on average. Uranium ore is crushed and rendered into a fine powder and then leached with either an acid or alkali . The leachate is subjected to one of several sequences of precipitation, solvent extraction, and ion exchange. The resulting mixture, called yellowcake , contains at least 75% uranium oxides U 3 O 8 . Yellowcake

15540-491: The military sector is in high-density penetrators. This ammunition consists of depleted uranium (DU) alloyed with 1–2% other elements, such as titanium or molybdenum . At high impact speed, the density, hardness, and pyrophoricity of the projectile enable the destruction of heavily armored targets. Tank armor and other removable vehicle armor can also be hardened with depleted uranium plates. The use of depleted uranium became politically and environmentally contentious after

15688-422: The mineral pitchblende is credited to Martin Heinrich Klaproth , who named the new element after the recently discovered planet Uranus . Eugène-Melchior Péligot was the first person to isolate the metal, and its radioactive properties were discovered in 1896 by Henri Becquerel . Research by Otto Hahn , Lise Meitner , Enrico Fermi and others, such as J. Robert Oppenheimer starting in 1934 led to its use as

15836-475: The name Uranus preferred among astronomers is / ˈ jʊər ə n ə s / YOOR -ə-nəs , with the long "u" of English and stress on the first syllable as in Latin Uranus , in contrast to / j ʊ ˈ r eɪ n ə s / yoo- RAY -nəs , with stress on the second syllable and a long a , though both are considered acceptable. Consensus on the name was not reached until almost 70 years after

15984-454: The name should follow the mythology so as not to stand out as different from the other planets, and that Uranus was an appropriate name as the father of the first generation of the Titans . He also noted the elegance of the name in that just as Saturn was the father of Jupiter , the new planet should be named after the father of Saturn. However, he was apparently unaware that Uranus was only

16132-488: The names Astraea , Cybele (now the names of asteroids), and Neptune , which would become the name of the next planet to be discovered. Georg Lichtenberg from Göttingen also supported Astraea (as Austräa ), but she is traditionally associated with Virgo instead of Taurus. Neptune was supported by other astronomers who liked the idea of commemorating the victories of the British Royal Naval fleet in

16280-570: The newly discovered metal itself (in fact, that powder was an oxide of uranium ). He named the newly discovered element after the planet Uranus (named after the primordial Greek god of the sky ), which had been discovered eight years earlier by William Herschel . In 1841, Eugène-Melchior Péligot , Professor of Analytical Chemistry at the Conservatoire National des Arts et Métiers (Central School of Arts and Manufactures) in Paris , isolated

16428-452: The nominal surface, which is defined to lie at a pressure of 1 bar. The Uranian atmosphere can be divided into three layers: the troposphere , between altitudes of −300 and 50 km (−186 and 31 mi) and pressures from 100 to 0.1 bar (10 MPa to 10 kPa); the stratosphere , spanning altitudes between 50 and 4,000 km (31 and 2,485 mi) and pressures of between 0.1 and 10  bar (10 kPa to 10  μPa ); and

16576-468: The north from the collar. In all other respects, Uranus looked like a dynamically dead planet in 1986. Voyager 2 arrived during the height of Uranus's southern summer and could not observe the northern hemisphere. At the beginning of the 21st century, when the northern polar region came into view, the Hubble Space Telescope (HST) and Keck telescope initially observed neither a collar nor

16724-606: The observation of the most eminent Astronomers in Europe it appears that the new star, which I had the honour of pointing out to them in March 1781, is a Primary Planet of our Solar System." In recognition of his achievement, King George III gave Herschel an annual stipend of £200 (equivalent to £30,000 in 2023) on condition that he moved to Windsor so that the Royal Family could look through his telescopes. The name Uranus references

16872-650: The only commercial reactors capable of using unenriched uranium fuel. Fuel used for United States Navy reactors is typically highly enriched in uranium-235 (the exact values are classified ). In a breeder reactor , uranium-238 can also be converted into plutonium-239 through the following reaction: Before (and, occasionally, after) the discovery of radioactivity, uranium was primarily used in small amounts for yellow glass and pottery glazes, such as uranium glass and in Fiestaware . The discovery and isolation of radium in uranium ore (pitchblende) by Marie Curie sparked

17020-413: The other giant planets; in astronomical terms, it has a low thermal flux . Why Uranus's internal temperature is so low is still not understood. Neptune, which is Uranus's near twin in size and composition, radiates 2.61 times as much energy into space as it receives from the Sun, but Uranus radiates hardly any excess heat at all. The total power radiated by Uranus in the far infrared (i.e. heat) part of

17168-482: The physical explanation in February 1939 and named the process " nuclear fission ". Soon after, Fermi hypothesized that fission of uranium might release enough neutrons to sustain a fission reaction. Confirmation of this hypothesis came in 1939, and later work found that on average about 2.5 neutrons are released by each fission of uranium-235. Fermi urged Alfred O. C. Nier to separate uranium isotopes for determination of

17316-400: The planet's discovery. During the original discussions following discovery, Maskelyne asked Herschel to "do the astronomical world the faver [ sic ] to give a name to your planet, which is entirely your own, [and] which we are so much obliged to you for the discovery of". In response to Maskelyne's request, Herschel decided to name the object Georgium Sidus (George's Star), or

17464-512: The planet's low temperature. Although there is no well-defined solid surface within Uranus's interior, the outermost part of Uranus's gaseous envelope that is accessible to remote sensing is called its atmosphere . Remote-sensing capability extends down to roughly 300 km below the 1 bar (100 kPa) level, with a corresponding pressure around 100 bar (10 MPa) and temperature of 320 K (47 °C; 116 °F). The tenuous thermosphere extends over two planetary radii from

17612-542: The point of its discovery northeast of the binary star Zeta Tauri twice—in March 1865 and March 1949—and will return to this location again in April 2033. Its average distance from the Sun is roughly 20  AU (3  billion   km ; 2 billion  mi ). The difference between its minimum and maximum distance from the Sun is 1.8 AU, larger than that of any other planet, though not as large as that of dwarf planet Pluto . The intensity of sunlight varies inversely with

17760-557: The possibility that these organisms could be used in bioremediation to decontaminate uranium-polluted water. The proteobacterium Geobacter has also been shown to bioremediate uranium in ground water. The mycorrhizal fungus Glomus intraradices increases uranium content in the roots of its symbiotic plant. In nature, uranium(VI) forms highly soluble carbonate complexes at alkaline pH. This leads to an increase in mobility and availability of uranium to groundwater and soil from nuclear wastes which leads to health hazards. However, it

17908-408: The powers at 460 and 932, and found that the diameter of the comet increased in proportion to the power, as it ought to be, on the supposition of its not being a fixed star, while the diameters of the stars to which I compared it were not increased in the same ratio. Moreover, the comet being magnified much beyond what its light would admit of, appeared hazy and ill-defined with these great powers, while

18056-471: The proposed Uranus Orbiter and Probe mission a top priority in the 2023–2032 survey, and the CNSA 's proposal to fly by the planet with a subprobe of Tianwen-4 . Like the classical planets , Uranus is visible to the naked eye, but it was never recognised as a planet by ancient observers because of its dimness and slow orbit. William Herschel first observed Uranus on 13 March 1781, leading to its discovery as

18204-667: The same method and call it Juno, Pallas, Apollo or Minerva, for a name to our new heavenly body. The first consideration of any particular event, or remarkable incident, seems to be its chronology: if in any future age it should be asked, when this last-found Planet was discovered? It would be a very satisfactory answer to say, 'In the reign of King George the Third'. Herschel's proposed name was not popular outside Britain and Hanover, and alternatives were soon proposed. Astronomer Jérôme Lalande proposed that it be named Herschel in honour of its discoverer. Swedish astronomer Erik Prosperin proposed

18352-486: The shorter half-lives of these parents and their lower production than U and Pu, the parents of thorium: the Cm/ U ratio at the formation of the Solar System was (7.0 ± 1.6) × 10 . Some bacteria, such as Shewanella putrefaciens , Geobacter metallireducens and some strains of Burkholderia fungorum , use uranium for their growth and convert U(VI) to U(IV). Recent research suggests that this pathway includes reduction of

18500-509: The soluble U(VI) via an intermediate U(V) pentavalent state. Other organisms, such as the lichen Trapelia involuta or microorganisms such as the bacterium Citrobacter , can absorb concentrations of uranium that are up to 300 times the level of their environment. Citrobacter species absorb uranyl ions when given glycerol phosphate (or other similar organic phosphates). After one day, one gram of bacteria can encrust themselves with nine grams of uranyl phosphate crystals; this creates

18648-399: The southern hemisphere the bright collar masks them—was shown to be incorrect. Nevertheless, there are differences between the clouds of each hemisphere. The northern clouds are smaller, sharper and brighter. They appear to lie at a higher altitude. The lifetime of clouds spans several orders of magnitude. Some small clouds live for hours; at least one southern cloud may have persisted since

18796-441: The spectrum is 1.06 ± 0.08 times the solar energy absorbed in its atmosphere . Uranus's heat flux is only 0.042 ± 0.047  W / m , which is lower than the internal heat flux of Earth of about 0.075  W / m . The lowest temperature recorded in Uranus's tropopause is 49 K (−224.2 °C; −371.5 °F), making Uranus the coldest planet in the Solar System. One of the hypotheses for this discrepancy suggests

18944-408: The square of the distance—on Uranus (at about 20 times the distance from the Sun compared to Earth), it is about 1/400 the intensity of light on Earth. The orbital elements of Uranus were first calculated in 1783 by Pierre-Simon Laplace . With time, discrepancies began to appear between predicted and observed orbits, and in 1841, John Couch Adams first proposed that the differences might be due to

19092-496: The stabilization of political and economical turmoil of the early 1990s. For example, in 1993 there were 29 incidents ranking above level 1 on the International Nuclear Event Scale , and this number dropped under four per year in 1995–2003. The number of employees receiving annual radiation doses above 20 mSv , which is equivalent to a single full-body CT scan , saw a strong decline around 2000. In November 2015,

19240-488: The stars preserved that lustre and distinctness which from many thousand observations I knew they would retain. The sequel has shown that my surmises were well-founded, this proving to be the Comet we have lately observed. Herschel notified the Astronomer Royal Nevil Maskelyne of his discovery and received this flummoxed reply from him on 23 April 1781: "I don't know what to call it. It is as likely to be

19388-651: The stratosphere is caused by absorption of solar UV and IR radiation by methane and other hydrocarbons , which form in this part of the atmosphere as a result of methane photolysis . Heat is also conducted from the hot thermosphere. The hydrocarbons occupy a relatively narrow layer at altitudes of between 100 and 300 km corresponding to a pressure range of 1,000 to 10 Pa and temperatures of between 75 and 170 K (−198 and −103 °C; −325 and −154 °F). The most abundant hydrocarbons are methane, acetylene , and ethane with mixing ratios of around 10 relative to hydrogen. The mixing ratio of carbon monoxide

19536-515: The successful development of a new absorbent material dubbed HiCap which performs surface retention of solid or gas molecules, atoms or ions and also effectively removes toxic metals from water, according to results verified by researchers at Pacific Northwest National Laboratory . In 2005, ten countries accounted for the majority of the world's concentrated uranium oxides: Canada (27.9%), Australia (22.8%), Kazakhstan (10.5%), Russia (8.0%), Namibia (7.5%), Niger (7.4%), Uzbekistan (5.5%),

19684-423: The symbols for the other planets while remaining distinct. This symbol predominates in modern astronomical use in the rare cases that symbols are used at all. The second symbol, [REDACTED] , was suggested by Lalande in 1784. In a letter to Herschel, Lalande described it as " un globe surmonté par la première lettre de votre nom " ("a globe surmounted by the first letter of your surname"). The second symbol

19832-436: The thermosphere extending from 4,000 km to as high as 50,000 km from the surface. There is no mesosphere . The composition of Uranus's atmosphere is different from its bulk, consisting mainly of molecular hydrogen and helium. The helium molar fraction , i.e. the number of helium atoms per molecule of gas, is 0.15 ± 0.03 in the upper troposphere, which corresponds to a mass fraction 0.26 ± 0.05 . This value

19980-513: The time splits into two smaller nuclei , releasing nuclear binding energy and more neutrons. If too many of these neutrons are absorbed by other uranium-235 nuclei, a nuclear chain reaction occurs that results in a burst of heat or (in some circumstances) an explosion. In a nuclear reactor, such a chain reaction is slowed and controlled by a neutron poison , absorbing some of the free neutrons. Such neutron absorbent materials are often part of reactor control rods (see nuclear reactor physics for

20128-447: The upper atmosphere, which can only originate from an external source such as infalling dust and comets . The troposphere is the lowest and densest part of the atmosphere and is characterised by a decrease in temperature with altitude. The temperature falls from about 320 K (47 °C; 116 °F) at the base of the nominal troposphere at −300 km to 53 K (−220 °C; −364 °F) at 50 km. The temperatures in

20276-716: The use of such munitions by the US, UK and other countries during wars in the Persian Gulf and the Balkans raised questions concerning uranium compounds left in the soil (see Gulf War syndrome ). Depleted uranium is also used as a shielding material in some containers used to store and transport radioactive materials. While the metal itself is radioactive, its high density makes it more effective than lead in halting radiation from strong sources such as radium . Other uses of depleted uranium include counterweights for aircraft control surfaces, as ballast for missile re-entry vehicles and as

20424-528: The use of uranium in manufacturing and metalwork. Tools made with these formulas remained in use for several decades, until the Manhattan Project and the Cold War placed a large demand on uranium for fission research and weapon development. A team led by Enrico Fermi in 1934 found that bombarding uranium with neutrons produces beta rays ( electrons or positrons from the elements produced; see beta particle ). The fission products were at first mistaken for new elements with atomic numbers 93 and 94, which

20572-402: The water molecules break down into a soup of hydrogen and oxygen ions, and deeper down superionic water in which the oxygen crystallises but the hydrogen ions move freely within the oxygen lattice. Although the model considered above is reasonably standard, it is not unique; other models also satisfy observations. For instance, if substantial amounts of hydrogen and rocky material are mixed in

20720-537: The whole facility (later, the town of Arco became the first in the world to have all its electricity come from nuclear power generated by BORAX-III , another reactor designed and operated by Argonne National Laboratory ). The world's first commercial scale nuclear power station, Obninsk in the Soviet Union , began generation with its reactor AM-1 on 27 June 1954. Other early nuclear power plants were Calder Hall in England, which began generation on 17 October 1956, and

20868-650: The world's largest single uranium deposit is located at the Olympic Dam Mine in South Australia . There is a significant reserve of uranium in Bakouma , a sub-prefecture in the prefecture of Mbomou in the Central African Republic . Some uranium also originates from dismantled nuclear weapons. For example, in 1993–2013 Russia supplied the United States with 15,000 tonnes of low-enriched uranium within

21016-577: Was believed that uranium was relatively rare, and that nuclear proliferation could be avoided by simply buying up all known uranium stocks, but within a decade large deposits of it were discovered in many places around the world. The X-10 Graphite Reactor at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, formerly known as the Clinton Pile and X-10 Pile, was the world's second artificial nuclear reactor (after Enrico Fermi's Chicago Pile) and

21164-494: Was from ex-Soviet sources. From 1993 to 2005 the Material Protection, Control, and Accounting Program , operated by the federal government of the United States , spent about US$ 550 million to help safeguard uranium and plutonium stockpiles in Russia. This money was used for improvements and security enhancements at research and storage facilities. Safety of nuclear facilities in Russia has been significantly improved since

21312-464: Was proposed by Johann Gottfried Köhler at Bode's request in 1782. Köhler suggested that the new planet be given the symbol for platinum , which had been described scientifically only 30 years before. As there was no alchemical symbol for platinum, he suggested ⛢ or ⛢ , a combination of the planetary-metal symbols ☉ (gold) and ♂ (iron), as platinum (or 'white gold') is found mixed with iron. Bode thought that an upright orientation, ⛢, fit better with

21460-447: Was reached that the planet be named after the Greek god Uranus (Ouranos), one of the Greek primordial deities . As of 2024, it had been visited up close only once when in 1986 the Voyager 2 probe flew by the planet. Though nowadays it can be resolved and observed by telescopes, there is much desire to revisit the planet, as shown by Planetary Science Decadal Survey 's decision to make

21608-481: Was the first reactor designed and built for continuous operation. Argonne National Laboratory 's Experimental Breeder Reactor I , located at the Atomic Energy Commission's National Reactor Testing Station near Arco, Idaho , became the first nuclear reactor to create electricity on 20 December 1951. Initially, four 150-watt light bulbs were lit by the reactor, but improvements eventually enabled it to power

21756-515: Was used as an analytical chemistry reporting standard. Uranus Uranus is the seventh planet from the Sun . It is a gaseous cyan -coloured ice giant . Most of the planet is made of water , ammonia , and methane in a supercritical phase of matter , which astronomy calls "ice" or volatiles . The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature (49 K (−224 °C; −371 °F)) of all

21904-450: Was working in his experimental laboratory in Berlin in 1789, Klaproth was able to precipitate a yellow compound (likely sodium diuranate ) by dissolving pitchblende in nitric acid and neutralizing the solution with sodium hydroxide . Klaproth assumed the yellow substance was the oxide of a yet-undiscovered element and heated it with charcoal to obtain a black powder, which he thought was

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