"atomic number gives a definitive, integer-based sequence for the elements. Moseley predicted, in 1913, that the only elements still missing between aluminium (Z=13) and gold (Z=79) were Z = 43, 61, 72, and 75, all of which were later discovered. The atomic number is the absolute definition of an element, and gives a factual basis for the ordering of the periodic table. The periodic table is used to predict the properties of new synthetic elements before they are produced and studied. In 1871, Mendeleev published his periodic table in a new form, with groups of similar elements arranged in columns"
"Astronomical unit The astronomical unit (symbol: au, ua, or AU) is a unit of length, roughly the distance from Earth to the Sun. However, that distance varies as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once a year. Originally conceived as the average of Earth's aphelion and perihelion, since 2012 it has been defined as exactly metres or about . The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length,"
"Group 11 element Group 11, by modern IUPAC numbering, is a group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), and gold (Au). Roentgenium (Rg) is also placed in this group in the periodic table, although no chemical experiments have yet been carried out to confirm that it behaves like the heavier homologue to gold. Group 11 is also known as the ""coinage metals"", due to their former usage. They were most likely the first three elements discovered. Copper, silver, and gold all occur naturally in elemental form. All the elements of the group except"
"Gold Gold is a chemical element with symbol Au (from ) and atomic number 79, making it one of the higher atomic number elements that occur naturally. In its purest form, it is a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold often occurs in free elemental (native) form, as nuggets or grains, in rocks, in veins, and in alluvial deposits. It occurs in a solid solution series with the native"
"taxonomy also has additional notations, appended to the spectral type. The letter ""U"" is a qualifying flag, used for asteroids with an ""unusual"" spectrum, that falls far from the determined cluster center in the numerical analysis. The notation "":"" (single colon) and ""::"" (two colons) are appended when the spectral data is ""noisy"" or ""very noisy"", respectively. For example, the Mars-crosser 1747 Wright has an ""AU:"" class, which means that it is an A-type asteroid, though with an unusual and noisy spectrum. This is a more recent taxonomy introduced by American astronomers Schelte Bus and Richard Binzel in 2002, based"
"the definition of the Astronomical Unit, or the AU, which defines a standard mean distance between the Sun and the Earth, conducted under the auspices of the Congressionally funded U.S. Transit of Venus Commission. The astronomical measurements taken of the transit of Venus by a number of countries since 1639 resulted in a progressively more accurate definition of the AU. Relying heavily on photographic methods, the naval observers returned 350 photographic plates in 1874, and 1,380 measurable plates in 1882. The results of the surveys conducted simultaneously from several locations around the world (for each of the two transits) produced"
"the symbol ""au"". In the 2014 revision of the SI Brochure, the BIPM used the unit symbol ""au"". Earth's orbit around the Sun is an ellipse. The semi-major axis of this elliptic orbit is defined to be half of the straight line segment that joins the perihelion and aphelion. The centre of the Sun lies on this straight line segment, but not at its midpoint. Because ellipses are well-understood shapes, measuring the points of its extremes defined the exact shape mathematically, and made possible calculations for the entire orbit as well as predictions based on observation. In addition, it mapped"
"the periodic table) is useful in nuclear reactors because of its high thermal neutron capture cross-section, good conduction of heat, mechanical stability, and resistance to corrosion in hot water. The word ""silver"" appears in Anglo-Saxon in various spellings, such as ""seolfor"" and ""siolfor"". A similar form is seen throughout the Germanic languages (compare Old High German ""silabar"" and ""silbir""). The chemical symbol Ag is from the Latin word for ""silver"", ""argentum"" (compare Ancient Greek ἄργυρος, ""árgyros""), from the Proto-Indo-European root *""h₂erǵ-"" (formerly reconstructed as ""*arǵ-""), meaning ""white"" or ""shining"": this was the usual Proto-Indo-European word for the metal, whose reflexes"
"AU is the average distance from the Earth to the Sun. Component C is an M5 class red dwarf star. There may be a fourth component to the system, orbiting with a ≤1000‑day period, responsible for the eccentricity of the 5.98-day orbit, but this has not been visually confirmed. The variability of BY Draconis is caused by activity in the stellar photosphere called starspots, which are comparable to sunspots on the Sun, in combination with rapid rotation that changes the viewing angle of the activity relative to the observer. This variation has an average periodicity of 3.8285 days, but the"
"Au file format The Au file format is a simple audio file format introduced by Sun Microsystems. The format was common on NeXT systems and on early Web pages. Originally it was headerless, being simply 8-bit µ-law-encoded data at an 8000 Hz sample rate. Hardware from other vendors often used sample rates as high as 8192 Hz, often integer factors of video clock signals. Newer files have a header that consists of six unsigned 32-bit words, an optional information chunk and then the data (in big endian format). Although the format now supports many audio encoding formats, it remains associated"
"Isotopes of gold Gold (Au) has one stable isotope, Au, and 36 radioisotopes, with Au being the most stable with a half-life of 186 days. Gold is currently considered the heaviest monoisotopic element (bismuth formerly held that distinction, but bismuth-209 has been found to be slightly radioactive). Gold-198 is a beta emitter with range in tissue of about 11 mm and half-life 2.7 days. Inside coker units at oil refineries, gold-198 is used to study the hydrodynamic behavior of solids in fluidized beds and can also be used to quantify the degree of fouling of bed internals. It is used"
"comprehensive table of the risings and settings of stars, which likely served as an agricultural calendar. Modern-day Aries was known as , ""The Agrarian Worker"" or ""The Hired Man"". Although likely compiled in the 12th or 11th century BC, the MUL.APIN reflects a tradition which marks the Pleiades as the vernal equinox, which was the case with some precision at the beginning of the Middle Bronze Age. The earliest identifiable reference to Aries as a distinct constellation comes from the boundary stones that date from 1350 to 1000 BC. On several boundary stones, a zodiacal ram figure is distinct from"
"Sun to the Earth. An astronomical unit (AU) is approximately the average distance between the Earth and Sun. It was redefined in 2012 as exactly . Previously the AU was not based on the International System of Units but in terms of the gravitational force exerted by the Sun in the framework of classical mechanics. The current definition uses the recommended value in metres for the previous definition of the astronomical unit, which was determined by measurement. This redefinition is analogous to that of the metre, and likewise has the effect of fixing the speed of light to an exact"
"Atomic units Atomic units (au or a.u.) form a system of natural units which is especially convenient for atomic physics calculations. There are two different kinds of atomic units, Hartree atomic units and Rydberg atomic units, which differ in the choice of the unit of mass and charge. This article deals with Hartree atomic units, where the numerical values of the following four fundamental physical constants are all unity by definition: In Hartree units, the speed of light is approximately formula_5. Atomic units are often abbreviated ""a.u."" or ""au"", not to be confused with the same abbreviation used also for"
"broadcast of UTC. International Atomic Time International Atomic Time (TAI, from the French name ) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid. It is the principal realisation of Terrestrial Time (with a fixed offset of epoch). It is also the basis for Coordinated Universal Time (UTC), which is used for civil timekeeping all over the Earth's surface. , when another leap second was added, TAI is exactly 37 seconds ahead of UTC. The 37 seconds results from the initial difference of 10 seconds at the start of 1972, plus"
"International Atomic Time International Atomic Time (TAI, from the French name ) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid. It is the principal realisation of Terrestrial Time (with a fixed offset of epoch). It is also the basis for Coordinated Universal Time (UTC), which is used for civil timekeeping all over the Earth's surface. , when another leap second was added, TAI is exactly 37 seconds ahead of UTC. The 37 seconds results from the initial difference of 10 seconds at the start of 1972, plus 27 leap seconds"
"the semi-major axis of Earth's orbit (the astronomical unit, AU), time in years, and mass in the total mass of the orbiting system ( ). The above equation is exact only within the approximation of the Earth's orbit around the Sun as a two-body problem in Newtonian mechanics, the measured quantities contain corrections from the perturbations from other bodies in the solar system and from general relativity. From 1964 until 2012, however, it was used as the definition of the astronomical unit and thus held by definition: Since 2012, the AU is defined as exactly, and the equation can no"
"Aries (astrology) Aries (♈) (meaning ""ram"") is the first astrological sign in the zodiac, spanning the first 30 degrees of celestial longitude (0°≤ <30°). Under the tropical zodiac, the Sun transits this sign from approximately March 20 to April 21 each year. This time duration is exactly the first month of Solar Hijri calendar (Hamal/Farvardin/Wray). The symbol of the ram is based on the Chrysomallus, the flying ram that provided the Golden Fleece. According to the tropical system of astrology, the Sun enters the sign of Aries when it reaches the March equinox, which time systems and the western calendar"
"Au (mobile phone company) au, or au by KDDI, is a mobile phone brand in Japan marketed by KDDI in the main islands of Japan and Okinawa Cellular in Okinawa. According to the brand creator, the name 'au' is based on the Japanese verbs for 'meet' (会う) and 'unite' (合う) (both pronounced 'au'). However, KDDI explains that au comes from two letters which stand for few words. 'A' is for access, always and amenity, and 'U' is for unique, universal and user. There is also a phrase, 'access to u(you)' that goes along the brand name. The network that would"
"time. The dimensions of ""k"" are those of the constant of gravitation (""G""), i.e., LMT. The term “unit distance” is also used for the length ""A"" while, in general usage, it is usually referred to simply as the “astronomical unit”, symbol au. An equivalent formulation of the old definition of the astronomical unit is the radius of an unperturbed circular Newtonian orbit about the Sun of a particle having infinitesimal mass, moving with a mean motion of radians per day. The speed of light in IAU is the defined value ""c"" = of the SI units. In terms of this"
"and is a ""clearinghouse"" for all non-planetary or non-moon bodies in the Solar System. The Working Group for Meteor Shower Nomenclature and the Meteor Data Center coordinate the nomenclature of meteor showers. The IAU was founded on 28 July 1919, at the Constitutive Assembly of the International Research Council (now International Council for Science) held in Brussels, Belgium. Two subsidiaries of the IAU were also created at this assembly: the ""International Time Commission"" seated at the International Time Bureau in Paris, France, and the ""International Central Bureau of Astronomical Telegrams"" initially seated in Copenhagen, Denmark. The 7 initial member states"
"the parsec. A variety of unit symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union (IAU) used the symbol ""A"" for the astronomical unit. In the astronomical literature, the symbol AU was (and remains) common. In 2006, the International Bureau of Weights and Measures (BIPM) recommended ua as the symbol for the unit. In the non-normative Annex C to ISO 80000-3 (2006), the symbol of the astronomical unit is ""ua"". In 2012, the IAU, noting ""that various symbols are presently in use for the astronomical unit"", recommended the use of"
"Period (periodic table) A period in the periodic table is a horizontal row. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law. For example, the alkali metals lie in the first column (group 1) and share similar properties, such as high reactivity and the tendency to lose one electron to arrive at a noble-gas electronic configuration. As of 2016, a"
"12 zodiac members, it is usually considered to be a pseudo-member. Ophiuchus and some of the fixed stars in it were sometimes used by some astrologers in antiquity as extra-zodiacal indicators (i.e. astrologically significant celestial phenomena lying outside of the 12-sign zodiac proper). The constellation is described in the astrological poem of Marcus Manilius: the ""Astronomica"", which is dated to around 10 AD. The poem describes how: Based on the 1930 IAU constellation boundaries, suggestions that ""there are really 13 astrological signs"" because ""the Sun is in the sign of Ophiuchus"" between November 30 and December 18 have been published"
"BC. They represent a tripartite division of the heavens: the northern hemisphere belonged to Enlil, the equator belonged to Anu, and the southern hemisphere belonged to Enki. The boundaries were at 17 degrees North and South, so that the Sun spent exactly three consecutive months in each third. The enumeration of stars in the ""Three Stars Each"" catalogues includes 36 stars, three for each month. The determiner glyph for ""constellation"" or ""star"" in these lists is MUL (), originally a pictograph of three stars, as it were a triplet of AN signs; e. g. the Pleiades are referred to as"
"Periodic table The periodic table, or periodic table of elements, is a tabular arrangement of the chemical elements, ordered by their atomic number, electron configuration, and recurring chemical properties, whose structure shows ""periodic trends"". Generally, within one row (period) the elements are metals to the left, and non-metals to the right, with the elements having similar chemical behaviours placed in the same column. Table rows are commonly called periods and columns are called groups. Six groups have accepted names as well as assigned numbers: for example, group 17 elements are the halogens; and group 18 are the noble gases. Also"
"of metals. Cu comes from Cuprum, Fe comes from Ferrum, Ag from Argentum. The symbols were not followed by a period (full stop) as with abbreviations. Later chemical elements were also assigned unique chemical symbols, based on the name of the element, but not necessarily in English. For example, sodium has the chemical symbol 'Na' after the Latin ""natrium"". The same applies to ""W"" (wolfram) for tungsten, ""Fe"" (ferrum) for iron, ""Hg"" (hydrargyrum) for mercury, ""Sn"" (stannum) for tin, ""K"" (kalium) for potassium, ""Au"" (aurum) for gold, ""Ag"" (argentum) for silver, ""Pb"" (plumbum) for lead, ""Cu"" (cuprum) for copper, and"
"a.u. Among these, ""AU"" and ""a.u."" are common abbreviations for astronomical units and atomic units. For this reason, Physical Review journals, the Japanese Journal of Applied Physics, and an increasing number of other academic journals, recommend against using ""a.u."" (Jpn. J. Appl. Phys recommends ""arb. unit"" instead). In UCUM, arbitrary unit is represented as ""[arb'U]"". While arbitrary unit is not a formally recognized unit, IUPAC and IFCC recognize the need to deal with ""unknown units"", and decided in 2008 to use the term ""procedure defined unit"" in their database. The decision forbids using factors or denominators in conjunction with p.d.u."
"unit, the IAU formally adopted a new definition. Although directly based on the then-best available observational measurements, the definition was recast in terms of the then-best mathematical derivations from celestial mechanics and planetary ephemerides. It stated that ""the astronomical unit of length is that length (""A"") for which the Gaussian gravitational constant (""k"") takes the value when the units of measurement are the astronomical units of length, mass and time"". Equivalently, by this definition, one AU is ""the radius of an unperturbed circular Newtonian orbit about the sun of a particle having infinitesimal mass, moving with an angular frequency of"
"ISO 1000, ISO 2955 and ANSI X3.50 by using: where: The International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Geological Sciences have jointly recommended defining the annus, with symbol ""a"", as the length of the tropical year in the year 2000: This differs from the above definition of 365.25 days by about 20 parts per million. The joint document says that definitions such as the Julian year ""bear an inherent, pre-programmed obsolescence because of the variability of Earth’s orbital movement"", but then proposes using the length of the tropical year as of 2000 AD (specified"
"meaning ""no life"") for ""nitrogen"". For purposes of international communication and trade, the official names of the chemical elements both ancient and more recently recognized are decided by the International Union of Pure and Applied Chemistry (IUPAC), which has decided on a sort of international English language, drawing on traditional English names even when an element's chemical symbol is based on a Latin or other traditional word, for example adopting ""gold"" rather than ""aurum"" as the name for the 79th element (Au). IUPAC prefers the British spellings ""aluminium"" and ""caesium"" over the U.S. spellings ""aluminum"" and ""cesium"", and the U.S."
"LÚ The cuneiform sign LÚ () is the sign used for ""man""; the opposite is the symbol for woman: ""šal"" (). Cuneiform ""LÚ"", (or ""lú"" as rendered in some texts) is found as a sumerogram in the ""Epic of Gilgamesh"". It also has a common usage in the 1350 BC Amarna letters as the sumerogram for ""man"". In the ""Epic of Gilgamesh"", ""LÚ"" is only used as the sumerogram, ""LÚ""-(58 times). Both ""lú"", for ""man"", and ""šal"" for ""woman"" are also considered as determinatives. In the Amarna letters' Rainey's glossary (Rainey 1970) which is the glossary for Akkadian language words,"
"can also lead to the accumulation of these metals in body tissue; the results are the irreversible but apparently harmless pigmentation conditions known as chrysiasis and argyria respectively. Due to being short lived and radioactive, roentgenium has no biological use but it is likely extremely harmful due to its radioactivity. Group 11 element Group 11, by modern IUPAC numbering, is a group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), and gold (Au). Roentgenium (Rg) is also placed in this group in the periodic table, although no chemical experiments have yet been carried out to"