Etymology.

The term was coined by Linnaeus in 1735 and is derived from Greek, gen. ("scale") and ("wing"). Sometimes, the term Rhopalocera is used for the clade of all butterfly species, derived from the Ancient Greek (') and (') meaning "club" and "horn", respectively, coming from the shape of the antennae of butterflies.  The origins of the common names "butterfly" and "moth" are varied and often obscure. The English word butterfly is from Old English ', with many variations in spelling. Other than that, the origin is unknown, although it could

Distribution and diversity.

The Lepidoptera are among the most successful groups of insects. They are found on all continents, except Antarctica, and inhabit all terrestrial habitats ranging from desert to rainforest, from lowland grasslands to mountain plateaus, but almost always associated with higher plants, especially angiosperms (flowering plants). Among the most northern dwelling species of butterflies and moths is the Arctic Apollo ("Parnassius arcticus"), which is found in the Arctic Circle in northeastern Yakutia, at an altitude of 1500 m above sea level. In the Himalayas, various Apollo species such as "Parnassius epaphus" have been recorded to occur up to an altitude of 6,000 m above sea level.  Some lepidopteran species exhibit symbiotic, phoretic, or parasitic lifestyles, inhabiting the bodies of organisms rather than the environment. Coprophagous pyralid moth species, called sloth moths, such as "Bradipodicola hahneli"

External morphology.

Lepidoptera are morphologically distinguished from other orders principally by the presence of scales on the external parts of the body and appendages, especially the wings. Butterflies and moths vary in size from microlepidoptera only a few millimeters long, to conspicuous animals with a wingspan greater than 25 centimetres, such as the Queen Alexandra's birdwing and Atlas moth. Lepidopterans undergo a four-stage life cycle: egg; larva or caterpillar; pupa or chrysalis; and imago (plural: imagines) / adult and show many variations of the basic body structure, which give these animals advantages for diverse lifestyles and environments.

Head.

The head is where many sensing organs and the mouth parts are found. Like the adult, the larva also has a toughened, or sclerotized head capsule. Here, two compound eyes, and "chaetosema", raised spots or clusters of sensory bristles unique to Lepidoptera, occur, though many taxa have lost one or both of these spots. The antennae have a wide variation in form among species and even between different sexes. The antennae of butterflies are usually filiform and shaped like clubs, those of the skippers are hooked, while those of moths have flagellar segments variously enlarged or branched. Some

Thorax.

The thorax is made of three fused segments, the prothorax, mesothorax, and metathorax, each with a pair of legs. The first segment contains the first pair of legs. In some males of the butterfly family Nymphalidae, the forelegs are greatly reduced and are not used for walking or perching. The three pairs of legs are covered with scales. Lepidoptera also have olfactory organs on their feet, which aid the butterfly in "tasting" or "smelling" out its food. In the larval form there are 3 pairs of true legs, with up to 11 pairs of abdominal legs (usually eight) and hooklets, called apical crochets.  The two pairs of wings are found on the

Abdomen.

The abdomen, which is less sclerotized than the thorax, consists of 10 segments with membranes in between, allowing for articulated movement. The sternum, on the first segment, is small in some families and is completely absent in others. The last two or three segments form the external parts of the species' sex organs. The genitalia of Lepidoptera are highly varied and are often the only means of differentiating between species. Male genitals include a valva, which is usually large, as it is used to grasp the female during mating. Female genitalia include three distinct sections.

Scales.

The wings, head, and parts of the thorax and abdomen of Lepidoptera are covered with minute scales, a feature from which the order derives its name. Most scales are lamellar, or blade-like, and attached with a pedicel, while other forms may be hair-like or specialized as secondary sexual characteristics.  The lumen or surface

Internal morphology.

Reproductive system.

In the reproductive system of butterflies and moths, the male genitalia are complex and unclear. In females the three types of genitalia are based on the relating taxa:'monotrysian', 'exoporian', and 'ditrysian'. In the monotrysian type is an opening on the fused segments of the sterna 9 and 10, which act as insemination and oviposition. In the exoporian type (in Hepaloidae and Mnesarchaeoidea) are two separate places for insemination and oviposition, both occurring on the same sterna as the monotrysian type, i.e. 9 and 10. The ditrysian groups have an

Digestive system.

In the digestive system, the anterior region of the foregut has been modified to form a pharyngeal sucking pump as they need it for the food they eat, which are for the most part liquids. An esophagus follows and leads to the posterior of the pharynx and in some species forms a form of crop. The midgut is short and straight, with the hindgut

Circulatory system.

In the circulatory system, hemolymph, or insect blood, is used to circulate heat in a form of thermoregulation, where muscles contraction produces heat, which is transferred to

Respiratory system.

Air is taken in through spiracles along the sides of the abdomen and thorax supplying the trachea with oxygen as it goes through the lepidopteran's respiratory system. Three

Polymorphism.

Polymorphism is the appearance of forms or "morphs", which differ in color and number of attributes within a single species. In Lepidoptera, polymorphism can be seen not only between individuals in a population, but also between the sexes as sexual dimorphism, between geographically separated populations in geographical polymorphism, and between generations flying at different seasons of the year (seasonal polymorphism or polyphenism). In some species, the polymorphism is limited to one sex, typically the female. This often includes the phenomenon of mimicry when mimetic morphs fly alongside nonmimetic morphs in a population of a particular species. Polymorphism occurs both at specific level with heritable variation in the overall morphological adaptations of individuals, as well as in certain specific morphological or physiological traits within a species.  Environmental polymorphism, in which traits are not inherited, is often termed as polyphenism, which in Lepidoptera is commonly seen in the form of seasonal morphs, especially in the butterfly families of Nymphalidae and Pieridae. An Old World pierid butterfly, the common grass yellow ("Eurema hecabe") has a darker summer adult morph, triggered by a long day exceeding 13 hours in duration, while the shorter diurnal

Reproduction and development.

Species of Lepidoptera undergo holometabolism or "complete metamorphosis". Their life cycle normally consists of an egg, a larva, a pupa, and an imago or adult. The larvae are commonly called caterpillars, and the pupae of moths encapsulated in silk are called cocoons, while the uncovered pupae of butterflies are called chrysalides.

Lepidopterans in diapause.

Unless the species reproduces year-round, a butterfly or moth may

Mating.

Males usually start eclosion (emergence) earlier than females and peak in numbers before females. Both of the sexes are sexually mature by the time of eclosion. Butterflies and moths normally do not associate with each other, except for migrating species, staying relatively asocial. Mating begins with an adult (female or male) attracting a mate, normally using visual stimuli, especially in diurnal species like most butterflies. However, the females of most nocturnal species, including almost all moth species, use pheromones to attract males, sometimes from long distances. Some species engage in a form of acoustic courtship, or attract mates using sound

Life cycle.

Eggs.

Lepidoptera usually reproduce sexually and are oviparous (egg-laying), though some species exhibit live birth in a process called ovoviviparity. A variety of differences in egg-laying and the number of eggs laid occur. Some species simply drop their eggs in flight (these species normally have polyphagous larvae, meaning they eat a variety of plants e. g., hepialids and some nymphalids) while most lay their eggs near or on the host plant on which the larvae feed. The number of eggs laid may vary from only a few to several thousand. The females of both butterflies and moths select the host plant instinctively, and primarily, by chemical cues.  The eggs are derived from materials ingested as a larva and in

Larvae.

The larvae or caterpillars are the first stage in the life cycle after hatching. Caterpillars, are "characteristic larvae with cylindrical bodies, short thoracic legs, and abdominal prolegs (pseudopods)". They have a toughened (sclerotised) head capsule with an adfrontal suture formed by medial fusion of the sclerites, mandibles (mouthparts) for chewing, and a soft tubular, segmented body, that may have hair-like or other projections, three pairs of true legs, and additional prolegs (up to five pairs). The body consists of thirteen segments, of which three are thoracic and ten are abdominal. Most larvae are herbivores, but a few are carnivores (some eat ants or other caterpillars) and detritivores.  Different herbivorous species have adapted to feed on every part of the plant and are normally considered pests to their host plants; some species have been found to lay their eggs on the fruit and other species lay their eggs on clothing or fur (e. g., "Tineola bisselliella", the common clothes moth). Some species are carnivorous and

Wing development.

No form of wing is externally visible on the larva, but when larvae are dissected, developing wings can be seen as disks, which can be found on the second and third thoracic segments, in place of the spiracles that are apparent on abdominal segments. Wing disks develop in association with a trachea that runs along the base of the wing, and are surrounded by a thin peripodial membrane, which is linked to the outer epidermis of the larva by a tiny

Pupa.

After about five to seven instars, or molts, certain hormones, like PTTH, stimulate the production of ecdysone, which initiates insect molting. Then, the larva puparium, a sclerotized or hardened cuticle of the last larval instar, develops into the pupa. Depending on the species, the pupa may be covered in a silk cocoon, attached to different types of substrates, buried in the ground, or may not be covered at all. Features of the imago are externally recognizable in the pupa. All the appendages on the adult head and thorax are found cased inside the cuticle (antennae, mouthparts, etc.), with the wings wrapped around, adjacent to the antennae. The pupae of some species have functional mandibles, while the pupal mandibles are not functional in others.

Adult.

Most lepidopteran species do not live long after eclosion, only needing a few days to find a mate and then lay their eggs. Others may remain active for a longer period (from one to several weeks), or go through diapause and overwintering as monarch butterflies do, or waiting out environmental stress. Some adult species of microlepidoptera go through a stage where no reproductive-related activity occurs, lasting through summer and winter, followed by mating and oviposition in the early spring.  While most butterflies and moths are terrestrial, many species of Pyralidae are truly aquatic with all stages except the adult occurring in water. Many species from other families such as Erebidae, Nepticulidae, Cosmopterygidae, Tortricidae, Olethreutidae, Noctuidae, Cossidae, and Sphingidae are aquatic or semiaquatic.

Behavior.

Flight.

Flight is an important aspect of the lives of butterflies and moths, and is used for evading predators, searching for food, and finding mates in a timely manner, as lepidopteran species do not live long after eclosion. It is the main form of locomotion in most species. In Lepidoptera, the forewings and hindwings are mechanically coupled and flap in synchrony. Flight is anteromotoric, or being driven primarily by action of the forewings. Although lepidopteran species reportedly can still fly when their hindwings are cut off, it reduces their linear flight and turning capabilities.  Lepidopteran species have to be warm, about, to fly. They depend on their body temperature being sufficiently high and since they cannot regulate it themselves, this is dependent on their environment. Butterflies living in cooler climates may use their wings to warm their bodies. They will bask in

Navigation.

Navigation is important to Lepidoptera species, especially for those that migrate. Butterflies, which have more species that migrate, have been shown to navigate using time-compensated sun compasses. They can see polarized light, so can orient even in cloudy conditions. The polarized light in the region close to the ultraviolet spectrum is suggested to be particularly important. Most migratory butterflies are those that live in semiarid areas where breeding seasons are short. The life histories of their host plants also influence the strategies of the butterflies. Other theories include the use of landscapes. Lepidoptera may use coastal lines, mountains, and even roads to orient themselves. Above sea, the flight direction is much more accurate if the coast is still visible.  Many studies have also shown that moths navigate. One study showed that many moths may use the Earth's magnetic field to navigate, as a study of the moth heart and dart suggests. Another study, of the migratory behavior of the silver Y, showed, even at high altitudes, the

Migration.

Lepidopteran migration is typically seasonal, as the insects moving to escape dry seasons or other disadvantageous conditions. Most lepidopterans that migrate are butterflies, and the distance travelled varies. Some butterflies that migrate include the mourning cloak, painted lady, American lady, red admiral, and the common buckeye. A notable species of moth that migrates long distances is the bogong moth. The most well-known migrations are those of the eastern population of the monarch butterfly from Mexico to northern United States and southern Canada, a distance of about. Other well-known migratory species include the painted lady and several of the danaine butterflies. Spectacular and large-scale migrations associated with the monsoons are seen in peninsular India. Migrations have been studied in more recent times using wing tags and stable hydrogen isotopes.  Moths also undertake migrations, an example being the uraniids. "Urania fulgens" undergoes population explosions and massive migrations that may be not surpassed by any other insect in the Neotropics. In Costa Rica and Panama, the first population movements may begin in July and early August and depending on the year, may be very massive, continuing unabated for as long as five months.

Communication.

Pheromones are commonly involved in mating rituals among species, especially moths, but they are also an important aspect of other forms of communication. Usually, the pheromones are produced by either the male or the female and detected by members of the opposite sex with their antennae. In many species, a gland between the eighth and ninth segments under the abdomen in the female produces the pheromones. Communication can also occur through stridulation, or producing sounds by rubbing various parts of the body together.  Moths are known to engage in acoustic forms of communication, most often as courtship, attracting mates

Ecology.

Moths and butterflies are important in the natural ecosystem. They are integral participants in the food chain; having co-evolved with flowering plants and predators, lepidopteran species have formed a network of trophic relationships between autotrophs and heterotrophs, which are included in the stages of Lepidoptera larvae, pupae, and adults. Larvae and pupae are links in the diets of birds and parasitic entomophagous insects. The adults are included in food webs in a much broader range of consumers (including birds, small mammals, reptiles, etc.).

Defense and predation.

Lepidopteran species are soft bodied, fragile, and almost defenseless, while the immature stages move slowly or are immobile, hence all stages are exposed to predation. Adult butterflies and moths are preyed upon by birds, bats, lizards, amphibians, dragonflies, and spiders. Caterpillars and pupae fall prey not only to birds, but also to invertebrate predators and small mammals, as well as fungi and bacteria. Parasitoid and parasitic wasps and flies may lay eggs in the caterpillar, which eventually kill it as they hatch inside its body and eat its tissues. Insect-eating birds are probably the largest predators. Lepidoptera, especially the immature stages, are an ecologically important food to many insectivorous birds, such as the great tit in Europe.  An "evolutionary arms race" can be seen between predator and prey species. The Lepidoptera

Pollination.

Most species of Lepidoptera engage in some form of entomophily (more specifically psychophily and phalaenophily for butterflies and moths, respectively), or the pollination of flowers. Most adult butterflies and moths feed on the nectar inside flowers, using their probosces to reach the nectar hidden at the base of the petals. In the process, the adults brush against the flowers' stamens, on which the reproductive pollen is made and stored. The pollen is transferred on appendages on the adults, which fly to the next flower to feed and unwittingly deposit the pollen on the stigma of the next flower, where the pollen germinates and fertilizes the seeds.  Flowers pollinated by butterflies tend to be large and flamboyant, pink or lavender in color, frequently having a landing area, and usually scented, as butterflies are typically day-flying. Since butterflies do not digest pollen (except for heliconid

Mutualism.

Mutualism is a form of biological interaction wherein each individual involved benefits in some way. An example of a mutualistic relationship would be that shared by yucca moths (Tegeculidae) and their host, yucca flowers (Liliaceae). Female yucca moths enter the host flowers, collect the pollen into a ball using specialized maxillary palps, then move to the apex of the pistil, where pollen is deposited on the stigma,

Parasitism.

Only 42 species of parasitoid lepidopterans are known (1 Pyralidae; 40 Epipyropidae). The larvae of the greater and lesser wax moths feed on the honeycomb inside bee nests and may become pests; they are also found in bumblebee and wasp nests, albeit to a lesser extent. In northern Europe, the wax moth is regarded as the most serious parasitoid of the bumblebee, and is found only in bumblebee nests. In some areas in southern England, as much as 80% of nests can be destroyed. Other parasitic larvae are known to prey upon cicadas and leaf hoppers.  In reverse, moths and butterflies may be subject to parasitic wasps and flies, which may lay eggs on the caterpillars,

Other biological interactions.

A few species of Lepidoptera are secondary consumers, or predators. These species typically prey upon the eggs of other insects, aphids, scale insects, or ant larvae. Some caterpillars are cannibals, and others prey on caterpillars of other species (e. g. Hawaiian "Eupithecia" ). Those of the 15 species in "Eupithecia" that mirror inchworms, are the only known species of butterflies and moths that are ambush predators. Four species are known to eat snails. For example, the Hawaiian caterpillar ("Hyposmocoma molluscivora") uses silk traps, in a manner similar to that of spiders, to

Evolution and systematics.

History of study.

Linnaeus in "Systema Naturae" (1758) recognized three divisions of the Lepidoptera: "Papilio", "Sphinx" and "Phalaena", with seven subgroups in "Phalaena". These persist today as 9 of the superfamilies of Lepidoptera. Other works on classification followed including those by Michael Denis & Ignaz Schiffermüller (1775), Johan Christian Fabricius (1775) and Pierre André Latreille (1796). Jacob Hübner described many genera, and the lepidopteran genera were catalogued by Ferdinand Ochsenheimer and Georg Friedrich Treitschke in a series of volumes on the lepidopteran fauna of Europe published between 1807 and 1835. Gottlieb August Wilhelm Herrich-Schäffer (several volumes, 1843–1856), and Edward Meyrick (1895) based their classifications primarily on wing venation. Sir George Francis Hampson worked on the microlepidoptera during this period and Philipp Christoph Zeller published "The Natural History of the Tineinae" also on microlepidoptera

Fossil record.

The fossil record for Lepidoptera is lacking in comparison to other winged species, and tends not to be as common as some other insects in habitats that are most conducive to fossilization, such as lakes and ponds; their juvenile stage has only the head capsule as a hard part that might be preserved. The location and abundance of the most common moth species are indicative that mass migrations of moths occurred over the Palaeogene North Sea, which is why there is a serious lack of moth fossils. Yet there are fossils, some preserved in amber and some in very fine sediments. Leaf mines are also seen in fossil leaves, although the interpretation of them is tricky.  Putative fossil stem group representatives of Amphiesmenoptera (the clade comprising Trichoptera and Lepidoptera) are known from the Triassic. The earliest known lepidopteran fossils are fossilized scales from the Triassic-Jurassic boundary. They were found as rare

Phylogeny.

Lepidoptera and Trichoptera (caddisflies) are sister groups, sharing many similarities that are lacking in others; for example the females of both orders are heterogametic, meaning they have two different sex chromosomes, whereas in most species the males are heterogametic and the females have two identical sex chromosomes. The adults in both orders display a particular wing venation pattern on their forewings. The larvae in the two orders have mouth structures and glands with which they make and manipulate silk. Willi Hennig grouped the two orders into the superorder Amphiesmenoptera; together they are sister to the extinct order Tarachoptera. Lepidoptera descend from a diurnal moth-like common

Taxonomy.

Taxonomy is the classification of species in selected taxa, the process of naming being called nomenclature. There are over 120 families in Lepidoptera, in 45 to 48 superfamilies. Lepidoptera have always been, historically, classified in five suborders, one of which is of primitive moths that never lost

Relationship to people.

Culture.

Artistic depictions of butterflies have been used in many cultures including as early as 3500 years ago, in Egyptian hieroglyphs. Today, butterflies are widely used in various objects of art and jewelry: mounted in frames, embedded in resin, displayed in bottles, laminated in paper, and in some mixed media artworks and furnishings. Butterflies have also inspired the "butterfly fairy" as an art and fictional character.  In many cultures the soul of a dead person is associated with the butterfly, for example in Ancient Greece, where the word for butterfly ψυχή (psyche) also means "soul" and "breath". In Latin, as in Ancient Greece, the word for "butterfly" papilio was associated with the soul of the dead. The skull-like marking on the thorax of the death's-head hawkmoth has helped these moths, particularly "A. atropos", earn a negative reputation, such as associations with the supernatural and evil. The moth

Pests.

The larvae of many lepidopteran species are major pests in agriculture. Some of the major pests include Tortricidae, Noctuidae, and Pyralidae. The larvae of the Noctuidae genus "Spodoptera" (armyworms), "Helicoverpa" (corn earworm), or "Pieris brassicae" can cause extensive damage to certain crops. "Helicoverpa zea" larvae (cotton bollworms or tomato fruitworms) are polyphagous, meaning they eat a variety of crops, including tomatoes and cotton. "Peridroma saucia" (variegated cutworms) are described as one of the most damaging pests to gardens, with the ability to destroy entire gardens and fields in a matter of days.  Butterflies and moths are one of the largest taxa to solely feed and be dependent on living plants, in terms of the number of species, and they are in many ecosystems, making up the largest biomass to do so. In many species, the female may produce anywhere from 200 to 600 eggs, while in some others it may go as high as 30,000 eggs in one day. This can create

Beneficial insects.

Even though most butterflies and moths affect the economy negatively, some species are a valuable economic resource. The most prominent example is that of the domesticated silkworm moth ("Bombyx mori"), the larvae of which make their cocoons out of silk, which can be spun into cloth. Silk is and has been an important economic resource throughout history. The species "Bombyx mori" has been domesticated to the point where it is completely dependent on mankind for survival. A number of wild moths such as "Bombyx mandarina", and "Antheraea" species, besides others, provide commercially important silks.  The preference of the

Food.

Lepidoptera feature prominently in entomophagy as food items on almost every continent. While in most cases, adults, larvae or pupae are eaten as staples by indigenous people, beondegi or silkworm pupae are eaten as a snack in Korean cuisine while Maguey worm is considered a delicacy in Mexico. In

Health.

Some larvae of both moths and butterflies have a form of hair that has been known to be a cause of human health problems. Caterpillar hairs sometimes have toxins in them and species from approximately 12 families of moths or butterflies worldwide can inflict serious human injuries (urticarial dermatitis and atopic asthma to osteochondritis, consumption coagulopathy, renal failure, and intracerebral hemorrhage). Skin rashes are the most common, but there have been fatalities. "Lonomia" is a frequent cause of envenomation in humans in

Lepidoptera (, from Ancient Greek "lepís" “scale” + "pterón" “wing”) is an order of insects that includes butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 families and 46 superfamilies, 10 per cent of the total described species of living organisms. It is one of the most widespread and widely recognizable insect orders in the world. The Lepidoptera show many variations of the basic body structure that have evolved to gain advantages in lifestyle and distribution. Recent estimates suggest the order may have more species than earlier thought, and is among the four most speciose orders, along with the Hymenoptera, Diptera, and Coleoptera.

Die Schmetterlinge (Lepidoptera, von „Schuppe“ und „Flügel“) bilden mit knapp 160.000 beschriebenen Arten, (Stand: 2011) etwa 130 Familien und 46 Überfamilien nach den Käfern (Coleoptera) die artenreichste Insekten-Ordnung. Jährlich werden etwa 700 Arten neu entdeckt. Schmetterlinge sind auf allen Kontinenten außer Antarktika verbreitet. In Mitteleuropa sind sie mit etwa 4.000 Arten vertreten; für Gesamteuropa verzeichnet der Katalog von Ole Karsholt über 10.600 Arten. In Deutschland sind es etwa 3.700 Arten.


Definition.

A particle, carrying a charge of one coulomb, and moving perpendicularly through a magnetic field of one tesla, at a speed of one metre per second, experiences a force with magnitude one newton, according to the Lorentz force law. As an SI derived unit, the tesla can also be expressed as  (The last equivalent is in SI base units).  Where A = ampere, C = coulomb, kg = kilogram, m = metre, N = newton, s = second, H = henry, V = volt, J = joule, and Wb = weber

Electric vs. magnetic field.

In the production of the Lorentz force, the difference between electric fields and magnetic fields is that a force from a magnetic field on a charged particle is generally due to the charged particle's movement, while the force imparted by an electric field on a charged particle is not due to the charged particle's movement. This may be appreciated by looking at the units for each. The unit of electric field in the MKS system of units is newtons per coulomb, N/C, while the magnetic field (in teslas) can be written as N/(C·m/s). The dividing factor between the two types of field is metres per second (m/s), which is velocity. This relationship immediately highlights the fact that whether a static electromagnetic field is seen as purely magnetic, or purely electric, or some combination of these, is dependent upon one's reference frame (that is, one's velocity relative to the field).  In ferromagnets, the movement creating the magnetic field is the electron spin (and to a lesser extent electron orbital angular momentum). In a current-carrying wire (electromagnets) the movement is due to electrons moving through the wire (whether the wire is straight or circular).

Conversions.

One tesla is equivalent to:  One tesla is equal to 1 V·s/m. This can be shown by starting with the speed of light in vacuum, "c" = (εμ), and inserting the SI values and units for "c" (), the vacuum permittivity ε (), and the vacuum permeability μ (). Cancellation of numbers and units then produces this relation.  For the relation to the units of the magnetising field (ampere per metre or Oersted), see the article on permeability.

Examples.

The following examples are listed in ascending order of field strength.

The tesla (symbol: T) is a derived unit of the magnetic induction (also, magnetic flux density) in the International System of Units.

Das Tesla (T) ist eine abgeleitete SI-Maßeinheit für die magnetische Flussdichte. Die Einheit wurde im Jahr 1960 auf der "Conférence Générale des Poids et Mesures" (CGPM) in Paris nach Nikola Tesla benannt.


Bulk properties.

Thorium is a moderately soft, paramagnetic, bright silvery radioactive actinide metal. In the periodic table, it lies to the right of actinium, to the left of protactinium, and below cerium. Pure thorium is very ductile and, as normal for metals, can be cold-rolled, swaged, and drawn. At room temperature, thorium metal has a face-centred cubic crystal structure; it has two other forms, one at high temperature (over 1360 °C; body-centred cubic) and one at high pressure (around 100 GPa; body-centred tetragonal).  Thorium metal has a bulk modulus (a measure of resistance to compression of a material) of 54 GPa, about the same as tin's (58.2 GPa). Aluminium's is 75.2 GPa; copper's 137.8 GPa; and mild steel's is 160–169 GPa. Thorium is about as hard as soft steel, so when heated it can be rolled into sheets and pulled into wire.  Thorium is nearly half as dense as uranium and plutonium and is harder than both. It becomes superconductive below 1.4 K. Thorium's melting point of 1750 °C is above both those of actinium (1227 °C) and protactinium (1568 °C). At the start of period 7, from francium to thorium, the melting points of the elements increase (as in other periods), because the number of delocalised electrons each atom

Isotopes.

All but two elements up to bismuth (element 83) have an isotope that is practically stable for all purposes ("classically stable"), with the exceptions being technetium and promethium (elements 43 and 61). All elements from polonium (element 84) onward are measurably radioactive. Th is one of the three nuclides beyond bismuth (the other two being U and U) that have half-lives measured in billions of years; its half-life is 14.05 billion years, about three times the age of the earth, and slightly longer than the age of the universe. Four-fifths of the thorium present at Earth's formation has survived to the present. Th is the only isotope of thorium occurring in quantity in nature. Its stability is attributed to its closed nuclear subshell with 142 neutrons. Thorium has a characteristic terrestrial isotopic composition, with atomic weight 232.0377(4). It is one of only four radioactive elements (along with bismuth, protactinium and uranium) that occur in large enough quantities on Earth for a standard atomic weight to be determined.  Thorium nuclei are susceptible to alpha decay because the strong nuclear force cannot overcome the electromagnetic repulsion between their protons. The alpha decay of Th initiates the 4"n" decay chain which includes isotopes with a mass number divisible by 4 (hence the name; it is also called the thorium series after its progenitor). This chain of consecutive alpha and beta decays begins with the decay of Th to Ra and terminates at Pb. Any sample of thorium or its compounds contains traces of these daughters, which are isotopes of thallium, lead, bismuth, polonium, radon, radium, and actinium. Natural thorium samples can be chemically purified to extract useful daughter nuclides, such as Pb, which is used in nuclear medicine for cancer therapy. Th (alpha emitter with an 18.68 days half-life) can also be used in cancer treatments such as targeted alpha therapies. Th also very occasionally undergoes spontaneous fission rather than alpha decay, and has left evidence of doing so in its minerals (as trapped xenon gas formed as a fission product), but the partial half-life of this process is very large at over 10 years and alpha decay predominates. Thirty radioisotopes have been characterised, which range in mass number from 209 to 238. After Th, the most stable of them (with respective half-lives) are Th (75,380 years), Th (7,340 years), Th (1.92 years), Th (24.10 days), and Th (18.68 days). All of these isotopes occur in nature as trace radioisotopes due to their presence in the decay chains of Th, U, U, and Np: the last of these is long extinct in nature due to its short half-life (2.14 million years), but is continually produced in minute traces from neutron capture in uranium ores. All of the remaining thorium isotopes have half-lives that are less than thirty days and the majority of these have half-lives that are less than ten minutes.  In deep seawaters the isotope Th makes up to 0.04% of natural thorium. This is because its parent U is soluble in water, but Th is insoluble and precipitates into the sediment. Uranium ores with low thorium concentrations can be purified to produce gram-sized thorium samples of which over a quarter is the Th isotope, since Th is one of the daughters of U. The International Union of Pure and Applied Chemistry (IUPAC) reclassified thorium as a binuclidic element in 2013; it had formerly been considered a mononuclidic element.  Thorium has three known nuclear isomers (or metastable states), Th, Th, and Th. Th has the lowest known excitation energy of any isomer, measured to be. This is so low that when it undergoes isomeric transition, the emitted gamma radiation is in the ultraviolet range.  Different isotopes of thorium are chemically identical, but have slightly differing physical properties: for example, the densities of pure Th, Th, Th, and Th are respectively expected to be 11.5, 11.6, 11.6, and 11.7 g/cm. The isotope Th is expected to be fissionable with a bare critical mass of 2839 kg, although with steel reflectors this value could drop to 994 kg. Th is not fissionable, but it is fertile as it can be converted to fissile U by neutron capture and subsequent beta decay.

Chemistry.

A thorium atom has 90 electrons, of which four are valence electrons. Three atomic orbitals are theoretically available for the valence electrons to occupy: 5f, 6d, and 7s. Despite thorium's position in the f-block of the periodic table, it has an anomalous [Rn]6d7s electron configuration in the ground state, as the 5f and 6d subshells in the early actinides are very close in energy, even more so than the 4f and 5d subshells of the lanthanides: thorium's 6d subshells are lower in energy than its 5f subshells, because its 5f subshells are not well-shielded by the filled 6s and 6p subshells and are destabilized. This is due to relativistic effects, which become stronger near the bottom of the periodic table, specifically the relativistic spin–orbit interaction. The closeness in energy levels of the 5f, 6d, and 7s energy levels of thorium results in thorium almost always losing all four valence electrons and occurring in its highest possible oxidation state of +4. This is different from its lanthanide congener cerium, in which +4 is also the highest possible state, but +3 plays an important role and is more stable. Thorium is much more similar to the transition metals zirconium and hafnium than to cerium in its ionization energies and redox potentials, and hence also in its chemistry: this transition-metal-like behaviour is the norm in the first half of the actinide series.  Despite the anomalous electron configuration for gaseous thorium atoms, metallic thorium shows significant 5f involvement. A hypothetical metallic state of thorium that had the [Rn]6d7s configuration with the 5f orbitals above the Fermi level should be hexagonal close packed like the group 4 elements titanium, zirconium, and hafnium, and not face-centred cubic as it actually is. The actual crystal structure can only be explained when the 5f states are invoked, proving that thorium, and not protactinium, acts as the first actinide metallurgically.  Tetravalent thorium compounds are usually colourless or yellow, like those of silver or lead, as the Th ion has no 5f or 6d electrons. Thorium chemistry is therefore largely that of an electropositive metal forming a single diamagnetic ion with a stable noble-gas configuration, indicating a similarity between thorium and the main group elements of the s-block. Thorium and uranium are the most investigated of the radioactive elements because their radioactivity is low enough not to require special handling in the laboratory.

Reactivity.

Thorium is a highly reactive and electropositive metal. With a standard reduction potential of −1.90 V for the Th/Th couple, it is somewhat more electropositive than zirconium or aluminium. Finely divided thorium metal can exhibit pyrophoricity, spontaneously igniting in air. When heated in air, thorium turnings ignite and burn with a brilliant white light to produce the dioxide. In bulk, the reaction of pure thorium with air is slow,

Inorganic compounds.

Most binary compounds of thorium with nonmetals may be prepared by heating the elements together. In air, thorium burns to form ThO, which has the fluorite structure. Thorium dioxide is a refractory material, with the highest melting point (3390 °C) of any known oxide. It is somewhat hygroscopic and reacts readily with water and many gases; it dissolves easily in concentrated nitric acid in the presence of fluoride.  When heated in air, thorium dioxide emits intense blue light; the light becomes white when

Coordination compounds.

In an acidic aqueous solution, thorium occurs as the tetrapositive aqua ion [Th(HO)], which has tricapped trigonal prismatic molecular geometry: at pH < 3, the solutions of thorium salts are dominated by this cation. The Th ion is the largest of the tetrapositive actinide ions, and depending on the coordination number can have a radius between 0.95 and 1.14 Å. It is quite acidic due to its high charge, slightly stronger than sulfurous acid: thus it tends to undergo hydrolysis and polymerisation (though to a lesser extent than Fe), predominantly to [Th(OH)] in solutions with pH 3 or below, but in more alkaline solution polymerisation continues until the gelatinous hydroxide Th(OH) forms and precipitates out (though equilibrium may take weeks to be reached, because the polymerisation usually slows down before the precipitation). As a hard Lewis acid, Th favours hard ligands with oxygen atoms

Organothorium compounds.

Most of the work on organothorium compounds has focused on the cyclopentadienyl complexes and cyclooctatetraenyls. Like many of the early and middle actinides (up to americium, and also expected for curium), thorium forms a cyclooctatetraenide complex: the yellow Th(CH), thorocene. It is isotypic with the better-known analogous uranium compound uranocene. It can be prepared by reacting KCH with thorium tetrachloride in tetrahydrofuran (THF) at the temperature of dry ice, or by reacting thorium tetrafluoride with MgCH. It is unstable in air and decomposes in water or at 190 °C. Half sandwich compounds are also known, such as ("η"-CH)ThCl(THF), which has a piano-stool structure and is made by reacting thorocene with thorium tetrachloride in tetrahydrofuran.  The simplest of

Occurrence.

Formation.

Th is a primordial nuclide, having existed in its current form for over ten billion years; it was forged in the cores of dying stars through the r-process and scattered across the galaxy by supernovae and neutron star mergers. The letter "r" stands for "rapid neutron capture", and occurs in core-collapse supernovae, where heavy seed nuclei such as Fe rapidly capture neutrons, running up against the neutron drip line, as neutrons are captured much faster than the resulting nuclides can beta decay back toward stability. Neutron capture is the only way for stars to synthesise elements beyond iron because of the increased Coulomb barriers that make interactions between charged particles difficult at high atomic numbers and the fact that fusion beyond Fe is endothermic. Because of the abrupt loss of stability past Bi, the r-process is the only process of stellar nucleosynthesis that can create thorium and uranium; all other processes are too slow and the intermediate nuclei alpha decay before they capture enough

On Earth.

Natural thorium is usually almost pure Th, which is the longest-lived and most stable isotope of thorium, having a half-life comparable to the age of the universe. Its radioactive decay is the largest single contributor to the Earth's internal heat; the other major contributors are the shorter-lived primordial radionuclides, which are U, K, and U in descending order of their contribution. (At the time of the Earth's formation, K and U contributed much more by virtue of their short half-lives, but they have decayed more quickly, leaving the contribution from Th and U predominant.) Its decay accounts for a gradual decrease of thorium content of the Earth: the planet currently has around 85% of the amount present at the formation of the Earth. The other natural thorium isotopes are much shorter-lived; of them, only Th is usually detectable, occurring in secular equilibrium with its parent U, and making up at most 0.04% of natural thorium.  Thorium only occurs as a minor constituent of most minerals, and was for this reason previously thought to be rare. Soil normally contains about 6 ppm of thorium.  In nature, thorium occurs

History.

Erroneous report.

In 1815, the Swedish chemist Jöns Jacob Berzelius analysed an unusual sample of gadolinite from a copper mine in Falun, central Sweden. He noted impregnated traces of a white mineral, which he cautiously assumed to be an earth (oxide in modern chemical nomenclature) of an unknown element. Berzelius had already discovered

Discovery.

In 1828, Morten Thrane Esmark found a black mineral on Løvøya island, Telemark county, Norway. He was a Norwegian priest and amateur mineralogist who studied the minerals in Telemark, where he served as vicar. He commonly sent the most interesting specimens, such as this one, to his father, Jens Esmark, a noted mineralogist and professor of mineralogy and geology at the Royal Frederick University in Christiania (today called Oslo). The elder Esmark determined that it was not a known mineral and sent a sample to Berzelius for examination. Berzelius determined that it contained

Initial chemical classification.

In the periodic table published by Dmitri Mendeleev in 1869, thorium and the rare-earth elements were placed outside the main body of the table, at the end of each vertical period after the alkaline earth metals. This reflected the belief at that time that thorium and the rare-earth metals were divalent. With the later recognition that

First uses.

While thorium was discovered in 1828 its first application dates only from 1885, when Austrian chemist Carl Auer von Welsbach invented the gas mantle, a portable source of light which produces

Radioactivity.

Thorium was first observed to be radioactive in 1898, by the German chemist Gerhard Carl Schmidt and later that year, independently, by the Polish-French physicist Marie Curie. It was the second element that was found to be radioactive, after the 1896 discovery of radioactivity in uranium by French physicist Henri Becquerel. Starting from 1899, the New Zealand physicist Ernest Rutherford and the American electrical engineer Robert Bowie Owens studied the radiation from thorium; initial observations showed that it varied significantly. It was determined that these variations came from a short-lived gaseous daughter of thorium, which they found to be a new element. This element is now named radon, the only one of the rare radioelements to be discovered

Further classification.

Up to the late 19th century, chemists unanimously agreed that thorium and uranium were analogous to hafnium and tungsten; the existence of the lanthanides in the sixth row was considered to be a one-off fluke. In 1892, British chemist Henry Bassett postulated a second extra-long periodic table row to accommodate known and undiscovered elements, considering thorium and uranium to be analogous to the lanthanides. In 1913, Danish physicist Niels Bohr published a theoretical model of the atom and its electron orbitals, which soon gathered wide acceptance. The model indicated that the seventh row of the periodic table should also have f-shells filling before the d-shells that were filled in the

Phasing out.

In the 1990s, most applications that do not depend on thorium's radioactivity declined quickly due to safety and environmental concerns as suitable safer replacements were found. Despite its radioactivity, the element has remained in use for applications where no suitable alternatives could be found. A 1981 study by the Oak Ridge National Laboratory in

Nuclear power.

Thorium has been used as a power source on a prototype scale. The earliest thorium-based reactor was built at the Indian Point Energy Center located in Buchanan, New York, United States in 1962. One of the largest supplies of thorium in the world is in the country of India, where there is not much uranium. In the 1950s, India targeted achieving energy independence with their three-stage nuclear power programme. In most countries, uranium was relatively abundant and the progress of thorium-based reactors was slow; in the 20th century, three reactors were built in India and twelve elsewhere. Large-scale research was begun in 1996 by the International Atomic Energy Agency to study the use of

Nuclear weapons.

When gram quantities of plutonium were first produced in the Manhattan Project, it was discovered that a minor isotope (Pu) underwent significant spontaneous fission, which brought into question the viability of a plutonium-fueled gun-type nuclear weapon. While the Los Alamos team began work on the implosion-type weapon to circumvent this issue, the Chicago team discussed reactor design solutions. Eugene Wigner proposed to use the Pu-contaminated plutonium to drive the conversion of thorium into U in a special converter reactor. It was hypothesized that the U would then be usable in a gun-type weapon, though concerns

Production.

The low demand makes working mines for extraction of thorium alone not profitable, and it is almost always extracted with the rare earths, which themselves may be by-products of production of other minerals. The current reliance on monazite for production is due to thorium being largely produced as a by-product; other sources such as thorite contain more thorium and could easily be used for production if demand rose. Present knowledge of the distribution of thorium resources is poor, as low demand has led to exploration efforts being relatively minor. In 2014, world production of the monazite concentrate, from which thorium would be extracted, was 2,700 tonnes.  The common production route of thorium constitutes concentration of thorium minerals; extraction of thorium from the concentrate; purification of thorium; and (optionally) conversion to compounds, such as thorium dioxide.

Concentration.

There are two categories of thorium minerals for thorium extraction: primary and secondary. Primary deposits occur in acidic granitic magmas and pegmatites. They are concentrated, but of small size. Secondary deposits occur at the mouths of rivers in granitic mountain regions. In these deposits, thorium is enriched along with other heavy minerals. Initial concentration varies with the type of deposit.  For the primary deposits, the source pegmatites, which are usually obtained by mining, are divided into small parts and then undergo flotation. Alkaline earth metal carbonates may be removed after reaction with

Acid digestion.

Acid digestion is a two-stage process, involving the use of up to 93% sulfuric acid at 210–230 °C. First, sulfuric acid in excess of 60% of the sand mass is added, thickening the reaction mixture as products are formed. Then, fuming sulfuric acid is added and the mixture is kept at the same temperature for another five hours to reduce the volume of solution remaining after dilution. The concentration of the sulfuric acid is selected based on reaction rate and viscosity, which both increase with concentration, albeit with viscosity retarding the reaction. Increasing the temperature also speeds up the

Alkaline digestion.

Alkaline digestion is carried out in 30–45% sodium hydroxide solution at about 140 °C for about three hours. Too high a temperature leads to the formation of poorly soluble thorium oxide and an excess of uranium in the filtrate, and too low a concentration of alkali leads to a very slow reaction. These reaction conditions are rather mild and require monazite sand with a particle size under 45 μm. Following filtration, the filter cake includes thorium and the rare earths as their hydroxides, uranium as sodium diuranate, and phosphate as trisodium phosphate. This crystallises trisodium phosphate decahydrate when cooled below 60 °C; uranium impurities in this

Purification.

High thorium concentrations are needed in nuclear applications. In particular, concentrations of atoms with high neutron capture cross-sections must be very low (for example, gadolinium concentrations must be lower than one part per million by weight).

Modern applications.

Non-radioactivity-related uses have been in decline since the 1950s due to environmental concerns largely stemming from the radioactivity of thorium and its decay products.  Most thorium applications use its dioxide (sometimes called "thoria" in the industry), rather than the metal. This compound has a melting point of 3300 °C (6000 °F), the highest of all known oxides; only a few substances have higher melting points. This helps the compound remain solid in a flame, and it considerably increases the brightness of the flame; this is the main reason thorium is used in gas mantles. All substances emit energy (glow) at high temperatures, but the light emitted by thorium is nearly all in the visible spectrum, hence the brightness of thorium mantles. Energy, some of it in the form of visible light, is emitted when thorium is exposed to a source of energy itself, such as a cathode ray, heat or ultraviolet light. This effect is shared by cerium dioxide, which converts ultraviolet light into visible light more efficiently, but thorium dioxide gives a higher flame temperature, emitting less infrared light. Thorium in mantles, though still common, has been progressively replaced with yttrium since the late 1990s. According to the 2005 review by the United Kingdom's National Radiological Protection Board, "although [thoriated gas mantles] were widely available a few years ago, they are not any more."  During the production of incandescent filaments, recrystallisation of tungsten is significantly lowered by adding small amounts of thorium dioxide to the tungsten sintering powder before drawing the filaments. A small addition of thorium to tungsten thermocathodes considerably reduces the work function of

Potential use for nuclear energy.

The main nuclear power source in a reactor is the neutron-induced fission of a nuclide; the synthetic fissile nuclei U and Pu can be bred from neutron capture by the naturally occurring quantity nuclides Th and U. U occurs naturally and is also fissile. In the thorium fuel cycle, the fertile isotope Th is bombarded by slow neutrons, undergoing neutron capture to become Th, which undergoes two consecutive beta decays to become first Pa and then the fissile U:  U is fissile and can be used as a nuclear fuel in the same way as U or Pu. When U undergoes nuclear fission, the neutrons emitted can strike further Th nuclei, continuing the cycle. This parallels the uranium fuel cycle in fast breeder reactors where U undergoes neutron capture to become U, beta decaying to first Np and then fissile Pu.

Advantages.

Thorium is more abundant than uranium, and can satisfy world energy demands for longer.  Th absorbs neutrons more readily than U, and U has a higher probability of fission upon neutron capture (92.0%) than U (85.5%) or Pu (73.5%). It also releases more neutrons upon fission on average. A single neutron capture by U produces transuranic waste along with the fissile Pu, but Th only produces this waste after five captures,

Disadvantages.

The used fuel is difficult and dangerous to reprocess because many of the daughters of Th and U are strong gamma emitters. All U production methods result in impurities of U, either from parasitic knock-out (n,2n) reactions on Th, Pa, or U that result in the loss of a neutron, or from double neutron capture of Th, an impurity in natural Th:  U by itself is not particularly harmful, but quickly decays to produce the strong gamma emitter Tl. (Th follows the same decay chain, but its much longer half-life means that the quantities of Tl produced are negligible.) These impurities of U make U easy to detect and dangerous to work on, and the impracticality of their separation limits the possibilities of nuclear proliferation using U as the fissile material. Pa has

Hazards.

Radiological.

Natural thorium decays very slowly compared to many other radioactive materials, and the emitted alpha radiation cannot penetrate human skin. As a result, handling small amounts of thorium, such as those in gas mantles, is considered safe, although the use of such items may pose some risks. Exposure to an aerosol of thorium, such as contaminated dust, can lead to increased risk of cancers of the lung, pancreas, and blood, as lungs and other internal organs can be penetrated by alpha radiation. Internal exposure to thorium leads to increased risk of liver diseases.  The decay products of Th include more dangerous radionuclides such as radium and radon. Although relatively little of those products are created as the result

Biological.

Thorium is odourless and tasteless. The chemical toxicity of thorium is low because thorium and its most common compounds (mostly the dioxide) are poorly soluble in water, precipitating out before entering the body as the hydroxide. Some thorium compounds are chemically moderately toxic, especially in the presence of strong complex-forming ions such as citrate that carry the thorium into the body in soluble form. If a thorium-containing object has been chewed or sucked, it loses 0.4% of thorium and 90% of its dangerous daughters to the body. Three quarters

Chemical.

Powdered thorium metal is pyrophoric: it ignites spontaneously in air. In 1964, the United States Department of the Interior listed thorium as "severe" on a table entitled "Ignition and explosibility of metal powders". Its ignition temperature was given as 270 °C (520 °F) for

Exposure routes.

Thorium exists in very small quantities everywhere on Earth although larger amounts exist in certain parts: the average human contains about 40 micrograms of thorium and typically consumes three micrograms per day. Most thorium exposure occurs through dust inhalation; some thorium comes with food and water, but because of its low solubility, this exposure is negligible.  Exposure is raised for people who live near thorium deposits or radioactive waste disposal sites, those who live near or work in uranium, phosphate, or

Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately hard, malleable, and has a high melting point. Thorium is an electropositive actinide whose chemistry is dominated by the +4 oxidation state; it is quite reactive and can ignite in air when finely divided.

Thorium (nach dem germanischen Gott Thor) ist ein chemisches Element mit dem Elementsymbol Th und der Ordnungszahl 90. Im Periodensystem steht es in der Gruppe der Actinoide (7. Periode, f-Block).


History.

The first unofficial world championship took place in 1909, and the first formation team was presented in 1932 by Olive Ripman at the Astoria Ballroom, London. Dancesport was first broadcast on TV in 1960.

Styles.

The term "dancesport" applies to the International Style as well the as American Style of competitive ballroom. It includes the following categories:  These categories apply to both individual couples and formation dance.

International governing organizations.

World Dance Council.

The World Dance Council (WDC) is a registered limited company, and the legal successor to the International Council of Ballroom Dancing (ICBD), which was formed in 1950 in Edinburgh. The WDC operates through a general council and two committees:  In 2007 the WDC Amateur League was created. This organisation runs a number of competitions and has its own world ranking system for amateur dancers.  Each member country in the WDC has its own national organisation, such as the British Dance Council, which acts as a forum for the many interested parties in that country. The national bodies decide on their delegates to the WDC.

World DanceSport Federation.

The World DanceSport Federation (WDSF), formerly the International DanceSport Federation (IDSF), is the international governing body of dancesport, as recognised by the International Olympic Committee (IOC).  Founded in 1957 as the International Council of Amateur Dancers (ICAD), it took up the name International DanceSport Federation in 1990. In 2011 it changed its name to World DanceSport Federation to emphasise the organization's global character.  In the past, the IDSF's focus was on administering amateur dancers and competitions. However, in 2010 the IDSF Professional Division was created (formerly known as the IPDSC), which extended this focus to professional dancesport.  WDSF members are only allowed to dance in competitions that are on the WDSF's official competition calendar, unless the member has obtained the WDSF's written permission to compete in an event that is not on the WDSF's calendar.

Competitions.

There are a wide variety of dance competitions. They range from the well known Blackpool Dance Festival, an event open to all, to competitions conducted exclusively for university students, such as those hosted by the Inter Varsity Dance Association in the UK.  Amateur competitions commonly include events that group dancers by age, experience, or both. For example, events might group young dancers by age, such as: juvenile (<12yrs), junior (12-16yrs), and youth (16-19yrs). Events may sometimes cover a wide range of ages, with groupings such as: under 21yrs, adult, senior I (Over 35yrs), senior II (Over 45yrs), senior III (Over 55yrs, and senior IV (Over 65yrs).  Competitors may also be grouped by experience level, with categories such as Beginner, Novice, Intermediate, Pre-Amateur and Amateur. These generally correspond to the number of the dances to be performed in the competition, with Beginners performing one dance, and those at Amateur level performing five. In some competitions these are categorized into grades from A to E, with "A" the equivalent of the Amateur level, and "E" corresponding to the "Beginner" level.

WDSF minimum competition dance area size standard.

WDSF governing bodies in different countries have the flexibility to decide on the dance area size for competitions held in the country.  In December 2011, the WDSF Open and the Australian Nationals were held at the Hisense Arena located within the Olympic park in Melbourne. The floor was at 84 by 37.7 meters which was 7.61 times the size of what WDSF requires.

Rules.

The World Dance Council (WDC) rules for international competitions are lengthy and detailed. The music for competitions is kept confidential until the event. The music always follows a strict tempo and, for a couples competition, it will have a duration of no less than 90 seconds, and no more than two minutes.  Some elementary competitions are restricted to "basic" steps, but international competitions are open as to choreography, within the limits of the traditional style of the individual dances. Only the Viennese waltz has defined choreography: it is limited to seven well-specified figures. Lifts are not permitted, except for Show Dance titles. The tempo for each dance is defined. In the finals, couples are marked under the skating system and judged by timing, footwork, rise and fall, alignment, direction and floor craft. Competitors must meet World Anti-Doping Agency rules.

Dancesport as an Olympic event.

After a long campaign, the World DanceSport Federation (WDSF), formerly IDSF, was recognized by the International Olympic Committee as the sole representative body for dancesport, on September 5, 1997. At that point, many dance organisations changed their titles to incorporate the word "sport". This recognition gives the IDSF, potentially, a unique status. The WDSF website shows letters and certificates from the IOC that recognise dancesport as an eligible sport for inclusion pursuant to rule 29 of the Olympic Charter. On its website, the IDSF gives an upbeat appraisal of the chances of dancesport being included in a future summer Olympic Games. However, dancesport has not been included as an official event at the Olympics since its recognition, and there are many who doubt that it ever will. The 2008 Beijing Olympics did not include ballroom dancing and neither did the 2012 London Olympics. However, it was announced in December 2016 that the dancesport discipline of breakdancing would form part of the programme for the 2018 Summer Youth Olympics, with men's, women's and mixed-team events included in a one-on-one battle format.

Physical demands.

Over the years, competitive ballroom dancing has evolved so much in its choreography, requiring a higher level of athleticism. Many individuals that spectate or dance socially often underestimate the physical attributes and demands of ballroom dancing. In order to compete at a world level, elite competitive dancers undergo rigorous training to help and enhance their competition performance. These dancers seem to perform at such a high level of energy expenditure that a deeper understanding of these energy demands may help build specific training programs used to sustain a high quality dance performance consistent over a few rounds of a competition.  In 1988, an Australian study was conducted to determine the heart rate and estimated energy expended during ballroom dancing. Professors Blanksby and Reidy of the Department of Human Movement and Recreation Studies at the University of Western had ten competitive ballroom dance couples simulate a dancesport competition, dancing their competitive routines in either the Latin American or Standard division. After administrating all required laboratory tests (in order to record their height, weight, body fat percentage, fat free mass and the resting/maximal heart rate and VO2 values), the couples danced a five-dance final, given a 15 to 20 second break between each dance. Throughout the final their heart rates were telemetered and recorded. The purpose of this study was to estimate the energy requirements from heart rates acquired during competition simulation and previously recorded measures of VO2 and HR.  The average heart rate for male dancers in Standard was 170 beats min and 168 beats min in the Latin American. Females elicited 179 beats min and 177 beats min respectively. Astrand and Rodahl (1977) classify any exercise being extremely heavy if it results in a heart rate above 150 beats min. They also classify an exercise as extremely heavy if oxygen consumption is higher than 2.0L min. All but the females in the Standard dance sequence did not exceed an oxygen consumption level of 2.0L min. Finally, the energy expenditure for male athletes was estimated to be 54.1 ± 8.1 kJ min for Standard and 54.0± 9.6kJ min in the Latin American dances. For females it was 34.7 ± 3.8 kJ min and 36.1 ± 4.1 kJ min respectively.  Two other similar experiments were conducted exhibiting very similar results and analyses.<ref name="Massidda, M. M., Cugusi L. C., Ibba M. I., Tradori l. t., Calò C, M, December 11, 2011 206&rft_id=info:pmid/22211197&rft.externalDocID=22211197"></ref> In all three of the experiments, significant differences in the energy expenditure between the male and female athletes were noticed. Generally males had a higher energy expenditure than their female counterparts. This is evident due to the anthropometric differences between the two sexes and the oxygen transport capacity.  Comparing the mean gross energy expenditures (in kJ min) between ballroom dancing and other sports, it is evident that competitive dancing is equally as demanding in comparison to other sporting activities such as basketball (35.83 kJ min) or cross-country running (44.37kJ min) (Consolazioetal, 1963), and that ballroom dancing requires a cardiovascular system to be able to work at a high energy level in order to match the given physiological strain.

Dancesport is competitive ballroom dancing, as contrasted to social or exhibition dancing. In the case of wheelchair dancesport, at least one of the dancers is in a wheelchair.

Beim Tanzsport wird Tanzen als Sportart ausgeübt. Wettkampfmäßigen Tanzsport nennt man auch Turniertanz. Sitzt dabei mindestens einer der Tänzer im Rollstuhl, ist es Rollstuhltanz.


Names.

The origin and the meaning of the name "Tuareg" have long been debated, with various etymologies hypothesized. It would appear that "Twārəg" is derived from the broken plural of "Tārgi", a name whose former meaning was "inhabitant of "Targa"", the Tuareg name of the Libyan region commonly known as Fezzan. "Targa" in Berber means "(drainage) channel". Another theory is that Tuareg is derived from "Tuwariq", the plural of the Arabic exonym "Tariqi".  The term for a Tuareg man is "Amajagh" (variants: "Amashegh", "Amahagh"), the term

Demography and languages.

The Tuareg today inhabit a vast area in the Sahara, stretching from far southwestern Libya to southern Algeria, Niger, Mali and Burkina Faso. Their combined population in these territories exceeds 2.5 million, with an estimated population in Niger of around 2 million (11% of inhabitants) and in Mali of another 0.5 million (3% of inhabitants). The Tuareg are also the majority ethnic group in the Kidal Region of northeastern Mali.

History.

Early history.

In antiquity, the Tuareg moved southward from the Tafilalt region into the Sahel under the Tuareg founding queen Tin Hinan, who is believed to have lived between the 4th and 5th century. The matriarch's 1,500 year old monumental Tin Hinan tomb is located in the Sahara at Abalessa in the Hoggar Mountains of southern Algeria. Vestiges of an inscription in Tifinagh, the Tuareg's traditional Libyco-Berber writing script, have

Colonial era.

At the turn of the 19th century, the Tuareg territory was organised into confederations, each ruled by a supreme Chief ("Amenokal"), along with a council of elders from each tribe. These confederations were sometimes called ""Drum Groups"" after the Amenokal's symbol of authority, a drum. Clan ("Tewsit") elders, called Imegharan (wisemen), were chosen to assist the chief of the confederation. Historically, there have been seven major confederations.  In the late 19th century, the Tuareg resisted the French colonial invasion of their Central Saharan homelands and annihilated a French expedition led by Paul Flatters in 1881. However, in the long run Tuareg broadswords were no match for the more advanced weapons of French troops. After numerous massacres on both sides, the

Post-colonial era.

When African countries achieved widespread independence in the 1960s, the traditional Tuareg territory was divided among a number of modern states: Niger, Mali, Algeria, Libya, and Burkina Faso. Competition for resources in the Sahel has since led to conflicts between the Tuareg and neighboring African groups, especially after political disruption following French colonization and independence. There have been tight restrictions placed on nomadization because of high population growth. Desertification is exacerbated by human activity i.e.; exploitation of resources and the increased firewood needs of growing cities. Some Tuareg are therefore experimenting with farming; some have been forced to abandon herding and seek jobs in towns and cities.  In Mali, a Tuareg uprising resurfaced in the Adrar N'Fughas mountains in the 1960s, following Mali's independence. Several Tuareg joined, including some from the Adrar des Iforas in northeastern Mali. The 1960s' rebellion was a fight between a group of Tuareg and the newly independent state of

Religion.

The Tuareg traditionally adhered to the Berber mythology. Archaeological excavations of prehistoric tombs in the Maghreb have yielded skeletal remains that were painted with ochre. Although this ritual practice was known to the Iberomaurusians, the custom seems instead to have been primarily derived from the ensuing Capsian culture. Megalithic tombs, such as the jedar sepulchres, were also erected for religious and funerary purposes. In 1926, one such tomb was discovered south of Casablanca. The monument was engraved with funerary inscriptions in the ancient Libyco-Berber writing script known as Tifinagh, which the Tuareg still use.  During the medieval period, the Tuareg adopted Islam after its arrival with the Umayyad Caliphate in the 7th century. In the 16th century, under the tutelage of El Maghili, the Tuareg embraced the Maliki school of the Sunni, which they now primarily follow. Despite being Muslim, they are not Arab. The Tuareg helped spread Islam further into

Society.

The Tuareg society has traditionally featured clan membership, social status and caste hierarchies within each political confederation.

Clans.

Clans have been a historic part of the Tuaregs. The 7th century invasion of North Africa from the Middle East triggered an extensive migration of Tuaregs such as the Lemta and the Zarawa, along with other fellow pastoral Berbers. Further invasions of Banu Hilal and Banu Sulaym Arab tribes into Tuareg regions in the 11th century moved the Tuareg southward into seven clans, which the oral tradition of Tuaregs claims to be descendants of the same mother.  Each Tuareg clan ("tawshet") is made up of family groups constituting a tribe, each led by its chief, the "amghar". A series of "tawsheten" (plural of "tawshet") may bond together under an "Amenokal", forming a "Kel" clan confederation. Tuareg self-identification

Social stratification.

Tuareg society has featured caste hierarchies within each clan and political confederation. These hierarchical systems have included nobles, clerics, craftsmen and unfree strata of people including widespread slavery.

Nobility, vassals and clerics.

Traditionally, Tuareg society is hierarchical, with nobility and vassals. The linguist Karl-Gottfried Prasse (1995) indicates that the nobles constitute the highest caste. They are known in the Tuareg language as "imúšaɣ" (approximately pronounced 'imohar' - also known as "Imajaghan", "the proud and free"). The nobles originally had a monopoly on carrying arms and owning camels, and were the warriors of the Tuareg regions. They may have achieved their social status by subjugating other Tuareg castes, keeping arms to defend their properties and vassals. They have also collected tribute from their vassals. This warrior nobility has traditionally married within their caste, not to individuals in strata below their own. A collection of tribes, each led by a noble, forms a confederation called "amanokal", whose chieftain is elected from among the nobles by the tribal chiefs. The chieftain is the overlord during times of war, and receives tribute and taxes from tribes as a sign of their submission to his authority.  The vassal-herdsmen are the second free strata within Tuareg society, occupying a position just below that of the

Castes.

According to the anthropologist Jeffrey Heath, Tuareg artisans belong to separate endogamous castes known as the "Inhædʕæn" ("Inadan"). These have included the blacksmith, jewelers, wood workers and leather artisan castes. They produced and repaired the saddles, tools, household items and other items for the Tuareg community. In Niger and Mali, where the largest Tuareg populations are found, the artisan castes were attached as clients to a family of nobles or vassals, and carried messages over distances for their patron family. They also are the ones who traditionally sacrifice animals during Islamic festivals.  These social strata, like caste systems found in many parts of West Africa, included singers, musicians and story tellers of the Tuareg, who kept their oral traditions. They are called "Agguta" by Tuareg, have been called upon to sing during ceremonies such as weddings or funerals. The origins of the artisanal castes are unclear. One theory

Slaves.

The Tuareg confederations acquired slaves as well as tribute paying states by conducting raids on communities to their south in West Africa. They also secured captives as war booty or purchased slaves in markets. The slaves or servile communities are locally called "Ikelan" (or "Iklan", "Eklan"), and slavery was inherited, with the descendants of the slaves known as "irewelen".  According to the ethnographer Johannes Nicolaisen (1963), the Ikelan are of assimilated Nilotic origin rather than of Berber heritage like the ethnic Tuareg. They often live in communities separated from other castes. The Ikelan's Nilotic extraction is denoted via the Ahaggar Berber word "Ibenheren" (sing. "Ébenher"), which alludes to slaves that only speak a

Chronology.

The Tuareg social stratification involving noble, clerical and artisanal castes likely emerged after the 10th century, as a corollary of the rising slavery system. Similar caste institutions are found among various other communities in Africa. According to the anthropologist Tal Tamari, linguistic evidence suggests that the Tuareg blacksmith and bard endogamous castes evolved under foreign contact with Sudanic peoples since the Tuareg terms for blacksmith and bard are of non-Berber origin. Correspondingly, the designation for the endogamous blacksmiths among the southern Tuareg is "gargassa"

Culture.

Tuareg culture is largely matrilineal. Tuareg women have high status compared with their Arab counterparts (see matrilineality). Other distinctive aspects of Tuareg culture include clothing, food, language, religion, arts, astronomy, nomadic architecture, traditional weapons, music, films, games, and economic activities.

Clothing.

In Tuareg society women do not traditionally wear the veil, whereas men do. The most famous Tuareg symbol is the "tagelmust" (also called éghéwed and, in Arabic, "litham"), sometimes referred to as a cheche (pronounced "shesh"), a combined turban and veil, often indigo-blue colored. The men's facial covering originates from the belief that such action wards off evil spirits. It may have related instrumentally from the need for protection from the harsh

Food.

Taguella is a flatbread made from wheat flour and cooked on a charcoal fire; the flat disk-shaped bread is buried under the hot sand. The bread is broken into small pieces and eaten with a meat sauce. Millet porridge called a cink or a liwa is a staple much like ugali and fufu. Millet is boiled with water to make a pap and eaten with milk or a heavy sauce.

Language.

The Tuareg natively speak the Tuareg languages. A dialect cluster, it belongs to the Berber branch of the Afroasiatic family. Tuareg is known as

Arts.

Much Tuareg art is in the form of jewelry, leather and metal saddle decorations called trik, and finely crafted swords. The "Inadan" community makes traditional handicrafts. Among

Astronomy.

The clear desert skies allowed the

Nomadic architecture.

While living quarters are progressively changing to adapt to a more sedentary lifestyle, Tuareg groups are well known for their nomadic architecture (tents). There are several documented styles, some covered with animal skin, some with mats. The style tends to vary by location or subgroup. The tent is traditionally constructed for the first time during the marriage ceremony and is considered an extension of the union, to the extent that the phrase "making a tent" is a metaphor for becoming married. Because the tent is considered to be under the ownership of a married woman, sedentary dwellings generally belong to men, reflecting a patriarchal shift in power dynamics.

Traditional weapons.

In 2007, Stanford's Cantor Arts Center opened an exhibition, "Art of Being Tuareg: Sahara Nomads in a Modern World", the first such exhibit in the United States. It was curated by Tom Seligman, director of the center. He had first spent time with the Tuareg in 1971 when he traveled through the Sahara after serving in the Peace Corps. The exhibition included

Music.

Traditional Tuareg music has two major components: the monochord violin "anzad" played often during night parties and a small "tambour" covered with goatskin called "tende", performed during camel and horse races, and other festivities. Traditional songs called "Asak" and "Tisiway" (poems) are sung by women and men during feasts and social occasions. Another popular Tuareg musical genre is "takamba", characteristic for its Afro percussions.  Vocal music  Children and youth music  Dance  In the 1980s rebel fighters founded Tinariwen, a Tuareg band that fuses electric

Music genres, groups and artists.

Traditional music  Ishumar music

Music and culture festivals.

The Desert Festival in Mali's Timbuktu provides one opportunity to see Tuareg culture and dance and hear their music. Other festivals include:

Films.

The first Tuareg feature film," A Love Apart ", released in 2004 by

Games.

Tuareg traditional

Economy.

Tuareg are distinguished in their native language as the "Imouhar", meaning the free people; the overlap of meaning has increased local cultural nationalism. Many Tuareg today are either settled agriculturalists or nomadic cattle breeders, though there are also blacksmiths and caravan leaders. The Tuareg are a pastoral people, having an economy based on livestock breeding, trading, and agriculture.  Caravan Trade  Since Prehistoric times Tuareg peoples: the Garamantes have been organising caravans for trading across the Sahara desert. The caravan in

Genetics.

Y-chromosome DNA.

Y-Dna haplogroups, passed on exclusively through the paternal line, were found at the following frequencies in Tuaregs: E1b1b is the most common paternal haplogroup among the Tuareg. Most belong to its E1b1b1b (E-M81) subclade, which is colloquially referred to as the "Berber marker" due to its prevalence among Mozabite, Middle Atlas, Kabyle and other Berber groups. It reaches frequencies of up to 100 percent in some parts of the Maghreb, and is dominated by its sub-clade E-M183. M81 is thought to have originated in North Africa up to

mtDNA.

According to mtDNA analysis by Ottoni et al. (2010), the Tuareg inhabiting the Fezzan region in Libya predominantly carry the H1 haplogroup (61%). This is the highest global frequency found so far of the maternal clade. The haplogroup peaks among Berber populations. The remaining Libyan Tuareg mainly belong to two other West Eurasian mtDNA lineages, M1 and V. M1 is today most common among other Afro-Asiatic speakers inhabiting East Africa, and is believed to have arrived on the continent along with the U6 haplogroup from the Near East around 40,000 years ago.  Pereira et al. (2010) observed greater matrilineal heterogeneity among the Tuareg inhabiting more southerly areas in the

The Tuareg people (; also spelt Twareg or Touareg; endonym: "Kel Tamasheq", "Kel Tagelmust") are a large Berber ethnic confederation. They principally inhabit the Sahara in a vast area stretching from far southwestern Libya to southern Algeria, Niger, Mali and Burkina Faso. Traditionally nomadic pastoralists, small groups of Tuareg are also found in northern Nigeria.

Die Tuareg (Singular: Targi (männlich), Targia (weiblich); zu dieser Eigenbezeichnung siehe Abschnitt Etymologie) sind ein zu den Berbern zählendes Volk in Afrika, dessen Siedlungsgebiet sich über die Wüste Sahara und den Sahel erstreckt.