The gentoo penguin is a penguin species in the genus Pygoscelis, most related to the Adélie penguin and the chinstrap penguin. The earliest scientific description was made in 1781 by Johann Reinhold Forster with a reference point of the Falkland Islands, they call in a variety of ways, but the most heard is a loud trumpeting which the bird emits with its head thrown back. The application of gentoo to the penguin is unclear. Gentoo was an Anglo-Indian term to distinguish Hindus from Muslims; the English term may have originated from the Portuguese gentil. Some speculate, it may be a variation of another name for this bird, "Johnny penguin", Johnny being Juanito in Spanish and sounds vaguely like gentoo. The Johnny rook, a predator, is named after the Johnny penguin; the specific name papua is a misnomer. There are no penguins in New Guinea, however. Others trace the error to a "possibly fraudulent claim" in 1776 by French naturalist Pierre Sonnerat, who alleged a Papuan location for the king penguin despite never having been to the island himself.
The gentoo penguin is one of three species in the genus Pygoscelis. Mitochondrial and nuclear DNA evidence suggests the genus split from other penguins around 38 million years ago, about 2 million years after the ancestors of the genus Aptenodytes. In turn, the Adelie penguins split off from the other members of the genus around 19 million years ago, the chinstrap and gentoo diverged around 14 million years ago. Two subspecies of this penguin are recognised: Pygoscelis papua papua and the smaller Pygoscelis papua ellsworthi; the gentoo penguin is recognized by the wide white stripe extending like a bonnet across the top of its head and its bright orange-red bill. It has pale whitish-pink webbed feet and a long tail – the most prominent tail of all penguin species. Chicks have grey backs with white fronts; as the gentoo penguin waddles along on land, its tail sticks out behind, sweeping from side to side, hence the scientific name Pygoscelis, which means "rump-tailed". Gentoos reach a height of 51 to 90 cm, making them the third-largest species of penguin after the emperor penguin and the king penguin.
Males have a maximum weight of about 8.5 kg just before molting, a minimum weight of about 4.9 kg just before mating. For females, the maximum weight is 8.2 kg just before molting, but their weight drops to as little as 4.5 kg when guarding the chicks in the nest. Birds from the north are on average 10 cm taller than the southern birds. Southern gentoo penguins reach 75–80 cm in length, they are the fastest underwater swimmers of all penguins, reaching speeds of up to 36 km/h. Gentoos are well adapted to cold and harsh climates; the breeding colonies of gentoo penguins are located on ice-free surfaces. Colonies can be directly on the shoreline or can be located inland, they prefer shallow coastal areas and nest between tufts of grass. In South Georgia, for example, breeding colonies are 2 km inland. Whereas in colonies farther inland, where the penguins nest in grassy areas, they shift location every year because the grass will become trampled over time. Gentoos breed on many sub-Antarctic islands.
The main colonies are on the Falkland Islands, South Georgia and the South Sandwich Islands, Kerguelen Islands. The total breeding population is estimated to be over 600,000 birds. Gentoos breed monogamously, infidelity is punished with banishment from the colony. Nests are made from a circular pile of stones and can be quite large, 20 cm high and 25 cm in diameter; the stones are jealously guarded and their ownership can be the subject of noisy disputes and physical attacks between individuals. They are prized by the females to the point that a male penguin can obtain the favors of a female by offering her a choice stone. Two eggs are laid, both weighing around 130 g; the parents share incubation. The eggs hatch after 34 to 36 days; the chicks remain in the nests for around 30 days before joining other chicks in the colony and forming crèches. The chicks go out to sea at around 80 to 100 days. Gentoos live on crustaceans, such as krill, with fish making up only about 15% of the diet. However, they are opportunistic feeders, around the Falklands are known to take equal proportions of fish, squat lobsters, squid.
The Gentoos' diet is high in salt as they eat organisms with the same salinity as sea water, this can lead to complications associated with high sodium concentrations in the body for Gentoo chicks. To counteract this, Gentoos as well as many other marine bird species have a developed salt gland located above their eyes that takes the high concentration of sodium within the body and produces a saline-concentrated solution that drips out of the body from the tip of the beak. Gentoo penguins do not store as much fat as the Adelie penguin, their closest relative: Gentoos require less energy
Polish Academy of Sciences
The Polish Academy of Sciences is a Polish state-sponsored institution of higher learning. Headquartered in Warsaw, it is responsible for spearheading the development of science across the country by a society of distinguished scholars and a network of research institutes, it was established in 1951, during the early period of the Polish People's Republic following World War II. The Polish Academy of Sciences PAN, is a Polish state sponsored institution of higher learning, headquartered in Warsaw, established by the merger of earlier learned societies, including the Polish Academy of Learning, with its seat in Kraków, the Warsaw Society of Friends of Learning, founded in the late 18th century; the Polish Academy of Sciences functions as a learned society acting through an elected corporation of leading scholars and research institutions. The Academy has operating through its committees, become a major scientific advisory body. Another aspect of the Academy is its overseeing of numerous research institutes.
PAN institutes employ over 2,000 people, are funded by about a third of the Polish government's budget for science. The Polish Academy of Sciences has numerous institutes, for example: Institute for the History of Science, Polish Academy of Sciences Institute of Economics of the Polish Academy of Sciences Mammal Research Institute of the Polish Academy of Sciences Institute of Mathematics of the Polish Academy of Sciences Nencki Institute of Experimental Biology Institute of Psychology Polish Institute of Physical Chemistry Bohdan Dobrzański Institute of Agrophysics Centre of Molecular and Macromolecular Studies, Polish Academy od Sciences in Lodz Institute of Fundamental Technological Research Institute of Metallurgy and Materials Science Institute of Pharmacology of the Polish Academy of Sciences - established, 1954, became an independent institute in 1974. Institute of Computer Science of the Polish Academy of Sciences Museum and Institute of Zoology Franciszek Bujak, historian Tomasz Dietl, physicist Aleksandra Dunin-Wąsowicz, archaeologist Maria Janion, scholar and theoretician of literature Zofia Kielan-Jaworowska, paleontologist Franciszek Kokot, nephrologist Stanisław Konturek, physician Leszek Kołakowski, philosopher Roman Kozłowski, paleontologist Wanda Leopold, author and literature critic Mieczysław Mąkosza, chemist Karol Myśliwiec, archeologist Witold Nowacki, mathematician Rafal Ohme, social psychologist Czesław Olech, mathematician Bohdan Paczyński, astrophysicist Włodzimierz Ptak, immunologist Andrzej Schinzel, mathematician Jan Strelau, psychologist Piotr Sztompka, sociologist Andrzej Trautman, physicist Andrzej Udalski and astronomer Jerzy Vetulani and neuroscientist Jan Woleński, philosopher Aleksander Wolszczan, astronomer Bernard Zabłocki and immunologist Stanisław Zagaja, pomologist and director of Research Institute of Pomology and Floriculture Aage Bohr, physicist Zbyszek Darzynkiewicz, cell biologist Joseph H. Eberly, physicist Erol Gelenbe, computer scientist and engineer Krzysztof Matyjaszewski, Polish chemist working at Carnegie Mellon University Karl Alexander Müller, physicist Roger Penrose, mathematician Carlo Rubbia, physicist Boleslaw Szymanski, computer scientist Chen Ning Yang, physicist George Zarnecki, art historian Stephen T. Holgate, immunopharmacologist Acta Arithmetica Acta Ornithologica Acta Palaeontologica Polonica Acta Physica Polonica Annales Zoologici Archaeologia Polona Fundamenta Mathematicae Academy of Sciences French Academy of Sciences Polish Academy of Learning Poznań Society of Friends of Learning Royal Society Unipress Warsaw Society of Friends of Learning PAN website
The Adélie penguin is a species of penguin common along the entire coast of the Antarctic continent, their only residence. They are the most spread penguin species, as well as the most southerly distributed of all penguins, along with the emperor penguin, they are named after Adélie Land, in turn named for Adèle Dumont d'Urville, the wife of French explorer Jules Dumont d'Urville, who discovered these penguins in 1840. They obtain their food by both predation and foraging, with a diet of krill and fish; the Adélie penguin is one of three species in the genus Pygoscelis. Mitochondrial and nuclear DNA evidence suggests the genus split from other penguin species around 38 million years ago, about 2 million years after the ancestors of the genus Aptenodytes. In turn, the Adélie penguins split off from the other members of the genus around 19 million years ago; these penguins are mid-sized, being 3.6 to 6.0 kg in weight. Distinctive marks are the white ring surrounding the feathers at the base of the bill.
These long feathers hide most of the red bill. The tail is a little longer than other penguins' tails; the appearance looks somewhat like a tuxedo. They are a little smaller than most other penguin species. Adélie penguins swim at around 5 miles per hour, they are able to leap some 3 metres out of the water to land on rocks or ice. Adélie penguins are preyed on by leopard seals, giant petrels and killer whales. Based on a 2014 satellite analysis of fresh guano-discoloured red/brown coastal areas, 3.79 million breeding pairs of Adélie penguins are in 251 breeding colonies, a 53% increase over a census completed 20 years earlier. The colonies are distributed around the coastline of the Antarctic ocean. Colonies have declined on the Antarctic Peninsula since the early 1980s, but those declines have been more than offset by increases in East Antarctica. During the breeding season, they congregate in large breeding colonies, some over a quarter of a million pairs. Individual colonies can vary in size, some may be vulnerable to climate fluctuations.
The Danger Islands have been identified as an "important bird area" by BirdLife International because it supports Adélie penguin colonies, with 751,527 pairs recorded in at least five distinct colonies. In March 2018, a colony of 1.5 million was discovered. Adélie penguins breed from October to February on shores around the Antarctic continent. Adélies build rough nests of stones. Two eggs are laid; the chicks remain in the nest for 22 days before joining crèches. The chicks go out to sea after 50 to 60 days. Apsley Cherry-Garrard was a survivor of Robert Falcon Scott’s ill-fated British Antarctic Expedition of 1910, he documented details of penguin behavior in his book The Worst Journey in the World. "They are extraordinarily like children, these little people of the Antarctic world, either like children or like old men, full of their own importance." George Murray Levick, a Royal Navy surgeon-lieutenant and scientist who accompanied Scott, commented on displays of selfishness among the penguins during his surveying in the Antarctic: "At the place where they most went in, a long terrace of ice about six feet in height ran for some hundreds of yards along the edge of the water, here, just as on the sea-ice, crowds would stand near the brink.
When they had succeeded in pushing one of their number over, all would crane their necks over the edge, when they saw the pioneer safe in the water, the rest followed."One writer observed how the penguin's curiosity could endanger them, which Scott found a particular nuisance: The great trouble with has been due to the fatuous conduct of the penguins. Groups of these have been leaping onto our floe. From the moment of landing on their feet their whole attitude expressed devouring curiosity and a pig-headed disregard for their own safety, they waddle forward, poking their heads to and fro in their absurd way, in spite of a string of howling dogs straining to get at them. "Hulloa!" they seem to say, "here’s a game – what do all you ridiculous things want?" And they come a few steps nearer. The dogs make a rush as far as their leashes allow; the penguins are not daunted in the least, but their ruffs go up and they squawk with semblance of anger.… Then the final fatal steps forward are taken and they come within reach.
There is a spring, a squawk, a horrid red patch on the snow, the incident is closed. Others on the mission to the South Pole were more receptive of this element of the Adélies' curiosity. Cherry-Garrard writes: Meares and Dimitri exercised the dog-teams out upon the larger floes when we were held up for any length of time. One day a team was tethered by the side of the ship, a penguin sighted them and hurried from afar off; the dogs became frantic with excitement as he neared them: he supposed it was a greeting, the louder they barked and the more they strained at their ropes, the faster he bustled to meet them. He was angry with a man who went and saved him from a sudden end, clinging to his trousers with his beak, furiously beating his shins with his flippers.… It was not an uncommon sight to see a little Adélie penguin standing within a few inches of the nose of a dog, frantic with desire and passion. Cherry-Garrard held the birds in great regard. "Whatever a penguin does has individuality, he lays bare his whole life for all to see.
He cannot fly away. And because he is quaint in all that he does, but still more becau
United Kingdom Hydrographic Office
The United Kingdom Hydrographic Office is the UK's agency for providing hydrographic and marine geospatial data to mariners and maritime organisations across the world. The UKHO is a trading fund of the Ministry of Defence and is located in Taunton, with a workforce of 900 staff; the UKHO is responsible for operational support to the Royal Navy and other defence customers. Supplying defence and the commercial shipping industry, they help ensure Safety of Life at Sea, protect the marine environment and support the efficiency of global trade. Together with other national hydrographic offices and the International Hydrographic Organization, the UKHO works to set and raise global standards of hydrography and navigation; the UKHO produces a commercial portfolio of ADMIRALTY Maritime Data Solutions, providing SOLAS-compliant charts and digital services for ships trading internationally. The Admiralty's first Hydrographer was Alexander Dalrymple, appointed in 1795 on the order of King George III and the existing charts were brought together and catalogued.
The first chart Dalrymple published as Hydrographer to the Admiralty did not appear until 1800. He issued Sailing Directions and Notices to Mariners. Dalrymple was succeeded on his death in 1808 by Captain Thomas Hurd, under whose stewardship the department was given permission to sell charts to the public in 1821. In 1819 Captain Hurd entered into a bi-lateral agreement with Denmark to exchange charts and publications covering areas of mutual interest; this is thought to be the earliest formal arrangement for the mutual supply of information between the British and any foreign Hydrographic Office. Hurd developed the specialism of Royal Navy hydrographic surveyors. Rear-Admiral Sir W. Edward Parry was appointed Hydrographer in 1823 after his second expedition to discover a Northwest Passage. In 1825 some 736 charts and coastal views were being offered for sale by the Hydrographic Office. In 1828 Captain Parry and the Royal Society organised a scientific voyage to the South Atlantic, in collaboration with the Hydrographers of France and Spain, using HMS Chanticleer.
In 1829, at the age of 55, Rear-Admiral Sir Francis Beaufort became Hydrographer. During his time as Hydrographer, he developed the eponymous Scale, saw the introduction of official tide tables in 1833 and instigated various surveys and expeditions. Several of these were by HMS Beagle, including one to Tierra del Fuego and Patagonia in 1826. In 1831 Captain Beaufort informed Captain FitzRoy that he had found a savant for the latter's surveying voyage to South America, Charles Darwin. After completing extensive surveys in South America he returned to Falmouth, Cornwall via New Zealand and Australia in 1836. By the time of Beaufort's retirement in 1855, the Chart Catalogue listed 1,981 charts and 64,000 copies of them had been issued to the Royal Navy. In the 1870s, the Royal Naval Surveying Service supported the Challenger expedition, a scientific exercise that made many discoveries, laying the foundation of oceanography; the cruise was named after HMS Challenger. On her 68,890-nautical-mile circumnavigation of the globe, 492 deep sea soundings, 133 bottom dredges, 151 open water trawls and 263 serial water temperature observations were taken.
The Challenger crew used a method of observation developed in earlier small-scale expeditions. To measure depth, the crew would lower a line with a weight attached to it until it reached the sea floor; the line was marked in 25 fathom intervals with flags denoting depth. Because of this, the depth measurements from the Challenger were at best accurate to 25 fathoms, or about 46 metres; as the first true oceanographic cruise, the Challenger expedition established an entire academic and research discipline. During the late 19th century, the UKHO took part in several international conferences, including the International Meridian Conference to determine a prime meridian for international use and other conferences working towards the establishment of a permanent international commission concerning hydrographic matters. Hydrographers to the Admiralty Board during this period included: Rear-Admiral John Washington, Rear-Admiral George Henry Richards, Captain Sir Frederick J O Evans and Rear-Admiral Sir William J L Wharton.
During Rear-Admiral A Mostyn Field's term as Hydrographer to the Admiralty Board, the Hydrographic Office lent instruments to the Nimrod Expedition of the British Antarctic Expedition led by Ernest Shackleton in 1907. Following the RMS Titanic in 1912, the Safety of Life at Sea convention was established, as well as the introduction of ice reporting and forecasting. During World War I, while Rear-Admiral Sir John F Parry was Hydrographer of the Navy, the Hydrographic Office produced numerous new charts and products to support the Royal Navy. Following the war, the First International Hydrographic Conference was held in London, it led to the establishment in 1921 of the International Hydrographic Organization. In the 1930s, the systematic and regular collection of oceanographic and naval meteorological data started. In the Second World War, while led by Vice-Admiral Sir John A Edgell, chart printing moved to Creechbarrow House in Taunton in June 1941; this was the first purpose-built chart making factory, was designed by the Chief Draughtsman, Mr Jowsey.
In 1968, compilation staff were transferred from Cricklewood to Taunton, thus bringing together the main elements of the Hydrographic Office. A purpose-built office, named after Alexander Dalrymple, was opened. Metrication and computerisation of charts began in the 1960s and early 1970s under the leadership of Rear-Admiral Sir Edmund G Irving, Rear-Admiral George Stephen Ritchie
Geomorphology is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or near the Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, to understand landform history and dynamics and to predict changes through a combination of field observations, physical experiments and numerical modeling. Geomorphologists work within disciplines such as physical geography, geodesy, engineering geology, archaeology and geotechnical engineering; this broad base of interests contributes to many research interests within the field. Earth's surface is modified by a combination of surface processes that shape landscapes, geologic processes that cause tectonic uplift and subsidence, shape the coastal geography. Surface processes comprise the action of water, ice and living things on the surface of the Earth, along with chemical reactions that form soils and alter material properties, the stability and rate of change of topography under the force of gravity, other factors, such as human alteration of the landscape.
Many of these factors are mediated by climate. Geologic processes include the uplift of mountain ranges, the growth of volcanoes, isostatic changes in land surface elevation, the formation of deep sedimentary basins where the surface of the Earth drops and is filled with material eroded from other parts of the landscape; the Earth's surface and its topography therefore are an intersection of climatic and biologic action with geologic processes, or alternatively stated, the intersection of the Earth's lithosphere with its hydrosphere and biosphere. The broad-scale topographies of the Earth illustrate this intersection of surface and subsurface action. Mountain belts are uplifted due to geologic processes. Denudation of these high uplifted regions produces sediment, transported and deposited elsewhere within the landscape or off the coast. On progressively smaller scales, similar ideas apply, where individual landforms evolve in response to the balance of additive processes and subtractive processes.
These processes directly affect each other: ice sheets and sediment are all loads that change topography through flexural isostasy. Topography can modify the local climate, for example through orographic precipitation, which in turn modifies the topography by changing the hydrologic regime in which it evolves. Many geomorphologists are interested in the potential for feedbacks between climate and tectonics, mediated by geomorphic processes. In addition to these broad-scale questions, geomorphologists address issues that are more specific and/or more local. Glacial geomorphologists investigate glacial deposits such as moraines and proglacial lakes, as well as glacial erosional features, to build chronologies of both small glaciers and large ice sheets and understand their motions and effects upon the landscape. Fluvial geomorphologists focus on rivers, how they transport sediment, migrate across the landscape, cut into bedrock, respond to environmental and tectonic changes, interact with humans.
Soils geomorphologists investigate soil profiles and chemistry to learn about the history of a particular landscape and understand how climate and rock interact. Other geomorphologists study how hillslopes change. Still others investigate the relationships between geomorphology; because geomorphology is defined to comprise everything related to the surface of the Earth and its modification, it is a broad field with many facets. Geomorphologists use a wide range of techniques in their work; these may include fieldwork and field data collection, the interpretation of remotely sensed data, geochemical analyses, the numerical modelling of the physics of landscapes. Geomorphologists may rely on geochronology, using dating methods to measure the rate of changes to the surface. Terrain measurement techniques are vital to quantitatively describe the form of the Earth's surface, include differential GPS, remotely sensed digital terrain models and laser scanning, to quantify, to generate illustrations and maps.
Practical applications of geomorphology include hazard assessment, river control and stream restoration, coastal protection. Planetary geomorphology studies landforms on other terrestrial planets such as Mars. Indications of effects of wind, glacial, mass wasting, meteor impact and volcanic processes are studied; this effort not only helps better understand the geologic and atmospheric history of those planets but extends geomorphological study of the Earth. Planetary geomorphologists use Earth analogues to aid in their study of surfaces of other planets. Other than some notable exceptions in antiquity, geomorphology is a young science, growing along with interest in other aspects of the earth sciences in the mid-19th century; this section provides a brief outline of some of the major figures and events in its development. The study of landforms and the evolution of the Earth's surface can be dated back to scholars of Classical Greece. Herodotus argued from observations of soils that the Nile delta was growing into the Mediterranean Sea, estimated its age.
Aristotle speculated that due to sediment transport into the sea those seas would fill while the land lowered. He claimed that this would mean that land and water would swap places, whereupon the proc
Amateur Radio Lighthouse Society
Founded in 2000 by Jim Weidner, K2JXW, the Amateur Radio Lighthouse Society is devoted to maritime communications, amateur radio and lightships. Its members travel to lighthouses around the world where they operate amateur radio equipment at or near the light. Collecting lighthouse QSLs is popular for some amateur radio operators. ARLHS is a membership organization with over 1665 members worldwide as of July 2009. A convention is held in October each year. In 2010 the gathering was in Mississippi. In earlier years it has been held in Solomons, Maryland, St. Simons, Port Huron and other sites. Membership benefits include a newsletter, email reflector, awards program, lighthouse expedition sponsorship, embroidered shoulder patch, a list of every known light beacon in the world capable of supporting a ham station, a web site at; the ARLHS has been featured in national magazines, such as WordRadio. Jim Weidner is its founding President; the club call sign is W7QF and the website is The ARLHS maintains a catalog of lighthouses called The World List of Lights.
Its main feature is a short, transmitted identification number for each lighthouse. The WLOL lists any lighthouse, or was an Aid to Navigation and can reasonably accommodate an amateur radio operation. Lights that are no longer in existence, but were once an ATN show up on the list, designated as historical. With over 15,000 entries, the WLOL is one of the most complete lighthouse catalogs in existence. Amateur Radio Lighthouse Society Website ARLHS Convention web site India's First ARLHS activation in Mahaballipuram, India Aug 2008 Kadalur Lighthouse Centenary and ILLW operation Aug 2009
Magnetism is a class of physical phenomena that are mediated by magnetic fields. Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments; the most familiar effects occur in ferromagnetic materials, which are attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. Only a few substances are ferromagnetic; the prefix ferro- refers to iron, because permanent magnetism was first observed in lodestone, a form of natural iron ore called magnetite, Fe3O4. Although ferromagnetism is responsible for most of the effects of magnetism encountered in everyday life, all other materials are influenced to some extent by a magnetic field, by several other types of magnetism. Paramagnetic substances such as aluminum and oxygen are weakly attracted to an applied magnetic field; the force of a magnet on paramagnetic and antiferromagnetic materials is too weak to be felt, can be detected only by laboratory instruments, so in everyday life these substances are described as non-magnetic.
The magnetic state of a material depends on temperature and other variables such as pressure and the applied magnetic field. A material may exhibit more than one form of magnetism as these variables change; as with magnetising a magnet, demagnetising a magnet is possible. "Passing an alternate current, or hitting a heated magnet in an east west direction are ways of demagnetising a magnet", quotes Sreekethav. Magnetism was first discovered in the ancient world, when people noticed that lodestones magnetized pieces of the mineral magnetite, could attract iron; the word magnet comes from the Greek term μαγνῆτις λίθος magnētis lithos, "the Magnesian stone, lodestone." In ancient Greece, Aristotle attributed the first of what could be called a scientific discussion of magnetism to the philosopher Thales of Miletus, who lived from about 625 BC to about 545 BC. The ancient Indian medical text Sushruta Samhita describes using magnetite to remove arrows embedded in a person's body. In ancient China, the earliest literary reference to magnetism lies in a 4th-century BC book named after its author, The Sage of Ghost Valley.
The 2nd-century BC annals, Lüshi Chunqiu notes: "The lodestone makes iron approach, or it attracts it." The earliest mention of the attraction of a needle is in a 1st-century work Lunheng: "A lodestone attracts a needle." The 11th-century Chinese scientist Shen Kuo was the first person to write—in the Dream Pool Essays—of the magnetic needle compass and that it improved the accuracy of navigation by employing the astronomical concept of true north. By the 12th century the Chinese were known to use the lodestone compass for navigation, they sculpted a directional spoon from lodestone in such a way that the handle of the spoon always pointed south. Alexander Neckam, by 1187, was the first in Europe to describe the compass and its use for navigation. In 1269, Peter Peregrinus de Maricourt wrote the Epistola de magnete, the first extant treatise describing the properties of magnets. In 1282, the properties of magnets and the dry compasses were discussed by Al-Ashraf, a Yemeni physicist and geographer.
In 1600, William Gilbert published his De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure. In this work he describes many of his experiments with his model earth called the terrella. From his experiments, he concluded that the Earth was itself magnetic and that this was the reason compasses pointed north. An understanding of the relationship between electricity and magnetism began in 1819 with work by Hans Christian Ørsted, a professor at the University of Copenhagen, who discovered by the accidental twitching of a compass needle near a wire that an electric current could create a magnetic field; this landmark experiment is known as Ørsted's Experiment. Several other experiments followed, with André-Marie Ampère, who in 1820 discovered that the magnetic field circulating in a closed-path was related to the current flowing through the perimeter of the path. James Clerk Maxwell synthesized and expanded these insights into Maxwell's equations, unifying electricity and optics into the field of electromagnetism.
In 1905, Einstein used these laws in motivating his theory of special relativity, requiring that the laws held true in all inertial reference frames. Electromagnetism has continued to develop into the 21st century, being incorporated into the more fundamental theories of gauge theory, quantum electrodynamics, electroweak theory, the standard model. Magnetism, at its root, arises from two sources: Electric current. Spin magnetic moments of elementary particles; the magnetic properties of materials are due to the magnetic moments of their atoms' orbiting electrons. The magnetic moments of the nuclei of atoms are thousands of times smaller than the electro