Book of Fixed Stars
The Book of Fixed Stars is an astronomical text written by Abd al-Rahman al-Sufi around 964. The book was written although the author himself was Persian, it was an attempt to create a synthesis of the comprehensive star catalogue in Ptolemy’s Almagest with the indigenous Arabic astronomical traditions on the constellations. The book was illustrated along with observations and descriptions of the stars, their positions, their magnitudes and their color, his results, as in Ptolemy's Almagest, were set out constellation by constellation. For each constellation, he provided two drawings, one from the outside of a celestial globe, the other from the inside; the work was influential and survives in numerous manuscripts and translations. The oldest manuscript, kept in the Bodleian Library, dates to 1009 and is the work of the author's son. There is a thirteenth-century copy in the British Library, he has the earliest known descriptions and illustrations of what he called "a little cloud", the Andromeda Galaxy.
He mentions it as lying before the mouth of an Arabic constellation. This "cloud" was commonly known to the Isfahan astronomers probably before 905; the first recorded mention of the Large Magellanic Cloud was given in the Book of Fixed Stars. These were the first galaxies other than the Milky Way to be observed from Earth; the Great Andromeda Nebula he observed was the first true nebula to be observed, as distinct from a star cluster. He also cataloged the Omicron Velorum star cluster as a "nebulous star", an additional "nebulous object" in Vulpecula, a cluster now variously known as Al-Sufi's Cluster, the "Coathanger asterism", Brocchi's Cluster or Collinder 399. Moreover, he mentions the two Magellanic Clouds, that they are not visible from Iraq nor Najd, but visible from Tihama, that they are called al-Baqar. There has not been a published English translation of the book, though it was translated into French by Hans Schjellerup in 1874; as of March 2012, one is in preparation by Ihsan Hafez of Townsville.
Text and French translation of Ṣūfī's introduction by J. J. A. Caussin de Perceval in Notices et extraits des manuscrits XII, Paris, 1831, pp. 236f. H. C. F. C. Schjellerup, Description des étoiles fixes par Abd-al-Rahman al-Sûfi, St. Petersburg, 1874. Complete French translation from two late mss. with selected portions in Arabic. Ketāb ṣowar al-kawākeb al-ṯābeta, edited from five mss. and accompanied by the Orǰūza of Ebn al-Ṣūfī, India, 1954. Facsimile edition of the Persian translation by Naṣīr-al-dīn Ṭūsī, Tehran, 1348 Š./1969. Critical edition of Ṭūsī's translation by Sayyed Moʿezz-al-dīn Mahdavī, Tehran, 1351 Š./1972. The star nomenclature of the Castilian version, of an Italian translation made from Castilian, was critically edited by O. J. Tallgren, "Los nombres árabes de las estrelas y la transcripción alfonsina", in Homenaje a R. Menéndez Pidal II, Madrid, 1925, with'Correcciones y adiciones' in Revista de filología española 12, 1925, pp. 52f. The Italian translation was edited by P. Knecht, I libri astronomici di Alfonso X in una versione fiorentina del trecento, Saragossa, 1965.
Paul Kunitzsch, The Arabs and the Stars: Texts and Traditions on the Fixed Stars, Their Influence in Medieval Europe Paul Kunitzsch, Arabische Sternnamen in Europa, Wiesbaden, 1959, pp. 230f. Paul Kunitzsch, "Ṣūfī Latinus", Zeitschrift der Deutschen Morgenländische Gesellschaft, 115, 1965, pp. 65–74. Paul Kunitzsch, "Al-Ṣūfī" in: Dictionary of Scientific Biography, XIII, New York, 1976, pp. 149–50. J. Upton, "A Manuscript of “The Book of the Fixed Stars” by ʿAbd ar-Raḥmān aṣ-Ṣūfī", Metropolitan Museum Studies, 4, 1933, pp. 179–97. E. Wellesz, An Islamic Book of Constellations, Oxford, 1965. H. J. J. Winter, "Notes on al-Kitab Suwar Al-Kawakib", Archives Internationales d’Histoire des Sciences, 8, 1955, pp. 126–33. Bodleian copy of Suwar al-Kawakib al-Thabitah Biography of Al Sufi Copy of al-Sufi's Book of the Fixed Stars Ulugh Beg in www.atlascoelestis.com Liber locis stellarum fixarum, 964, manoscritto del 1417 riprodotto il 1730 in www.atlascoelestis.com Pergamenthandschrift M II 141 in www.atlascoelestis.com A page about Muslim Astronomers Al-Sufi's constellations Al-Ṣūfī’s Book of the Constellations of the Fixed Stars and its Influence on Islamic and Western Celestial Cartography - includes a detailed bibliography and a list of all known manuscripts of al-Ṣūfī's Book of the Fixed Stars.
Forgotten History: Al-Sufi's Book Of Fixed Stars Slides and audio recording from a presentation on the book, with images and quotations from many different manuscripts. Illustrations from Book of Fixed Stars by ‛Abd al-Rahman ibn ‛Umar al-Ṣūfī. Moya Carey, Painting the Stars in a Century of Change: A thirteenth-century copy of al-Sufi's "Treatise on the Fixed Stars" - British Library Or.5323
Barred spiral galaxy
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in two thirds of all spiral galaxies. Bars affect both the motions of stars and interstellar gas within spiral galaxies and can affect spiral arms as well; the Milky Way Galaxy, where our own Solar System is located, is classified as a barred spiral galaxy. Edwin Hubble classified spiral galaxies of this type as "SB" in his Hubble sequence and arranged them into sub-categories based on how open the arms of the spiral are. SBa types feature bound arms, while SBc types are at the other extreme and have loosely bound arms. SBb-type galaxies lie in between the two. SB0 is a barred lenticular galaxy. A new type, SBm, was subsequently created to describe somewhat irregular barred spirals, such as the Magellanic Clouds, which were once classified as irregular galaxies, but have since been found to contain barred spiral structures. Among other types in Hubble's classifications for the galaxies are the spiral galaxy, elliptical galaxy and irregular galaxy.
Barred galaxies are predominant, with surveys showing that up to two-thirds of all spiral galaxies contain a bar. The current hypothesis is that the bar structure acts as a type of stellar nursery, fueling star birth at their centers; the bar is thought to act as a mechanism that channels gas inwards from the spiral arms through orbital resonance, in effect funneling the flow to create new stars. This process is thought to explain why many barred spiral galaxies have active galactic nuclei, such as that seen in the Southern Pinwheel Galaxy; the creation of the bar is thought to be the result of a density wave radiating from the center of the galaxy whose effects reshape the orbits of the inner stars. This effect builds over time to stars orbiting further out, which creates a self-perpetuating bar structure. Bars are thought to be temporary phenomena in the lives of spiral galaxies. Past a certain size the accumulated mass of the bar compromises the stability of the overall bar structure. Barred spiral galaxies with high mass accumulated in their center tend to have stubby bars.
Since so many spiral galaxies have bar structures, it is that they are recurring phenomena in spiral galaxy development. The oscillating evolutionary cycle from spiral galaxy to barred spiral galaxy is thought to take on the average about two billion years. Recent studies have confirmed the idea that bars are a sign of galaxies reaching full maturity as the "formative years" end. A 2008 investigation found that only 20 percent of the spiral galaxies in the distant past possessed bars, compared with about 65 percent of their local counterparts; the general classification is "SB". The sub-categories are based on how tight the arms of the spiral are. SBa types feature bound arms. SBc types are at the other extreme. SBb galaxies lie in between. SBm describes somewhat irregular barred spirals. SB0 is a barred lenticular galaxy. Galaxy morphological classification Galaxy formation and evolution Lenticular galaxy Firehose instability Britt, Robert Roy. "Milky Way’s Central Structure Seen with Fresh Clarity."
SPACE.com 16 August 2005. An article about the Spitzer Space Telescope's Milky Way discovery Devitt, Terry. "Galactic survey reveals a new look for the Milky Way." 16 August 2005. The original press release regarding the article above, from the Univ. of Wisconsin'Barred' Spiral Galaxy Pic Highlights Stellar Birth." SPACE.com 2 March 2001. Hastings and Jane Hastings. Classifying Galaxies: Barred Spirals, 1995. "Astronomers Find Multiple Generations of Star Formation in Central Starburst Ring of a Barred Spiral Galaxy." January 15, 2000. A press release concerning NGC 1326 Barred spirals come and go Sky & Telescope April 2002. "ESO Provides An Infrared Portrait of the Barred Spiral Galaxy Messier 83." November 29, 2001. A press release from the European Southern Observatory. Horton, Adam. "Spitzer NGC 1291 barred spiral galaxy seen in infrared." 22 October 2014
Milky Way
The Milky Way is the galaxy that contains our Solar System. The name describes the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye; the term Milky Way is a translation of the Latin via lactea, from the Greek γαλαξίας κύκλος. From Earth, the Milky Way appears as a band. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610; until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies; the Milky Way is a barred spiral galaxy with a diameter between 200,000 light-years. It is estimated to contain 100 -- more than 100 billion planets; the Solar System is located at a radius of 26,490 light-years from the Galactic Center, on the inner edge of the Orion Arm, one of the spiral-shaped concentrations of gas and dust.
The stars in the innermost 10,000 light-years form a bulge and one or more bars that radiate from the bulge. The galactic center is an intense radio source known as Sagittarius A*, assumed to be a supermassive black hole of 4.100 million solar masses. Stars and gases at a wide range of distances from the Galactic Center orbit at 220 kilometers per second; the constant rotation speed contradicts the laws of Keplerian dynamics and suggests that much of the mass of the Milky Way is invisible to telescopes, neither emitting nor absorbing electromagnetic radiation. This conjectural mass has been termed "dark matter"; the rotational period is about 240 million years at the radius of the Sun. The Milky Way as a whole is moving at a velocity of 600 km per second with respect to extragalactic frames of reference; the oldest stars in the Milky Way are nearly as old as the Universe itself and thus formed shortly after the Dark Ages of the Big Bang. The Milky Way has several satellite galaxies and is part of the Local Group of galaxies, which form part of the Virgo Supercluster, itself a component of the Laniakea Supercluster.
The Milky Way is visible from Earth as a hazy band of white light, some 30° wide, arching across the night sky. In night sky observing, although all the individual naked-eye stars in the entire sky are part of the Milky Way, the term “Milky Way” is limited to this band of light; the light originates from the accumulation of unresolved stars and other material located in the direction of the galactic plane. Dark regions within the band, such as the Great Rift and the Coalsack, are areas where interstellar dust blocks light from distant stars; the area of sky that the Milky Way obscures is called the Zone of Avoidance. The Milky Way has a low surface brightness, its visibility can be reduced by background light, such as light pollution or moonlight. The sky needs to be darker than about 20.2 magnitude per square arcsecond in order for the Milky Way to be visible. It should be visible if the limiting magnitude is +5.1 or better and shows a great deal of detail at +6.1. This makes the Milky Way difficult to see from brightly lit urban or suburban areas, but prominent when viewed from rural areas when the Moon is below the horizon.
Maps of artificial night sky brightness show that more than one-third of Earth's population cannot see the Milky Way from their homes due to light pollution. As viewed from Earth, the visible region of the Milky Way's galactic plane occupies an area of the sky that includes 30 constellations; the Galactic Center lies in the direction of Sagittarius. From Sagittarius, the hazy band of white light appears to pass around to the galactic anticenter in Auriga; the band continues the rest of the way around the sky, back to Sagittarius, dividing the sky into two equal hemispheres. The galactic plane is inclined by about 60° to the ecliptic. Relative to the celestial equator, it passes as far north as the constellation of Cassiopeia and as far south as the constellation of Crux, indicating the high inclination of Earth's equatorial plane and the plane of the ecliptic, relative to the galactic plane; the north galactic pole is situated at right ascension 12h 49m, declination +27.4° near β Comae Berenices, the south galactic pole is near α Sculptoris.
Because of this high inclination, depending on the time of night and year, the arch of the Milky Way may appear low or high in the sky. For observers from latitudes 65° north to 65° south, the Milky Way passes directly overhead twice a day; the Milky Way is the second-largest galaxy in the Local Group, with its stellar disk 100,000 ly in diameter and, on average 1,000 ly thick. The Milky Way is 1.5 trillion times the mass of the Sun. To compare the relative physical scale of the Milky Way, if the Solar System out to Neptune were the size of a US quarter, the Milky Way would be the size of the contiguous United States. There is a ring-like filament of stars rippling above and below the flat galactic plane, wrapping around the Milky Way at a diameter of 150,000–180,000 light-years, which may be part of the Milky Way itself. Estimates of the mass of the Milky Way vary, depending upon the method and data used; the low end of the estimate range is 5.8×1011 solar masses, somewhat less than that of the Andromeda Galaxy.
Measurements using the Very Long Baseline Array in 2009 found
Europe
Europe is a continent located in the Northern Hemisphere and in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west and the Mediterranean Sea to the south, it comprises the westernmost part of Eurasia. Since around 1850, Europe is most considered to be separated from Asia by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas and the waterways of the Turkish Straits. Although the term "continent" implies physical geography, the land border is somewhat arbitrary and has been redefined several times since its first conception in classical antiquity; the division of Eurasia into two continents reflects East-West cultural and ethnic differences which vary on a spectrum rather than with a sharp dividing line. The geographic border does not follow political boundaries, with Turkey and Kazakhstan being transcontinental countries. A strict application of the Caucasus Mountains boundary places two comparatively small countries and Georgia, in both continents.
Europe covers 2 % of the Earth's surface. Politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a total population of about 741 million as of 2016; the European climate is affected by warm Atlantic currents that temper winters and summers on much of the continent at latitudes along which the climate in Asia and North America is severe. Further from the sea, seasonal differences are more noticeable than close to the coast. Europe, in particular ancient Greece, was the birthplace of Western civilization; the fall of the Western Roman Empire in 476 AD and the subsequent Migration Period marked the end of ancient history and the beginning of the Middle Ages. Renaissance humanism, exploration and science led to the modern era. Since the Age of Discovery started by Portugal and Spain, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at various times the Americas all of Africa and Oceania and the majority of Asia.
The Age of Enlightenment, the subsequent French Revolution and the Napoleonic Wars shaped the continent culturally and economically from the end of the 17th century until the first half of the 19th century. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to radical economic and social change in Western Europe and the wider world. Both world wars took place for the most part in Europe, contributing to a decline in Western European dominance in world affairs by the mid-20th century as the Soviet Union and the United States took prominence. During the Cold War, Europe was divided along the Iron Curtain between NATO in the West and the Warsaw Pact in the East, until the revolutions of 1989 and fall of the Berlin Wall. In 1949 the Council of Europe was founded, following a speech by Sir Winston Churchill, with the idea of unifying Europe to achieve common goals, it includes all European states except for Belarus and Vatican City. Further European integration by some states led to the formation of the European Union, a separate political entity that lies between a confederation and a federation.
The EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The currency of most countries of the European Union, the euro, is the most used among Europeans. In classical Greek mythology, Europa was a Phoenician princess; the word Europe is derived from her name. The name contains the elements εὐρύς, "wide, broad" and ὤψ "eye, countenance", hence their composite Eurṓpē would mean "wide-gazing" or "broad of aspect". Broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. There have been attempts to connect Eurṓpē to a Semitic term for "west", this being either Akkadian erebu meaning "to go down, set" or Phoenician'ereb "evening, west", at the origin of Arabic Maghreb and Hebrew ma'arav. Michael A. Barry, professor in Princeton University's Near Eastern Studies Department, finds the mention of the word Ereb on an Assyrian stele with the meaning of "night, sunset", in opposition to Asu " sunrise", i.e. Asia.
The same naming motive according to "cartographic convention" appears in Greek Ἀνατολή. Martin Litchfield West stated that "phonologically, the match between Europa's name and any form of the Semitic word is poor." Next to these hypotheses there is a Proto-Indo-European root *h1regʷos, meaning "darkness", which produced Greek Erebus. Most major world languages use words derived from Europa to refer to the continent. Chinese, for example, uses the word Ōuzhōu. In some Turkic languages the Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa; the prevalent definition of Europe as a geographical term has been in use since the mid-19th century. Europe is taken to be bounded by large bodies of water
Antonio Pigafetta
Antonio Pigafetta was an Italian scholar and explorer from the Republic of Venice. He joined the expedition to the Spice Islands led by explorer Ferdinand Magellan under the flag of King Charles I of Spain and, after Magellan's death in the Philippines, the subsequent voyage around the world. During the expedition, he served as Magellan's assistant and kept an accurate journal which assisted him in translating the Cebuano language, it is the first recorded document concerning the language. Pigafetta was one of the 18 men who returned to Spain in 1522, under the command of Juan Sebastián Elcano, out of the 240 who set out three years earlier; these men completed the first circumnavigation of the world. Pigafetta's surviving journal is the source for much of what is known about Magellan and Elcano's voyage. At least one warship of the Italian Navy, a destroyer of the Navigatori class, was named after him in 1931. Pigafetta belonged to a rich family city of Vicenza in northeast Italy. In his youth he studied astronomy and cartography.
He served on board the ships of the Knights of Rhodes at the beginning of the 16th century. Until 1519, he accompanied Monsignor Francesco Chieregati, to Spain. In Seville, Pigafetta heard of Magellan's planned expedition and decided to join, accepting the title of supernumerary, a modest salary of 1,000 maravedís. During the voyage, which started in August 1519, Pigafetta collected extensive data concerning the geography, flora and the native inhabitants of the places that the expedition visited, his meticulous notes proved invaluable to future explorers and cartographers due to his inclusion of nautical and linguistic data, to latter-day historians because of its vivid, detailed style. The only other sailor to maintain a journal during the voyage was Francisco Albo, Victoria's last pilot, who kept a formal logbook. Pigafetta was wounded on Mactan in the Philippines, where Magellan was killed in the Battle of Mactan in April 1521 by the local ruler Lapu-Lapu, he recovered and was among the 18 who accompanied Juan Sebastián Elcano on board the Victoria on the return voyage to Spain.
Upon reaching port in Sanlúcar de Barrameda in the modern Province of Cadiz in September 1522, three years after his departure, Pigafetta returned to the Republic of Venice. He related his experiences in the "Report on the First Voyage Around the World", composed in Italian and was distributed to European monarchs in handwritten form before it was published by Italian historian Giovanni Battista Ramusio in 1550–59; the account centers on the events in the Mariana Islands and the Philippines, although it included several maps of other areas as well, including the first known use of the word "Pacific Ocean" on a map. The original document was not preserved. However, it was not through Pigafetta's writings that Europeans first learned of the circumnavigation of the globe. Rather, it was through an account written by a Flanders-based writer Maximilianus Transylvanus, published in 1523. Transylvanus had been instructed to interview some of the survivors of the voyage when Magellan's surviving ship Victoria returned to Spain in September 1522 under the command of Juan Sebastian Elcano.
After Magellan and Elcano's voyage, Pigafetta utilized the connections he had made prior to the voyage with the Knights of Rhodes to achieve membership in the order. Antonio Pigafetta wrote a book, in which a detailed account of the voyage was given, it is quite unclear when it was first published and what language had been used in the first edition. The remaining sources of his voyage were extensively studied by Italian archivist Andrea da Mosto, who wrote a critical study of Pigafetta's book in 1898 and whose conclusions were confirmed by J. Dénucé. Today, four manuscripts survive. One of the three books is in French. Of the four manuscripts, three are in French, one in Italian. From a philological point of view, the French editions seem to derive from an Italian original version, while the remaining Italian editions seem to derive from a French original version; because of this, it's still quite unclear whether the original version of Pigafetta's manuscript was in French or Italian though it wasn't in French language.
The most complete manuscript, the one, supposed to be more related to the original manuscript, is the one found by Carlo Amoretti inside the Biblioteca Ambrosiana and published in 1800. Amoretti, in his printed edition, modified many words and sentences whose meaning was uncertain; the modified version published by Amoretti was translated in other languages and therefore the edits by Amoretti spread in foreign editions too. Andrea da Mosto critically analyzed the original version stored in the Biblioteca Ambrosiana and published a faithful version of Pigafetta's book in 1894. Andrea da Mosto's edition is deemed more rigorous than Amoretti's edition. Regarding the French versions of Pigafetta's book, J. Dénucé extensively studied them and published a critical edition. A
Galaxy morphological classification
Galaxy morphological classification is a system used by astronomers to divide galaxies into groups based on their visual appearance. There are several schemes in use by which galaxies can be classified according to their morphologies, the most famous being the Hubble sequence, devised by Edwin Hubble and expanded by Gérard de Vaucouleurs and Allan Sandage; the Hubble sequence is a morphological classification scheme for galaxies invented by Edwin Hubble in 1926. It is known colloquially as the “Hubble tuning-fork” because of the shape in which it is traditionally represented. Hubble's scheme divides galaxies into three broad classes based on their visual appearance: Elliptical galaxies have smooth, featureless light distributions and appear as ellipses in images, they are denoted by the letter "E", followed by an integer n representing their degree of ellipticity on the sky. Spiral galaxies consist of a flattened disk, with stars forming a spiral structure, a central concentration of stars known as the bulge, similar in appearance to an elliptical galaxy.
They are given the symbol "S". Half of all spirals are observed to have a bar-like structure, extending from the central bulge; these barred spirals are given the symbol "SB". Lenticular galaxies consist of a bright central bulge surrounded by an extended, disk-like structure but, unlike spiral galaxies, the disks of lenticular galaxies have no visible spiral structure and are not forming stars in any significant quantity; these broad classes can be extended to enable finer distinctions of appearance and to encompass other types of galaxies, such as irregular galaxies, which have no obvious regular structure. The Hubble sequence is represented in the form of a two-pronged fork, with the ellipticals on the left and the barred and unbarred spirals forming the two parallel prongs of the fork. Lenticular galaxies are placed between the ellipticals and the spirals, at the point where the two prongs meet the “handle”. To this day, the Hubble sequence is the most used system for classifying galaxies, both in professional astronomical research and in amateur astronomy.
The de Vaucouleurs system for classifying galaxies is a used extension to the Hubble sequence, first described by Gérard de Vaucouleurs in 1959. De Vaucouleurs argued that Hubble's two-dimensional classification of spiral galaxies—based on the tightness of the spiral arms and the presence or absence of a bar—did not adequately describe the full range of observed galaxy morphologies. In particular, he argued that rings and lenses are important structural components of spiral galaxies; the de Vaucouleurs system retains Hubble's basic division of galaxies into ellipticals, lenticulars and irregulars. To complement Hubble's scheme, de Vaucouleurs introduced a more elaborate classification system for spiral galaxies, based on three morphological characteristics: The different elements of the classification scheme are combined — in the order in which they are listed — to give the complete classification of a galaxy. For example, a weakly barred spiral galaxy with loosely wound arms and a ring is denoted SABc.
Visually, the de Vaucouleurs system can be represented as a three-dimensional version of Hubble's tuning fork, with stage on the x-axis, family on the y-axis, variety on the z-axis. De Vaucouleurs assigned numerical values to each class of galaxy in his scheme. Values of the numerical Hubble stage T run from −6 to +10, with negative numbers corresponding to early-type galaxies and positive numbers to late types. Elliptical galaxies are divided into three'stages': compact ellipticals, normal ellipticals and late types. Lenticulars are subdivided into early and late types. Irregular galaxies can be of type magellanic irregulars or'compact'; the use of numerical stages allows for more quantitative studies of galaxy morphology. Created by American astronomer William Wilson Morgan. Together with Philip Keenan, Morgan developed the MK system for the classification of stars through their spectra; the Yerkes scheme uses the spectra of stars in the galaxy. Thus, for example, the Andromeda Galaxy is classified as kS5.
Morphological Catalogue of Galaxies Galaxy color–magnitude diagram Galaxy Zoo William Wilson Morgan Fritz Zwicky Galaxies and the Universe - an introduction to galaxy classification Near-Infrared Galaxy Morphology Atlas, T. H. Jarrett The Spitzer Infrared Nearby Galaxies Survey Hubble Tuning-Fork, SINGS Spitzer Space Telescope Legacy Science Project Go to GalaxyZoo.org to try your hand at classifying galaxies as part of an Oxford University open community project
Abd al-Rahman al-Sufi
'Abd al-Rahman al-Sufi (Persian: عبدالرحمن صوفی was a Persian astronomer known as'Abd ar-Rahman as-Sufi,'Abd al-Rahman Abu al-Husayn,'Abdul Rahman Sufi, or'Abdurrahman Sufi and in the West as Azophi and Azophi Arabus. The lunar crater Azophi and the minor planet 12621 Alsufi are named after him. Al-Sufi published his famous Book of Fixed Stars in 964, describing much of his work, both in textual descriptions and pictures. Al-Biruni reports, he lived at the Buyid court in Isfahan.'Abd al-Rahman al-Sufi was one of the famous nine Muslim astronomers. His name implies, he lived at the court of Emir Adud ad-Daula in Isfahan and worked on translating and expanding Greek astronomical works the Almagest of Ptolemy. He contributed several corrections to Ptolemy's star list and did his own brightness and magnitude estimates which deviated from those in Ptolemy's work, he was a major translator into Arabic of the Hellenistic astronomy, centered in Alexandria, the first to attempt to relate the Greek with the traditional Arabic star names and constellations, which were unrelated and overlapped in complicated ways.
He identified the Large Magellanic Cloud, visible from Yemen, though not from Isfahan. He made the earliest recorded observation of the Andromeda Galaxy in 964 AD; these were the first galaxies other than the Milky Way to be observed from Earth. He observed that the ecliptic plane is inclined with respect to the celestial equator and more calculated the length of the tropical year, he observed and described the stars, their positions, their magnitudes and their colour, setting out his results constellation by constellation. For each constellation, he provided two drawings, one from the outside of a celestial globe, the other from the inside. Al-Sufi wrote about the astrolabe, finding numerous additional uses for it: he described over 1000 different uses, in areas as diverse as astronomy, horoscopes, surveying, Qibla, Salat prayer, etc. Since 2006, Astronomy Society of Iran – Amateur Committee hold an international Sufi Observing Competition in the memory of Al-Sufi; the first competition was held in 2006 in the north of Semnan Province and the second was held in the summer of 2008 in Ladiz near the Zahedan.
More than 100 attendees from Iran and Iraq participated in the event. List of Iranian scientists List of Muslim scientists Astronomy in Islam Liber locis stellarum fixarum, 964 da www.atlascoelestis.com Liber locis stellarum fixarum, 964, manoscritto del 1417 riprodotto il 1730 da www.atlascoelestis.com Ulug Beg in www.atlascoelestis.com Al-Sufi's constellations Al-Sūfī’s Book of the Constellations of the Fixed Stars and its Influence on Islamic and Western Celestial Cartography
