A teapot is a vessel used for steeping tea leaves or a herbal mix in boiling or near-boiling water, for serving the resulting infusion, called tea. Dry tea is available either in tea bags or as loose tea, in which case a tea infuser or tea strainer may be of some assistance, either to hold the leaves as they steep or to catch the leaves inside the teapot when the tea is poured. Teapots have an opening with a lid at their top, where the dry tea and hot water are added, a handle for holding by hand and a spout through which the tea is served; some teapots have a strainer built-in on the inner edge of the spout. A small air hole in the lid is created to stop the spout from dripping and splashing when tea is poured. In modern times, a thermal cover called a tea cosy may be used to enhance the steeping process or to prevent the contents of the teapot from cooling too rapidly; the teapot was invented in China during the Yuan Dynasty. It was derived from ceramic kettles and wine pots, which were made of bronze and other metals and were a feature of Chinese life for thousands of years.
Tea preparation during previous dynasties did not use a teapot. In the Tang Dynasty, a cauldron was used to boil ground tea, served in bowls. Song Dynasty tea was made by boiling water in a kettle pouring the water into a bowl with finely ground tea leaves. A brush was used to stir the tea. Written evidence of a teapot appears in the Yuan Dynasty text Jiyuan Conghua, which describes a teapot that the author, Cai Shizhan, bought from the scholar Sun Daoming. By the Ming Dynasty, teapots were widespread in China; the earliest example of a teapot that has survived to this day seems to be the one in the Flagstaff House Museum of Teaware. Early teapots are small by western standards because they are designed for a single drinker, the Chinese drank the tea directly from the spout; the size reflects the importance of serving single portions so that the flavours can be better concentrated and controlled repeated. From the end of the 17th century tea was shipped from China to Europe as part of the export of exotic spices and luxury goods.
The ships that brought the tea carried porcelain teapots. The majority of these teapots were painted in white underglaze. Porcelain, being vitrified, will withstand sea water without damage, so the teapots were packed below deck whilst the tea was stowed above deck to ensure that it remained dry. Tea drinking in Europe was the preserve of the upper classes, due the expense. Porcelain teapots were desirable because porcelain could not be made in Europe at that time, it wasn't until 1708 that Ehrenfried Walther von Tschirnhaus devised a way of making porcelain in Dresden and started the Meissen factory in 1710. When European potteries began to make their own tea wares they were inspired by the Chinese designs. In colonial America, Boston became the epicenter for silver artistry. Among the many artists in Boston there were four major families in the city's silver market: Edwards, Revere and Hurd, their works of art included silver teapots. To keep teapots hot after tea is first brewed, early English households employed the tea cosy, a padded fabric covering, much like a hat, that slips over the tea pot.
Decorated with lace or log cabin motifs in the early 1900s, the modern tea cosy has come back into fashion with the resurgence of loose leaf tea ateliers. In Morocco, stainless steel teapots are an essential to make Moroccan mint tea. Moroccan teapots can be put directly on the stove. With colorful tea glasses, they are part of the Moroccan tea ritual, their designs can go from minimalistic to decorated. A chocolate teapot is a teapot, it is supposed that such a teapot would melt, be impossible to use, therefore the term is used as an analogy for any useless item. Experimental researchers in 2001 did indeed fail to use a chocolate teapot they had made. Research, however, by The Naked Scientists in 2008, showed that such a teapot could be used to make tea, provided that the walls of the teapot were more than one centimetre thick. Re-usable pots are now available online. A teapot has a rather distinctive shape, its fame may sometimes have little to do with its primary function; the Utah Teapot is a standard reference object of the computer graphics community, comparable to Hello, World for its popularity.
It is included as a graphics primitive in many graphics packages, including AutoCAD, POV-Ray, OpenGL, Direct3D, 3ds Max. Russell's teapot, is an analogy, devised by Bertrand Russell, which attacks the unfalsifiability of religious claims, comparing them to the eponymous teapot; the concept in turn inspired the title of the 1973 album Flying Teapot by the Franco-British rock band Gong. The teapot has been featured in the American children's song from 1939, "I'm a Little Teapot". In Korea, the teapot is used as a serving container for various types of wines. Part of the constellation of Sagittarius contains an asterism. The'Teapot Game' is a word game described by Mary White's Book of Games, involves guessing a word, replaced by "teapot" in various sentences; the Teapot is a tale by Hans Christian Andersen. In 2004, a Malaysian cult called the Sky Kingdom constructed a 35 foot tall, cream colored teapot, with an unusually long spout, higher than the pot itself on its property as part of its own private symbolism which included a large blue vase next to the teapot.
As part of a crackdown on the se
Indus is a constellation in the southern sky created in the late sixteenth century. Indus does not contain any bright stars. Alpha Indi, the brightest star in the constellation, is an orange giant of magnitude 3.1, 101 light-years from Earth. Beta Indi is an orange giant of 600 light-years from Earth. Delta Indi is a white star of 185 light-years from Earth. Epsilon Indi is one of the closest stars to Earth 11.8 light years away. It is an orange dwarf of magnitude 4.7, meaning that the yellow dwarf Sun is hotter and larger. The system has been discovered to contain a pair of binary brown dwarfs, has long been a prime candidate in SETI studies. Indus is home to one bright binary star. Theta Indi is a binary star divisible in 97 light-years from Earth, its primary is a white star of magnitude 4.5 and its secondary is a white star of magnitude 7.0. T Indi is the only bright variable star in Indus, it is a semi-regular coloured red giant with a period of 11 months, 1900 light-years from Earth. Its minimum magnitude is 7 and its maximum magnitude is 5.
Galaxies include NGC 7090 and NGC 7049. All Sky Automated Survey for SuperNovae in 2015 detected a superluminous supernova, named ASASSN-15lh. Based on the study conducted by Subo Dong and team from the Kavli Institute for Astronomy and Astrophysics at Peking University, ASAS-SN-15lh was two times more luminous than any supernova discovered, at peak was 50 times more luminous than the entire Milky Way galaxy The constellation was created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. Plancius portrayed the figure as a nude male with arrows in both hands but no bow. Ridpath, Ian. Stars and Planets Guide, London. ISBN 978-0-00-725120-9. Princeton University Press, Princeton. ISBN 978-0-691-13556-4. Media related to Indus at Wikimedia Commons Starry Night Photography: Indus Constellation Star Tales–Indus
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
The apparent magnitude of an astronomical object is a number, a measure of its brightness as seen by an observer on Earth. The magnitude scale is logarithmic. A difference of 1 in magnitude corresponds to a change in brightness by a factor of 5√100, or about 2.512. The brighter an object appears, the lower its magnitude value, with the brightest astronomical objects having negative apparent magnitudes: for example Sirius at −1.46. The measurement of apparent magnitudes or brightnesses of celestial objects is known as photometry. Apparent magnitudes are used to quantify the brightness of sources at ultraviolet and infrared wavelengths. An apparent magnitude is measured in a specific passband corresponding to some photometric system such as the UBV system. In standard astronomical notation, an apparent magnitude in the V filter band would be denoted either as mV or simply as V, as in "mV = 15" or "V = 15" to describe a 15th-magnitude object; the scale used to indicate magnitude originates in the Hellenistic practice of dividing stars visible to the naked eye into six magnitudes.
The brightest stars in the night sky were said to be of first magnitude, whereas the faintest were of sixth magnitude, the limit of human visual perception. Each grade of magnitude was considered twice the brightness of the following grade, although that ratio was subjective as no photodetectors existed; this rather crude scale for the brightness of stars was popularized by Ptolemy in his Almagest and is believed to have originated with Hipparchus. In 1856, Norman Robert Pogson formalized the system by defining a first magnitude star as a star, 100 times as bright as a sixth-magnitude star, thereby establishing the logarithmic scale still in use today; this implies that a star of magnitude m is about 2.512 times as bright as a star of magnitude m + 1. This figure, the fifth root of 100, became known as Pogson's Ratio; the zero point of Pogson's scale was defined by assigning Polaris a magnitude of 2. Astronomers discovered that Polaris is variable, so they switched to Vega as the standard reference star, assigning the brightness of Vega as the definition of zero magnitude at any specified wavelength.
Apart from small corrections, the brightness of Vega still serves as the definition of zero magnitude for visible and near infrared wavelengths, where its spectral energy distribution approximates that of a black body for a temperature of 11000 K. However, with the advent of infrared astronomy it was revealed that Vega's radiation includes an Infrared excess due to a circumstellar disk consisting of dust at warm temperatures. At shorter wavelengths, there is negligible emission from dust at these temperatures. However, in order to properly extend the magnitude scale further into the infrared, this peculiarity of Vega should not affect the definition of the magnitude scale. Therefore, the magnitude scale was extrapolated to all wavelengths on the basis of the black-body radiation curve for an ideal stellar surface at 11000 K uncontaminated by circumstellar radiation. On this basis the spectral irradiance for the zero magnitude point, as a function of wavelength, can be computed. Small deviations are specified between systems using measurement apparatuses developed independently so that data obtained by different astronomers can be properly compared, but of greater practical importance is the definition of magnitude not at a single wavelength but applying to the response of standard spectral filters used in photometry over various wavelength bands.
With the modern magnitude systems, brightness over a wide range is specified according to the logarithmic definition detailed below, using this zero reference. In practice such apparent magnitudes do not exceed 30; the brightness of Vega is exceeded by four stars in the night sky at visible wavelengths as well as the bright planets Venus and Jupiter, these must be described by negative magnitudes. For example, the brightest star of the celestial sphere, has an apparent magnitude of −1.4 in the visible. Negative magnitudes for other bright astronomical objects can be found in the table below. Astronomers have developed other photometric zeropoint systems as alternatives to the Vega system; the most used is the AB magnitude system, in which photometric zeropoints are based on a hypothetical reference spectrum having constant flux per unit frequency interval, rather than using a stellar spectrum or blackbody curve as the reference. The AB magnitude zeropoint is defined such that an object's AB and Vega-based magnitudes will be equal in the V filter band.
As the amount of light received by a telescope is reduced by transmission through the Earth's atmosphere, any measurement of apparent magnitude is corrected for what it would have been as seen from above the atmosphere. The dimmer an object appears, the higher the numerical value given to its apparent magnitude, with a difference of 5 magnitudes corresponding to a brightness factor of 100. Therefore, the apparent magnitude m, in the spectral band x, would be given by m x = − 5 log 100 , more expressed in terms of common logarithms as m x
Antares designated α Scorpii, is on average the fifteenth-brightest star in the night sky, the brightest object in the constellation of Scorpius. Distinctly reddish when viewed with the naked eye, Antares is a slow irregular variable star that ranges in brightness from apparent magnitude +0.6 to +1.6. Referred to as "the heart of the scorpion", Antares is flanked by σ Scorpii and τ Scorpii in the center of the constellation. Antares appears as a single star at naked eye, but it is a binary star with its two components called α Scorpii A and α Scorpii B. Classified as a red supergiant of spectral type M1.5Iab-Ib, Antares is the brightest, most massive, most evolved stellar member of the nearest OB association, the Scorpius–Centaurus Association. Antares is a member of the Upper Scorpius subgroup of the Scorpius–Centaurus Association, which contains thousands of stars with mean age 11 million years at a distance of 170 parsecs, its exact size remains uncertain, but if placed at the center of the Solar System it would reach to somewhere between the orbits of Mars and Jupiter.
Its mass is calculated to be around 12 times that of the Sun. Α Scorpii is the star's Bayer designation. It has the Flamsteed designation 21 Scorpii, as well as catalogue designations such as HR 6134 in the Bright Star Catalogue and HD 148478 in the Henry Draper Catalogue; as a prominent infrared source, it appears in the Two Micron All-Sky Survey catalogue as 2MASS J16292443-2625549 and the Infrared Astronomical Satellite Sky Survey Atlas catalogue as IRAS 16262-2619. It is catalogued as a double star WDS J16294-2626 and CCDM J16294-2626, its traditional name Antares derives from the Ancient Greek Ἀντάρης, meaning "rival to-Ares", due to the similarity of its reddish hue to the appearance of the planet Mars. The comparison of Antares with Mars may have originated with early Mesopotamian astronomers. However, some scholars have speculated that the star may have been named after Antar, or Antarah ibn Shaddad, the Arab warrior-hero celebrated in the pre-Islamic poems Mu'allaqat. In 2016, the International Astronomical Union organised a Working Group on Star Names to catalog and standardise proper names for stars.
The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Antares for the star α Scorpii A. It is now so entered in the IAU Catalog of Star Names. Antares and its red color have been known since antiquity. Antares is a variable star and is listed in the General Catalogue of Variable Stars but as a Bayer-designated star it does not have a separate variable star designation. Research published in 2017 demonstrated that Aboriginal people from South Australia observed the variability of Antares and incorporated it into their oral traditions as Waiyungari. Antares is visible in the sky all night around May 31 of each year, when the star is at opposition to the Sun. At this time, Antares sets at dawn as seen at the equator. For two to three weeks on either side of November 30, Antares is not visible in the night sky, because it is near conjunction with the Sun. Antares is a type LC slow irregular variable star, whose apparent magnitude varies between extremes of +0.6 and +1.6, although near magnitude +1.0.
There is no obvious periodicity, but statistical analyses have suggested periods of 1,733 days or 1650±640 days. No separate long secondary period has been detected, although it has been suggested that primary periods longer than a thousand days are analogous to long secondary periods. Antares is 4.57 degrees south of the ecliptic, one of four first magnitude stars within 6.5° of the ecliptic and so can be occulted by the Moon. On 31 July 2009, Antares was occulted by the Moon; the event was visible in much of the Middle East. Every year around December 2 the Sun passes 5° north of Antares. Lunar occultations of Antares are common, depending on the Saros cycle; the last cycle ended in 2010 and the next begins in 2023. Shown at right is a video of a reappearance event showing events for both components. Antares can be occulted by the planets, e.g. Venus, but these events are rare; the last occultation of Antares by Venus took place on September 17, 525 BC. Other planets have been calculated not to have occulted Antares over the last millennium, nor will this occur during the next millennium, as the planets following the ecliptic always pass northward of Antares due to the actual planetary node positions and inclinations.
Antares is a red supergiant star with a stellar classification of M1.5Iab-Ib, is indicated to be a spectral standard for that class. Due to the nature of the star, the derived parallax measurements have large errors, so that the true distance of Antares is 550 light-years from the Sun; the brightness of Antares at visual wavelengths is about 10,000 times that of the Sun, but because the star radiates a considerable part of its energy in the infrared part of the spectrum, the true bolometric luminosity is around 100,000 times that of the Sun. There is a large margin of error assigned to values for the bolometric luminosity 30% or more. There is considerable variation between values published by different authors, for example 75,900 L☉ and 97,700 L☉ published in 2012 and 2013; the mass of the star has been cal
The South Pole known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of Earth and lies on the opposite side of Earth from the North Pole. Situated on the continent of Antarctica, it is the site of the United States Amundsen–Scott South Pole Station, established in 1956 and has been permanently staffed since that year; the Geographic South Pole is distinct from the South Magnetic Pole, the position of, defined based on Earth's magnetic field. The South Pole is at the center of the Southern Hemisphere. For most purposes, the Geographic South Pole is defined as the southern point of the two points where Earth's axis of rotation intersects its surface. However, Earth's axis of rotation is subject to small "wobbles", so this definition is not adequate for precise work; the geographic coordinates of the South Pole are given as 90°S, since its longitude is geometrically undefined and irrelevant.
When a longitude is desired, it may be given as 0°. At the South Pole, all directions face north. For this reason, directions at the Pole are given relative to "grid north", which points northwards along the prime meridian. Along tight latitude circles, clockwise is east, counterclockwise is west, opposite to the North Pole; the Geographic South Pole is located on the continent of Antarctica. It sits atop a featureless, barren and icy plateau at an altitude of 2,835 metres above sea level, is located about 1,300 km from the nearest open sea at Bay of Whales; the ice is estimated to be about 2,700 metres thick at the Pole, so the land surface under the ice sheet is near sea level. The polar ice sheet is moving at a rate of 10 metres per year in a direction between 37° and 40° west of grid north, down towards the Weddell Sea. Therefore, the position of the station and other artificial features relative to the geographic pole shift over time; the Geographic South Pole is marked by a stake in the ice alongside a small sign.
The sign records the respective dates that Roald Amundsen and Robert F. Scott reached the Pole, followed by a short quotation from each man, gives the elevation as "9,301 FT.". A new marker stake is fabricated each year by staff at the site; the Ceremonial South Pole is an area set aside for photo opportunities at the South Pole Station. It is located some meters from the Geographic South Pole, consists of a metallic sphere on a short bamboo pole, surrounded by the flags of the original Antarctic Treaty signatory states. Amundsen's Tent: The tent was erected by the Norwegian expedition led by Roald Amundsen on its arrival on 14 December 1911, it is buried beneath the snow and ice in the vicinity of the Pole. It has been designated a Historic Site or Monument, following a proposal by Norway to the Antarctic Treaty Consultative Meeting; the precise location of the tent is unknown, but based on calculations of the rate of movement of the ice and the accumulation of snow, it is believed, as of 2010, to lie between 1.8 and 2.5 km from the Pole at a depth of 17 m below the present surface.
Argentine Flagpole: A flagpole erected at the South Geographical Pole in December 1965 by the First Argentine Overland Polar Expedition has been designated a Historic Site or Monument following a proposal by Argentina to the Antarctic Treaty Consultative Meeting. In 1820, several expeditions claimed to have been the first to have sighted Antarctica, with the first being the Russian expedition led by Fabian Gottlieb von Bellingshausen and Mikhail Lazarev; the first landing was just over a year when American Captain John Davis, a sealer, set foot on the ice. The basic geography of the Antarctic coastline was not understood until the mid-to-late 19th century. American naval officer Charles Wilkes claimed that Antarctica was a new continent, basing the claim on his exploration in 1839–40, while James Clark Ross, in his expedition of 1839–43, hoped that he might be able to sail all the way to the South Pole. British explorer Robert Falcon Scott on the Discovery Expedition of 1901–04 was the first to attempt to find a route from the Antarctic coastline to the South Pole.
Scott, accompanied by Ernest Shackleton and Edward Wilson, set out with the aim of travelling as far south as possible, on 31 December 1902, reached 82°16′ S. Shackleton returned to Antarctica as leader of the British Antarctic Expedition in a bid to reach the Pole. On 9 January 1909, with three companions, he reached 88°23' S – 112 miles from the Pole – before being forced to turn back; the first men to reach the Geographic South Pole were the Norwegian Roald Amundsen and his party on December 14, 1911. Amundsen named his camp Polheim and the entire plateau surrounding the Pole King Haakon VII Vidde in honour of King Haakon VII of Norway. Robert Falcon Scott returned to Antarctica with his second expedition, the Terra Nova Expedition unaware of Amundsen's secretive expedition. Scott and four other men reached the South Pole on January 17, 1912, thirty-four days after Amundsen. On the return trip and his four companions all died of starvation and extreme cold. In 1914 Ernest Shackleton's Imperial Trans-Antarctic Expedition set out with the goal of crossing Antarctica via the South Pole, but his ship, the Endurance, was frozen in pack ice and sank 1
Claudius Ptolemy was a Greco-Roman mathematician, astronomer and astrologer. He lived in the city of Alexandria in the Roman province of Egypt, wrote in Koine Greek, held Roman citizenship; the 14th-century astronomer Theodore Meliteniotes gave his birthplace as the prominent Greek city Ptolemais Hermiou in the Thebaid. This attestation is quite late, and, according to Gerald Toomer, the translator of his Almagest into English, there is no reason to suppose he lived anywhere other than Alexandria, he died there around AD 168. Ptolemy wrote several scientific treatises, three of which were of importance to Byzantine and Western European science; the first is the astronomical treatise now known as the Almagest, although it was entitled the Mathematical Treatise and known as the Great Treatise. The second is the Geography, a thorough discussion of the geographic knowledge of the Greco-Roman world; the third is the astrological treatise in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day.
This is sometimes known as the Apotelesmatika but more known as the Tetrabiblos from the Greek meaning "Four Books" or by the Latin Quadripartitum. Ptolemaeus is a Greek name, it occurs once in Greek mythology, is of Homeric form. It was common among the Macedonian upper class at the time of Alexander the Great, there were several of this name among Alexander's army, one of whom made himself pharaoh in 323 BC: Ptolemy I Soter, the first king of the Ptolemaic Kingdom. All male kings of Hellenistic Egypt, until Egypt became a Roman province in 30 BC ending the Macedonian family's rule, were Ptolemies; the name Claudius is a Roman nomen. It would have suited custom if the first of Ptolemy's family to become a citizen took the nomen from a Roman called Claudius, responsible for granting citizenship. If, as was common, this was the emperor, citizenship would have been granted between AD 41 and 68; the astronomer would have had a praenomen, which remains unknown. The ninth-century Persian astronomer Abu Maʿshar presents Ptolemy as a member of Egypt's royal lineage, stating that the descendants of Alexander's general Ptolemy I, who ruled Egypt, were wise "and included Ptolemy the Wise, who composed the book of the Almagest".
Abu Maʿshar recorded a belief that a different member of this royal line "composed the book on astrology and attributed it to Ptolemy". We can evidence historical confusion on this point from Abu Maʿshar's subsequent remark "It is sometimes said that the learned man who wrote the book of astrology wrote the book of the Almagest; the correct answer is not known." There is little evidence on the subject of Ptolemy's ancestry, apart from what can be drawn from the details of his name. Ptolemy can be shown to have utilized Babylonian astronomical data, he was a Roman citizen, but was ethnically either a Greek or a Hellenized Egyptian. He was known in Arabic sources as "the Upper Egyptian", suggesting he may have had origins in southern Egypt. Arabic astronomers and physicists referred to him by his name in Arabic: بَطْلُمْيوس Baṭlumyus. Ptolemy's Almagest is the only surviving comprehensive ancient treatise on astronomy. Babylonian astronomers had developed arithmetical techniques for calculating astronomical phenomena.
Ptolemy, claimed to have derived his geometrical models from selected astronomical observations by his predecessors spanning more than 800 years, though astronomers have for centuries suspected that his models' parameters were adopted independently of observations. Ptolemy presented his astronomical models in convenient tables, which could be used to compute the future or past position of the planets; the Almagest contains a star catalogue, a version of a catalogue created by Hipparchus. Its list of forty-eight constellations is ancestral to the modern system of constellations, but unlike the modern system they did not cover the whole sky. Across Europe, the Middle East and North Africa in the Medieval period, it was the authoritative text on astronomy, with its author becoming an mythical figure, called Ptolemy, King of Alexandria; the Almagest was preserved, in Arabic manuscripts. Because of its reputation, it was sought and was translated twice into Latin in the 12th century, once in Sicily and again in Spain.
Ptolemy's model, like those of his predecessors, was geocentric and was universally accepted until the appearance of simpler heliocentric models during the scientific revolution. His Planetary Hypotheses went beyond the mathematical model of the Almagest to present a physical realization of the universe as a set of nested spheres, in which he used the epicycles of his planetary model to compute the dimensions of the universe, he estimated the Sun was at an average dis