Ancient Greek astronomy
Greek astronomy is astronomy written in the Greek language in classical antiquity. Greek astronomy is understood to include the ancient Greek, Greco-Roman, Late Antiquity eras, it is not limited geographically to Greece or to ethnic Greeks, as the Greek language had become the language of scholarship throughout the Hellenistic world following the conquests of Alexander. This phase of Greek astronomy is known as Hellenistic astronomy, while the pre-Hellenistic phase is known as Classical Greek astronomy. During the Hellenistic and Roman periods, much of the Greek and non-Greek astronomers working in the Greek tradition studied at the Musaeum and the Library of Alexandria in Ptolemaic Egypt; the development of astronomy by the Greek and Hellenistic astronomers is considered, by historians, to be a major phase in the history of astronomy. Greek astronomy is characterized from the start by seeking a rational, physical explanation for celestial phenomena. Most of the constellations of the northern hemisphere derive from Greek astronomy, as are the names of many stars and planets.
It was influenced by Egyptian and Babylonian astronomy. References to identifiable stars and constellations appear in the writings of Homer and Hesiod, the earliest surviving examples of Greek literature. In the oldest European texts, the Iliad and the Odyssey, Homer has several astronomical phenomena including solar eclipses. Eclipses that can permit the dating of these events as the place is known and the calculation of the time is possible if other celestial phenomena are described at the same time. In the Iliad and the Odyssey, Homer refers to the following celestial objects: the constellation Boötes the star cluster Hyades the constellation Orion the star cluster Pleiades Sirius, the Dog Star the constellation Ursa Major Hesiod, who wrote in the early 7th century BC, adds the star Arcturus to this list in his poetic calendar Works and Days. Though neither Homer nor Hesiod set out to write a scientific work, they hint at a rudimentary cosmology of a flat Earth surrounded by an "Ocean River."
Some stars set. At certain times of the year, certain stars will set at sunrise or sunset. Speculation about the cosmos was common in Pre-Socratic philosophy in the 6th and 5th centuries BC. Anaximander described a cyclical earth suspended in the center of the cosmos, surrounded by rings of fire. Philolaus the Pythagorean described a cosmos with the stars, Sun, Earth, a counter-Earth —ten bodies in all—circling an unseen central fire; such reports show that Greeks of the 6th and 5th centuries BC were aware of the planets and speculated about the structure of the cosmos. A more detailed description about the cosmos, Sun and the Earth can be found in the Orphism, which dates back to the end of the 5th century BC, it is even older. Within the lyrics of the Orphic poems we can find remarkable information such as that the Earth is round, it has an axis and it moves around it in one day, it has three climate zones and that the Sun magnetizes the Stars and planets; the name "planet" comes from the Greek term πλανήτης, meaning "wanderer", as ancient astronomers noted how certain lights moved across the sky in relation to the other stars.
Five planets can be seen with the naked eye: Mercury, Mars and Saturn, the Greek names being Hermes, Ares and Cronus. Sometimes the luminaries, the Sun and Moon, are added to the list of naked eye planets to make a total of seven. Since the planets disappear from time to time when they approach the Sun, careful attention is required to identify all five. Observations of Venus are not straightforward. Early Greeks thought that the evening and morning appearances of Venus represented two different objects, calling it Hesperus when it appeared in the western evening sky and Phosphorus when it appeared in the eastern morning sky, they came to recognize that both objects were the same planet. Pythagoras is given credit for this realization. In classical Greece, astronomy was a branch of mathematics; this tradition began with the Pythagoreans. The study of number comprising the four arts was called the Quadrivium. Although he was not a creative mathematician, Plato included the quadrivium as the basis for philosophical education in the Republic.
He encouraged Eudoxus of Cnidus, to develop a system of Greek astronomy. According to a modern historian of science, David Lindberg: "In their work we find a shift from stellar to planetary concerns, the creation of a geometrical model, the "two-sphere model," for the representation of stellar and planetary phenomena, the establishment of criteria governing theories designed to account for planetary observations"; the two-sphere model is a geocentric model that divides the cosmos into two regions, a spherical Earth and motionless and a spherical heavenly realm centered on the Earth, which may contain multiple rotating spheres made of aether. Plato's main books on cosmology are the Republic. In them he described the two-sphere model and said there were eight circles or spheres carrying the seven planets and the fixed stars. According to the "Myth of Er" in the Republic, the cosmos is the Spindle of Nec
Samos is a Greek island in the eastern Aegean Sea, south of Chios, north of Patmos and the Dodecanese, off the coast of Asia Minor, from which it is separated by the 1.6-kilometre -wide Mycale Strait. It is a separate regional unit of the North Aegean region, the only municipality of the regional unit. In ancient times Samos was an rich and powerful city-state known for its vineyards and wine production, it is home to Pythagoreion and the Heraion of Samos, a UNESCO World Heritage Site that includes the Eupalinian aqueduct, a marvel of ancient engineering. Samos is the birthplace of the Greek philosopher and mathematician Pythagoras, after whom the Pythagorean theorem is named, the philosopher Epicurus, the astronomer Aristarchus of Samos, the first known individual to propose that the Earth revolves around the sun. Samian wine was well known in antiquity, is still produced on the island; the island was governed by the semi-autonomous Principality of Samos under Ottoman suzerainty from 1835 until it joined Greece in 1912.
Strabo derived the name from the Phoenician word sama meaning "high". The area of the island is 477.395 km2, it is 43 km long and 13 km wide. It is separated from Anatolia by the 1-mile-wide Mycale Strait. While mountainous, Samos has several large and fertile plains. A great portion of the island is covered with vineyards; the most important plains except the capital, Vathy, in the northeast, are that of Karlovasi, in the northwest, Pythagoreio, in the southeast, Marathokampos in the southwest. The island's population is 33,814, the 9th most populous of the Greek islands; the Samian climate is Mediterranean, with mild rainy winters, warm rainless summers. Samos' relief is dominated by two large mountains and Kerkis; the Ampelos massif is the larger of the two and occupies the center of the island, rising to 1,095 metres. Mt. Kerkis, though smaller in area is the taller of the two and its summit is the island's highest point, at 1,434 metres; the mountains are a continuation of the Mycale range on the Anatolian mainland.
According to Strabo, the name Samos is from Phoenician meaning "rise by the shore". Samos is home to many surprising species including the golden jackal, stone marten, wild boar and monk seal. Samos is one of the sunniest places in Europe with 3300 hours of sunshine annually or 74% of the day time, its climate is wet in winter and dry in summer. In classical antiquity the island was a center of Ionian culture and luxury, renowned for its Samian wines and its red pottery, its most famous building was the Ionic order archaic Temple of goddess Hera—the Heraion. Concerning the earliest history of Samos, literary tradition is singularly defective. At the time of the great migrations it received an Ionian population which traced its origin to Epidaurus in Argolis: Samos became one of the twelve members of the Ionian League. By the 7th century BC it had become one of the leading commercial centers of Greece; this early prosperity of the Samians seems due to the island's position near trade-routes, which facilitated the importation of textiles from inner Asia Minor, but the Samians developed an extensive oversea commerce.
They helped to open up trade with the population that lived around the Black Sea as well as with Egypt, Cyrene and Chalcis. This caused them to become bitter rivals with Miletus. Samos was able to become so prominent despite the growing power of the Persian empire because of the alliance they had with the Egyptians and their powerful fleet; the Samians are credited with having been the first Greeks to reach the Straits of Gibraltar. The feud between Miletus and Samos broke out into open strife during the Lelantine War, with which we may connect a Samian innovation in Greek naval warfare, the use of the trireme; the result of this conflict was to confirm the supremacy of the Milesians in eastern waters for the time being. About 535 BC, when the existing oligarchy was overturned by the tyrant Polycrates, Samos reached the height of its prosperity, its navy not only ruled supreme in Aegean waters. The city was beautified with public works, its school, of sculptors, metal-workers and engineers achieved high repute.
In the 6th century BC Samos was ruled by the famous tyrant Polycrates. During his reign, two working groups under the lead of the engineer Eupalinos dug a tunnel through Mount Kastro to build an aqueduct to supply the ancient capital of Samos with fresh water, as this was of the utmost defensive importance. Eupalinos' tunnel is notable because it is the second earliest tunnel in history to be dug from both ends in a methodical manner. With a length of over 1 km, Eupalinos' subterranean aqueduct is today regarded as one of the masterpieces of ancient engineering; the aqueduct is now part of the Pythagoreion. After Polycrates' death Samos suffered a severe blow when the Persian Achaemenid Empire conquered and depopulated the island, it had regained much of its power when in 499 BC it joined the general revolt of the Ionian city-states against Persia.
Polycrates, son of Aeaces, was the tyrant of Samos from c. 538 BC to 522 BC. He had a reputation as both an enlightened tyrant. Polycrates took power during a festival of Hera with his brothers Pantagnotus and Syloson, but soon had Pantagnotus killed and exiled Syloson to take full control for himself, he assembled a navy of 100 penteconters, which became the most powerful navy in the Greek world –– Herodotus says that Polycrates was the first Greek ruler to understand the importance of sea power –– and an army of 1,000 archers, with these forces he implemented a plan to bring all the Greek islands and cities of Ionia under his rule. In pursuit of this goal, he conquered several islands and towns, fought successful actions against Miletus and Lesbos, formed an alliance with King Amasis of Egypt. Under Polycrates the Samians developed an engineering and technological expertise to a level unusual in ancient Greece, they built an aqueduct in the form of a tunnel 1100 yards long which can still be seen and, known as the Tunnel of Eupalinos.
The tunnel was constructed by two teams tunneling from opposite sides of a ridge who met in the middle with an error of only six feet -- a remarkable engineering feat for the time, one which reflects the practical geometry skills which the Samians had learned from the Egyptians. Polycrates sponsored the construction of a large temple of Hera, the Heraion, to which Amasis dedicated many gifts, which at 346 feet long was one of the three largest temples in the Greek world at that time, he upgraded the harbor of his capital city Pythagorion, ordering the construction of a deep-water mole nearly a quarter mile long, still used to shelter Greek fishing boats today. One use to which Polycrates put his powerful navy was to control the island of Delos, one of the most important religious centers in Greece, control of which would bolster Polycrates' claim to be the leader of the Ionian Greeks. In 522 BC Polycrates celebrated an unusual double festival in honour of the god Apollo of Delos and of Delphi.
Polycrates was a patron of the poets Anacreon and Ibycus. The philosopher Pythagoras was on Samos during his reign but left for Croton about 531 BC out of dissatisfaction with his dictatorship, he attracted to his court, sometimes by offering generous subsidies, an array of prominent craftsmen and professionals from throughout the Greek world, including Eupalinos, the architect of the Tunnel, from Megara, the famous physician Demodocus of Croton, Rhoikos the architect of the Heraion, the master metal-worker Theodoros, who had wrought a famous silver bowl which Croesus dedicated at Delphi and, described by Herodotus, who made the ring, Polycrates' most treasured personal possession. Polycrates established a library on Samos, showed a sophisticated approach to economic development, importing improved breeds of sheep and dogs from elsewhere in the Greek world. According to Herodotus, Amasis thought Polycrates was too successful, advised him to throw away whatever he valued most in order to escape a reversal of fortune.
Polycrates threw a jewel-encrusted ring into the sea. While Polycrates' cooks were preparing the fish for eating, they discovered the ring inside of it. Polycrates told Amasis of his good fortune, Amasis broke off their alliance, believing that such a lucky man would come to a disastrous end, it is more that the alliance was ended because Polycrates allied with the Persian king Cambyses II against Egypt. By this time, Polycrates had created a navy of 40 triremes becoming the first Greek state with a fleet of such ships, he manned these triremes with men he considered to be politically dangerous, instructed Cambyses to execute them. They could not take the island. Spartan attackThe rebels sailed to mainland Greece and allied with Sparta and Corinth. Sparta attempted to invade the island of Samos circa 520. After 40 days they withdrew their unsuccessful siege. Herodotus tells the story of Polycrates' death. Near the end of the reign of Cambyses, the governor of Sardis, planned to kill Polycrates, either because he had been unable to add Samos to Persia's territory, or because Polycrates had snubbed a Persian ambassador.
In any case, Polycrates was invited to Magnesia, where Oroetus lived, despite the prophetic warnings of his daughter, who had dreamt of him hanging in the air, being washed by Zeus and anointed by the Sun God Helios, he went and was assassinated. The manner is not recorded by Herodotus, as it was an undignified end for a glorious tyrant, but he may have been impaled and his dead body was crucified; the prophecy was fulfilled as when it rained he was'washed by Zeus' and when the sun shone he was'anointed by Helios', as the moisture was sweated from him. After the murder of Polycrates by Oroetes, Samos was ruled by Maiandrios. After some time, the brother of Polycrates, was installed as governor of Samos by Achaemenid ruler Darius I, receiving the help of general Otanes to expell the imposter who had taken control after Oroetes. Polycrates is mentioned in Byron's famous stanzas "The Isles of Greece:" Fill high the bowl with Samian wine! We will not think of themes like these
The Hellenistic period covers the period of Mediterranean history between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire as signified by the Battle of Actium in 31 BC and the subsequent conquest of Ptolemaic Egypt the following year. The Ancient Greek word Hellas is the original word for Greece, from which the word Hellenistic was derived. At this time, Greek cultural influence and power was at its peak in Europe, North Africa and Western Asia, experiencing prosperity and progress in the arts, literature, architecture, mathematics and science, it is considered a period of transition, sometimes of decadence or degeneration, compared to the enlightenment of the Greek Classical era. The Hellenistic period saw the rise of New Comedy, Alexandrian poetry, the Septuagint and the philosophies of Stoicism and Epicureanism. Greek science was advanced by the works of the polymath Archimedes; the religious sphere expanded to include new gods such as the Greco-Egyptian Serapis, eastern deities such as Attis and Cybele and a syncretism between Hellenistic culture and Buddhism in Bactria and Northwest India.
After Alexander the Great's invasion of the Achaemenid Empire in 330 BC and its disintegration shortly after, the Hellenistic kingdoms were established throughout south-west Asia, north-east Africa and South Asia. The Hellenistic period was characterized by a new wave of Greek colonization which established Greek cities and kingdoms in Asia and Africa; this resulted in the export of Greek culture and language to these new realms, spanning as far as modern-day India. However, these new kingdoms were influenced by the indigenous cultures, adopting local practices where beneficial, necessary, or convenient. Hellenistic culture thus represents a fusion of the Ancient Greek world with that of the Near East, Middle East, Southwest Asia; this mixture gave rise to a common Attic-based Greek dialect, known as Koine Greek, which became the lingua franca through the Hellenistic world. Scholars and historians are divided as to; the Hellenistic period may be seen to end either with the final conquest of the Greek heartlands by Rome in 146 BC following the Achean War, with the final defeat of the Ptolemaic Kingdom at the Battle of Actium in 31 BC, or the move by Roman emperor Constantine the Great of the capital of the Roman Empire to Constantinople in 330 AD.
"Hellenistic" is distinguished from "Hellenic" in that the first encompasses the entire sphere of direct ancient Greek influence, while the latter refers to Greece itself. The word originated from the German term hellenistisch, from Ancient Greek Ἑλληνιστής, from Ἑλλάς. "Hellenistic" is a 19th-century concept. Although words related in form or meaning, e.g. Hellenist, have been attested since ancient times, it was Johann Gustav Droysen in the mid-19th century, who in his classic work Geschichte des Hellenismus, coined the term Hellenistic to refer to and define the period when Greek culture spread in the non-Greek world after Alexander's conquest. Following Droysen and related terms, e.g. Hellenism, have been used in various contexts; the major issue with the term Hellenistic lies in its convenience, as the spread of Greek culture was not the generalized phenomenon that the term implies. Some areas of the conquered world were more affected by Greek influences than others; the term Hellenistic implies that the Greek populations were of majority in the areas in which they settled, but in many cases, the Greek settlers were the minority among the native populations.
The Greek population and the native population did not always mix. While a few fragments exist, there is no complete surviving historical work which dates to the hundred years following Alexander's death; the works of the major Hellenistic historians Hieronymus of Cardia, Duris of Samos and Phylarchus which were used by surviving sources are all lost. The earliest and most credible surviving source for the Hellenistic period is Polybius of Megalopolis, a statesman of the Achaean League until 168 BC when he was forced to go to Rome as a hostage, his Histories grew to a length of forty books, covering the years 220 to 167 BC. The most important source after Polybius is Diodorus Siculus who wrote his Bibliotheca historica between 60 and 30 BC and reproduced some important earlier sources such as Hieronymus, but his account of the Hellenistic period breaks off after the battle of Ipsus. Another important source, Plutarch's Parallel Lives although more preoccupied with issues of personal character and morality, outlines the history of important Hellenistic figures.
Appian of Alexandria wrote a history of the Roman empire that includes information of some Hellenistic kingdoms. Other sources include Justin's epitome of Pompeius Trogus' Historiae Philipicae and a summary of Arrian's Events after Alexander, by Photios I of Constantinople. Lesser supplementary sources include Curtius Rufus, Pausanias and the Byzantine encyclopedia the Suda. In the field of philosophy, Diogenes Laër
Eratosthenes of Cyrene was a Greek mathematician, poet and music theorist. He was a man of becoming the chief librarian at the Library of Alexandria, he invented the discipline of geography, including the terminology used today. He is best known for being the first person to calculate the circumference of the Earth, which he did by comparing angles of the mid-day Sun at two places a known North-South distance apart, his calculation was remarkably accurate. He was the first to calculate the tilt of the Earth's axis, again with remarkable accuracy. Additionally, he may have calculated the distance from the Earth to the Sun and invented the leap day, he created the first map of the world, incorporating parallels and meridians based on the available geographic knowledge of his era. Eratosthenes was the founder of scientific chronology. Eratosthenes dated The Sack of Troy to 1183 BC. In number theory, he introduced the sieve of Eratosthenes, an efficient method of identifying prime numbers, he was a figure of influence in many fields.
According to an entry in the Suda, his critics scorned him, calling him Beta because he always came in second in all his endeavors. Nonetheless, his devotees nicknamed him Pentathlos after the Olympians who were well rounded competitors, for he had proven himself to be knowledgeable in every area of learning. Eratosthenes yearned to understand the complexities of the entire world; the son of Aglaos, Eratosthenes was born in 276 BC in Cyrene. Now part of modern-day Libya, Cyrene had been founded by Greeks centuries earlier and became the capital of Pentapolis, a country of five cities: Cyrene, Berenice and Apollonia. Alexander the Great conquered Cyrene in 332 BC, following his death in 323 BC, its rule was given to one of his generals, Ptolemy I Soter, the founder of the Ptolemaic Kingdom. Under Ptolemaic rule the economy prospered, based on the export of horses and silphium, a plant used for rich seasoning and medicine. Cyrene became a place of cultivation. Like any young Greek, Eratosthenes would have studied in the local gymnasium, where he would have learned physical skills and social discourse as well as reading, arithmetic and music.
Eratosthenes went to Athens to further his studies. There he was taught Stoicism by its founder, Zeno of Citium, in philosophical lectures on living a virtuous life, he studied under Aristo of Chios, who led a more cynical school of philosophy. He studied under the head of the Platonic Academy, Arcesilaus of Pitane, his interest in Plato led him to write his first work at a scholarly level, inquiring into the mathematical foundation of Plato's philosophies. Eratosthenes investigated the art of poetry under Callimachus, he was a imaginative poet. He wrote poems: one in hexameters called Hermes, illustrating the god's life history, he wrote Chronographies, a text that scientifically depicted dates of importance, beginning with the Trojan War. This work was esteemed for its accuracy. George Syncellus was able to preserve from Chronographies a list of 38 kings of the Egyptian Thebes. Eratosthenes wrote Olympic Victors, a chronology of the winners of the Olympic Games, it is not known when he wrote his works.
These works and his great poetic abilities led the pharaoh Ptolemy III Euergetes to seek to place him as a librarian at the Library of Alexandria in the year 245 BC. Eratosthenes thirty years old, accepted Ptolemy's invitation and traveled to Alexandria, where he lived for the rest of his life. Within about five years he became Chief Librarian, a position that the poet Apollonius Rhodius had held; as head of the library Eratosthenes tutored the children of Ptolemy, including Ptolemy IV Philopator who became the fourth Ptolemaic pharaoh. He expanded the library's holdings: in Alexandria all books had to be surrendered for duplication, it was said that these were copied so that it was impossible to tell if the library had returned the original or the copy. He sought to maintain the reputation of the Library of Alexandria against competition from the Library of Pergamum. Eratosthenes created a whole section devoted to the examination of Homer, acquired original works of great tragic dramas of Aeschylus and Euripides.
Eratosthenes made several important contributions to mathematics and science, was a friend of Archimedes. Around 255 BC, he invented the armillary sphere. In On the Circular Motions of the Celestial Bodies, Cleomedes credited him with having calculated the Earth's circumference around 240 BC, using knowledge of the angle of elevation of the Sun at noon on the summer solstice in Alexandria and on Elephantine Island near Syene. Eratosthenes believed there was good and bad in every nation and criticized Aristotle for arguing that humanity was divided into Greeks and barbarians, that the Greeks should keep themselves racially pure; as he aged he contracted ophthalmia, becoming blind around 195 BC. Losing the ability to read and to observe nature plagued and depressed him, leading him to voluntarily starve himself to death, he died in 194 BC at 82 in Alexandria. Eratosthenes calculated the Earth's circumference without leaving Alexandria, he knew that at local noon on the summer solstice in Syene (modern Asw
Thales of Miletus
Thales of Miletus was a pre-Socratic Greek philosopher and astronomer from Miletus in ancient Greek Ionia. He was one of the Seven Sages of Greece. Many, most notably Aristotle, regarded him as the first philosopher in the Greek tradition, he is otherwise recognized as the first individual in Western civilization known to have entertained and engaged in scientific philosophy, he can be regarded as one of the first option traders. Thales is recognized for breaking from the use of mythology to explain the world and the universe, instead explaining natural objects and phenomena by theories and hypotheses, in a precursor to modern science. All the other pre-Socratic philosophers followed him in explaining nature as deriving from a unity of everything based on the existence of a single ultimate substance, instead of using mythological explanations. Aristotle regarded him as the founder of the Ionian School and reported Thales' hypothesis that the originating principle of nature and the nature of matter was a single material substance: water.
In mathematics, Thales used geometry to calculate the heights of pyramids and the distance of ships from the shore. He is the first known individual to use deductive reasoning applied to geometry, by deriving four corollaries to Thales' theorem, he is the first known individual. The dates of Thales' life are not known, but are established by a few datable events mentioned in the sources. According to Herodotus, Thales predicted the solar eclipse of May 28, 585 BC. Diogenes Laërtius quotes the chronicle of Apollodorus of Athens as saying that Thales died at the age of 78 during the 58th Olympiad and attributes his death to heat stroke while watching the games. Thales was born in the city of Miletus around the mid-620s BC; the ancient writer Apollodorus of Athens writing during the 2nd century BC, thought Thales was born about the year 625 BC. Herodotus, writing in the fifth century BC, described Thales as "a Phoenician by remote descent". Tim Whitmarsh noted that Thales regarded water as the primal matter, because thal is the Phoenician word for moisture, his name may have derived from this circumstance."According to the historian Diogenes Laërtius, in his third century AD Lives of the Philosophers, references Herodotus and Democritus, who all agree "that Thales was the son of Examyas and Cleobulina, belonged to the Thelidae who are Phoenicians."
Their names are Greek, respectively. Diogenes states that "Most writers, represent him as a native of Miletus and of a distinguished family." However, his supposed mother Cleobulina has been described as his companion. Diogenes delivers more conflicting reports: one that Thales married and either fathered a son or adopted his nephew of the same name. Plutarch had earlier told this version: Solon visited Thales and asked him why he remained single. Several years anxious for family, he adopted his nephew Cybisthus, it is assumed. Diogenes Laërtius wrote. Thales is hailed as "the first Greek mathematician". While some historians, such as Colin R. Fletcher, point out that there could have been a predecessor to Thales who would've been named in Eudemus' lost book History of Geometry, it is admitted that without the work "the question becomes mere speculation." Fletcher holds that as there is no viable predecessor to the title of first Greek mathematician, the only question is whether Thales qualifies as a practitioner in that field.
He derived this assumption from seeing that the nutriment of everything is moist, that heat itself is generated from moisture and depends upon it for its existence. He derived his assumption from this. Thales involved himself including engineering; some say that he left no writings, others say that he wrote On the Solstice and On the Equinox, the Nautical Star-guide has been attributed to him, but was disputed in ancient times. However, no writing attributed to him has survived. Diogenes Laërtius quotes two letters from Thales: one to Pherecydes of Syros, offering to review his book on religion, one to Solon, offering to keep him company on his sojourn from Athens. A story, with different versions, recounts how Thales achieved riches from an olive harvest by prediction of the weather. In one version, he bought all the olive presses in Miletus after predicting the weather and a good harvest for a particular year. Another version of the story has Aristotle explain that Thales had reserved presses in advance, at a discount, could rent them out at a high price when dem
Hipparchus of Nicaea was a Greek astronomer and mathematician. He is considered the founder of trigonometry but is most famous for his incidental discovery of precession of the equinoxes. Hipparchus was born in Nicaea and died on the island of Rhodes, Greece, he is known to have been a working astronomer at least from 162 to 127 BC. Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity, he was the first whose accurate models for the motion of the Sun and Moon survive. For this he made use of the observations and the mathematical techniques accumulated over centuries by the Babylonians and by Meton of Athens, Aristyllus, Aristarchus of Samos and Eratosthenes, among others, he developed trigonometry and constructed trigonometric tables, he solved several problems of spherical trigonometry. With his solar and lunar theories and his trigonometry, he may have been the first to develop a reliable method to predict solar eclipses.
His other reputed achievements include the discovery and measurement of Earth's precession, the compilation of the first comprehensive star catalog of the western world, the invention of the astrolabe of the armillary sphere, which he used during the creation of much of the star catalogue. There is a strong tradition that Hipparchus was born in Nicaea, in the ancient district of Bithynia, in what today is the country Turkey; the exact dates of his life are not known, but Ptolemy attributes astronomical observations to him in the period from 147–127 BC, some of these are stated as made in Rhodes. His birth date was calculated by Delambre based on clues in his work. Hipparchus must have lived some time after 127 BC because he analyzed and published his observations from that year. Hipparchus obtained information from Alexandria as well as Babylon, but it is not known when or if he visited these places, he is believed to have died on the island of Rhodes, where he seems to have spent most of his life.
It is not known what Hipparchus's economic means were nor how he supported his scientific activities. His appearance is unknown: there are no contemporary portraits. In the 2nd and 3rd centuries coins were made in his honour in Bithynia that bear his name and show him with a globe. Little of Hipparchus's direct work survives into modern times. Although he wrote at least fourteen books, only his commentary on the popular astronomical poem by Aratus was preserved by copyists. Most of what is known about Hipparchus comes from Strabo's Geography and Pliny's Natural History in the 1st century. Hipparchus was amongst the first to calculate a heliocentric system, but he abandoned his work because the calculations showed the orbits were not circular as believed to be mandatory by the science of the time. Although a contemporary of Hipparchus', Seleucus of Seleucia, remained a proponent of the heliocentric model, Hipparchus' rejection of heliocentrism, supported by ideas from Aristotle, remained dominant for nearly 2000 years until Copernican heliocentrism turned the tide of the debate.
Hipparchus's only preserved work is Τῶν Ἀράτου καὶ Εὐδόξου φαινομένων ἐξήγησις. This is a critical commentary in the form of two books on a popular poem by Aratus based on the work by Eudoxus. Hipparchus made a list of his major works, which mentioned about fourteen books, but, only known from references by authors, his famous star catalog was incorporated into the one by Ptolemy, may be perfectly reconstructed by subtraction of two and two thirds degrees from the longitudes of Ptolemy's stars. The first trigonometric table was compiled by Hipparchus, now known as "the father of trigonometry". Hipparchus was in the international news in 2005, when it was again proposed that the data on the celestial globe of Hipparchus or in his star catalog may have been preserved in the only surviving large ancient celestial globe which depicts the constellations with moderate accuracy, the globe carried by the Farnese Atlas. There are a variety of mis-steps in the more ambitious 2005 paper, thus no specialists in the area accept its publicized speculation.
Lucio Russo has said that Plutarch, in his work On the Face in the Moon, was reporting some physical theories that we consider to be Newtonian and that these may have come from Hipparchus. According to one book review, both of these claims have been rejected by other scholars. A line in Plutarch's Table Talk states that Hipparchus counted 103049 compound propositions that can be formed from ten simple propositions. 103049 is the tenth Schröder–Hipparchus number, which counts the number of ways of adding one or more pairs of parentheses around consecutive subsequences of two or more items in any sequence of ten symbols. This has led to speculation that Hipparchus knew about enumerative combinatorics, a field of mathematics that developed independently in modern mathematics. Earlier Greek astronomers and mathematicians were influenced by Babylonian astronomy to some extent, for instance the period relations of the Metonic cycle and Saros cycle may have come from Babylonian sources (see "Babylonian astron