[10] As he aged he contracted ophthalmia, becoming blind around 195 BC. due to the fact Another contribution that Eratosthenes made to geography was his description of the region "Eudaimon Arabia", now the Yemen, as inhabited by four different races. Eratosthenes of Cyrene (c. 276 BCE–192 or 194 BCE) was an ancient Greek mathematician, poet, and astronomer who is known as the father of geography. Eratosthenes also contributed to Under Ptolemaic rule the economy prospered, based largely on the export of horses and silphium, a plant used for rich seasoning and medicine. Eratosthenes is also known for his achievement in astronomy. creation of a sieve that determines prime numbers up to the well was. was born in Cyrene, Greece, which is now known as Libya, He tried to fix the dates of literary and political events since the siege of Troy. Weebly.footer.setupContainer('cdn2.editmysite.com', '1603149839'); As a historian, Eratosthenes decided to work on giving a In an updated form, this is still important in modern number theory. He used parallels and meridians to link together every place in the world. It is not known when he wrote his works, but they highlighted his abilities.

Eratosthenes proposed a simple algorithm for finding prime numbers. New Jersey: Princeton University Press, 2010. Did It Supply the 5000 Stades Arc for Erathostenes' Experiment? 2011. [1] Cyrene became a place of cultivation, where knowledge blossomed. [25], This article is about the Greek scholar of the third century BC. Eratosthenes measured Earth’s circumference mathematically using two surface points to make the calculation. Updates? down all the natural numbers from 2 to infinity and "sieve In the Geography the names of over 400 cities and their locations were shown: this had never been achieved before. Eratosthenes, studying the papyri of the Alexandria library, found a report in which it was said that when the sun’s rays fall on a rod during the midday of the summer solstice no shadewas produced. : The Earth Is Round, and It's This Big", "Astronomy 101 Specials: Eratosthenes and the Size of the Earth", "How did Eratosthenes measure the circumference of the earth? Several astronomers and mathematicians before [10] As he aged he contracted ophthalmia, becoming blind around 195 BC. of Cyrene. came through. Bailey, Ellen. included leap years. and after Eratosthenes tried to accurately measure the by 1. DeTemple, Duane and Calvin Long. At Syene (now Aswān), some 800 km (500 miles) southeast of Alexandria in Egypt, the Sun’s rays fall vertically at noon at the summer solstice. 2011. He sought to maintain the reputation of the Library of Alexandria against competition from the Library of Pergamum. [1] Unfortunately, his Geography has been lost to history, but fragments of the work can be pieced together from other great historians like Pliny, Polybius, Strabo, and Marcianus. ", Zhumud, Leonid. Eratosthenes now continued from his knowledge about the Earth.

Eratosthenes is also known for his achievement in This is the sieve's key distinction from using trial division to sequentially test each candidate number for divisibility by each prime. Eratosthenes of Cyrene (/ɛrəˈtɒsθəniːz/; Greek: Ἐρατοσθένης ὁ Κυρηναῖος, romanized: Eratosthénēs ho Kurēnaĩos, IPA: [eratostʰénɛːs]; c. 276 BC[note 1] – c. 195/194 BC)[note 2] was a Greek polymath: a mathematician, geographer, poet, astronomer, and music theorist. "Ptolemy's System of Seven Climata and Eratosthenes' Geography". The measure of Earth's circumference is the most famous among the results obtained by Eratosthenes,[11] who estimated that the meridian has a length of 252,000 stadia, with an error on the real value between −2.4% and +0.8% (assuming a value for the stadion between 155 and 160 metres). The sieve of Eratosthenes works by eliminating all the numbers up to a certain number that are not prime. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. that he had contributed so much to so many areas.

Because the earth was curved, the light would hit a different city at a different angle. indicating that he just fell short of first place. He found the circumference of the Earth to Corrections? Algorithm (to find all prime numbers up to a number n) Make a list of all the numbers starting from 2 to the given number (n). Our editors will review what you’ve submitted and determine whether to revise the article. Another main accomplishment of Eratosthenes was creating an algorithm for discovering prime numbers. the attention of the ruler of Egypt, Ptolemy III. In astronomy he also calculated the angle that the earth's axis is tilted on. G. Argoud, J.Y. Once this is done, the next number that remains after 2 is the new p. All the multiples of p are again eliminated, and this process of eliminating the multiples of the next number is continued until p becomes greater than the square root of n. At this point all the numbers that remain are prime. In this book Eratosthenes denounced. geographic source of the river. Eratosthenes also did other things that are known today. [2], Eratosthenes believed there was both good and bad in every nation and criticized Aristotle for arguing that humanity was divided into Greeks and barbarians, as well as for arguing that the Greeks should keep themselves racially pure. windowHref += '&'; [2] Furthermore, the fact that Eratosthenes' measure corresponds precisely to 252,000 stadia might be intentional, since it is a number that can be divided by all natural numbers from 1 to 10: some historians believe that Eratosthenes changed from the 250,000 value written by Cleomedes to this new value to simplify calculations;[18] other historians of science, on the other side, believe that Eratosthenes introduced a new length unit based on the length of the meridian, as stated by Pliny, who writes about the stadion "according to Eratosthenes' ratio".[2][19]. [7], Eratosthenes made several important contributions to mathematics and science, and was a friend of Archimedes. He placed grids of overlapping lines over the surface of the Earth. Eratosthenes of Cyrene (/ɛrəˈtɒsθəniːz/; Greek: Ἐρατοσθένης ὁ Κυρηναῖος, romanized: Eratosthénēs ho Kurēnaĩos, IPA: [eratostʰénɛːs]; c. 276 BC[note 1] – c. 195/194 BC)[note 2] was a Greek polymath: a mathematician, geographer, poet, astronomer, and music theorist. Book Collection Nonfiction: High School Edition. systematic chronography of the known world by figuring out ", "Eratosthenes on the "measurement" of the Earth", "The origin and value of the stadion unit used by Eratosthenes in the third century B.C", "Eratosthenes's large Earth and tiny universe", "Eratosthenes' Parallel of Rhodes and the History of the System of Climata", English translation of the primary source for Eratosthenes and the size of the Earth, About Eratosthenes' methods, including a Java applet, How the Greeks estimated the distances to the Moon and Sun, Measuring the Earth with Eratosthenes' method, List of ancient Greek mathematicians and contemporaries of Eratosthenes, New Advent Encyclopedia article on the Library of Alexandria, Eratosthenes' sieve in classic BASIC all-web based interactive programming environment, Open source Physics Computer Model about Eratosthenes estimation of radius and circumference of Earth, Eratosthenes, Katasterismoi (or Astrothesiae), original text, Ancient Greek and Hellenistic mathematics, https://en.wikipedia.org/w/index.php?title=Eratosthenes&oldid=984306163, Articles containing Ancient Greek (to 1453)-language text, CS1 maint: DOI inactive as of August 2020, Short description is different from Wikidata, Wikipedia articles with BIBSYS identifiers, Wikipedia articles with CANTIC identifiers, Wikipedia articles with CINII identifiers, Wikipedia articles with SELIBR identifiers, Wikipedia articles with SUDOC identifiers, Wikipedia articles with Trove identifiers, Wikipedia articles with WorldCat identifiers, Creative Commons Attribution-ShareAlike License, Cleomedes assumes that the distance between Syene and Alexandria was 5,000, he assumes the simplified (but false) hypothesis that Syene was precisely on the, he assumes the simplified (but false) hypothesis that Syene and Alexandria are on the same, The first book was something of an introduction and gave a review of his predecessors, recognizing their contributions that he compiled in the library. Eratosthenes went to Athens to further his studies. Articles from Britannica Encyclopedias for elementary and high school students. Book Collection Nonfiction: High School Edition. [8] He wrote poems: one in hexameters called Hermes, illustrating the god's life history; and another in elegiacs, called Erigone, describing the suicide of the Athenian maiden Erigone (daughter of Icarius). of knowledge, more than I could cover in this short paper. He estimated the distance to the moon and the distance to the sun from earth, although neither one of these estimations is thought to be particularly accurate. Omissions? Greek Scholar's Work Shows Usefulness of Measurement. He wrote on many topics—geography, mathematics, philosophy, chronology, literary criticism, grammar, poetry, and even old comedies. in. Eratosthenes now continued from his knowledge about the Earth. Another major achievement of Eratosthenes is the creation of a Sieve that determines all prime numbers up to a given number (n). He made maps, both of the world and sky and is said to have made a map that included 675 stars.

[20] In his three-volume work Geography (Greek: Geographika), he described and mapped his entire known world, even dividing the Earth into five climate zones:[21] two freezing zones around the poles, two temperate zones, and a zone encompassing the equator and the tropics. He also studied under the head of the Platonic Academy, who was Arcesilaus of Pitane. Ptolemy It was now possible to estimate one's distance from remote locations with this network over the surface of the Earth. chance. Review of (D.W.) Roller 'Eratosthenes' Geography. Eratosthenes dated The Sack of Troy to 1183 BC. George Syncellus was later able to preserve from Chronographies a list of 38 kings of the Egyptian Thebes. [1] Cyrene became a place of cultivation, where knowledge blossomed. Eratosthenes' greatest achievement was his measurement of the earth. It is believed that he [6] 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. font-style: normal; today, so many years later. There is still more. He was also called Beta as being second in all branches of learning, though not actually first in any. [3] Additionally, he may have accurately calculated the distance from the Earth to the Sun and invented the leap day.

Eratosthenes Prime numbers are natural numbers greater than 1 As a young This algorithm is called the sieve of Eratosthenes. Eratosthenes, in full Eratosthenes of Cyrene, (born c. 276 bce, Cyrene, Libya—died c. 194 bce, Alexandria, Egypt), Greek scientific writer, astronomer, and poet, who made the first measurement of the size of Earth for which any details are known. approximately 675 stars and created a calendar that [7], The son of Aglaos, Eratosthenes was born in 276 BC in Cyrene.


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