facts about eratosthenes

In an updated... • In about 240 BC Eratosthenes calculated Earth’s size with good accuracy. Contents. Measuring the Earth's circumference. She has been featured by NPR and National Geographic for her ancient history expertise. ), a mathematician, is known for his mathematical calculations and geometry. He also knew, from measurement, that in Alexandria, the angle of elevation of the sun would be 1/50 of a full circle (7°12') south of the zenith at the same time. [2] Eratosthenes was a friend of Archimedes, who also lived and worked in Alexandria. The method is an early application of trigonometry in the measurement science of geodesy. Chief among these is the calculation of the circumference of the earth and the development of a mathematical sieve named after him. He made a calendar with leap years, a 675-star catalog, and maps. The sun shone directly into a well at Syene at noon. Eratosthenes was called "Beta" (the second letter of the Greek alphabet) because he was never first, but he is more famous than his "Alpha" teachers because his … Eratosthenes was also the founder of scientific chronology; he wanted to fix the dates of the chief literary and political events from the conquest of Troy. The exact size of the stadion he used is frequently argued. Born: 276 BC in Cyrene (modern day Libya) Died: 194 BC (at age 82) in Alexandria, Egypt Nationality: Greek Famous For: Calculating the Earth's circumference Eratosthenes was a mathematician and astronomer from Greek antiquity. [7] It works efficiently for the smaller primes (below 10 million). The sieve of Eratosthenes. Some content of the original page may have been edited to make it more suitable for younger readers, unless otherwise noted. Eratosthenes made several remarkable discoveries and inventions. His estimated distance between the cities was 5000 stadia (about 500 geographical miles or 800 km) by estimating the time that he had taken to travel from Syene to Alexandria by camel. Archimedes was the greatest mathematician and inventor of the age, so perhaps the Beta nickname was not unjust. The sieve was described and attributed to Eratosthenes in the Introduction to Arithmetic by Nicomachus. Eratosthenes (c.276 to 194 B.C. Gill is a Latinist, writer, and teacher of ancient history and Latin. His most famous calculation, in the now lost treatise On the Measurement of the Earth, explains how he compared the shadow of the sun at Summer Solstice noon in two places, Alexandria and Syene. [9], Eratosthenes went further and computed the tilt of the Earth's axis to within a degree. By using this site, you agree to the Terms of Use Privacy Policy. According to the Suda,[1] his contemporaries nicknamed him Beta, (the second letter of the Greek alphabet), because he was the second best in the world in almost any field. Eratosthenes described his technique in a book entitled On the measure of the Earth, which has not been preserved. He tells us that the works of Eratosthenes were On the measurement of the Earth and Geographica. The common Attic stadium was about 185 metres (607 feet), which would imply a circumference of 46,250 kilometres or 28,740 miles, which is 6,250 kilometres (3,880 miles) different from the currently accepted circumference of the Earth (40,000 kilometres or 25,000 miles). He was head of the Library of Alexandria from 240 BC until his death: this was the most important library of the ancient world. Eratosthenes made several remarkable discoveries and inventions. He suggested that calendars should have a leap day every fourth year, an idea taken up two centuries later by Julius Caesar.[3]. Born in the Cyrene, the young lad was remarkably curious from an early age. 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. He tells us that the works of Eratosthenes were On the measurement of the Earth and Geographica. Archimedes was the greatest mathematician and inventor of the age, so perhaps the Beta nickname was not unjust. The exact size of the stadion he used is frequently argued. By using ThoughtCo, you accept our, Eratosthenes Calculates the Circumference of the Earth, Biography of Eratosthenes, Greek Mathematician and Geographer, Famous People Who Worked at the Ancient Library of Alexandria, Inventions and Discoveries of Ancient Greek Scientists, Claudius Ptolemy: Astronomer and Geographer from Ancient Egypt, Euclid of Alexandria and His Contributions to Geometry, Aristarchus of Samos: An Ancient Philosopher With Modern Ideas, Ancient Egypt: Birthplace of the Modern Calendar, Geodesy and the Size and Shape of the Planet Earth, The Ptolemies: Dynastic Egypt From Alexander to Cleopatra, M.A., Linguistics, University of Minnesota. Other discoveries and inventions. Other discoveries and inventions. He rounded the result to a final value of 700 stadia per degree, which implies a circumference of 252,000 stadia. However, if we assume that Eratosthenes used the "Egyptian stadium" of about 157.5 m, his measurement turns out to be 39,375 km, an error of less than 1%. [8] The works Eratosthenes wrote are known to us only indirectly: the great Library was destroyed, and no copies survived. He created a map of the world based on the available geographical knowledge of the era. Eratosthenes was the third librarian at the famous Library of Alexandria. Content is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. The measure of Earth's circumference is the most famous among the results obtained by Eratosthenes, 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). Eratosthenes was a friend of Archimedes, who also lived and worked in Alexandria. Assuming that Alexandria was due north of Syene he concluded that the distance from Alexandria to Syene must be 1/50 of the total circumference of the Earth (360 degrees). In mathematics, the sieve of Eratosthenes (Greek: κόσκινον Ἐρατοσθένους) is a simple, ancient algorithm for finding all prime numbers up to a specified integer. He was born in what is now Libya, to parents who were probably Chaldean. According to the Suda, his contemporaries nicknamed him Beta, (the second letter of the Greek alphabet), because he was the second best in the world in almost any field. He studied under the Stoic philosopher Zeno, Ariston, Lysanias, and the poet-philosopher Callimachus. The sieve was described and attributed to Eratosthenes in the Introduction to Arithmetic by Nicomachus. Fast Facts: Eratosthenes Known For: Eratosthenes was a Greek polymath who became known as the father of geography. Much of what Eratosthenes wrote is now lost, including a geometrical treatise, On Means, and one on the mathematics behind Plato's philosophy, Platonicus. He pursued higher education from Athens where he was taught by the best teachers of the day. He also deduced the length of the year as 365¼ days. Quick Guide – Eratosthenes’ Greatest Achievements • Eratosthenes produced a reliable, logical method to discover prime numbers: The Sieve of Eratosthenes. Eratosthenes of Cyrene (276 – 194 BC) was a 3rd century BC Greek mathematician, geographer and astronomer.

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