Eratosthenes is famous for many things, including a mapping method that used latitudes and longitudes, and his accurate computation of the circumference of earth. Other discoveries and inventions. He created a map of the world based on the available geographical knowledge of the era. He knew that on the summer solstice at local noon at the city now called Aswan on the Tropic of Cancer, the sun would appear at the zenith, directly overhead. He pursued higher education from Athens where he was taught by the best teachers of the day. The exact size of the stadion he used is frequently argued. [2] Eratosthenes was a friend of Archimedes, who also lived and worked in Alexandria. He rounded the result to a final value of 700 stadia per degree, which implies a circumference of 250,000 stadia. The method is an early application of trigonometry in the measurement science of geodesy. 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. Fast Facts: Eratosthenes Known For: Eratosthenes was a Greek polymath who became known as the father of geography. Eratosthenes was the third librarian at the famous Library of Alexandria. Much of what Eratosthenes wrote is now lost, including a geometrical treatise, On Means, and one on the mathematics behind Plato's philosophy, Platonicus. 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. Measuring the Earth's circumference. 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 (c.276 to 194 B.C. This page was last changed on 28 April 2020, at 21:19. The Prime Glossary: "The Sieve of Eratosthenes", https://web.archive.org/web/20070205033538/http://traianus.rediris.es/topo01/surveying.pdf, "How did Eratosthenes measure the circumference of the earth? 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. With this information, and knowing that Syene was 787 km due south of Alexandrian Eratosthenes calculated the circumference of the earth to be 250,000 stadia (about 24,662 miles). Eratosthenes facts for kids. Eratosthenes measured the circumference of the Earth without leaving Egypt. [7] It works efficiently for the smaller primes (below 10 million). Eratosthenes wrote a Geographica based on his calculations of the circumference of the earth. Other discoveries and inventions. Eratosthenes was a friend of Archimedes, who also lived and worked in Alexandria. Archimedes was the greatest mathematician and inventor of the age, so perhaps the Beta nickname was not unjust. It works efficiently for the smaller primes (below 10 million). [8] Strabo (~63BC–24AD) wrote about geography in antiquity. This is the tilt which is the main cause of the annual climate cycle of spring, summer, autumn, winter. 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%. Eratosthenes made several remarkable discoveries and inventions. He also deduced the length of the year as 365¼ days. Eratosthenes was responsible for bring to notice some of the most important discoveries in geography, astronomy and mathematics. 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 discoveries are still used today. The works Eratosthenes wrote are known to us only indirectly: the great Library was destroyed, and no copies survived. Chief among these is the calculation of the circumference of the earth and the development of a mathematical sieve named after him. Eratosthenes made several remarkable discoveries and inventions. 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.