1. ERATOSTHENES - Who Was Eratosthenes Of Cyrene? Discusses this early Grecian's discoveries in finding a good approximation of the circumference of the earth, the tilt angle of our planet and a tool for finding prime numbers. Page includes biographical information. http://www.eranet.gr/eratosthenes/html/eoc.html

Eratosthenes of Cyrene (276-194 BC) Eratosthenes was born in Cyrene which is now in Libya. After studying in Alexandria and Athens, he became the director of the Great Library in Alexandria. It was there where he read about a deep vertical well near Syene (now Aswan) in southern Egypt, which, once a year at noon (on the day of the Summer Solstice), was entirely lit up to the bottom by the sun, that is, the sun was directly overhead, with its rays shining directly into it. He then placed a vertical post at Alexandria (which was almost due north of Syenne) and measured the angle of its shadow on that exact date and time. Making the assumptions that (a) the earth is round and that (b) the sun's rays are essentially parallel, Eratosthenes knew from geometry that the size of the measured angle equaled the size of the angle at the earth's center between Syene and Alexandria. Knowing also that the arc of an angle this size was 1/50 of a circle, and that the distance between Syene and Alexandria was 5000 stadia, he multiplied 5000 by 50 to find the earth's circumference. His result, 250,000 stadia (about 46,250 km), is quite close to modern measurements.

2. ERATOSTHENES - Who Was Eratosthenes Of Cyrene? eratosthenes of cyrene (276194 BC) Eratosthenes was born in Cyrene which is now in Libya. http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

3. Chronology For 500BC To 1AD eratosthenes of cyrene estimates the Earth s circumference with remarkable accuracyfinding a value which is about 15% too big. About 230BC http://www-groups.dcs.st-and.ac.uk/~history/Chronology/500BC_1AD.html

4. Eratosthenes Of Cyrene Students will demonstrate their ability to research the Internet to learn important facts about the life of eratosthenes of cyrene, a noted Greek http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

5. Eratosthenes The interactive applet on this page illustrates the Sieve of Eratosthenes.There are also links and information about eratosthenes of cyrene. http://www.math.utah.edu/~alfeld/Eratosthenes.html

Peter Alfeld, Department of Mathematics, College of Science University of Utah Eratosthenes of Cyrene A versatile scholar, Eratosthenes of Cyrene lived approximately 275-195 BC. He was the first to estimate accurately the diameter of the earth. For several decades, he served as the director of the famous library in Alexandria. He was highly regarded in the ancient world, but unfortunately only fragments of his writing have survived. Eratosthenes died at an advanced age from voluntary starvation, induced by despair at his blindness. Here are some links to Eratosthenes related web pages: A worldwide experiment based on Eratosthenes original computation of the Earth's circumference. A page on Ancient Geography. Maps, lists, resources, and links pertaining to ancient Greek mathematics. The library of Alexandria.

6. Eratosthenes Eratosthenes (276 195 B.C.) Eratosthenes used geometry to estimate the circumference of the Earth. http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

7. Eratosthenes Of Cyrene Encyclop Dia Britannica eratosthenes of cyrene Greek scientific writer, astronomer, and poet, the first man known to have calculated the Earth's circumference. http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

8. Eratosthenes Of Cyrene eratosthenes of cyrene. eratosthenes of cyrene lived approximately 275195 BC.He was born in Cyrene which is now in Libya in North Africa. http://space.about.com/cs/astronomerbios/a/Eratosthenesbio.htm

var zLb=6; zJs=10 zJs=11 zJs=12 zJs=13 zc(5,'jsc',zJs,9999999,'') About Homework Help Space / Astronomy People - Bios/Jobs/Life ... Astronomer Biographies Eratosthenes of Cyrene Homework Help Space / Astronomy Essentials Education ... Help zau(256,140,140,'el','http://z.about.com/0/ip/417/C.htm','');w(xb+xb+' ');zau(256,140,140,'von','http://z.about.com/0/ip/496/6.htm','');w(xb+xb); FREE Newsletter Sign Up Now for the Space / Astronomy newsletter! See Online Courses Search Space / Astronomy Eratosthenes of Cyrene Public Domain Stay up to date! Eratosthenes of Cyrene Public Domain Email to a friend Print this page Suggested Reading Biography of Ptolemy Biography of Copernicus Recent Discussions Planet X Mars Close Approach Mercury vs Earth Recent Discussions Apollo 1 Fire Comet Man First Lady of Astronomy Most Popular Close Approach of Mars in 2005 Mars Closest To Earth in 50... Shuttle Challenger Disaster Space and Astronomy Pictures What's Hot Anaxagoras of Clazomenae Bio NASA Honors High Flying Space The Fisher Space Pen Saturn/Apollo 04 (Apollo 1) ... Astronomy 101 - Final Exam Eratosthenes of Cyrene From Nick Greene Your Guide to Space / Astronomy FREE Newsletter.

9. Eratosthenes The interactive applet on this page illustrates the Sieve of Eratosthenes. There are also links and information about eratosthenes of cyrene http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

10. Eratosthenes Of Cyrene eratosthenes of cyrene lived approximately 275195 BC. He was born in Cyrenewhich is now in Libya in North Africa. He studied with the scholar Lysanias of http://space.about.com/b/a/044894.htm

zJs=10 zJs=11 zJs=12 zJs=13 zc(5,'jsc',zJs,9999999,'') About Homework Help Space / Astronomy Homework Help ... Help zau(256,140,140,'el','http://z.about.com/0/ip/417/C.htm','');w(xb+xb+' ');zau(256,140,140,'von','http://z.about.com/0/ip/496/6.htm','');w(xb+xb); FREE Newsletter Sign Up Now for the Space / Astronomy newsletter! See Online Courses Search Space / Astronomy Eratosthenes of Cyrene Space/Astronomy Blog Main November 21, 2003 Eratosthenes of Cyrene Eratosthenes of Cyrene lived approximately 275-195 BC. He was born in Cyrene which is now in Libya in North Africa. He studied with the scholar Lysanias of Cyrene and the philosopher Ariston of Chios who had studied under Zeno, the founder of the Stoic school of philosophy. Later, he studied under the poet and scholar Callimachus who had also been born in Cyrene. He then spent some years studying in Athens. Eratosthenes is probably best known for the surprisingly accurate measurement of the circumference of the Earth he made. Comparing the noon shadow at midsummer between Syene (now Aswan on the Nile in Egypt) and Alexandria, assuming that the sun was so far away that its rays were essentially parallel, using the distance between Syene and Alexandria, he calculated the length of the circumference of the Earth as 250,000 stadia (about 46,250 km). The actual distance at the equator is 40,075km. Email a Friend Display Latest Headlines Read Archives Advertisement Most Popular Close Approach of Mars in 2005 Mars Closest To Earth in 50...

11. Eratosthenes Of Cyrene eratosthenes of cyrene. eratosthenes of cyrene lived approximately 275195 BC. He was born in Cyrene which is now in Libya in North Africa. Another http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

12. Eratosthenes Of Cyrene (ca. 284-ca. 192 BC) -- From Eric Weisstein's World Of Sc eratosthenes of cyrene (ca. 284ca. 192 BC) Although most of Eratosthenes writings are lost, many are preserved through the writings of commentators. http://scienceworld.wolfram.com/biography/Eratosthenes.html

Branch of Science Astronomers Branch of Science Geographers ... Greek Eratosthenes of Cyrene (ca. 284-ca. 192 BC) Consummate Greek scholar whose status as second best in each field earned him the nickname "Beta." He served as librarian at the great library in Alexandria, and wrote works of mathematics, geography, philosophy, and astronomy. He also wrote a poem called Hermes which described the fundamentals of astronomy in verse! Although most of Eratosthenes' writings are lost, many are preserved through the writings of commentators. Among Eratosthenes' accomplishments was the accurate measurement the diameter of the Earth by observing that, on the day of the summer solstice the Sun zenith in Alexandria, which he assumed was due north of Syene (Dunham 1990). Unfortunately, since the original work On the Measurement of the Earth was lost, the details of Eratosthenes' procedure are not known. Eratosthenes also determined the obliquity of the ecliptic prepared a star map containing 675 stars suggested that a leap day be added every fourth year, tried to construct an accurately-dated history, and developed the " sieve of Eratosthenes " method of finding

13. A Really 'big' Story The San Diego Union-Tribune From Eratosthenes in ancient Cyrene (what's now modernday Libya), who brilliantly deduced the size and distance of planets based on shadows http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

14. The Eratosthenes Project eratosthenes of cyrene (275194 BC) was a Greek scholar who lived and worked inCyrene and Alexandria. Eratosthenes was director of the famous library in http://www.phys-astro.sonoma.edu/observatory/eratosthenes/

The Eratosthenes Project The Original Experiment Some Deatils Our Experiment The Project Observations ... Project Results The Original Experiment Eratosthenes of Cyrene (275-194 B.C.) was a Greek scholar who lived and worked in Cyrene and Alexandria. Eratosthenes was director of the famous library in Alexandria, and is known for numerous important contributions to mathamatics, geography, and astronomy. In particular, he is remembered for a technique he introduced which enabled him to compute the first reliable determination of the true size of the earth. This technique is based on the observation by Eratosthenes that the sun is directly overhead at noon in Syene in southern Egypt on the first day of summer. (This is the time of the summer solstice.) While visiting Syene Eratosthenes apparently stopped at a well and noted that the noon sun reflected directly back from the water in the bottom of the well. Since Eratosthenes knew that the earth was a sphere, he correctly reasoned that if he could determine the altitude of the noon sun at some other location on the first day of summer, AND if he knew the distance between these two locations, he could compute the circumference of the earth as a simple ratio. This principle is illustrated in the following illustration, along with a sketch of a reconstructed map of the world as known by Eratosthenes. The Eratosthenes Technique for Determining the Size of the Earth When Eratosthenes returned to Alexandria, being a good astronomer, he knew he could wait until next year on the first day of summer and measure the altitude of the noon sun. Then since he had kept track of how far he had traveled from Syene to Alexandria, he could determine the circumference and the diameter of the earth.

15. Eratosthenes eratosthenes of cyrene http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

16. Eratosthenes Of Cyrene --  Encyclopædia Britannica eratosthenes of cyrene Greek scientific writer, astronomer, and poet, the firstman known to have calculated the Earth s circumference. http://www.britannica.com/eb/article-9032863

Home Browse Newsletters Store ... Subscribe Already a member? Log in Content Related to this Topic This Article's Table of Contents Eratosthenes Print this Table of Contents Shopping Price: USD $1495 Revised, updated, and still unrivaled. The Official Scrabble Players Dictionary (Hardcover) Price: USD $15.95 The Scrabble player's bible on sale! Save 30%. Merriam-Webster's Collegiate Dictionary Price: USD $19.95 Save big on America's best-selling dictionary. Discounted 38%! More Britannica products Eratosthenes of Cyrene  Encyclopædia Britannica Article Page 1 of 1 born c. BC , Cyrene, Libya died c. 194, Alexandria, Egypt Greek scientific writer, astronomer, and poet, the first man known to have calculated the Earth's circumference. Eratosthenes Of Cyrene... (75 of 275 words) var mm = [["Jan.","January"],["Feb.","February"],["Mar.","March"],["Apr.","April"],["May","May"],["June","June"],["July","July"],["Aug.","August"],["Sept.","September"],["Oct.","October"],["Nov.","November"],["Dec.","December"]]; To cite this page: MLA style: "Eratosthenes Of Cyrene."

17. Eratosthenes Of Cyrene (c.276-c.196 BC) Library Of Congress eratosthenes of cyrene (c.276c.196 BC) Library of Congress Citations The Little Search Engine that Could http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

18. Cyrene --  Encyclopædia Britannica eratosthenes of cyrene Greek scientific writer, astronomer, and poet, eratosthenes of cyrene Biographical sketch of this Greek scientific writer, http://www.britannica.com/eb/article-9028425

Home Browse Newsletters Store ... Subscribe Already a member? Log in Content Related to this Topic This Article's Table of Contents Cyrene Print this Table of Contents Shopping Price: USD $1495 Revised, updated, and still unrivaled. The Official Scrabble Players Dictionary (Hardcover) Price: USD $15.95 The Scrabble player's bible on sale! Save 30%. Merriam-Webster's Collegiate Dictionary Price: USD $19.95 Save big on America's best-selling dictionary. Discounted 38%! More Britannica products Cyrene  Encyclopædia Britannica Article Page 1 of 1 in Greek mythology, a nymph, daughter of Hypseus (king of the Lapiths) and Chlidanope (a Naiad). One day Cyrene wrestled a lion that had attacked her father's flocks. Apollo , who was watching, fell in love with her and carried her off from Mt. Pelion, in Thessaly, to Libya. There he founded the city of Cyrene and made her its queen. Cyrene was the mother by Apollo of Aristaeus q.v.

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20. Eratosthenes Of Cyrene eratosthenes of cyrene (c. 276 BC Cyrene – c. Remembering, however, thateratosthenes of cyrene, employing mathematical theories and geometrical methods http://www.mlahanas.de/Greeks/Eratosthenes.htm

Eratosthenes for Children Eratosthenes of Cyrene Michael Lahanas Die Messung des Erdumfangs nach Eratosthenes C leomedes On the Circular Motions of the Celestial Bodies ( de motu circulari corporum coelestium And it is necessary that the distance between Syene and Alexandria is one-fiftieth of the Earth's circumference. Since this distance is 5000 stades the circumference length is 250000 stades. Eratosthenes of Cyrene Library of Alexandria . He is best remembered for his prime number sieve which, in modified form, is still an important tool in number theory research. Eratosthenes measured the tilt of the Earth's axis with great accuracy and compiled a star catalogue containing 675 stars (now lost); he suggested that a leap day be added every fourth year and tried to construct an accurately-dated history. He became blind in his old age and is said to have committed suicide by starvation, like Democrit . Eratosthenes came to Alexandria from Athens to be the chief librarian of Ptolemy Euergetes. He was not merely an astronomer and a geographer, but a poet and grammarian as well. His contemporaries jestingly called him Beta the Second , because he was said through the universality of his attainments to be "a second Plato" in philosophy, "a second Thales" in astronomy, and so on throughout the list. For the same reason he was called a

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