1 Eratosthenes Quotes

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"Eratosthenes of Cyrene, Libya/Cyrene" was a Greek mathematician, geographer, poet, astronomer, and music theory/music theorist. He was a man of learning, 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 History of geodesy#Hellenic world/circumference of the Earth, which he did by applying a measuring system using stades, or the length of stadia during that time period. His calculation was remarkably accurate. He was also the first to calculate the Axial tilt#Obliquity of the ecliptic (Earth's axial tilt)/tilt of the Earth's axis (again with remarkable accuracy). Additionally, he may have accurately calculated the Astronomical unit/distance from the Earth to the Sun and invented the leap day. He created the first Ancient world maps#Eratosthenes/map of the world incorporating Circle of latitude/parallels and Longitude/meridians, based on the available geographical knowledge of the era.

Eratosthenes was the founder of scientific chronology; he endeavored to revise the dates of the chief literary and political events from the conquest of Troy. In number theory, he introduced the sieve of Eratosthenes, an efficient method of identifying prime numbers.