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.
Eratosthenes’ only surviving work is Catasterisms, a book about the constellations, which gives a description and story for each constellation, as well as a count of the number of stars contained in it, but the attribution of this work has been doubted by some scholars. His mathematical work is known principally from the writings of the Greek geometer Pappus of Alexandria, and his geographical work from the first two books of the Geography of the Greek geographer Strabo.
After study in Alexandria and Athens, Eratosthenes settled in Alexandria about 255 BCE and became director of the great library there. He tried to fix the dates of literary and political events since the siege of Troy. His writings included a poem inspired by astronomy, as well as works on the theatre and on ethics. Eratosthenes was afflicted by blindness in his old age, and he is said to have committed suicide by voluntary starvation.
Credit : Britannica
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