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Eratosthenes ( Father of Geography ) : Greek Mathematician, Geographer, Poet, Astronomer, and Music Theorist

Eratosthenes (276 BC-194 BC)

Eratosthenes or Eratosthenes of Cyrene was a renowned Greek personality. He was a mathematician, geographer, astronomer, polymath and music theorist. Eratosthenes is known as the father of Geography. He was the first person to calculate the circumference of earth and axial tilt of earth.

He was the creator of the world’s first map with parallels and meridians. In mathematics he is known for his sieve of Eratosthenes, a method for identifying prime numbers. He was a chief librarian at the great library of Alexandria. 

Time and Place of Birth 

Eratosthenes was born in 276 BC in Cyrene which is now a part of Libya. 

Life history 

Eratosthenes was born in the Greek empire of Northern Africa. His father’s name was Aglaos. He went to the local gymnasium for primary education and Athens for higher studies. In 245 BC due to his fame Pharaoh Ptolemy III Eugretes summoned him and appoint as a librarian in the Great library of Alexandria.

After this he lived the rest of his life here. Eratosthenes was a well known personality of his time and was a friend of another mathematician Archimedes. He became blind around 195 BC after this he cut all his ties with this world and starved himself to death after sometime of this. 


At the age of 82 in 194 BC, Eratosthenes died in Alexandria. 

Education and Career 

Eratosthenes got his primary education in a local gymnasium of Cyrene. He went to Athens for further studies. In Athens he learned stoicism from its founder Zeno. Then he studied under the head of Ptolemaic academy. After some time he went to Alexandria and became Chief librarian of Great library of Alexandria. 

Contribution in Mathematics 

In mathematics Eratosthenes is known for his Sieve of Eratosthenes, a method for finding prime numbers.  

Sieve of Eratosthenes 

This is a simple method for finding prime numbers. In this a simple algorithm is used for finding prime numbers. 

Red More : Hipparchus of Nicaea a Greek astronomer, geographer, and mathematician.

Contribution in other fields 

Apart from maths he had been a significant scholar in other subjects like science and geography. 


In science he is known for his two works, the first one is calculating the circumference of earth and the second one is calculating the tilt of earth’s axis. 


He is known as the father of geography because he was the first man to project a world map. He was also the first one to use longitudes and latitudes in the maps.

Read More : Claudius Ptolemy was a mathematician, astronomer, natural philosopher, geographer 


He was a poet too and wrote many literary works like Trojan War and Olympic Victors. 

Interesting facts about Eratosthenes 

  • Eratosthenes was the teacher of a Ptolemic Pharaoh Ptolemy IV Philaphator. 
  • His devotees named him Pantathlos for his all round scholar abilities. Pantothlos is an adjective for olympic athletes with allround abilities. 

Read More : Hero of Alexandria was a Greek mathematician and engineer

Books written by the Eratosthenes 

  • Catasterismi 
  • Catasterismorum Reliquiae 


What is Eratosthenes famous for?

Eratosthenes is known for calculating the circumference of earth. 

What did Eratosthenes discover?

System of longitude and latitude. 

Read More : Diophantus of Alexandria was an Alexandrian mathematician,

Who is the father of geography?


Who is the first geographer?


Which country is Eratosthens from?

Greece, Ancient Empire of Greece

See also 

Eratosthenes is from Greece, a country that is known for founding the roots of western civilization. This country gave this world many great mathematical personalities in ancient time like Archemedis, Thale, Heron, and Hipparchus etc.

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