Geminus of Rhodes was a Greek astronomer and mathematician. His date of birth is approximately 10 BC, and he is believed to have died about 60 AD.

He was a stoic philosopher and studied at a school in Rhodes with Posidonius. During his career he wrote introductory works in mathematics and astronomy. His astronomical observations noted that the length of the day varied in different parts of the world. His book Isagoge was based on the work of Hipparchus.

His mathematical work divided the field into pure and applied mathematics. Pure mathematics included number theory and the various properties of numbers. In applied mathematics he included surveying, musical harmony, optics, astronomy, mechanics, and accounting.

Geminus crater on the Moon is named for him.

Bibliography

• Isagoge (or Introduction to Astronomy)
• Theory of Mathematics (now lost)

See also

• Antikythera mechanism

External links

• Technology Museum of Thessaloniki entry
• University of St. Andrews biography