Aristarchus
# Aristarchus of Samos

### Born: about 310 BC
in Greece

Died: about 230 BC
in Greece

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**Aristarchus** was a mathematician and astronomer who is celebrated as the exponent of a Sun-centred universe and for his pioneering attempt to determine the sizes and distances of the Sun and Moon.

Aristarchus was a student of Strato of Lampsacus, head of Aristotle's Lyceum, coming between Euclid and Archimedes. Little evidence exists concerning the origin of his belief in a heliocentric system, the theory was not accepted by the Greeks and is known only because of a summary statement in Archimedes' The Sand-Reckoner and a reference by Plutarch.
The only surviving work of Aristarchus, On the Sizes and Distances of the Sun and Moon, provides the details of his remarkable geometric argument, based on observation, whereby he determined that the Sun was about 20 times as distant from the Earth as the Moon, and 20 times the Moon's size.

Both these estimates were an order of magnitude too small, but the fault was in Aristarchus' lack of accurate instruments rather than in his correct method of reasoning.

Aristarchus also found an improved value for the length of the length of the solar year.

**References (8 books/articles)**

**References elsewhere in this archive:**

There is a **Crater Aristarchus** on the moon. There is also a **Rimae Aristarchus**. You can see a list of lunar features named after mathematicians.

**Other Web sites:**

Clarke University, USA

JOC/EFR December 1996