Aristarchus of Samos

Aristarchus of Samos was one of the oldest mathematicians and astronomers of ancient Greece. He proposed a quite revolutionary astronomical hypothesis for his time. He said that the Sun, not the Earth, was the fixed center of the universe and the Earth , along with the rest of the planets revolved around the sun . He also said that the stars were distant suns that remained impassive and that the size of the universe was much larger than his contemporaries believed. Author of the scientific work ” On the magnitude and distance of the Sun and the Moon “, one of the most accurate calculations regarding the distance from the sun.

Personal information:

  • When was born: 310 BC
  • Where he was born:  Samos, Greece
  • When he died: 230 BC C.
  • Where he died:  Alexandria, Greece

Who was Aristarchus of Samos?

Aristarchus of Samos was the first scientist to study accurately the distance between the sun and the earth and between the earth and the moon. Creator of the heliocentric theory  claimed that the sun was the center of the universe and not the earth.

Biography of Aristarchus of Samos:

With regard to his life there is very little information recorded. However, it is known that he was born in Samos , Greece, that he was an important astronomer and mathematician and that he lived his life in Alexandria around 310 and 230 BC Just as the influence of Egypt caused Greek mathematics to develop several centuries before , the influence of Babylon had an equivalent stimulus on Greek astronomy . The opening of the East with Alexander the Great produced an exchange of ideas that contributed significantly to Greek astronomical notions. This is the context in which Aristarchus of Samos  developed his theory.

Contributions of Aristarchus of Samos:

Aristarco managed to discover that the planets were orbiting around the Sun and not the Earth as was thought for many years. He used clear logic to make estimates of the size of the Earth , the size of the moon, and the distance to it, relative to the size and distance of the sun. He also discovered that the stars were bodies similar to the sun that were found at enormous distances. He left behind the heliocentric model , which explains that the sun is the center of the universe and not the earth.

Heliocentric theory:

In ancient times there were a lot of theories about the universe, many of them were full of fantasy. The heliocentric theory was based on seven general principles , which said that:

  • The celestial bodies are not revolving around a single point.
  • The center of the Earth is the center of the lunar sphere, which means that the orbit of the moon is around the Earth.
  • All the spheres of the universe are revolving around the sun , and the sun is near the center of the universe .
  • The distance between the Earth and the Sun is a negligible fraction of the distance from the Earth and the Sun to the stars, so no parallax is observed in the stars.
  • The stars are immovable , their apparent daily movement is caused by the daily rotation of the Earth.
  • The Earth moves in a sphere around the Sun , causing the Sun’s apparent annual migration . The Earth has more than one motion.
  • The orbital movement of the Earth around the Sun causes the apparent retreat in the direction of the movements of the planets.

From these statements he continued to collect data to obtain a more detailed work, and in the year 1532, he had already completed the manuscript of his masterpiece known as ” In the revolutions of the celestial spheres .” In this manuscript, he showed his seven main arguments, but in more detail and with detailed calculations to back them up.

Works of Aristarco de Samos:

Two works by Aristarco de Samos are known, one of them was called “ On the sizes and distances of the sun and the moon” . The other became known as ” The revolutions of the celestial spheres“.


Within the history of Aristarco de Samos there is no record of famous phrases said by this important scientist. The only one known in ancient books is the following:

“Being is, not being is not”

Importance of Aristarchus of Samos:

Aristarchus of Samos was the first person to formulate the heliocentric theory . He recognized that the earth had a complete orbit lasting one year around the sun . He managed to locate the earth between Venus and Mars and that the stars were at an infinite distance from the sun. From these discoveries he inherited the idea and the concept that the center of the universe was occupied by the sun and not by the earth as previously believed, and that the planet earth was not revolving only around the sun, but was revolving around its own axis.

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