Aristarch and problems of a heliocentric model
Today we take the rotation of the earth around the sun as given and obvious. But consider that a point on the periphery moves around 40000 kilometers in 24 hours. With this rotation we move faster than the speed of sound and faster than a jet and still how is it possible that there is no strong wind from this very rapid earth rotation? If we thrown and object upwards it will fall on the same place. How is this possible as the ground moves faster than a jet? We do not feel this extreme rotation speed. These arguments were probably the reason that Aristotle and others did not accept Aristarchus idea that the earth rotates around its axis and around the sun. But this speed is nothing compared to the speed with which the earth rotates around the sun. If we consider a simplified circle instead of an ellipse and a distance of 150 million kilometers to the sun as the radius of the circle, then the earth moves with more than 100000 kilometers per hour around 100 times the speed of sound, or 50 times faster than a fighter jet.
But Aristarchus with a clever geometric argument estimated the size of the Sun and found it to be enormously larger than the Earth; He concluded that it is not logical that the tiny earth rotates around the gigantic sun and rather the opposite should be true. Once he concluded this, he concluded that the Earth must rotate on its axis in order to explain the apparent motion of the stars. In this way Aristarchus actually discovered the heliocentric model more than 17 centuries before Copernicus who knew the opinion of Aristarch but decided not to mention this in his publication! He eliminated the reference before the publication.
Aristarchus of Samos (310 B.C. - 230 B.C.) a Greek mathematician and astronomer 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.