Aristarchus of Samos

Little is known about the life of Aristarchus of Samos. Like any scholar, he was active in Alexandria, which at the time was considered the centre of ancient science and learning. All his writings were sooner or later lost or destroyed. But his ideas persist in the works of the authors who followed him. One small but important work survives, On the Size and Distance of the Sun and Moon, which laid the foundations for attempts to measure these distances.

According to several authors, he was to construct a complex sundial and introduce the concept of the "great year", which was equivalent to 2484 years.

He was the first to declare that at the centre of the universe lies the stationary sun and everything else orbits around it. Thus he became the originator of the idea of the heliocentric model. At that time, 5 planets were known, but they moved irregularly and it was Aristarchus' system that gave order to this.

He also argued that the Sun must be much larger than the Earth. The basis of this idea was the size of the shadow of the moon on the Earth. Calculations concluded that the Moon is about 3 times smaller than the Earth (actually 0.273) and the Sun, on the other hand, is about 7 times larger than our planet (realistically 109 times larger). So the calculation doesn't work out too well, but methodologically he was correct.

Finally, he also stated that the universe is infinite and the stars are analogous to our sun. He was then labeled a godless man and indicted. His ideas and models were rejected and long forgotten. These ideas were rediscovered only in the 17th century by Nicolaus Copernicus. And that's why Aristarchus is sometimes called the ancient Copernicus.

Within philosophy, he developed and defended Aristotle's ideas.