If you browse “who proposed the heliocentric model first” the most presumable answer will be Nicolaus Copernicus, who published a book on heliocentrism from his death bed in 1543 afraid of the mass opposition from people who believed in Geocentrism. But was he the first?
Even before the mathematician, Claudius Ptolemy supported the idea of geocentrism, that survived for 1500 years, there lived a Greek astronomer and mathematician named Aristarchus of Samos (c.310 – c.230 BC).
Aristarchus of Samos is credited as the first person to present the Heliocentric model. The book where he depicted his idea was among the vast marvel collection of the Great Library of Alexandria but it didn’t survive its destruction. The only main reference of Aristarchus’ work is Archimedes’ book named ‘The Sand Reckoner’. But, the true essence of his first-hand understandings is lost in the obscured pages of history.
When Plato and Aristotle emphasized on the geocentric model a generation ago, Aristarchus wasn’t appealing to the thought. Probably inspired by the views of Philolaus of Croton, he believed in a Sun-centered Universe and went on to determine the distance from the Earth to the Moon and Sun with the primitive instruments of the time and geometry.
He knew that at the first and last quarter moons, a right triangle would be created between the three celestial bodies and he observed the angle between the Sun and Moon to be 87°(the actual angle was about 89°50′). Further, he calculated the Sun to be 18-20 times (400 times in actual) farther than the Moon and about 6.3-7.2 times (109 times in actual) larger than the Earth.
Even though highly inaccurate, his predictions were truly an astounding achievement for an astronomer living 2300 years ago. Aristarchus’ model went unnoticed as geocentrism ascended to its peak during the time and had to wait another 2000 years until Copernicus. Also, Aristarchus was the first person to place the planets in order from the Sun and suspected all the other stars to be far-away Suns.
Aristarchus was a right man at the right place in the wrong time and a pure genius the world wasn’t ready for.
Reference: Aristarchus of Samos
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