Aristarchus of Samos (c. 310 – c. 230 BC)

A long time ago, in a galaxy far far away……too much of Star Wars (inside joke). I bet most of us in the entire world probably heard of Copernicus. However, only little of us knew about Aristarchus of Samos, ( Ἀρίσταρχος ὁ Σάμιος, Aristarkhos ho Samios-his name in Greek) an ancient Greek astronomer and a mathematician I would say who first proposed a ‘Sun-Centered Solar System’ eighteen centuries before Copernicus.WOW! ( I can see the face of the enthusiasm among all of you).

Image result for aristarchus of samos
The image of Aristarchus of Samos

However, the Greeks rejected his astronomical ideas that the Earth goes around the Sun especially from the two famous astronomers:  Aristotle and Ptolemy, which are now known to be incorrect. Do you know why did they reject the real explanation for planetary motion?

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GIF of curiosity taken from GIPHY 

Although there were many reasons the Greeks were reluctant to abandon their original idea (Earth-centered universe), the most ultimate reason was their inability to detect stellar parallax. Stellar parallax is a parallax on an interstellar scale, means that there is slight apparent shifts in stellar positions over a course of the year. Since stellar parallax is only detectable with telescopes, his accurate astronomical theory was unprovable at the time. Besides, his theory did not gain wide acceptance until almost 2000 years later.To know more about the stellar parallax, there are few links that I shared in this post.

Stellar Parallax

Stellar Parallax Video

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GIF of seeing a telescope

Since there is no observable stellar parallax, he suggested that the Stars were extremely very far away.Why? This is because parallax is a function of distance. In other words, distant objects exhibiting smaller parallax than nearer objects. To further strengthen his argument, he estimated the sizes of the Moon and the Sun. He estimated the Moon’s size by observing the shadow of Earth on the Moon during a lunar eclipse and measured the angle between the Moon and the Sun at first and third quarter phases of the Moon. Based on these experiments, he concluded that the Sun must be larger than the Earth hence he believed that Earth should be the one that is orbiting the Sun.

Warner Archive oh eye roll sci fi i see
I finally understand from GIPHY

Today, we can detect stellar parallax with the aid of the telescopes. Thus, Aristarchus of Samos was right and we have a direct proof that the Earth really does orbit the Sun.

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5 thoughts on “Aristarchus of Samos (c. 310 – c. 230 BC)

  1. Even though Aristarchus proposed the heliocentric model, he didn’t pursue it because of the lack of any evidence for the claim. It is pretty interesting looking forward to when Copernicus published his book in support of the theory, citing Aristarchus as though to lessen the attention on himself. While Aristarchus did not have concrete proof, his assertion was never forgotten.

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    1. Yep, that is true man. However, the main problem during that time was the people can’t explain about the parallax. Otherwise, the Ancient Greek would probably use the heliocentric model. By the way, thanks for the comment bro.

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      1. That makes sense. If the stars were closer, maybe the Galileo trial wouldn’t have been such a big deal. Do you know if parallax was detected by Copernicus or was that a more modern discovery?

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      2. That is a good question. Based on my previous reading, I figured out that the first person to observe this effect is Giuseppe Calandrelli and the one who measured the first successful parallax is Friedrich Bessel. Friedrich used Fraunhofer heliometer to observe the parallax of the star 61 Cygni.

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