Who is Aristarchus of Samos?

Who is Aristarchus of Samos?

June 26, 2021 Off By Felso

Aristarchus (Greek: Ἀρίσταρχος, Arístarchos; 310 BC – ca. 230 BC) Greek astronomer and mathematician, born on the island of Samos.

He was one of the first known proponents of the heliocentric belief that put the sun, not the earth, at the center of the universe. He was influenced by Pythagoras and Philolaus. Although both put the sun in the center, he differed from Philolaus regarding the order of the planets. His astronomical ideas remained unpopular with the geocentric theories of Aristotle and Ptolemy, which remained valid for 1800 years, until the discoveries of Copernicus, Kepler, and Newton. The Aristarchus Crater on the moon is named after him.

The work, which is based on the heliocentric model of the universe named The Magnitudes and Distances of the Moon and Sun, which has survived to the present day, is attributed to Aristarchus. This work is an attempt to solve astronomy problems with his knowledge of geometry. His studies on astronomy later formed the basis for the Copernican model. Although the original of the book is lost, Archimedes wrote the following about another work of Aristarchus in Archimedes’s Sand Calculations:

“You (King Gelon) as you know, “universe” is the name many astronomers give to the area that is also the center of the earth, and its radius is equal to the length of the line between the center of the earth and the center of the sun. This calculation is the consensus of astronomers until now. But Aristarchus’ hypotheses “As a result of the assumptions in his book, it is claimed that the universe is actually much larger than thought. According to the hypothesis, while the fixed stars and the sun do not move, the earth revolves around the sun in a certain orbit, the sun is in the center, and the fixed stars stay around the same center with the sun.”

According to Aristarchus, the stars must have been very far away because at that time there was no apparent parallax for the stars, according to the parallax method, a method used to calculate the distance of planets from the earth. In fact, the stars were much further away than was thought at the time because the stellar parallax could only be determined with a telescope.

The geocentric model explained why the stellar angle is unobservable, in accordance with the planetary parallax angle. According to the geocentric approach, if the earth were rotating, it would have to move very quickly and the living things living on it would have to feel it. Even according to Klaentes (the leader of the Stoics living in the same era), blaming Aristacrus not every Greek had a duty, because it was blasphemous to defend the idea that the sun was in the center.

In ancient times, it would be the Babylonian astronomer Seleucid Seleucid who would live a century after him who accepted his heliocentric model of the universe.[

Aristarchus gave the distances and radii in terms of earth radii, since the size of any celestial body was not known at that time in his work titled “The Sizes and Distances of the Moon and the Sun”. He followed the phases of the Moon and found the ratio of the Moon and Sun distances from his observations here.

Aristarchus measured the Moon’s elongation at 87° 08′. In fact, the Moon’s elongation angle; It is 89°50′ 30″. It was surprising that he could calculate this angle only with the help of the eye at that time.
The error of Aristarchus was that he did not take into account the refraction of the Earth’s atmosphere.[5] He estimated that the sun was 18-20 times further away from the moon, based on this angle, in reality the sun-earth distance is 400 times the moon-earth distance.

Taking into account that the sun and moon appear to be almost the same size from the earth, Aristarchus predicted that their diameters would increase in proportion to their distance from the earth. That’s why he claimed that the diameter of the sun is 18-20 times longer than the diameter of the moon. He also calculated the ratio of the diameter of the sun to the diameter of the earth to be 1 in 7, but this is about 1 in 109.

As a result, Aristarchus followed a correct method, but made wrong observations and calculations. Even so, he concluded that the sun is larger than the earth in size, and nevertheless reached the thesis that the earth should revolve around the sun logically.