Aristarchus of Samos (c. 310 – c. 230 BCE) was an ancient Greek astronomer and mathematician who presented the first known heliocentric model that placed the Sun at the center of the known universe, with the Earth revolving around the Sun once a year and rotating about its axis once a day.

Aristarchus was born on the island of Samos in Greece. He was a student of Strato of Lampsacus, who was the third head of the Peripatetic School in Greece. Aristarchus is best known for his heliocentric model of the universe, which was a radical departure from the prevailing geocentric model, which placed the Earth at the center of the universe.

Aristarchus’s heliocentric model was based on his observations of the Sun and Moon. He noted that the Sun and Moon appeared to be the same size in the sky, even though the Sun is much larger than the Moon. This led him to conclude that the Sun must be much farther away from the Earth than the Moon.

Aristarchus also calculated the relative distances of the Sun and Moon from the Earth. He did this by measuring the angle between the Sun and Moon when the Moon is half-illuminated. He found that the Sun is about 20 times farther away from the Earth than the Moon.

Aristarchus’s heliocentric model was not widely accepted in his lifetime. The geocentric model was supported by Aristotle and Ptolemy, two of the most influential philosophers and astronomers of the ancient world. However, Aristarchus’s model laid the foundation for the heliocentric model that was eventually accepted by scientists in the 16th century.

In addition to his work on the heliocentric model, Aristarchus also made contributions to mathematics and astronomy. He calculated the circumference of the Earth and the distance to the Moon. He also studied the motion of the planets and the stars.

Aristarchus was a brilliant astronomer and mathematician who made significant contributions to our understanding of the universe. His heliocentric model was a radical departure from the prevailing geocentric model, but it laid the foundation for the heliocentric model that is now accepted by scientists.

Aristarchus’s work was not widely accepted in his lifetime, but it was eventually rediscovered and studied by later astronomers. His work helped to pave the way for the Copernican Revolution, which overthrew the geocentric model and established the heliocentric model as the dominant model of the universe.

Aristarchus of Samos is considered one of the most important astronomers of the ancient world. His work helped to shape our understanding of the universe and laid the foundation for the scientific revolution.

Ptolemy of Alexandria: The Great Astronomer of Alexandria

November 24, 2023

2 min