When did Aristarchus of Samos propose his heliocentric model Why wasn it accepted at that time?
It probably was accepted; locally. There were many philosophers in Greece at the time, and each one was popular in his City. Greek people were not much bothered by scientific evidence. They usually went along with whoever was the most popular and the most eloquent. In matters of astronomy, those were Archimedes and Ptolemy. They were so popular that when Cleanthes (of the Stoics) heard about the teachings of Aristachus, he wanted him banned. (Today, we’d say he wanted to prosecute him for spreading falsehoods). But we do not know exactly when Aristarchus proposed his model. In fact, the very few writings we have about it come from others (e.g., Archimedes). This would place the proposal around the year 240 BC.
