Tag Archives: ptolemy

History of Astronomy Part 3: Copernicus and Heliocentrism

Professor Dave again, let’s rethink the solar system. When we left off with Aristarchus, he had correctly proposed that the sun is the center of the solar system, rather than the earth. But he was way ahead of his time, and the geocentric model remained in place for centuries. This model was perfected by Ptolemy… Read More »

Mercury retrograde, explained WITHOUT astrology

You may have heard that Mercury is retrograde again. But if you try to find out what that means, search results are dominated by astrologers who believe Mercury can make you spill coffee on your favorite shirt or cause your car to break down. But if you set aside all those creative interpretations, there’s actually… Read More »