
A telescope toppled an old universe
Copernicus proposed a heliocentric model with the Sun near the center, but Ptolemy’s geocentric system still ruled. Aristarchus had even proposed a heliocentric cosmos long before—and was rejected.From Ptolemy to Galileo: How Heliocentrism Won

Why Copernicus didn’t win—yet
His model eliminated the equant, which astronomers praised, but it didn’t displace Ptolemy’s.From Ptolemy to Galileo: How Heliocentrism Won