Most people may not realize how harmful incorrect theories, ideologies, and viewpoints can be—especially those that are widely spread and accepted. Take, for example, the geocentric and heliocentric models. Before the 18th century, humanity firmly believed in the geocentric theory, which held that the Earth was the center of the universe. This belief significantly hindered the advancement of astronomy. After the 18th century, however, the geocentric model was replaced by the heliocentric theory, which posits that the Sun is at the center. In just the short span of about 300 years since then, astronomy has made tremendous progress.