Part 2/12:
Today, we confidently count eight planets in our solar system. However, this was not always the case. Historically, the solar system harbored many more entities classified as planets. Post their initial discovery, asteroids were often treated as complete planets until scientific consensus shifted. For example, an 1828 English book titled First Steps to Astronomy and Geography reflected this view, stating the planets included not just Mercury, Venus, Earth, and Mars, but also several asteroids: Vesta, Juno, Ceres, Pallas, alongside Jupiter, Saturn, and Herschel (the provisional name for Uranus).