Up until the 17th century, the universe was thought to have only three bodies (Earth, Moon, Sun). True False

**False.** Up until the 17th century, the prevailing cosmological model was the **Ptolemaic system**, which was **geocentric**—placing the Earth at the center of the universe. However, this model recognized *more* than just three celestial bodies. In addition to the Earth, Moon, and Sun, it included the **five visible planets** (Mercury, Venus, Mars, Jupiter, and Saturn) and the **fixed stars**. Furthermore, ancient and medieval astronomers like **Claudius Ptolemy** and others had developed intricate models to explain the motions of these additional celestial bodies, incorporating concepts such as **epicycles** and **deferents** to maintain the geocentric framework. It wasn't until the **17th century** that the **heliocentric model** proposed by **Nicolaus Copernicus**, and later supported by **Galileo Galilei** and **Johannes Kepler**, gained significant acceptance. This model placed the Sun at the center and recognized a more complex universe with multiple planets orbiting it. Therefore, the universe was understood to contain more than just the Earth, Moon, and Sun well before the 17th century.