Although it isn’t the biggest planet in the Solar System and the closest planet from the Earth, Venus is the brightest when you at the sky at night. Even without any telescopes, one can see the Venus during certain points of the day. The same can be said about the four other classical planets—Mercury, Mars, Jupiter, and Saturn. But since Venus, named aptly after the god of love and beauty, is the brightest, it is easily the most visible. The visibility made the planet more observed than the other classical planets, such as Mercury. As a classical planet, the discovery of the planet is not credited to anyone.

Since it is a bright planet, people from the ancient civilizations made observations on Venus. Like Mercury, people actually thought that it was a star; in fact, people thought Venus was two stars. It was corrected by Pythagoras, the famous Greek philosopher credited for the Pythagorean Theorem, who recognized that the so-called stars were just one object. Other discoveries were centered on Venus’ distance and appearance. Avicenna observed the planet’s transit and realized that it is closer to the Sun than the Earth. Ibn Bajjah also saw Venus’ transit together with Mercury.

But the very first thorough study with the knowledge that Venus is a planet just like Earth is that of Galileo Galilee’s. During his observation, he saw Venus in a half-lit phase when away from the Sun and in the full phase when it is close to the Sun—something that could only be possible if the planet, in fact, orbited the Sun. This observation is among the first ones to prove that the Earth is not the center of the Solar System.