When was Jupiter found?

Jupiter was "known by the ancients," and so it does not have an official discovery date, according to NASA. There is evidence that pre-modern civilizations knew about the planet long before space exploration began.

As the largest planet in the solar system, and one of only five planets that can be seen from Earth, people have likely been observing it for years, making it difficult to know exactly when it was discovered. While scientists do not know when Jupiter was discovered, they do know that four of its moons were discovered by Italian astronomer Galileo Galilei. The first probe to circle the planet was named after him.