Who discovered Jupiter's moons?

Answer 1

Galileo discovered the four major moons. Others were added over the years by different people and by close up viewing by probes.
The planet Jupiter has been known since ancient times and is visible to the naked eye in the night sky. The Romans named the planet after the Roman god Jupiter (also called Jove). The astronomical symbol for the planet is a stylized representation of the god's lightning bolt.

The Chinese, Korean, Japanese, and Vietnamese refer to the planet as the wood star based on the Chinese Five Elements. In Vedic Astrology, Hindu astrologers refer to Jupiter as Brihaspati, or "Guru" which means the "Big One". In Hindi, Thursday is referred to as Guruvaar (day of Jupiter). In the English language Thursday is rendered as Thor's day, with Thor being identified with the Roman god Jupiter.

In 1610, Galileo Galilei discovered the four largest moons of Jupiter, Io, Europa, Ganymede and Callisto (now known as the Galilean moons) using a telescope, the first observation of moons other than Earth's. This was also the first discovery of a celestial motion not apparently centered on the Earth. It was a major point in favor of Copernicus' heliocentric theory of the motions of the planets; Galileo's outspoken support of the Copernican theory placed him under the threat of the Inquisition.

In 1892, E. E. Barnard observed a fifth satellite of Jupiter with the 36-inch refractor at Lick Observatory in California. The discovery, a testament to his extraordinary eyesight, made him quickly famous. The moon was later named Amalthea.

Answer 2

Galileo Galilei discovered the moons using his homemade telescope.