On this date, Jan. 7, 1610, astronomer Galileo Galilei, with a homemade telescope, noticed three points of light near Jupiter.

Galileo Galilei identified four of Jupiter's orbiting moons, examined Saturn, observed the varying phases of Venus, and scrutinized sunspots on the surface of the sun.

Galileo continued writing in conversational language for his landmark 1632 work, Dialogo sopra i due massimi sistemi del ...

"Eight minutes later, the orbiter started receiving data from the descent probe, which slammed into the top of the Jovian atmosphere at a comet-like speed of 170,000 kilometers per hour," NASA ...

More than 400 years ago, Italian astronomer Galileo Galilei peered at Jupiter through his telescope, inspecting what he thought were three stars. In looking, he realized they were not stars but ...

Explore Jupiter's 92 moons including the infamous Galilean satellites and the largest moon in the solar system, Ganymede.

Jupiter’s four largest and most well-studied moons were first discovered more than 400 years ago. And they still make for wonderful observational targets.

The four "Galilean moons" were named after Italian astronomer Galileo Galilei, who is thought to have discovered them in 1610.

But the question of how many natural satellites the planet truly has is a bit more complicated. Jupiter's four best-known moons are the Galilean moons, discovered by Galileo Galilei in 1610.

Jupiter has four so-called Galilean moons — Europa, Callisto, Ganymede and Io — which were first discovered by Italian astronomer Galileo Galilei in 1610.