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.

First, Earthlings could see three of Jupiter’s Galilean moons — Europa, Ganymede and Callisto — simultaneously crossing in front of the planet, known as a triple transit.

♪♪ -"Galileo's Moon." ♪♪ [ Suspenseful chord strikes ] -Rare books can fetch hundreds of thousands, if not millions, of dollars. ♪♪ They are a tangible piece of history and knowledge.

On this date, Jan. 7, 1610, astronomer Galileo Galilei, with a homemade telescope, noticed three points of light near Jupiter. Initially believing they were distant stars, Galileo’s repeated ...

Jupiter is the largest planet in our solar system with 80 moons. Galileo was the first to discover the moons of Jupiter on this day in history, Jan. 7, 1610.

The first astronomer to discover moons around Jupiter was Galileo, back in the year 1610, but astronomers are still finding more and more moons around this gas giant.

How many moons does Jupiter have? Scientists have discovered dozens of them, but the answer may be more complicated than it seems.

Jupiter's Galilean moons are also visible this evening, but spotting them may be challenging with the planet so low. If you want to try, note that your location - which will affect the time you're ...

Jupiter moons Callisto and Ganymede are among the biggest in the solar system, and potential grounds for liquid water and alien life. NASA's JUICE mission will probe them for signs of both.

The brutal conditions also make Io intriguing to NASA scientists intent on learning more about the innermost and third-largest of Jupiter’s four Galilean moons.

How many moons does Jupiter have? Scientists have discovered dozens of them, but the answer may be more complicated than it seems.