By Matt Francis

 Europa’s surface is one of the brightest in the Solar System. Its face is also one of the smoothest in the galaxy. Europa is named Phoenician princess in Greek mythology. It was discovered in 1610 by Galileo Galilee. It is 670,900 kilometers from Jupiter. It orbits Jupiter completely in about 3 days.

 Io is one of the most volcanic bodies known. It has lava lakes, lava flows, and billowing volcanic geysers. It has much taller mountains than the ones on Earth, reaching over 16 kilometers. Io orbits closer to Jupiter’s clouds than the moon does to Earth. I acts as an electrical generator. It passes through Jupiter’s magnetic field and generates 400,000 volts that transfers to the planet’s ionosphere.

 Callisto is Jupiter’s 2 nd largest moon. It is also the 3 rd largest in the Solar System. It orbits just beyond Jupiter’s radiation belt. It is the has the most craters of anything in the Solar System. Its crust dates back 4 billion. It doesn't have any huge mountains. Craters are about the only landforms found. Scientists believe that within Callisto’s 200 kilometer thick crust is a possible salty ocean.

 Ganymede is the largest moon in our Solar System. It’s larger than Mercury and Pluto. There is also a thin oxygen atmosphere. It is split into 2 terrains. An older, darker terrain and a lighter, younger terrain. The cause of the lighter terrain’s geology is not fully known. It is also the only satellite in the Solar System to possess a magnetosphere. The 1 st 2 probes to examine Ganymede were Pioneer 10 and 11.