If you mean the black markings, they are called maria (mar-e-a), which means "sea" in Latin. In old times the ancient Romans thought that the maria were oceans on the moon. We now know that the black...
The four largest moons that orbit Jupiter are Io, Europa, Ganymede, and Callisto. These four moons are known as the Galilean Moons, because they were the first moons discovered around Jupiter by...