This means that Io is around 4.5 billion years old and was formed around the same time when Jupiter was born.ġ2. Age of Io: Io is just as old as Jupiter itself. So, to avoid being caught, Zeus turned Io into a cow. However, he was afraid that Hera would catch him with Io.

According to Greek mythology, Zeus fell in love with Io. Io was the daughter of Inachus, who was in turn, the King of Argos.ġ0. Io comes from Greek mythology where Io was the priestess of Hera – the wife of Zeus.

So, in the mid 1800’s the name of Jupiter I was changed to Io. The name he gave was used till the mid 1800’s when it became clear that using numbers as names will only create a lot of confusion.ĩ. Nonetheless, coming back to Io, Galileo actually named the Jovian moon as Jupiter I (because it was the first Jovian moon he discovered). Still, to this day, West refuses to give him the credit he deserves.Ĩ. His observations and studies are all recorded in his work ‘Aryabhatiya’ – an astronomical treatise. The truth however is that it was an ancient Indian mathematician-astronomer by the name Aryabhata (born 470 CE) who actually told that planets orbit the Sun and not the solar system orbiting Earth. It was his discovery of these moons that eventually led people to believe that planets orbit Sun and NOT the solar system orbiting Earth. Discovery of Io, Europa, Callisto and Ganymede was the first ever discovery of any moon orbiting any other planet but Earth. Hence, it is said that the discovery was done on 8th January.ĥ. Things became clear to him on the next night, that is, 8th January. However, that night, Galileo failed to distinguish between Europa and Io. Actually, Io was not discovered on January 8. However, if we are to arrange the four Galilean moons in order of distance from Jupiter, Io takes the 1st spot.Ĥ. If we are to arrange all 67 moons of Jupiter in order of distance from Jupiter, Io takes the 5th spot. If we are to compare the volume and mass of the four Galilean moons of Jupiter, they ranking they get is:ģ. The other three moons that were discovered by Galileo are:Ģ. It was one of the four Jovian moons that were discovered by Galileo and hence, it is often referred to as the Galilean Moon of Jupiter. It is going to be one hell of a read… Io Facts: 1-5ġ. In this article on Io facts, we are going to share some of the most mind-blowing information about this interesting Jovian moon. It is one of the 67 moons of Jupiter and is quite an interesting object hanging out there in the void. Io – that’s perhaps the smallest name of any celestial object known to humans.

Fun facts about io moon