In 1995 the Galileo mission meet the biggest planet of the Solar System, Jupiter, to study it after Pioneer and Voyager probes in the ‘80s. At that time Galileo, among the various measurement it made, discovered that the atmosphere of Jupiter was very shoal, with a very low quantity of water measured into it. Even if the presence of lightning suggested that the water was present, this low value surprised the scientists. Another factor was surprising too: while the Galileo probe was descending in the atmosphere, measured more and more water as it went down, until the loss of the signal (the probe was in self-destruction mode, ending the mission). This specified that Jupiter atmosphere was not well-mixed, giving an incomplete situation of the environment.

After first publications based on Juno measurement, scientists have discovered that the quantity of water present on Jupiter is much greater as Galileo probe found! Almost 3 times higher than the Sun: obviously, not liquid water, but the molecules that made it (oxygen and hydrogen).Probably Galileo probe took his measurement in a particularly shoal point: it was wrong, but because of bad luck! It can happen. In the next months surely we will know more and more about it, as the data coming from Juno will be analyzed.

This teaches us that Jupiter, and among all our entire Solar System, has always something hidden to show us and to allow us to improve our knowledge.