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Jupiter contains more water than previously thought, according to data from NASA鈥檚 Juno spacecraft, which could help us understand how the planet formed in the first place.

We have been confused about Jupiter鈥檚 water for some time. In 1996, NASA鈥檚 Galileo probe found that the planet鈥檚 water levels, and thus oxygen levels, were a lot lower than expected, contradicting theories about how the solar system formed.

We think that the solar system was created when a gigantic ball of gas collapsed, forming the sun and a disc of material around it. As the disc cooled, the parts closest to the sun formed the rocky planets, while those further away condensed and made large ice clumps. These clumps pulled in hydrogen to form the gas giants, of which Jupiter is the largest.

The Galileo findings contradicted this theory, because it predicts higher levels of oxygen present on Jupiter today than those measured by the probe. Now new information from Juno, which is currently in orbit around Jupiter, suggests that there is 2.7 times more oxygen per kilogram of the gassy planet than there is in the sun. That is far more than Galileo found, potentially solving the contradiction.

Cheng Li at the California Institute of Technology and his colleagues, who conducted the research, think that perhaps Galileo didn鈥檛 go deep enough into Jupiter鈥檚 atmosphere. Juno measured the water levels at the equator, but will now look at different parts of Jupiter and confirm that these findings are true for the entire planet.

鈥淚f we know how much water was incorporated into the forming giant planets, we鈥檇 have a window on the deep past of the solar system,鈥� says Leigh Fletcher at the University of Leicester, UK. 鈥淚 think this new measurement will spark a flurry of activity from planet formation modellers and I can鈥檛 wait for the era when we have comparable measurements for the other giant worlds of our solar system.鈥�