By looking from two ground-based telescopes at wavelengths sensitive to thermal radiation leaking from the depths of Jupiter’s mysterious, roiling storm called the Great Red Spot, a NASA-led team of astronomers and astrophysicists detected the chemical signatures of water. The pressure of the water, combined with the measurements of carbon monoxide, imply that Jupiter has two to nine times more oxygen than the Sun. This finding supports theoretical and computer-simulation models that have predicted abundant water on Jupiter made of oxygen tied up with molecular hydrogen.

“Jupiter is a gas giant that contains more than twice the mass of all of our other planets combined,” said co-author Dr. Máté Ádámkovics, from the College of Science at Clemson University.

“And though 99% of Jupiter’s atmosphere is composed of hydrogen and helium, even solar fractions of water on a planet this massive would add up to a lot of water — many times more water than we have here on Earth.”

“The moons that orbit Jupiter are mostly water ice, so the whole neighborhood has plenty of water,” said lead author Dr. Gordon Bjoraker, an astrophysicist at NASA’s Goddard Space Flight Center.

“Why wouldn’t the planet — which is this huge gravity well, where everything falls into it — be water rich, too?”

Dr. Bjoraker, Dr. Ádámkovics and co-authors searched for water in the Great Red Spot by using radiation data collected by: the iSHELL spectrograph on NASA’s Infrared Telescope Facility and the Near Infrared Spectograph on the Keck II Telescope, both of which are located on the remote summit of Maunakea in Hawaii.

The researchers found evidence of three cloud layers in the Great Red Spot, with the deepest cloud layer at 5-7 bars (a metric unit of pressure that approximates the average atmospheric pressure on Earth at sea level). Altitude on Jupiter is measured in bars because the planet doesn’t have an Earth-like surface from which to measure elevation.

At about 5-7 bars — or about 100 miles (161 km) below the cloud tops — is where they believed the temperature would reach the freezing point for water.

The deepest of the three cloud layers identified by the team was believed to be composed of frozen water.

“The discovery of water on Jupiter using our technique is important in many ways,”

“Our current study focused on the Great Red Spot, but future projects will be able to estimate how much water exists on the entire planet,” Dr. Ádámkovics said.

“Water may play a critical role in Jupiter’s dynamic weather patterns, so this will help advance our understanding of what makes the planet’s atmosphere so turbulent. And, finally, where there’s the potential for liquid water, the possibility of life cannot be completely ruled out. So, though it appears very unlikely, life on Jupiter is not beyond the range of our imaginations.”

The discovery is reported in the Astronomical Journal.

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G.L. Bjoraker et al. 2018. The Gas Composition and Deep Cloud Structure of Jupiter’s Great Red Spot. AJ 156, 101; doi: 10.3847/1538-3881/aad186