Citizen scientists change our view of Jupiter’s clouds

A study combining data from amateur and professional astronomers has stunned scientists by revealing that Jupiter’s clouds are not what we thought.

It was previously believed that Jupiter’s clouds were made of ammonia ice. The new research, published in the Journal of Geophysical Research, suggests that they may actually be composed of ammonium hydrosulphide and smog.

The team used data from the Multi Unit Spectroscopic Explorer (MUSE) instrument at the European Southern Observatory’s Very Large Telescope in Chile. MUSE uses spectroscopic analysis to determine the compounds in gases on Jupiter from the wavelength of light emitted by them.

Computer simulations showed that the outer layer of clouds had to be deeper than previously thought. This means that they are in a region of higher pressure and temperature – too warm for pure ammonia ice to be present.

Previous MUSE observations had hinted at this result but used extremely complex methods which were difficult to corroborate.

The new research was based on a much simpler model. The researchers compared the brightnesses in adjacent, narrow-coloured filters getting the same results as the more complex approach. And the new method can be done using a backyard telescope.

“I am astonished that such a simple method is able to probe so deep in the atmosphere and demonstrate so clearly that the main clouds cannot be pure ammonia ice!” says lead researcher Patrick Irwin from the University of Oxford, UK.

“These results show that an innovative amateur using a modern camera and special filters can open a new window on Jupiter’s atmosphere and contribute to understanding the nature of Jupiter’s long-mysterious clouds and how the atmosphere circulates.”

“I always like to push my observations to see what physical measurements I can make with modest, commercial equipment,” says co-author Steven Hill who is an amateur astronomer with a PhD in astrophysics and works in space weather forecasting.

“The hope is that I can find new ways for amateurs to make useful contributions to professional work. But I certainly did not expect an outcome as productive as this project has been!”