Jupiter looked at as aliens would see it

Washington: Astronomers have observed Jupiter for centuries but a new study that looks at the gas giant as if it was an exoplanet could help make more reliable interpretations of Jupiter. The results largely confirm the conventional picture of Jupiter but also reveal some surprises, including clouds of ice crystals previously unheard of the planet, the scientific journal Nature reported.

Astrophysicist Pilar Montanes-Rodriguez at the Astrophysics Institute of the Canary Islands in Tenerife, Spain and colleagues has devised a way to apply the idea to studying Jupiter. The technique used for exoplanet atmospheres does not immediately translate to Jupiter because its orbit never takes it between the Earth and the Sun.

Instead of looking directly at sunlight filtered through Jupiter's atmosphere, the team analysed light reflected back from the Jovian moon Ganymede when Jupiter passed between it and the Sun. By examining the data, the team built up a picture of the chemical make-up of the Jovian atmosphere. That spectrum shows that Jupiter is a methane-rich planet wrapped in a layer of cloud that scatters light and makes it harder to see more detailed composition.

"The findings should boost astronomers' confidence that similar hazes found on many of the exoplanets whose atmospheres have been studied so far are real and not due to a confounding effect, such as activity on the parent star," explained co-author Enric Palle from the Astrophysics Institute of the Canary Islands. "These clouds often obscure other elements and dissecting the results on Jupiter could help astronomers to tease more out of existing spectra," Palle added.