It’s raining Helium – and some Neon!

When the Galileo mission released a probe into the atmosphere of Jupiter, they found a similar set up to the composition of the outer envelope of the Sun. Similar, but not identical. The amount of Helium and Neon was lower in the Jovian atmosphere than in the Sun. Since both the Sun and Jupiter sprang out of the same disc, this has led to some confusion, but a study has been released that may have the answer.

Dr Hugh Wilson and Assistant Professor Burkhard Militzer of the University of California, Berkeley spend their days modelling the interior of Jupiter. Their present model contains not only the familiar rocky core surrounded by highly dense metallic hydrogen, itself wrapped in an envelope of gaseous molecular hydrogen, but in the boundary between the two states of hydrogen, there is a thin layer of something else. Helium mist. Here, the pressure and temperature conditions are such that helium condenses out of the atmosphere like a form of rain. The droplets increase in size as they fall towards the oceans of hydrogen and enter them. Above this layer, the helium in the outer envelope tries to replace the stuff lost to the mist and the result is an outer envelope with less helium than otherwise would be the case. Furthermore, it has been calculated that neon could dissolve in these droplets and so be removed along with helium. The result is rather than seeing neon at a mass density of one part in six hundred, as in the Sun, neon is seen at one part in six thousand. In Saturn’s atmosphere, it is believed the condensation of helium leads to the release of enough latent heat of evaporation to warm the lower atmosphere. In Jupiter, there’s a similar energy balance need to fill. Warm shower anyone?

Image credit: Burkhard Militzer

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