Helium rain explains scarcity of neon in Jupiter's atmosphere

Washington, March 23 (ANI): In a new research, scientists at the UC (University of California) Berkeley, US, have suggested that helium rain is the best way to explain the scarcity of neon in the outer layers of Jupiter.

Neon dissolves in the helium raindrops and falls towards the deeper interior where it re-dissolves, depleting the upper layers of both elements, consistent with observations.

"Helium condenses initially as a mist in the upper layer, like a cloud, and as the droplets get larger, they fall toward the deeper interior," said UC Berkeley post-doctoral fellow Hugh Wilson, co-author of the research paper.

"Neon dissolves in the helium and falls with it. So, our study links the observed missing neon in the atmosphere to another proposed process, helium rain," he added.

Wilson's co-author, Burkhard Militzer, UC Berkeley assistant professor of earth and planetary science and of astronomy, noted that "rain" - the water droplets that fall on Earth - is an imperfect analogy to what happens in Jupiter's atmosphere.

The helium droplets form about 10,000 to 13,000 kilometers (6,000-8,000 miles) below the tops of Jupiter's hydrogen clouds, under pressures and temperatures so high that "you can't tell if hydrogen and helium are a gas or a liquid," he said.

They're all fluids, so the rain is really droplets of fluid helium mixed with neon falling through a fluid of metallic hydrogen.

The two modelers embarked on their current research because of a discovery by the Galileo probe that descended through Jupiter's atmosphere in 1995 and sent back measurements of temperature, pressure and elemental abundances until it was crushed under the weight of the atmosphere.

All elements seemed to be as slightly enriched compared to the abundance on the sun, which is assumed to be similar to the elemental abundances 4.56 billion years ago when the solar system formed, except for helium and neon.

Neon stood out because it was one-tenth as abundant as it is in the sun.

Their simulations showed that the only way neon could be removed from the upper atmosphere is to have it fall out with helium, since neon and helium mix easily, like alcohol and water.

Militzer and Wilson's calculations suggest that at about 10,000 to 13,000 kilometers into the planet, where the temperature about 5,000 degrees Celsius and the pressure is 1 to 2 million times the atmospheric pressure on Earth, hydrogen turns into a conductive metal.

Helium, not yet a metal, does not mix with metallic hydrogen, so it forms drops, like drops of oil in water.

This provided an explanation for the removal of neon from the upper atmosphere. (ANI)