APS: Helium rain on Jupiter

[bystander]

Helium rain on Jupiter
American Physical Society via EurekAlert! - 2010 March 22

New research suggests that helium rain could be washing neon out of Jupiter's upper atmosphere.

When NASA's Galileo probe reached Jupiter in 1995 and began sending back data about the gas giant, astronomers were in for a surprise: Jupiter was unusually poor in helium and neon, the two lightest noble gases. New simulations of the physics inside the planet reveal why. The results, which provide a glimpse into Jupiter's turbulent innards, are reported in the current issue of Physical Review Letters and highlighted with a Viewpoint by Jonathan Fortney (University of California, Santa Cruz) in the March 22 issue of Physics (http://physics.aps.org).

Viewpoint: Peering into Jupiter

• Physics 3, 26 (2010) DOI: 10.1103/Physics.3.26 (2010 March 22)

Ab initio simulations account for the peculiar abundance characteristics of noble gases in Jupiter

Sequestration of Noble Gases in Giant Planet Interiors

• Physical Review Letters 104, 121101 (2010) DOI: 10.1103/PhysRevLett.104.121101 (2010 March 22)

The Galileo probe showed that Jupiter’s atmosphere is severely depleted in neon compared to protosolar values. We show via ab initio simulations of the partitioning of neon between hydrogen-helium phases that the observed depletion can be explained by the sequestration of neon into helium-rich droplets within the postulated hydrogen-helium immiscibility layer of the planets interior. We also demonstrate that this mechanism will not affect argon explaining the observed lack of depletion of this gas. This provides strong indirect evidence for hydrogen-helium immiscibility in Jupiter.

[bystander]

Helium rain on Jupiter explains lack of neon in atmosphere
UC Berkeley News - 2010 March 22

On Earth, helium is a gas used to float balloons, as in the movie "Up."

In the interior of Jupiter, however, conditions are so strange that, according to predictions by University of California, Berkeley, scientists, helium condenses into droplets and falls like rain.

Helium rain was earlier proposed to explain the excessive brightness of Saturn, a gas giant like Jupiter, but one-third the mass.

On Jupiter, however, UC Berkeley scientists claim that helium rain is the best way to explain the scarcity of neon in the outer layers of the planet, the solar system's largest. 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.