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Space

Physicists Find New Evidence For Helium 'Rain' On Saturn (sciencemag.org) 27

sciencehabit writes: Using one of the world's most powerful lasers, physicists have found experimental evidence for Saturn's helium 'rain,' a phenomenon in which a mixture of liquid hydrogen and helium separates like oil and water, sending droplets of helium deep in the planet's atmosphere. The results show the range of blistering temperatures and crushing pressures at which this takes place. But they also suggest that a helium rain could also fall on Jupiter, where such behavior was almost completely unexpected.
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Physicists Find New Evidence For Helium 'Rain' On Saturn

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  • by Anonymous Coward

    Millot says it took about 5 years and 300 laser shots to sketch out the phase transition across temperatures between 3000 and 20,000 kelvins and pressures between 30 and 300 gigapascals.

    That's not what I expected when I read about "rain" - the helium "rain" apparently falls through an "atmosphere" of metallic hydrogen.

    • by mikael ( 484 )

      Sounds more like a giant spherical lava lamp made from liquid helium and hydrogen. A solid core of liquid hydrogen at the core with a outer shell of liquid helium with all sorts of bubbling and rain in a turbulence layer.

      It would be like those science fair experiments that involve mixing colored liquids of different densities. Over time they separate out, but heating and shaking mix them up. Imagine doing that experiment in zero gravity. Instead of having a cylindrical tank of of colored layers, you would h

    • by Rei ( 128717 ) on Saturday December 19, 2015 @04:34PM (#51151145) Homepage

      It would have to be far, far colder to support liquid helium at normal atmospheric pressures.

      An interesting possibility that I've pondered is that if you have a very distant body (no relevant stellar heat input), small enough to not have relevant internal heat, which is losing helium to a tidally locked partner, it would be experiencing evaporative cooling to below the cosmic microwave background... to the point that the helium becomes a superfluid. My calculations show that you don't need some sort of extreme helium loss rate because radiative heat exhange with the cosmic microwave background is so incredibly slow. That would be an incredibly bizarre world to see...

      Further in the future, the cosmic microwave background will drop below helium's triple point, and superfluid He4 will become common in the universe :)

      • Especially since superfluids are totally bizzare. People should hit youtube and search for superfluids, I bet they'd find some really weird stuff. (Like a tubular fountain of liquid that never stops, liquids crawling up the sides of the container, and even liquids that appear to be leaking out the bottom of a glass.)
      • by Rei ( 128717 )

        ** that should read "lambda point", not "triple point"; of course :)

      • It would have to be far, far colder to support liquid helium at normal atmospheric pressures.

        In fact, these Ts & Ps would put the helium far into the supercritical realm. At which point the distinction between liquid and gas is a bit irrelevant.

  • by Nkwe ( 604125 ) on Saturday December 19, 2015 @01:20PM (#51150423)
    Somewhere in the back of my head I am hearing the song Helium Rain begin sung to the tune of Purple Rain, but after taking a bit hit on a helium balloon.
    • Don't bogart the balloon, dude!

  • by mark_reh ( 2015546 ) on Saturday December 19, 2015 @02:12PM (#51150635) Journal

    I want to get funded to build a rocket to go there and scoop up helium and bring it back to earth to fill party balloons!
    Contribute $5 and you'll get a helium filled balloon. For bigger contributions you can go all the way up to a Macy's parade style balloon, with the very top tier of rewards for BIG contributors reserved for people to ride along on the trip to Saturn.

  • That's so cool. Like, -450 F.

    • That's so cool. Like, -450 F.

      Nope. Even the surface of Saturn is about 120K, which is far warmer than -450F. But this "rain" is happening deep within Saturn where the temperature is several thousand K, hot enough to melt iron.

      • hot enough to vapourise iron.

        FTFY Well, actually, at these Ts and Ps, and particularly with a low partial pressure of metals (astronomer sense : anything that is not hydrogen or helium), a dilute solution of supercritical iron vapour in supercritical hydrogen-helium vapour. But that's probably what makes it hard to calculate - working out the equation of state for the phase change at those Ts and Ps.

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