We silly humans tend to think of rain just in our own terms, the falling water tainted with various toxins that draws out our umbrellas and cancels our baseball games. But across the solar system, it rains on other worlds with thick atmospheres–it’s just not rain we would recognize. On Saturn’s moon Titan, for instance, it rains methane. And now, a group of scientists says in Physical Review Letters, computer simulations have confirmed that it rains helium on Jupiter.

The term “rain” applies loosely here, because the hellfire precipitation happening on Jupiter isn’t much like a pleasant afternoon shower here on Earth. Droplets of helium form thousands of miles below the tops of hydrogen clouds, at temperatures around 9,000 degrees Fahrenheit–the helium stays in fluid form because of the planet’s high atmospheric pressure. Pressures and temperatures on Jupiter are so high that the droplets of liquid helium are falling through a fluid of metallic hydrogen [Space.com].

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Krypton and xenon make up trace amounts of the Earth’s atmosphere—about one part per million for the former, and even less for the latter. But these minor components could have a major impact in scientists’ understanding of how the atmosphere came to be. According to findings published in Science, many of the atmosphere’s gases that you’re breathing right now might have come from outer space rather than inside the Earth, as previously thought.

Researchers believed that when the Earth congealed from the gas and dust cloud that formed the solar system, some gases got trapped in the planet’s mantle. Then, over hundreds of millions of years, volcanic eruptions returned the gases to Earth’s surface, where gravity kept them from drifting off into space. The mixing of these gases–along with the oxygen and other molecules added by life–created the atmosphere we have today [ScienceNOW Daily News]. That’s been the common wisdom, anyway.

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