Weird Water That’s Both Liquid and Solid Reveals Lopsided Magnetic Fields of Neptune and Uranus
Scientists have confirmed the existence of superionic ice water—water that occupies a simultaneously liquid and solid state. Though it doesn’t exist anywhere on Earth as far as we know, it’s possible that it might exist on Uranus and Neptune, according to The New York Times. It might finally help us understand why those planets’ magnetic fields are so crooked.
Structurally, superionic ice water (or superionic ice or superionic water—the choice is pretty much yours) is composed of hydrogen atoms moving around inside a solid, unyielding lattice of oxygen atoms. (Think of a crisscrossing shape kind of like a rose trellis.)
Under what we perceive as normal circumstances, liquid water comprises a V-shape of two hydrogen atoms bonded to one oxygen atom, and expands when it freezes from a liquid state into a solid one. But researchers from the Lawrence Livermore National Laboratory and the Department of Earth and Planetary Science at the University of California, Berkeley, have now shown that in more extreme environments, like those found on Uranus and Neptune, intense heat could melt those bonds. This would let hydrogen ions pass through, but intense pressure would still hold the structure together—giving the water the characteristics of both solid and liquid matter. A paper describing the research was published in the scientific journal Nature.
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Now consider the role of Earth’s magnetic field. As viewed from space, Earth’s magnetic field lines connect straight from the North Pole all the way around to the South Pole. This is because our magnetic field is generated from the central point of the planet’s liquid ion core, giving it a balanced, nonlopsided geometry. But not all magnetic fields necessarily originate from a planet’s core.
In the 1980s, the two Voyager spacecraft were sent to study outer planets, including Neptune and Uranus, and discovered that the geometry of the magnetic fields on those planets was different from our own. Instead of being generated from the core, they appeared to be generated from the planets’ outermost layer, the mantle.
“Because our field is created right at the center, our planet’s geometry is dipolar, so with two poles, aligned with the rotation of the planet,” corresponding author Marius Millot, a physicist at the Lawrence Livermore National Laboratory, told Newsweek. “But with these [other planets], the geometry is more complex; it’s not dipolar, so it’s not aligned with their rotation.”
The presence of superionic water could explain that crooked alignment. Neptune and Uranus could have thin exterior shells of liquid water and thick interior mantles of superionic ice water. Since superionic ice water isn’t a metal, it’s not a great conductor—but it’s still a conductor. It would mean the currents on those planets are carried by ions with positive charges rather than electrons with negative charges, which is what we’re used to seeing with our own magnetic field here on Earth. This would account for their strange geometry—verifying the data gathered by the Voyager missions 30 years ago.