Tag: Neptune

Newly Discovered Form Of Water Ice Is ‘Really Strange’

Scientists believe that superionic water might be found in the mantles of Neptune, pictured, or Uranus, and could explain the lopsided magnetic fields of these planets.

Scientists have created a “strange” new form of water that behaves like a cross between a liquid and a solid.

The substance, known as “superionic water ice”, is thought to be a key component in the structure of distant planets in our solar system.

Researchers had predicted the existence of such a substance as far back as 1988, and while numerical simulations appeared to prove its existence, these are the first experiments to confirm those findings.

These are very challenging experiments, so it was really exciting to see that we could learn so much from the data,” said Dr Marius Millot, a physicist at Lawrence Livermore National Laboratory in California, who led the study.

“Especially since we spent about two years making the measurements and two more years developing the methods to analyse the data.”




The scientists used a technique called “laser-driven shock compression” to not only confirm the existence of the substance, but also verify predictions about the composition of planets like Neptune and Uranus.

Our work provides experimental evidence for superionic ice and shows that these predictions were not due to artefacts in the simulations, but actually captured the extraordinary behaviour of water at those conditions,” said Dr Millot.

While normal ice consists of water molecules linked up to form a solid, superionic water ice is made up of ions – atoms that carry positive or negative charges.

Specifically, its structure consists of hydrogen ions flowing through a solid crystal made from oxygen ions.

Unlike conventional ice, the superionic variety requires incredibly high temperatures to form, as well as high pressures.

The research team achieved this by crushing ice between two diamonds, before firing a laser at it to further increase the pressure and heat.

Laser-driven shock compression experiment to recreate planetary interior conditions and study the properties of superionic water ice (M Millot/E Kowaluk/J Wickboldt/LLNL/LLE/NIF)

At nearly 5,000C and two times atmospheric pressure, the scientists saw evidence a superionic water ice had formed and then melted. In total, the whole experiment only took between 10 and 20 nanoseconds.

The next step, according to the scientists, is to determine the structure of the oxygen crystals found in superionic water ice.

Though superionic water ice is not found anywhere on Earth, it may be present in large quantities inside Uranus and Neptune, where the high temperatures and pressures are similar to those created by Dr Millot and his team in their experiments.

Some scientists have suggested the presence of this matter inside these distant planets may explain their unusual magnetic fields.

Magnetic fields provide crucial information about the interiors and evolution of planets, so it is gratifying that our experiments can test – and in fact, support – the thin-dynamo idea that had been proposed for explaining the truly strange magnetic fields of Uranus and Neptune,” said Professor Raymond Jeanloz, a co-author of the paper based at the University of California, Berkeley.

It’s also mind-boggling that frozen water ice is present at thousands of degrees inside these planets, but that’s what the experiments show.”

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Pass it on: New Scientist

Neptune’s Moon: Triton

We don’t know with what beverage William Lassell may have celebrated his discovery of Neptune’s moon, Triton, but beer made it possible.

Lassell was one of 19th century England’s grand amateur astronomers, using the fortune he made in the brewery business to finance his telescopes.

He spotted Triton on 10 October 1846 — just 17 days after a Berlin observatory discovered Neptune.

Curiously, a week before he found the satellite, Lassell thought he saw a ring around the planet. That turned out to be a distortion caused by his telescope.

But when NASA’s Voyager 2 visited Neptune in 1989, it revealed that the gas giant does have rings, though they’re far too faint for Lassell to have seen them.

Since Neptune was named for the Roman god of the sea, its moons were named for various lesser sea gods and nymphs in Greek mythology.




Triton (not to be confused with Saturn’s moon, Titan), is far and away the largest of Neptune’s satellites. Dutch-American astronomer Gerard Kuiper (for whom the Kuiper Belt was named) found Neptune’s third-largest moon, Nereid, in 1949.

He missed Proteus, the second-largest, because it’s too dark and too close to Neptune for telescopes of that era.

Proteus is a slightly non-spherical moon, and it is thought to be right at the limit of how massive an object can be before its gravity pulls it into a sphere.

Proteus and five other moons had to wait for Voyager 2 to make themselves known. All six are among the darker objects found in the solar system.

Astronomers using improved ground-based telescopes found more satellites in 2002 and 2003, bringing the known total to 13.

Voyager 2 revealed fascinating details about Triton. Part of its surface resembles the rind of a cantaloupe.

Ice volcanoes spout what is probably a mixture of liquid nitrogen, methane and dust, which instantly freezes and then snows back down to the surface.

One Voyager 2 image shows a frosty plume shooting 8 km (5 miles) into the sky and drifting 140 km (87 miles) downwind.

Triton’s icy surface reflects so much of what little sunlight reaches it that the moon is one of the coldest objects in the solar system, about -400 degrees Fahrenheit (-240 degrees Celsius).

Triton is the only large moon in the solar system that circles its planet in a direction opposite to the planet’s rotation (a retrograde orbit), which suggests that it may once have been an independent object that Neptune captured.

The disruptive effect this would have had on other satellites could help to explain why Nereid has the most eccentric orbit of any known moon it’s almost seven times as far from Neptune at one end of its orbit as at the other end.

Neptune’s gravity acts as a drag on the counter-orbiting Triton, slowing it down and making it drop closer and closer to the planet.

Millions of years from now, Triton will come close enough for gravitational forces to break it apart possibly forming a ring around Neptune bright enough for Lassell to have seen with his telescope.

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Pass it on: New Scientist

Diamonds Probably Don’t Crystallize In The Atmosphere Of Uranus

A new study finds that diamonds probably don’t crystallize in the atmospheres of planets such as Uranus and Neptune.

The conclusion is contrary to recent speculation that small diamonds would spontaneously form in carbon rich layers of the gas giant planets. White dwarf stars, according to the study, are veritable diamond factories.

Physicists at the Universtiet van Amsterdam and the FOM Institute for Atomic and Molecular Physics in the Netherlands performed a numerical analysis showing that at the temperatures and pressures in gas giant planets like Uranus.

Arrangements of carbon atoms would be much more suitable for creating tiny bits of graphite rather than diamond.




In white dwarfs, on the other hand, the simulation shows that the conditions would cause the carbon atoms to line up in configurations that are much more amenable for diamond crystallization.

The conclusion is consistent with the 2004 discovery of a cooling white dwarf star that appears to have a solid diamond core 4000 kilometers across.

Although diamond formation in the atmospheres of gas giants is not strictly impossible, the Dutch physicists say that the odds are exceedingly slim that a diamond could have formed under the conditions that exist in Uranus in the entire lifetime of the universe.

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Pass it on: Popular Science