Tag: Neptune

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