Where did Pluto get its red spot from? – Wikipedia

The correctness of the saying “all cats are gray at night” can be confirmed by astronomers, especially when studying the celestial bodies of the outer solar system. They are all much happier when they discover that the places they crave are more colorful than they thought.

When American astronomer James W. Christie accidentally discovered Charon, the largest moon of the dwarf planet Pluto, in 1978, all he saw in the image was a gray bump on the edge of a hazy patch of light. Not even the NASA spacecraft new Horizons When flying by Charon in 2015 at a distance of about 30,000 km, astronomers discovered an elegant red spot in the North Pole, which is slightly weaker but visually comparable to a red spot that Jupiter also has. However, Charon’s cute sign has an entirely different reason.

Scientists soon speculated that the stain might be tholin-like material. Then, a red-brown mixture of hydrocarbons would cover a lowland nearly 500 km wide in the Arctic – astronomers informally named Mordor Makula, after the dark world in JRR Tolkien’s book The Lord of the Rings.

True, this assumption has not yet been directly proven. Charon and Pluto are currently about five billion kilometers away from us and new Horizons He was the only visitor so far. However, in two related studies, scientists have now experimentally re-modeled and conceptually modeled Charon’s atmospheric conditions. “Until now, no one has been able to directly detect the composition of such tholins,” says Ujwal Raut of the Southwest Research Institute in Texas, who was lead author and co-author on both studies. “However, our experiments strongly suggest that complex hydrocarbons can form from methane ice via active processes.”

The methane required does not come from Charon, but from neighboring Pluto. The Moon, which has a measurement of 2,300 km, and its main body, which is only twice its size, form a system that orbits each other at a distance of less than 20,000 km. So Charon continues to fly through a cloud of methane ejected by Pluto. The study authors said that Charon’s gravity traps many gas molecules, which then bounce across its surface until they are detected in the extreme cold of the polar lowlands. Since the Charon-Pluto system takes 248 years to complete one orbit around the Sun and also tilts sharply outside the orbital plane, Charon, like Earth, has distinct seasons. Thus, temperatures in the deep cold traps could drop as low as minus 260 degrees Celsius during the 124-year Winter of Sharon. Hence, even the escaped methane settles there as ice until it melts in the early spring of Sharon and continues its journey across the surface until the following winter.

However, a small portion of the methane ice is optically broken down by UV rays and converted into other materials, primarily into slightly larger and longer-lived ethane molecules. However – even ethane ice is transparent. “Photolysis of methane alone can’t explain the red colour,” says Raut. “Therefore, the solar wind must also process the ethane to produce longer reddish hydrocarbons. But we haven’t yet discovered exactly what these molecules are.”

These planetary gas transfers are unique in the solar system, says Raut, because no other planetary orb comes close to Pluto and Charon. Ice processes at the poles cannot be compared to those on Earth or Mars either. “We estimate that about 80 individual layers of light products accumulate at the poles in a Pluto year,” says Raut. “Over millions of years, these will likely grow to several micrometers in thickness.” For comparison: aluminum foil is about 15 microns thick.

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