More than a year after the New Horizons spacecraft has swept past Pluto in July 2015, fascinating news from the dwarf planet and its largest moon Charon continue to come out. Cameras have shown that the moon's north polar regions had a reddish color.
A new study has revealed that when Pluto releases its colorless methane gas, the smoke is absorbed by the gravity of the moon. The molecules, which envelope the lunar atmosphere, are known as tholins.
Because Pluto is so small and has so little gravity, the dwarf planet loses a lot of its atmosphere to space. It is presumed that Charon, which is locked in Pluto's orbit, catches some of the matters from that atmosphere. It is also probable that the moon's chilly polar regions can prevent the gas from immediately escaping. During spring, the sun rays can also add color to the moon.
The atmospheric transfer is further reinforced by conditions happening in Charon. When Pluto and its largest moon orbit the sun for 248 years, Charon's poles go through century-long periods of total sunlight and absolute darkness. In a pitch-black, 100-year winter, Charon has a temperature of minus 430 degrees Fahrenheit. At this figure, methane freezes solid.
Planetary scientist and the study's lead author Will Grundy said that the development supports the idea that Pluto and Charon are a double planet. Although most moons in the solar system are smaller than their planets, Charon is almost the same size as Pluto. The size proximity allows an exchange in surface materials. It is probable that if the large moon is not orbiting around Pluto, Charon can be seen as a separate heavenly entity. The finding is particularly notable since the largest moon had been previously thought to be gray.
New Horizons' principal scientist and the study's co-author Alan Stern has stated that similar things can be happening elsewhere. The mystery found in Charon paves way towards possibilities in a faraway twilight zone known as Kuiper Belt.
The study has also noted that Pluto's small moon Nix had a spot covered in red. Since it orbits away from Pluto, the amount of color is minimal.
