what’s with the color? Launched in 2006, NASA’s New Horizons interplanetary space probe got its first glimpse. The dwarf planetary system of Pluto and Charon looked like never before. There appeared Pluto’s moon with a red north pole. Why is it like that?
Randy Gladstone is a planetary scientist at the Southwest Research Institute in the United States. He says, “It’s an unusual feature. Charon has a striking red layer centered on its north pole.”
Tolinas at the poles
Red is a usual color on iron-rich worlds like ours, or like Mars. But in the icy suburbs of the solar system, it could mean something else. It’s about tar-like compounds called tolines. A reddish-brown jumble of chemicals.
On Pluto, methane would be a likely starting point. To become tolins, these hydrocarbons would have to absorb a very specific color of UV light. Pluto’s pinkish glow has been the subject of study for decades. The New Horizons probe revealed the precise pattern of toluene on its surface in high definition. The finding of an oxidized dye in the cap of its moon was an intriguing surprise.
It was assumed that methane shed from Pluto might reach its orbiting moon. But there is another theory. Charon’s weak gravity plays a role. When the distant sunlight heats up, it melts the methane frost. It rises again from the surface.
Warming of the north pole would take place over several years. A blanket of frost evaporates at one pole while at the other pole it would begin to freeze.
“We believe that ionizing radiation from the solar wind breaks down polar frost. It synthesizes increasingly complex and redder materials responsible for the unique albedo of this enigmatic moon.” says the scientist.
This research was published in Science y Geophysical Research Letters.