NASA: Charon's red spot comes from 'graffiti artist' Pluto

Pluto's moon Charon has a red spot, which NASA recently showcased in a high-resolution photo captured by New Horizons. That red spot, it turns out, is a bit of graffiti 'gifted' from Pluto itself; the stain is composed of an organic material dubbed tholins that originate from Pluto's methane gas. When the methane gas escapes Pluto's atmosphere, the space agency says, it ends up trapped by Charon's gravity and eventually freezes in place, finally converting into heavy hydrocarbons via exposure to the sun's ultraviolet rays.

The photo you see above is the post-processed result of images taken by NASA's New Horizons' spacecraft in July 2015. The final image shows the combined result of multiple images taken with infrared, blue, and red light, and the result was a bit of a mystery at first: that red discolored spot that resembles dirt from southwestern US states. The red spot is located at the top of the moon, and it has been named the "Mordor Macula" — unofficially, at least.

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According to NASA, this red spot's initial debut surprised researchers who then spent a year seeking an answer. A spot like this had never before been spotted in our solar system. Because of the way the gas escapes and eventually discolors the moon, the recently published study's author and New Horizon's co-investigator Will Grundy described it as "spray-painting."

Who would have thought that Pluto is a graffiti artist, spray-painting its companion with a reddish stain that covers an area the size of New Mexico? Every time we explore, we find surprises. Nature is amazingly inventive in using the basic laws of physics and chemistry to create spectacular landscapes.