In a laboratory chamber, a group of Dutch researchers reproduced the conditions reported in Pluto's atmosphere, then bombarded it with plasma to simulate space radiation.
According to New Scientist, their mission was to look into a curious phenomenon on the dwarf planet's surface initially seen by NASA's New Horizons probe in 2015. The largest, dubbed the Cthulhu Macula for its menacing nature, is a drawn-out dark region near the dwarf planet's equator.
The reddish blotches, according to scientists, are caused by tholins. These are organic molecules formed in the atmosphere when ultraviolet or cosmic radiation heats carbon, methane, and carbon dioxide-containing compounds, which eventually precipitate onto the planet's surface. The blobs seen by New Horizons are thought to be caused by the radiation turning these compounds into a dark and murky red.
IN SPACE - JULY 14: In this handout provided by the National Aeronautics and Space Administration (NASA), Pluto nearly fills the frame in this image from the Long Range Reconnaissance Imager (LORRI) aboard NASA's New Horizons spacecraft, taken on July 13, 2015, when the spacecraft was 476,000 miles (768,000 kilometers) from the surface. This is the last and most detailed image sent to Earth before the spacecraft's closest approach to Pluto. New Horizons spacecraft is nearing its July 14 fly-by when it will close to a distance of about 7,800 miles (12,500 kilometers). The 1,050-pound piano-sized probe, which was launched January 19, 2006, aboard an Atlas V rocket from Cape Canaveral, Florida, travels 30,800 mph as it approaches.
However, it is still unclear how these patches came to be. While comets may have strewn tholins onto Pluto's surface, light or high-energy radiation may have chemically reacted with the dwarf planet's surface to produce these compounds. Both of these actions would have darkened Pluto's surface. However, the existence of brilliant water-ice bedrock observed there contradicts this.
The Delft University of Technology researchers found it impossible to recreate the reddish hues of the Cthulhu Macula region using the chemical composition observed by New Horizons.
Experts published their study, titled "Testing Tholins as Analogues of the Dark Reddish Material Covering Pluto's Cthulhu Region," in the journal Icarus.
Did Pluto's Weird Red Spots Result From Crash That Spawned Charon?
A separate team of researchers suggests that Pluto's equator's mysterious dark reddish streaks may result from the enormous collision that helped construct the dwarf planet's largest moon Charon.
Astronomers claim this discovery could help explain the surprisingly wide array of hues seen in faraway objects in the solar system's Kuiper belt.
The dark reddish material seen in vast areas around Pluto's equator, which NASA's New Horizons probe captured during its July 2015 approach, is one of the most stunning aspects of the dwarf planet. The region informally known as Cthulhu (pronounced "k-thu-lu"), which spans nearly halfway around Pluto's equator, is the most prominent example of these patches.
Space.com said Cthulhu, named after the mythical monster deity from H. P. Lovecraft's works, is around 1,850 miles (3,000 kilometers) long and 450 miles (750 kilometers) wide. It is larger than Alaska, with a surface area of more than 700,000 square miles (1.8 million square kilometers).
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Japanese researchers believe that the enormous collision that gave birth to Charon generated this dark reddish material. Charon allegedly emerged from the debris of a Mars-sized body colliding with the newborn Earth. It was similar to how Earth's moon likely arose from the debris of a Mars-sized body colliding with the newborn Earth.
According to the scientists, Pluto and whatever hit it likely contained simple organic chemicals present in comets, such as formaldehyde. They further speculated that these molecules might have found their way into temporary pools of heated liquid water formed after the impact melted a large portion of Pluto's surface.
Researchers published their study, "The Charon-Forming Giant Impact as a Source of Pluto's Dark Equatorial Regions," in the journal Nature Astronomy.
Recreating Tholins
Meanwhile, the Delft University of Technology researchers did not rule out the possibility that tholins are to blame for the red patches. Still, something else could be contributing to their development as well, as Science Alert explained.
The way tholins reflect light could be changing due to cosmic rays, or the planet's regions could be becoming more porous due to ice sublimation. According to the research, Pluto's weak gravity might alternatively be allowing the tholins to form a light coating of tholins, resulting in a porous crust, which is the team's "preferred hypothesis."
However, there are still many unanswered concerns about Pluto's massive red patches. While scientists have proposed a return mission to Pluto, NASA has stated that it does not intend to return to the dwarf planet anytime soon.
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