NASA’s New Horizons mission keeps revealing new surprises about Pluto.
The latest: The far-flung dwarf planet has blue skies and small patches of water ice on its surface.
“Who would have expected a blue sky in the Kuiper Belt?” Alan Stern, the mission’s principal investigator, said in a written statement, referring to the belt of small bodies beyond the orbit of Neptune. “It’s gorgeous.”
On Earth, blue skies are the result of the scattering of sunlight by gas molecules in the atmosphere. Things are a bit different on Pluto. There, sunlight is scattered not by molecules but by a haze of soot-like particles called tholins, which are created as a result of chemical reactions involving methane and nitrogen high above Pluto.
Another difference is that while Earth’s sky looks blue to us most of the time, that doesn’t seem to be the case on Pluto. If you stood on Pluto and looked straight up, the sky would actually appear black, the BBC reported.
“The haze is pretty thin, so you’d mostly see the color of the haze as blue sunrises and sunsets,” New Horizons team member Carly Howett told the BBC.
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The water ice was detected in several places on Pluto’s surface, including impact craters and valleys. And if you’re envisioning patches of whitish-bluish stuff like the ice seen in chilly spots on Earth, think again. Pluto’s water ice is a crimson color–perhaps as a result of ice-covered tholins that fall to the surface.
“I’m surprised that this water ice is so red,” Silvia Protopapa, a New Horizons science team member from the University of Maryland, College Park, said in the statement. “We don’t yet understand the relationship between water ice and the reddish tholin colorants on Pluto’s surface.”
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