NASA spacecraft finds blue skies, water ice on Pluto
In a major finding, the first colour images of Pluto’s atmospheric hazes beamed by NASA’s New Horizons spacecraft show that the icy-dwarf planet has blue skies similar to Earth and frozen water on its surface.
“Who would have expected a blue sky in the Kuiper Belt? It’s gorgeous,” said Alan Stern, New Horizons principal investigator from Southwest Research Institute (SwRI), Boulder, Colorado.
The haze particles themselves are likely grey or red, but the way they scatter blue light has gotten the attention of the New Horizons science team.”That striking blue tint tells us about the size and composition of the haze particles,” said science team researcher Carly Howett, also of SwRI.
“A blue sky often results from scattering of sunlight by very small particles. On Earth, those particles are very tiny nitrogen molecules. On Pluto they appear to be larger — but still relatively small — soot-like particles we call Holsteins,” said Hewett.
Scientists believe the tholin particles form high in the atmosphere, where ultraviolet sunlight breaks apart and ionizes nitrogen and methane molecules and allows them to react with each other to form more and more complex negatively and positively charged ions.
When they recombine, they form very complex macro molecules, a process first found to occur in the upper atmosphere of Saturn’s moon Titan.
The more complex molecules continue to combine and grow until they become small particles; volatile gases condense and coat their surfaces with ice frost before they have time to fall through the atmosphere to the surface, where they add to Pluto’s red coloring.
The discovery was made from data collected by the Ralph spectral composition mapper on New Horizons. A curious aspect of the detection is that the areas showing the most obvious water ice spectral signatures correspond to areas that are bright red in recently released color images.The New Horizons spacecraft is currently 5 billion kilometers from Earth, with all systems healthy and operating normally.