NASA’s New Horizons spacecraft, currently flying about 3 billion miles (5 Billion KM) from Earth has sent back color photographs of Pluto’s atmospheric hazes. These photos reveal that the hazes appear to have a blue tint to them.
The blue tinge in the haze is a result of the scattering of sunlight by haze particles. “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 tholins.” according to New Horizons team member Carly Howett from the Southwest Research Institute (SwRI) in Boulder, Colorado.
Scientists used software to produce images in colors that an observer standing on Pluto would see with the naked eye. Sunrises and sunsets would appear blue to a person standing on Pluto. Scientists are uncertain as to whether a blue sky would be visible during the day because the hazes are so thin, according to Howett.
Blue skies are produced as a result of the way particles scatter blue light. Earth’s blue sky is created by very small nitrogen particles in the atmosphere. On Pluto, the haze particles are believed to be gray or red, Howett says the particles are larger than Earth’s nitrogen particles, but still relatively small ones, called tholins.
Another significant find by New Horizons was the location of numerous patches of water ice on the surface of Pluto. The discovery was made from data collected by the Ralph spectral composition mapper on New Horizons. The ice patches appear to be red. This has scientists curious. “Large expanses of Pluto don’t show exposed water ice,” said science team member Jason Cook, of SwRI, “because it’s apparently masked by other, more volatile ices across most of the planet. Understanding why water appears exactly where it does, and not in other places, is a challenge that we are digging into.”
The vast distance between Earth and New Horizons creates the problem of very low data rates in the transmissions from the spacecraft. It may be well into 2016 before all the data is collected on the ground.
