There could be further calls for Pluto to be reinstated as a planet in our solar system based on new evidence from NASA's New Horizons project suggesting that there might be cloud-like formations on the surface of the dwarf planet. The images capture spots in Pluto's layered haze that some researchers believe are clouds hovering at its limb (edge) and across parts of its surface.
The New Horizons spacecraft that passed Pluto and its largest moon Charon on July 14 of last year continues to reveal a number of unexpected findings connected to the former ninth planet's atmosphere and chemical compositions: its reddish color variations have been linked to the presence of methane gas, and recent high-resolution images indicate that Pluto has blue skies and water ice.
These discoveries have led the mission's principal investigator Alan Stern to recently describe the dwarf planet as "alive."
"It has weather, it has hazes in the atmosphere, [and] active geology," Stern explained during a lecture at the University of Alberta in Canada late last year. He has also said that the presence of clouds in Pluto's atmosphere would certainly boost the case for Pluto's planet status.
Technically, however, Pluto will still fail to match the International Astronomical Union's rubric for what constitutes a planet, because it does not possess "a clear neighborhood of orbiting bodies."
The first indication of clouds was noted in September of last year, when Will Grundy from the Lowell Observatory in Arizona wrote that there are "a few fairly localized low-altitude features just above the limb... but also a few bright cloud-like [features] that seem to be above and cutting across the topography."
Additional data is needed to determine whether the formations are really clouds, but Stern has outlined that "one way to think of it is that clouds are discrete features, hazes widespread." If the formations are indeed clouds, they would likely be composed of mostly nitrogen, with small amounts of ethane, methane, acetylene and ethylene.
It takes several months for data to be transmitted from the spacecraft to the research team. At least half of the data from the July 14 encounter remains to be received and analyzed as the New Horizons researchers learn more about Pluto's unexpectedly complex atmosphere.
Pluto was memorably demoted from official planet status in 2006 and is now officially categorized as a dwarf planet.
