It's been over a year since new Horizon's historic flyby of Pluto in July 2015, but data from that brief encounter – which is still being sent back – continues to provide scientists with fascinating insights into the dwarf planet. At the American Astronomical Society Division for Planetary Sciences and European Planetary Science Congress meeting in Pasadena, California, NASA scientists revealed evidence from the unmanned deep space probe that indicates Pluto may have clouds, and that its next destination in the Kuiper belt may be more like Pluto than previously thought.

Pluto may be a dwarf planet on the edge of the Solar System, but the New Horizons flyby showed conclusively it has a tenuous atmosphere. Its pressure is 100,000 times less than the Earth's atmosphere and it is made up mainly of nitrogen with traces of methane and carbon monoxide, all of which have sublimated from Plutonian ice, but NASA says the hazy atmosphere is complex and shows strong seasonal changes that take decades to occur as the various ices sublimate then refreeze on other areas of the planet.

However, the one thing that hasn't been seen before on Pluto is clouds, which Alan Stern, principal investigator from Southwest Research Institute in Boulder, Colorado says would indicate a much more complex atmosphere than previously thought. But as New Horizons passed Pluto in 2015 and turned its Long Range Reconnaissance Imager and Multispectral Visible Imaging Camera on the sunlit rim, what seem isolated condensation clouds were seen.

2014 MU69

Another new finding about Pluto based on New Horizons data and images captured by NASA's Hubble Space Telescope indicate that new Horizons next destination may be very like Pluto. Kuiper Belt object 2014 MU69 is small and lies a billion miles (1.6 billion km) beyond Pluto's orbit, but Hubble and the New Horizons cameras show that is as red, if not redder, than Pluto itself.

NASA says MU69 is the smallest KBo to have its color measured, but the data confirms it's part of the oldest material left over from the formation of the Solar System. This means when New Horizons flies past it on January 1, 2019, it will be looking at an "ancient building blocks of the planets."


One oddity from the New Horizons data is what wasn't found. According to NASA, landslides are common on rocky and icy planets, and New Horizons even saw them on Pluto's moon Charon, but not on Pluto itself. The space agency is now looking forward to seeing if such formations will be seen in other Kuiper Belt inhabitants.

New Horizons is now 3.4 billion miles (5.5 billion km) from Earth and 340 million miles (540 million km) beyond Pluto, traveling toward interstellar space at 9 mi/s (14 km/s). It has returned 99 percent of its data and will continue transmission of the remainder through October 23. The probe won't encounter another object until it reaches 2014 MU69 in 2019.

"We're excited about the exploration ahead for New Horizons, and also about what we are still discovering from Pluto flyby data," says Stern."Now, with our spacecraft transmitting the last of its data from last summer's flight through the Pluto system, we know that the next great exploration of Pluto will require another mission to be sent there."

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