Backlit by the Sun, Pluto’s atmosphere rings its silhouette in this image taken by NASA’s New Horizons spacecraft around midnight EDT on 15 July. The image, with the north displayed at the top of the frame, was captured when the spacecraft was about 1.25 million miles (2 million kilometers) past Pluto. The image, delivered to Earth on 23 July and publicly released today, shows structures as small as 12 miles across. Credit: NASA/JHUAPL/SwRI

New images of Pluto provide stunning glimpses of the dwarf planet’s atmosphere and its diversity of geological features, scientists with NASA’s New Horizons mission said in a briefing at NASA headquarters in Washington, D. C., today.

Images of a band of light around Pluto, taken after the spacecraft had sped past, show that there is extensive haze in its atmosphere, said Michael Summers, New Horizons co-investigator at George Mason University in Fairfax, Va. Summers said that the haze, which shows up as two layers, extends to at least 100 miles above Pluto’s surface, 5 times farther than models predicted. He said that this and other data are “basically changing the way we think about Pluto’s atmosphere.”

The silhouette image “is our equivalent on New Horizons of the Apollo Earth rise photograph that proved we were there.”

“For 25 years, we have known that Pluto has an atmosphere, but it’s been known by numbers,” he said. “This is the first time we’ve really seen it.”

Alan Stern, New Horizons principal investigator at the Southwest Research Institute in Boulder, Colo., said that the silhouette image “is our equivalent on New Horizons of the Apollo Earth rise photograph that proved we were there. You can only get this image by going to Pluto and crossing to the far side and looking back.”

The newly released images also reveal more details about Pluto’s geology. They show rugged mountains and glaciers in the informally named Sputnik Planum, a Texas-sized plain in the western half of the dwarf planet’s heart-shaped feature dubbed Tombaugh Regio.

William McKinnon, New Horizons co-investigator at Washington University in St. Louis, Mo., said that the images show a pattern indicating the flow of viscous ice toward a cliff boundary; scientists interpret this as being just like glacier flow on Earth. He noted, though, that the kind of ice that scientists think makes up the planum—nitrogen, carbon monoxide, or methane ice—is geologically soft and malleable and will flow even in Pluto’s –390 degrees Fahrenheit temperature.

“We knew that there was nitrogen ice on Pluto from spectra,” McKinnon said. “But to see evidence of recent geological activity is simply a dream come true.”

—Randy Showstack, Staff Writer

Citation: Showstack, R. (2015), Pluto image shows first picture of its atmosphere, Eos, 96, doi:10.1029/2015EO033317. Published on 24 July 2015.

Text © 2015. The authors. CC BY-NC 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.