Sunday, June 5, 2016

Backlit Pluto photo shows evidence of possible clouds

 David Lumb

Can't get enough of the ninth planet-no-longer in our solar system? Neither can NASA, which continues to receive images that its New Horizons spacecraft took on its Pluto flyby last year. One shot on July 15th caught the dwarf planet backlit by the sun, which revealed never-before-seen atmospheric phenomena that might just be the first evidence of clouds.

Taking these rearward shots of Pluto shows things the spacecraft's approach photos don't, thanks to sunlight reflecting off the dwarf planet's surface and illuminating the haze in its thin sky. The top of the photo shows long wispy formations that could be clouds, the first evidence of any from New Horizons' photo collection and possible proof of the methane clouds predicted by models of Pluto's atmosphere. The bottom of the image shows a cleaner silhouette of mountain ranges and valleys.

This photo was taken from 13,400 miles past Pluto 19 minutes after New Horizon's closest approach. At that distance, the picture has a higher resolution at 1,400 feet per pixel than shots taken as New Horizons headed toward the dwarf planet. Obviously, less distance means clearer detail of terrestrial features, but the closest we've seen was a photo strip of the surface at 9,850 miles out. Unless NASA has more images up its sleeve, these might be the sharpest of the planet we'll see for a while.