NASA detects possible polar cap on Pluto
Artist's concept, obtained courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI), of the New Horizons spacecraft as it approaches Pluto (AFP Photo/-)

Pluto may have a polar ice cap, NASA scientists said Wednesday after analyzing the latest images from an unmanned spacecraft that is approaching the distant dwarf planet.

The New Horizons spacecraft will fly by Pluto on July 14, and has already begun sending back blurry pictures of the celestial body and its Texas-sized moon, Charon.

NASA combined 13 images taken over the course of six days in April with the New Horizons Long Range Reconnaissance Imager, or LORRI, to make a brief movie.

While pixelated, the images show dark and light areas on Pluto's surface.

These areas were first detected with the Hubble telescope many years ago, but as Pluto's features come into better focus with New Horizons, scientists are beginning to wonder if one consistent light area indicates the presence of a polar cap on Pluto.

"This brightening in Pluto's polar region might be caused by a 'cap' of highly reflective snow on the surface," NASA said.

"The 'snow' in this case is likely to be frozen molecular nitrogen ice. New Horizons observations in July will determine definitively whether or not this hypothesis is correct."

Pluto was long considered the ninth planet in the solar system, and the furthest from the sun. It was reclassified as a dwarf planet in 2006.