WASHINGTON (PTI): Scientists at NASA claim to have gathered evidence that dwarf planet Pluto is no longer a ball of ice and rock, but a dynamic world undergoing dramatic seasonal and atmospheric changes – just like on Earth.

A series of spectacular photos taken by Hubble Space Telescope show an icy and dark molasses-coloured, mottled world which is undergoing seasonal changes in its surface colour and brightness as well.

Pluto has also become significantly redder, while its illuminated northern hemisphere is getting brighter – in fact these changes are the likely consequences of surface ices sublimating on the sunlit pole and then refreezing on other pole as the dwarf planet heads into the next phase of its 248 -year-long seasonal cycle, say the scientists.

The dramatic change in colour apparently took place in a two-year period, from 2000 to 2002, the space agency said.

The researchers said they would compare Hubble pictures taken in 1994 with some from 2002 and 2003 to search for more signs of seasonal and atmospheric changes in the dwarf planet.

Principal investigator Marc Buie of Southwest Research Institute in Colorado said the images allowed astronomers to better interpret more than three decades of Pluto observations from other telescopes.

“The Hubble observations are the key to showing how it all makes sense by providing a context based on weather and seasonal changes which open other new lines of investigation,” he said.

Pluto is less than 1,500 miles in diameter and lies at the edge of the solar system. It is so far from the Sun that it takes 248 years for it to complete one orbit.