Pluto

The images sent by Nasa’s New Horizons spacecraft have revealed blue skies and water ice on Pluto, while the Curiosity Rover confirmed the presence of an ancient lake on Mars.

The first colour images of Pluto’s atmospheric hazes sent by New Horizons shows that the hazes are blue.

New Horizons Southwest Research Institute (SwRI) in Boulder, Colorado’s principal investigator Alan Stern said: "Who would have expected a blue sky in the Kuiper Belt?

"It’s gorgeous."

SwRI science team researcher Carly Howett said: "That striking blue tint tells us about the size and composition of the haze particles.

"A blue sky often results from scattering of sunlight by very small particles.

"On Earth, those particles are very tiny nitrogen molecules. On Pluto they appear to be larger, but still relatively small, soot-like particles we call tholins."

The researchers think that the haze particles in Pluto’s atmosphere are the right size and composition to carry blue light in sunlight.

On Earth, nitrogen particles spread light, while the same tholins make the surface red on Pluto.

"We don’t yet understand the relationship between water ice and the reddish tholin colourants on Pluto’s surface."

Scientists believe that tholin particles form high in the atmosphere, as they do not form naturally on Earth.

Apart from the blue haze, New Horizons has also detected numerous small, exposed patches of water ice on Pluto.

SwRI science team member Jason Cook said: "Large expanses of Pluto don’t show exposed water ice…because it’s apparently masked by other, more volatile ices across most of the planet.

"Understanding why water appears exactly where it does, and not in other places, is a challenge that we are digging into."

University of Maryland, College Park science team member Silvia Protopapa said: "I’m surprised that this water ice is so red.

"We don’t yet understand the relationship between water ice and the reddish tholin colourants on Pluto’s surface."

Currently, New Horizons spacecraft is five billion km away from Earth and operating normally.

In another study, Nasa’s Mars Science Laboratory, Curiosity Rover has confirmed that billions of years ago water storing lakes were present on Mars.

Image: Image received from Nasa’s New Horizons spacecraft depicting blue skies and water ice on Pluto. Photo: courtesy of Nasa.