The icy haze of the Pluto atmosphere is a wondrous sight

27 Jul 2015

A false-colour image of the surface of Pluto. Image via NASA/JHUAPL/SwRI

It’s been nearly two weeks since New Horizons zoomed past Pluto and since its closest approach it continues to send back stunning images, including the recent icy haze of Pluto’s thin atmosphere.

The New Horizons craft is entering the second phase of its mission to monitor the Pluto atmosphere for its composition and, for NASA scientists, it is already beginning to show rather exciting results.

This incredible new image published by NASA was taken just seven hours after its closest approach to the dwarf planet and it is seen capturing sunlight streaming through the atmosphere and revealing atmospheric haze as high as 130km above Pluto’s surface.

Based off a preliminary analysis of the image, the findings show that there are in fact two distinct layers of haze – one about 80km above the surface while the other is at an altitude of 50km.

By analysing the dwarf planet’s atmosphere, NASA scientists hope to discover more about what’s happening on the surface below.

According to NASA’s proposed models, Pluto’s hazes form when ultraviolet (UV) sunlight breaks up methane gas particles into a simple hydrocarbon.

Pluto atmosphere haze

Pluto’s hazy atmosphere. Image via NASA/JHUAPL/SwRI

This facilitates the build-up of more complex hydrocarbon gases, such as ethylene and acetylene.

The ice particles are then formed as these hydrocarbons fall into the lower, colder parts of the atmosphere, with the UV sunlight chemically converting these hazes into tholins that form the dark hydrocarbons that create the distinctive red hue colour of Pluto’s surface.

This throws previous calculations of Pluto’s atmosphere out the window, with suggestions that the planet would be too warm for hazes to form.

Speaking of the surprise, Michael Summers, co-investigator of the New Horizons mission, said: “We’re going to need some new ideas to figure out what’s going on.”

Colm Gorey was a senior journalist with Silicon Republic