Scientists using the new Cosmic Origins Spectograph (COS) on the Hubble Space Telescope, while studying Pluto, spotted new evidence of complex organic molecules, the carbon-containing building blocks of life, on its frigid surface – which is what gives Pluto it’s color.

The Southwest Research Institute’s (News - Alert) scientists discovered a strong ultraviolet-wavelength absorber on the dwarf planet’s surface, which suggests that there are complex hydrocarbon and nitrile molecules strewn on the ground.

Pluto is known to harbor ices of methane, carbon monoxide and nitrogen on its surface. The ultraviolet-absorbing chemical species may have been produced when sunlight or super-speedy subatomic particles known as cosmic rays interacted with the harbor ices.

Alan Stern, study leader, of the Southwest Research Institute in Boulder, Colorado, said this research provides us with more details on Pluto than ever known before. “This is an exciting finding because complex Plutonian hydrocarbons and other molecules that could be responsible for the ultraviolet spectral features we found with the Hubble may, among other things, be responsible for giving Pluto its ruddy color,” said Stern.

The team found the high UV absorption using the COS, a new instrument installed during the final Hubble servicing mission in 2009. The new data marked the first time the COS was turned to Pluto and its largest companion, Charon. The COS is designed to split light apart and measure its components.

During the measurements made in 2010, the team also discovered evidence of changes in Pluto’s ultraviolet spectrum compared to earlier measurements from the 1990s. This indicates the dwarf planet’s surface might be changing, due to some unknown influence, or its atmosphere might have increased pressure.

Overall, the new Hubble observations shed further light on Pluto a few years ahead of the first-ever spacecraft to visit to the cold, distant world.

“The discovery we made with Hubble reminds us that even more exciting discoveries about Pluto’s composition and surface evolution are likely to be in store when NASA’s New Horizons spacecraft arrives at Pluto in 2015,” said Stern.

The New Horizons spacecraft was launched back in 2006 to make the 4-billion-mile journey to Pluto. Researchers said the spacecraft is due to make its closest approach to Pluto on July 14, 2015 – making the spacecraft only 7,767 miles away from the dwarf planet.