Have Complex Molecules Been Found on Pluto’s Surface?

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First there was the recent story about evidence for a possible subsurface ocean on Pluto, of all places. Now there is a new report regarding evidence for complex molecules on its surface, from scientists at Southwest Research Institute and Nebraska Wesleyan University. Little enigmatic Pluto is starting to get even more interesting…

The findings come from the Hubble Space Telescope, using the new and highly sensitive Cosmic Origins Spectrograph which indicate that there is a strong ultraviolet-wavelength absorber on the surface. This absorbing material is thought to likely be complex hydrocarbons and/or nitriles. The results have been published in the Astronomical Journal.

Pluto’s surface is known to be coated with ices composed of methane, carbon monoxide and nitrogen (it is extremely cold there!). The putative molecules can be produced by sunlight or cosmic rays interacting with those ices.

“This is an exciting finding because complex Plutonian hydrocarbons and other molecules that could be responsible for the ultraviolet spectral features we found with Hubble may, among other things, be responsible for giving Pluto its ruddy color,” said project leader Dr. Alan Stern.

The team also found evidence for surface changes in the ultraviolet spectrum, comparing current observations to those from the 1990s. The cause may be an increase in the pressure of Pluto’s tenuous atmosphere or different terrain which is being viewed at different times.

In a unique first for Universe Today, Dr. Alan Stern was the first researcher to be asked questions from readers via the comments section of this recent interview article by Ray Sanders. His answers to the top five questions (as ranked by “likes” on the discussion posts) will be posted soon in a subsequent article. Stern is also the principal investigator for the New Horizons spacecraft currently en route to Pluto.

A copy of the paper by Stern et al. is available here.

With all of the new discoveries already being made about Pluto, it should be very interesting when New Horizons gets there in 2015, providing us with the first close-up look of this fascinating little world.