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Complex Molecules on Pluto

I hope everyone is having a happy holiday season and looking forward to the upcoming New Year’s festivities. In the intervening window, let’s look at the outer Solar System. No other spacecraft has ever come as close to Pluto as New Horizons now has, already halfway between the Earth and the distant dwarf planet. It’s also worth mentioning that New Horizons is only the fifth spacecraft to venture so deep into the Solar System, following the two Voyagers and the Pioneer spacecraft. July of 2015 will be an extraordinary time as we wait for data return from the mission and begin to find answers to some of the many questions that await us there.

But studies from closer to home are continuing to reveal more about Pluto/Charon as well. The Cosmic Origins Spectrograph aboard the Hubble Space Telescope has found evidence for complex hydrocarbon and/or nitrile molecules on the planetary surface. Alan Stern, principal investigator for New Horizons, is behind the study, whose work was recently published in the Astronomical Journal. It’s assumed that what we’re seeing on Pluto’s surface is the result of interactions between sunlight or cosmic rays with methane, carbon monoxide and nitrogen ices.

Image: The Cosmic Origins Spectrograph aboard NASA’s Hubble Space Telescope recently discovered a strong ultraviolet-wavelength absorber on Pluto’s surface. Credit: NASA/STScI.

“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 Stern.

Also more than a little interesting in light of New Horizons’ upcoming encounter is the fact that the team found evidence for changes in Pluto’s ultraviolet spectrum as compared to earlier Hubble measurements from the 1990s. Whether this is the result of differing terrains being observed in the two studies or surface changes related to atmospheric pressure variations during the time period involved is not known. New Horizons, it’s hoped, will tell us much more.

The paper is Stern et al., “First Ultraviolet Reflectance Spectra of Pluto and Charon by the Hubble Space Telescope Cosmic Origins Spectrograph: Detection of Absorption Features and Evidence for Temporal Change,” Astronomical Journal Vol. 143, No., 1 (9 December 2011), p. 22. Abstract available.


Comments on this entry are closed.

  • Antonio December 27, 2011, 15:04

    Salve a voi tutti.
    Leggendo questo articolo, ho pensato che possa interessare molti di voi, questo altro articolo, letto pochi minuti fa.
    Ecco il link.
    Saluti da Antonio.

    Via Google Translate:

    Hello to you all.
    By reading this article, I thought it might be of interest to many of you, this other article, read a few minutes ago.
    Here’s the link.
    Greetings from Anthony.

  • Nick December 27, 2011, 16:17

    Do the hydrocarbons get recycled deeper into Pluto, or do they just form a very thin veneer at its surface?

  • Daniel Suggs December 28, 2011, 0:46

    Antonio I had just finished the UT article and it dovetails nicely with this current article. Thanks for reminding everyone.

  • Alex Tolley December 29, 2011, 2:09

    Aren’t these the tholins that we see on other icy bodies in the outer system? If so, what makes the Pluto/Charon findings of these compounds a surprise?

  • ljk January 10, 2012, 15:17

    Review: Beyond Pluto

    by Jeff Foust

    Monday, January 9, 2012

    Beyond Pluto: Exploring the Outer Limits of the Solar System

    by John Davies
    Cambridge Univ. Press, 2011
    softcover, 242 pp., illus.
    ISBN 978-1-107-40261-4

    Over the last decade astronomers and planetary scientists have reshaped our knowledge of the Kuiper Belt and the outer solar system. Their work includes the discovery of a number of large bodies in the outskirts of the solar system, notably Eris, Quaoar, and Sedna. This, in turn, helped push the International Astronomical Union in 2006 to approve a formal definition of the term “planet” that demoted Pluto to the new category of “dwarf planet”, along with some of these newly-discovered bodies. These discoveries and other research would provide plenty of material for a book about our knowledge of the outer solar system—after all, several books have been written about Pluto’s standing as a (dwarf) planet in the last few years alone.

    Full article here:


  • ljk January 16, 2012, 10:23

    UPDATED: Patsy Tombaugh, community leader and wife of Pluto’s founder mourned after passing at age 99 (2:42 p.m.)

    By S. Derrickson Moore / dmoore@lcsun-news.com

    Posted: 01/13/2012 10:06:14 AM MST

    LAS CRUCES – Patricia “Patsy” Edson Tombaugh, community leader, educator, artist, and enthusiastic supporter of her astronomy pioneer husband Clyde, discover of the planet Pluto, died Thursday at the Arbors of Del Rey in Las Cruces. She was 99.

    Full article here:


    To quote:

    She attracted new friends and fans after her 2010 appearance on “The Pluto Files” on PBS’s NOVA series, focusing on the conflict over the 2006, still-controversial meeting of the International Astronomical Union, when a vote involving 424 astronomers defined the term “planet” for the first time, a definition which excluded Pluto and added it as a member of the new “dwarf planet” category.

    The NOVA crew came to Las Cruces 2009 to film locations that included Alden Tombaugh’s home and the Tombaugh Art Gallery, which houses a stained glass window depicting Clyde’s life, at the Unitarian Universalist Church, which the Tombaughs helped found in 1954.

    “She spoke lucidly and articulately about their life together. This was a treasure of storytelling. That has got to be the friendliest family I have ever spent time with in my life. I learned how friendly people can be, even in times of intellectual conflict,” said NOVA host Neil Tyson. Tyson had been one of the ringleaders in the effort to demote Pluto, but changed his mind after meeting Patricia and her family.