Letter | Published:

Possible tropical lakes on Titan from observations of dark terrain

Nature volume 486, pages 237239 (14 June 2012) | Download Citation


Titan has clouds, rain and lakes—like Earth—but composed of methane rather than water. Unlike Earth, most of the condensable methane (the equivalent of 5 m depth globally averaged1) lies in the atmosphere. Liquid detected on the surface (about 2 m deep) has been found by radar images only poleward of 50° latitude2,3, while dune fields pervade the tropics4. General circulation models explain this dichotomy, predicting that methane efficiently migrates to the poles from these lower latitudes5,6,7. Here we report an analysis of near-infrared spectral images8 of the region between 20° N and 20° S latitude. The data reveal that the lowest fluxes in seven wavelength bands that probe Titan's surface occur in an oval region of about 60 × 40 km2, which has been observed repeatedly since 2004. Radiative transfer analyses demonstrate that the resulting spectrum is consistent with a black surface, indicative of liquid methane on the surface. Enduring low-latitude lakes are best explained as supplied by subterranean sources (within the last 10,000 years), which may be responsible for Titan’s methane, the continual photochemical depletion of which furnishes Titan's organic chemistry9.

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Research by C.A.G., J.T., L.D., C.S. and M.G.T. are funded by NASA’s Planetary Astronomy and Cassini Data Analysis programmes. J.T. was also funded by a NASA Space Grant.

Author information


  1. Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721, USA

    • Caitlin A. Griffith
    • , Juan M. Lora
    • , Jake Turner
    • , Robert H. Brown
    • , Martin G. Tomasko
    • , Lyn Doose
    •  & Charles See
  2. Universidade de São Paulo, IAG, Rua do Matao 1226, São Paulo, SP 05508-090, Brazil

    • Paulo F. Penteado


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C.A.G. supervised all work, and conducted the radiative tranfer analyses. J.M.L. worked on the analyses of surface albedos within the wavelength windows. R.H.B. worked on the surface identification and, as the VIMS Pricipal Investigator, all technical aspects regarding the VIMS observations. M.G.T., L.D. and C.S. collaborated on the radiative transfer analyses. J.T. conducted searches of the VIMS data base, using software written by P.F.P.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Caitlin A. Griffith.

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    This file, which discusses further the geography and spectral characteristics of the dark terrains detected on Titan’s tropical surface, as well as the spectral characteristics of methane lakes and the uncertainties in the analysis, contains Supplementary Text and Data 1–4, Supplementary Tables 1–3, Supplementary Figures 1–4 and additional references.

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