Abstract
Titan’s surface–atmosphere system bears remarkable similarities to Earth’s, the most striking being an active, global methane cycle akin to Earth’s water cycle1,2. Like the hydrological cycle of Earth, Titan’s seasonal methane cycle is driven by changes in the distribution of solar energy2. The Cassini spacecraft, which arrived at Saturn in 2004 in the midst of northern winter and southern summer, has observed surface changes, including shoreline recession, at Titan’s south pole3,4 and equator5. However, active surface processes have yet to be confirmed in the lakes and seas in Titan’s north polar region6,7,8. As the 2017 northern summer solstice approaches, the onset of dynamic phenomena in this region is expected6,7,9,10,11,12. Here we present the discovery of bright features in recent Cassini RADAR data that appeared in Titan’s northern sea, Ligeia Mare, in July 2013 and disappeared in subsequent observations. We suggest that these bright features are best explained by the occurrence of ephemeral phenomena such as surface waves, rising bubbles, and suspended or floating solids. We suggest that our observations are an initial glimpse of dynamic processes that are commencing in the northern lakes and seas as summer nears in the northern hemisphere.
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Acknowledgements
J.D.H. gratefully acknowledges the Cassini RADAR and VIMS Teams for the data and the opportunity to lead the analysis and the Cassini Project and Natural Sciences and Engineering Research Council of Canada, Post Graduate Scholarship Program for financial support. A.G.H. was partially supported by NASA grant NNX13AG03G. A portion of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.
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J.D.H. led the analysis and writing of the letter. A.G.H. and J.I.L. worked closely with J.D.H. on all aspects of the analysis and writing. H.Z. worked closely with J.D.H. on the NRCS analysis. B.W.S. contributed the SAR processing and artefact analysis and that section of the letter. C.S., J.W.B. and E.P.T. contributed to the VIMS and Imaging Science Subsystem analysis and the cloud discussion. All authors contributed to the data acquisition and discussions.
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Hofgartner, J., Hayes, A., Lunine, J. et al. Transient features in a Titan sea. Nature Geosci 7, 493–496 (2014). https://doi.org/10.1038/ngeo2190
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DOI: https://doi.org/10.1038/ngeo2190
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