26 March 2013
The IAU Working Group for Planetary System Nomenclature has approved some changes for Mercury nomenclature. Arecibo Vallis has been changed to Arecibo Catena, Goldstone Vallis has been changed to Goldstone Catena, Haystack Vallis has been changed to Haystack Catena, and Simeiz Vallis has been dropped. The theme for catenae on Mercury is "Radio telescope facilities," and the theme for valles is "Abandoned cities (or towns or settlements) of antiquity." For more information, see the feature categories in the Gazetteer of Planetary Nomenclature.