Seasonal evolution of Titan's dark polar hood: midsummer disappearance observed by the Hubble Space Telescope

Abstract

Titan, Saturn's largest moon, has a dense organic-laden atmosphere that displays dramatic seasonal variations in composition and appearance. Here we document the evolution of the dark polar hood, first seen in 1980 by Voyager 1 around the north pole, and report quantitative measurements of the hood's disappearance from the south pole in 2002-2003 using previously unpublished observations with the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS). These data support a model of the hood as a transient structure associated with downwelling during polar winter.