Observational Evidence for Summer Rainfall at Titan's North Pole

Research areas:
Year:
2019
Keywords:
precipitation on Titan's north pole, broad specular reflection, ephemeral feature on Titan's north pole, wet-sidewalk effect, surface roughness, rainfall on Titan
Authors:
  • Rajani D. Dhingra
  • Jason W. Barnes
  • Robert H. Brown
  • Bonnie J. Burrati
  • Christophe Sotin
  • Phillip D. Nicholson
  • Kevin H. Baines
  • Roger N. Clark
  • Jason M. Soderblom
  • Ralf Jauman
  • Sebastien Rodriguez
  • Stéphane Le Mouélic
  • Elizabeth P. Turtle
  • Jason E. Perry
  • Valeria Cottini
  • Don E. Jennings
Journal:
Geophysical Research Letters
Volume:
46
Number:
3
Pages:
1205-1212
Abstract:
Abstract Methane rain on Saturn's moon Titan makes it the only place, other than Earth, where rain interacts with the surface. When and where that rain wets the surface changes seasonally in ways that remain poorly understood. Here we report the discovery of a bright ephemeral feature covering an area of 120,000 km2 near Titan's north pole in observations from Cassini's near-infrared instrument, Visual and Infrared Mapping Spectrometer on 7 June 2016. Based on the overall brightness, spectral characteristics, and geologic context, we attribute this new feature to specular reflections from a rain-wetted solid surface like those off of a sunlit wet sidewalk. The reported observation is the first documented rainfall event at Titan's north pole and heralds the arrival of the northern summer (through climatic evidence), which has been delayed relative to model predictions. This detection helps constrain Titan's seasonal change and shows that the “wet-sidewalk effect can be used to identify other rain events.”