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Updated: Sep 8, 2026

Simulation of the Planetary Interior Differentiation Processes in the Laboratory
Published on: November 16, 2013
Titan under a red giant sun: a new kind of "habitable" moon
R D Lorenz1, J I Lunine, C P McKay
1Department of Planetary Sciences, University of Arizona, Tucson 85721-0092, USA. rlorenz@lpl.arizona.edu
Abstract:
We explore the response of Titan's surface and massive atmosphere to the change in solar spectrum and intensity as the sun evolves into a red giant. Titan's surface temperature is insensitive to insolation increases as the haze-laden atmosphere "puffs up" and blocks more sunlight. However, we find a window of several hundred Myr exists, roughly 6 Gyr from now, when liquid water-ammonia can form oceans on the surface and react with the abundant organic compounds there. The window opens due to a drop in haze production as the ultraviolet flux from the reddening sun plummets. The duration of such a window exceeds the time necessary for life to have begun on Earth. Similar environments, with approximately 200K water-ammonia oceans warmed by methane greenhouses under red stars, are an alternative to the approximately 30OK water-CO2 environments considered the classic "habitable" planet.
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