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Alien Life May Depend on Planetary Tilt
Image: Habitable planets might have too short a window for life to develop before gravitational interactions with a close, red star destroy obliquity, and therefore seasons. Credit: David A. Aguilar, CfA
Although winter now grips the Northern Hemisphere, those who dislike the cold weather can rest assured that warmer months shall return. This familiar pattern of spring, summer, fall and winter does more than merely provide variety, however. The fact that life can exist at all on Earth is closely tied to seasonality, which is a sign of global temperature moderation.
The driver of our seasons is the slight “lean” Earth has in its rotational axis as it revolves around the sun, known as axial tilt or obliquity. According to René Heller, a postdoctoral research associate at the Leibniz Institute for Astrophysics in Potsdam, Germany, astrobiologists have not yet paid much attention to this variable in gauging the possibility for alien life to exist on distant planets.
“Obliquity and seasonal aspects are an important issue in understanding exoplanet habitability that has mostly been neglected so far,” Heller said.
To address this gap, Heller and his colleagues published two papers recently looking at how the gravitational interactions of stars and planets eventually erode a planet’s axial tilt. The findings do not bode well for planets residing in the habitable, or “Goldilocks,” zones around red dwarf stars smaller than the sun. These zones are the just-right temperature bands wherein water can remain liquid on the surface of a planet.
(via ikenbot)
