25 février 2015

De la vie sur Titan?


C'est bien beau de chercher de la vie sur des planètes qui ressemblent à la nôtre, mais il ne serait pas complètement impossible d'en trouver également dans des environnements plus extrêmes!

Extrait de l'article:

Our understanding of life on exoplanets and exomoons must be based on what we know about life on Earth. Liquid water is the common ecological requirement for Earth life. Temperature on an exoplanet is the first parameter to consider both because of its influence on liquid water and because it can be directly estimated from orbital and climate models of exoplanetary systems. Life needs some water, but deserts show that even a little can be enough. Only a small amount of light from the central star is required to provide for photosynthesis. Some nitrogen must be present for life and the presence of oxygen would be a good indicator of photosynthesis and possibly complex life.

(...) Saturn's moon Titan has an atmosphere, liquids on the surface and even a weather cycle. But instead of water, its liquids are methane and ethane, and its atmosphere is a choking haze of nitrogen and methane. But Titan has also shown evidence that it has complex molecules that may be building blocks for life. "Titan is a little reminder that there are perhaps more things in heaven and Earth than we can imagine, as Hamlet said. It's a cautionary tale," says McKay. "If we discover something new, we will have to rewrite this chapter."



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