Extreme Life Forms
Astronomers have discovered a veritable rogues' gallery of odd exoplanets -- from scorching hot worlds with molten surfaces
to frigid ice balls.
And while the hunt continues for the elusive "blue dot" - a planet with roughly the same characteristics as Earth - new research reveals that life might actually be able to survive on some of the many exoplanetary oddballs that exist. "When we're talking about a habitable planet, we're talking about a world where liquid water can exist," said Stephen Kane, a scientist with the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena. "A planet needs to be the right distance from its star - not too hot and not too cold." Determined by the size and heat of the star, this temperature range is commonly referred to as the "habitable zone" around a star. Kane and fellow Exoplanet Science Institute scientist Dawn Gelino have created a resource called the "Habitable Zone Gallery." It calculates the size and distance of the habitable zone for each exoplanetary system that has been discovered and shows which exoplanets orbit in this so-called "goldilocks" zone.
But not all exoplanets have Earth-like orbits that remain at a fairly constant distance from their stars. One of the unexpected revelations of planet hunting has been that many planets travel in very oblong, eccentric orbits that vary greatly in distance from their stars. "Planets like these may spend some, but not all of their time in the habitable zone," Kane said. "You might have a world that heats up for brief periods in between long, cold winters, or you might have brief spikes of very hot conditions." Though planets like these would be very different from Earth, this might not preclude them from being able to support alien life. Scientists have found microscopic life forms on Earth that can survive all kinds of extreme conditions. Some organisms can basically drop their metabolism to zero to survive very long-lasting, cold conditions. We know that others can withstand very extreme heat conditions if they have a protective layer of rock or water, " Kane said.
There have even been studies performed on Earth-based spores, bacteria and lichens, which show they can survive in both harsh environments on Earth and the extreme conditions of space.
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