Admittedly, only the most extreme varieties of life would endure

Sep 12, 2012 18:01 GMT  ·  By
Rendition of an eccentric orbit, compared to Earth's (the habitable zone around the Sun appears in green)
   Rendition of an eccentric orbit, compared to Earth's (the habitable zone around the Sun appears in green)

According to the conclusions of a new study by experts at the NASA Jet Propulsion Laboratory (JPL) in Pasadena, California, it would appear that extreme lifeforms may be able to endure in the harsh environments of extrasolar planets on eccentric orbits around their parent stars.

This discovery is very significant, considering the high number of exoplanets confirmed thus far. More than 770 alien worlds have been checked and double-checked to date, and about 2,300 others are currently awaiting confirmation.

These planets range in size and temperature from hot Jupiter-class worlds orbiting very close to their parent stars to exoplanets that are frigid ice balls, located very far from their stars. In between are worlds on eccentric or retrograde orbits, which give astronomers nausea.

A planet is cataloged as having a retrograde orbit if its direction of travel is opposite to that of the body around which it spins. If the parent star spins to the left, then the planet would travel to the right.

An eccentric orbit is one that takes a planet or a moon outside of the star system's plane. A good example is Pluto, which has a significant eccentricity from the solar system's plane.

Given that worlds in these categories make up the bulk of alien planets, JPL experts set out to discover if they could possibly support life. Their work is detailed in the latest issue of the journal Astrobiology.

In the case of eccentric planets, the problem is that they do not have circular orbits, like Earth's. In fact, their orbits are highly elliptical, which means that they only pass through their parent stars' habitable zones. Certain portions of their orbits take them outside these zones.

“Planets like these may spend some, but not all of their time in the habitable zone. 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,” says Stephen Kane.

He holds an appointment as a scientist at the California Institute of Technology's (Caltech) Exoplanet Science Institute. “When we're talking about a habitable planet, we're talking about a world where liquid water can exist,” he adds.

“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,” Kane goes on to say.

Under such circumstances, it may not be such a stretch to assume that lifeforms may endure on eccentric exoplanets, provided that they could emerge in the first place.