Finding Life Outside Our Solar System

The search for extraterrestrial life has taken many forms through the years starting with pure imagination. The panic caused by the original broadcast of H.G. Wells’ War of the Worlds is plenty of proof that people are willing to believe in the possibility of life from beyond Earth, a belief that has lead to the development of the discipline known as Astrobiology and the search for life outside our solar system.

A Look at SETI

The very directly named SETI is an organized effort that is the Search for Extra Terrestrial Intelligence. The key word here is the last word, intelligence. SETI focuses on scanning the skies for radio transmissions or other signals entering the atmosphere that could have originated from an intelligence off-planet. An offshoot of SETI, called “active SETI” or METI (Messages to Extra Terrestrial Intelligence) is about sending messages out in hopes of being received and in turn being sent a response. Life in the universe may not be intelligent, however, and so the search for life off planet must be expanded beyond listening for signals.

Examining the Neighbourhood

Because of the vastness of space and the limit of our reach, Earth scientists must do a lot of guessing and inferring when dealing with subjects that are light years away. Habitable zones have been outlined (the distance from a star that a planet could be in and support life) as well as habitable type planets (no tidal lock, a source of liquid water, the proper atmosphere) so the first step in determining if there is life in a particular region of space is to determine if life is even possible. The recently (2007) discovered super-Earth Gliese 581 c is relatively close (20 light years) to Earth, is in the habitable zone of its star, and might meet the other criteria for a habitable planet, and thus makes a prime candidate for a likely spot for life.

Life in Unlikely Places

The narrow band of conditions that once was used to define the possibility of life developing has been expanded in recent years. Thanks to studies of living-but-dormant 40,000 year old moss in permafrost from Siberia and micrograms found thriving in hydrothermal, highly acidic vents under the ocean, a new class of life has been identified; the extremophiles. The extremophiles are life forms that can live in very extreme environments that before were considered too hot, too cold—generally too lethal for life to exist. Because of these discoveries scientists now believe life could exist in the water-ammonia ocean they think exists under the ice of Europa, or perhaps in the permafrost under the Martian soil. But these life forms would be found inside our solar system—what of outside?

Final Thoughts

The search for life outside our solar system is closely linked to all scientific exploration headed in that direction. SETI plays a role, and always will, in monitoring potential intelligent transmission which, should it ever come, will almost certainly originate form outside the solar system. Gliese 581 c will certainly be observed in years to come as our technology catches up to our desire, and the mapping of the known universe will continue with one question always waiting to be answered- will this region support life?