While many believe the search for extraterrestrial life to be inherently tied to the observation of neighboring stars and their subsequent systems, some have decided to turn their gaze elsewhere. Recently, a team of astronomers in Hawaii discovered a new exoplanet, not orbiting a star, but floating alone through space.
At 80 light-years away, PSO J318.5-22 is the lowest mass, free-floating object found to date. That’s not the surprising part, however. What has got scientists running around like coffee-frenzied hamsters is the discovery that the surface temperature of said rogue planet is about 1,100O Kelvin, or 1,520O Fahrenheit for the laypeople. Granted, while that is far too hot for habitation, it does point out a very important fact: it is possible for free-floating exoplanets to retain heat in the cold abyss of interstellar space. Fascinating, I know. But this actually has huge implications for the search for life beyond Earth.
It has been hypothesized before that rogues might be able to maintain their heat away from any parent star. Hypothetically speaking, if a planet had a thick atmosphere with a high hydrogen content, its intense greenhouse effect would be able to retain a much higher surface temperature than Earth’s atmosphere is capable of. In addition, being far away from any star would mean that harmful UV radiation, which strips most orbitally-bound planets of their outer atmospheres, wouldn’t be able to reach said planet. Thus, its retention capabilities would be unaffected for most of its lifetime. When you add this to the fact that radioactive decay will continue to produce heat deep in the planet’s core, enabling almost permanent volcanic activity, you are left with a nearly self-sufficient island of heat in the interstellar sea. An island that could even maintain temperatures above the melting temperature of water (or higher, in the case of PSO J324.5-22), and thus feature large surface oceans.
Based on research done here on Earth, scientists believe that it is very possible that life could originate and evolve under these conditions. One of the leading theories for how life began on Earth says that microbes were born around deep sea volcanic vents, utilizing chemical energy from minerals found in volcanic material. Such vents could potentially exist on free-floating planets, although the potential for complex or intentional life is very small, given the impossibility of photosynthesis in the darkness of space.
While we can’t say that the possibility of life on PSO J324.5-22 is very high, what we can say is that this discovery has changed our understanding of habitability, and opened our eyes to an entirely new avenue in the pursuit of extraterrestrial life.
http://arxiv.org/abs/1310.0457
http://cdn4.sci-news.com/images/2013/10/image_1450_1-PSO-J3185-22.jpg
http://www.cnn.com/2013/10/10/tech/space-new-planet/index.html
