In the Milky Way there could be a hundred million planets in addition to Earth capable of harboring complex life forms. To reach this conclusion, a team of astronomers from various US institutions coordinated by Louis Irwin, a professor at the University of Texas at El Paso, has devised a new computer model that correlates data obtained from more than a thousand extrasolar worlds.
As these experts clarify in the journal Challenges, the study does not indicate that life exists in all these objects, but rather that the planetary conditions necessary for organisms to develop above what could be called the microbial level exist. And they insist: “ Complex life does not have to amount to intelligent life ; not even animal life; the idea, rather, is that organisms could organize themselves into trophic chains similar to those that exist in terrestrial ecosystems ”.
The researchers took into account the density of the planets examined, their age, composition, temperature and distance from their star, among other factors. From this information they built a measurement system called the Biological Complexity Index. This revealed that almost 2% of the observed worlds had better conditions than Europa, a satellite of Jupiter that under its frozen surface hoards a large underground ocean of water in a liquid state and that, on occasions, reaches the surface. Some astrobiologists suspect that life could have arisen on this moon .
Now, Irwin and his colleagues estimate that in the Milky Way, in which there are about 10 billion stars , there would be about 100 million worlds with appropriate conditions for it to develop satisfactorily. Of course, despite the fact that there are many, the galaxy is so large that those with the highest scores on the Biological Complexity Index are very far from each other. For example, one of the closest systems with planets in which complex biospheres could have formed is Gliese 581, about 20 light years from Earth. “It seems highly unlikely that we are alone in the universe. However, we are possibly so far removed from other life forms with a level of complexity similar to ours that encountering them is highly unlikely in the near future , “the astronomers say.
