Astrobiologists recently released a new map of the Milky Way, which shows that about 1.2 percent of all stars in our galaxy are capable of supporting complex life in their orbit, or at least were capable of doing so at a given time in the past.
Given that the galaxy has billions of stars, 1.2 percent of them could easily represent several million stars, all capable of supporting life on extrasolar planets orbiting inside their respective parent stars' habitable zones.
These area are regions of star systems were temperatures are just right to support the presence of liquid water on planets. Earth is located in the middle of the Sun's habitable zone, with Venus and Mars skimming at the inner and outer edges of this area, respectively.
Interestingly, this study is based on a relatively new idea in astronomy, which states that life is more likely to occur in certain areas of the Milky Way. In other words, life does not have the same chance of developing near the galactic core as it has in the outer arms.
The Milky Way's galactic habitable zone is estimated to stretch for about 30 light-years around the galactic core. However, they do not form very close to the supermassive black hole powering up the entire galaxy, and neither very far away in space.
Experts at the University of Hawaii in Honolulu, led by expert Michael Gowanlock, believe that the habitable galactic zone is in fact a lot more complex that a simple diameter. The new dataset contains datasets collected from some of the latest studies on exoplanets.
For example, observatories such as the NASA Kepler Telescope determined that exoplanets are more likely to form around stars displaying high metallicity, which basically means that they are richer in elements heavier than hydrogen and helium than other stars.
“We predict that [about]1.2% of all stars host a planet that may have been capable of supporting complex life at some point in the history of the Galaxy,” Gowanlock and his coauthors write in the online journal arXiv.
The expert adds that supernova explosions – which many experts believe have the potential to wipe out life on other planets – most likely devastated planets in the inner parts of the galaxy, but that they left behind enough worlds to allow for the development of complex life, Technology Review reports.