A recent study led by NASA and the SETI (Search for Extraterrestrial Intelligence) Institute made the most advanced estimate to date of the number of inhabitable planets in the galaxy: the number came to about 300 million.
While there are some indications that microscopic life may exist as far out in the Solar System as the clouds of Venus or the liquid ocean of Jupiter’s moon Europa, if the search extends to the far reaches of our galaxy, the possibilities multiply.
The study revealed that about half the stars that have a similar temperature to our sun (plus or minus up to 1,500 degrees Fahrenheit) may also have a rocky planet capable of supporting liquid water on its surface. At least four of these possibly habitable planets are within 30 light years. The closest is about 20 light years away, according to NASA.
Though this result is far from a final value, and water on a planet’s surface is only one of many factors to support life, it’s extremely exciting that we calculated these worlds are this common with such high confidence and precision
Steve Bryson, lead author of the study
The Drake Equation is the mathematical formula devised by astronomer Frank Drake in 1961, which calculates the number of intelligent civilizations capable of emitting radio waves from seven variables.
Although the result depends entirely on the relative values that each research assigns to it, the Equation serves as a basis for different astrobiology studies based on the estimation of worlds with potential for life.
This is the first time all the pieces have come together to provide a reliable measure of the number of potentially habitable planets in our galaxy
Jeff Coughlin, researcher at SETI and director of the Kepler Science Office
On this occasion, the researchers relied on rocky exoplanets with a size similar to Earth, which were in the habitability zone with respect to their star and therefore had the atmospheric and temperature conditions to harbor liquid water in their interiors.
They also looked for stars with an average lifetime similar to or longer than that of our Sun, so that their light and heat would maintain sufficient conditions for the development of simple forms of life that would not be threatened by the end of their star’s fuel.
We are one step closer on the long road to discovering whether we are alone in the cosmos
Jeff Coughlin, researcher at SETI and director of the Kepler Science Office
The authors of the study stated that of the 300 million, some are within a distance of less than 30 light years from the sun, a figure that, although it seems insurmountable for current technology, could allow us to know more about them in the future.
