NASA reported that research from its retired Kepler space telescope, part of a planet-hunting mission, indicates our galaxy contains about 300 million potentially habitable planets, whose rocky surface is capable of supporting liquid and thus, nurture life.
“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,” said Steve Bryson, lead author of the study and a researcher at NASA’s Ames Research Center.
Researchers estimated that at least 50% and at most 75% of the stars in the Milky Way are similar in temperature to our Sun — that is, an infernal 816°C. Such stars could host life-supporting planets, or more precisely, exoplanets.
NASA defines exoplanets as planets that exist beyond our solar system. As of January 25 2021, there are 4331 confirmed exoplanets, whose existence has been validated by NASA using two or more discovery methods.
Kepler’s field of view covered 0.25% of the sky, the area that would be covered by your hand if you held it up towards the ether. However, the deceptively modest area helped scientists extrapolate significance of the mission’s data with regards to the rest of the Milky Way. Astronomers are continuing the study with TESS, the current planet-hunting telescope.
“To me, this result is an example of how much we’ve been able to discover just with that small glimpse beyond our solar system,” Bryson said. “What we see is that our galaxy is a fascinating one, with fascinating worlds, and some that may not be too different from our own.”
NASA said that the latest research differs from Kepler’s original mission, in its novel approach to habitability. In their estimations of occurrence rate, previous iterations of the study have ignored the relationship between the star’s temperature and the light it emits that is absorbed by the planet.
The new analysis, however, considers this star-planet relationship and offers a comprehensive understanding of whether a planet might support liquid water. NASA yielded such results by combining Kepler’s final dataset of planetary signals with data about each star’s energy output, which is sourced from the European Space Agency’s Gaia mission.
The data from Gaia revealed the amount of energy that falls on a planet from its host star based on the total amount of energy emitted in a certain area of the star over a certain time. Such information helped astronomers account for the diversity of stars and solar systems in our galaxy.
“We always knew defining habitability simply in terms of a planet’s physical distance from a star, so that it’s not too hot or cold, left us making a lot of assumptions,” said co-author Ravi Kopparapu of NASA’s Goddard Space Flight Center. “Gaia’s data on stars allowed us to look at these planets and their stars in an entirely new way.”
Wiki Production Code: A0514