SPACE – There are an estimated 300 million habitable planets in...

New research using data from the Kepler space telescope estimates that there could be as many as 300 million potentially habitable planets in our galaxy.

Some could even be quite close, with several likely within 30 light years of our Sun. The findings will be published in The Astronomical Journal and the research was a collaboration of scientists from NASA, the SETI Institute, and other organizations around the world.

“This is the first time that all the pieces have been put together to provide a reliable measure of the number of potentially habitable planets in the galaxy,” said co-author Jeff Coughlin, an exoplanet researcher at the SETI Institute and director of Kepler’s Office of Science. . “This is a key term in the Drake Equation, which is used to estimate the number of transmissible civilizations; we are one step closer on the long road to discovering whether we are alone in the cosmos.”

The Drake Equation is a probabilistic argument that details the factors to consider when estimating the potential number of technologically advanced civilizations in the galaxy that could be detected. The Drake Equation is also often seen as a roadmap for astrobiology and guides much of the research at the SETI Institute.

To develop a reasonable estimate, the researchers looked at exoplanets similar in size to Earth and therefore more likely to be rocky planets. They also observed so-called Sun-like stars, roughly the same age as our Sun and at roughly the same temperature. Another consideration for habitability is whether the planet could have the necessary conditions to support liquid water.

Previous estimates for determining the number of potentially habitable exoplanets in our galaxy were based largely on the planet’s distance from its star. This new research also considers how much light reaches the planet from its star, which would affect the likelihood that the planet can contain liquid water. To do this, the team examined not only Kepler data, but also data from the European Space Agency’s Gaia mission on how much energy the planet’s star emits.

By taking Kepler and Gaia data into account, the results better reflect the diversity of stars, solar systems, and exoplanets in our galaxy.

“Knowing how common different types of planets are is extremely valuable in designing upcoming exoplanet search missions,” said co-author Michelle Kunimoto, who worked on this paper after finishing her PhD in exoplanet occurrence rates at the University of British Columbia. and recently joined the Transiting Exoplanet Survey Satellite, or TESS, team at the Massachusetts Institute of Technology. “Surveys targeting small, potentially habitable planets around Sun-like stars will rely on results like these to maximize their chances of success.”

More research will be needed to understand the role of a planet’s atmosphere in its ability to support liquid water. In this analysis, the researchers used a conservative estimate of the effect of the atmosphere to estimate the appearance of Sun-like stars with rocky planets that could have liquid water.

The Kepler mission, which officially stopped collecting data in 2018, has identified more than 2,800 confirmed exoplanets, with several thousand more candidates waiting to be confirmed. So far, researchers have identified several hundred planets in their star’s habitable zone in the Kepler data.