We bring you the news that Kepler is the gift that keeps on giving. Although its mission ended, the data collected continues to be analyzed. A new paper in the Astronomical Journal estimates that there could be as many as 300 million potentially habitable planets in our galaxy, and some may even be as close as 30 light-years of the Sun.

Co-author Jeff Coughlin, an exoplanet researcher at the SETI Institute and Director of Kepler’s Science Office, stated: This is the first time that all of the pieces have been put together to provide a reliable measurement of the number of potentially habitable planets in the galaxy. This is a key term of the Drake Equation, used to estimate the number of communicable civilizations — we’re one step closer on the long road to finding out if we’re alone in the cosmos.

The Drake Equation uses probability to theorize how many technologically advanced civilizations might be in our galaxy. It is not a mathematical equation that can be solved, as we don’t know the statistical values for each variable, yet. Instead, we estimate those values as we get more and more data, something Kepler provided a lot of.

Per the press release: …the researchers looked at exoplanets similar in size to Earth and thus most likely to be rocky planets. They also looked at so-called Sun-like stars, around the same age as our Sun and approximately the same temperature. Another consideration for habitability is whether the planet could have the conditions necessary to support liquid water.

That all sounds familiar. What is new here is that the team also used data from the European Space Agency’s Gaia mission to understand how much energy a planet’s star emits, taking into account the amount of light hitting the exoplanets. The new results now give a better picture of the diversity of the stars, solar systems, and exoplanets we can find.

Next for the team is an analysis of the role a planet’s atmosphere plays in the ability of the exoplanet to support liquid water. As we continue to narrow in on what may be out there, we can narrow down the search for life beyond our solar system.

More Information

SETI Institute press release 

NASA Ames article 

“The Occurrence of Rocky Habitable Zone Planets Around Solar-Like Stars from Kepler Data,” Steve Bryson, Michelle Kunimoto et al., 2020, to appear in the Astronomical Journal (preprint on arxiv.org)