6 billion planets like Earth? Scientists make stunning estimate
Astronomers do new research using data from NASA’s Kepler space telescope. According to the researchers, there could be as many as six billion Earth-like planets in our galaxy alone. The scientists looked for worlds that could sustain life.
Maybe you think one Earth is enough. But what if the number was in the billions? According to new research, the number of Earth-like planets in our Milky Way galaxy could approach 6 billion.
Astronomers at the University of British Columbia (UBC) used data from NASA’s Kepler spacecraft to reach the astonishing conclusion. From 2009 to 2018, the Kepler planet-hunting spacecraft collected data on 200,000 stars.
The scientists’ criteria for picking such a planet included that it had to be rocky, around the same size as Earth, and orbiting a star like our Sun. This planet had to be in the habitable zone of its star, where the conditions would be ideal for water and life to exist.
UBC researcher Michelle Kunimoto, who co-authored the new study, and previously discovered 17 new planets (“exoplanets”) outside our Solar System, said their calculations “place an upper limit of 0.18 Earth-like planets per G-type star.” In other words, that’s about 5 planets per Sun.
The study’s co-author UBC astronomer Jaymie Matthews put this from another perspective, explaining that “Our Milky Way has as many as 400 billion stars, with seven percent of them being G-type. That means less than six billion stars may have Earth-like planets in our Galaxy.”
To conduct the study, Kunimoto utilized a technique known as ‘forward modelling,’ which allowed her to overcome the issue that Earth-like planets are hard to spot on account of being small and orbiting far from their star.
“I started by simulating the full population of exoplanets around the stars Kepler searched,” expounded the researcher in UBC’s press release. “I marked each planet as ‘detected’ or ‘missed’ depending on how likely it was my planet search algorithm would have found them. Then, I compared the detected planets to my actual catalogue of planets. If the simulation produced a close match, then the initial population was likely a good representation of the actual population of planets orbiting those stars.”
While the scientists came up with an astounding number of possible Earths, this does not necessarily imply the number of such planets or whether they would support life comparable to ours. But this new estimate definitely expands the possibility that similar planets are out there.
Check out the new study in The Astronomical Journal.