Maybe you think one Earth is enough. But
what if there were billions? Researchers make a new estimate that the number of
Earth-like planets in our Milky Way galaxy can reach as high as 6
Astronomers at the University of British
Columbia (UBC) analyzed data from NASA’s Kepler mission to
reach a stunning conclusion. The information on 200,000 stars was gathered by
planet-hunting spacecraft from 2009 to 2018.
The criteria used by the scientists for
selecting such a planet maintained it had to be rocky, about the same size as
Earth, and orbiting a star like our Sun. This planet also had to be in the
habitable zone of its star, where the conditions would be just right to
potentially allow for water and life.
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
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
To conduct the study, Kunimoto utilized a
technique known as ‘forward modeling,’ 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
While the scientists came up with an
impressive number of possible Earths, this likely doesn’t mean that’s how many
such planets there are and if they would have a life like ours. But this new
estimate definitely expands the possibility that similar planets are out there.
Check out the new study in The Astronomical Journal.