• Astronomers provided an estimated regarding the possible number of Earth-like exoplanets in the galaxy
  • The astronomers used the data collected by NASA's Kepler Space Telescope for their study
  • There could be 0.18 Earth-like exoplanets per Sun-like star in the Milky Way

A team of astronomers was able to provide an estimate regarding the possible number of exoplanets that have Earth-like qualities within the Milky Way Galaxy. The astronomers based their findings on the data collected by NASA’s exoplanet-hunting mission, Kepler.

The new study about Earth-like exoplanets was carried out by astronomers from the University of British Columbia. They presented their findings through a new paper published in The Astronomical Journal.

According to the astronomers, in order to be considered Earth-like, an exoplanet must have a rocky surface and should be about as big as Earth. Also, similar to the blue planet, Earth-like exoplanets orbit Sun-like stars known as G-types within the Goldilocks zone. This zone refers to a range of distances that is not too far or too close to the host star.

By orbiting within the Goldilocks zone, Earth-like exoplanets could have the ideal environmental conditions to support liquid water.

Earth-like planets have been the focus of various exoplanet-hunting missions due to their potential to be habitable. In order to find Earth-like exoplanets, astronomers start by looking for G-type stars.

According to studies, there are about 400 billion stars within the galaxy, with 7% of them being G-types. Initial reports indicated that there are roughly 0.02 Earth-like exoplanets per Sun-like star.

After going through the data collected by NASA’s Kepler Space Telescope, which mainly focused on finding Earth-like alien worlds, astronomers were able to provide an updated estimate regarding the number of exoplanets orbiting G-type stars.

Instead of 0.02, the astronomers estimated that there could actually be 0.18 Earth-like planets per G-type star. This means that there could be about six billion Earth-like exoplanets within the galaxy.

As noted by the astronomers, having an accurate estimate regarding the number of Earth-like exoplanets in the Milky Way could guide future missions.

“My calculations place an upper limit of 0.18 Earth-like planets per G-type star,” Michelle Kunimoto, co-author of the study, said in a statement. “Estimating how common different kinds of planets are around different stars can provide important constraints on planet formation and evolution theories, and help optimize future missions dedicated to finding exoplanets.”

Exoplanet GJ180
Picture: Artist's illustration of "super Earth" GJ180 in orbit around a nearby red dwarf. Robin Dienel/Carnegie Institution of Science