Billions of Earth-like alien planets likely reside in our Milky Way galaxy, and the nearest such world may be just a stone’s throw away in the cosmic scheme of things, a new study reports.
Astronomers have calculated that 6 percent of the galaxy’s 75 billion or so red dwarfs — stars smaller and dimmer than the Earth’s own sun — probably host habitable, roughly Earth-size planets. That works out to at least 4.5 billion such “alien Earths,” the closest of which might be found a mere dozen light-years away, researchers said.
“We thought we would have to search vast distances to find an Earth-like planet,” study lead author Courtney Dressing, of the Harvard-Smithsonian Center for Astrophysics (CfA), said in a statement. “Now we realize another Earth is probably in our own backyard, waiting to be spotted.”
Kepler’s keen eye
Dressing and her team analyzed data gathered by NASA’s prolific Kepler space telescope, which is staring continuously at more than 150,000 target stars. Kepler spots alien planets by flagging the tiny brightness dips caused when the planets transit, or cross the face of, their stars from the instrument’s perspective.