Rocky exoplanet milestone in hunt for Earth-like worlds
"This report... will be marked as among the most profound scientific discoveries in human history”
- Geoffrey Marcy University of California Berkeley
Astronomers have discovered the smallest planet outside our solar system, and the first that is undoubtedly rocky like Earth.
"We want to know if we're alone in the galaxy, simply put - and this is one link in the chain toward getting to that objective."
With the size of the host star, the details of the planet's and star's mutual dance, and the planet's radius, the density of the planet can be calculated.
"All of our very best capabilities have converged on this one result and they all converge to form a picture of this planet," said Natalie Batalha, a San Jose State University professor of astrophysics who helps lead the Kepler science mission for Nasa.
She told BBC News that the result was unique in an ever-expanding field of exoplanet discoveries, with smaller and smaller exoplanets discovered as experimental methods improve.
"We're always pushing down toward smaller and less massive, so it's natural that we're arriving there," she said.
"But perhaps what's not so natural is that we've pinned down the properties of this planet with such fantastic accuracy that we're able to say without a doubt that this is a rocky world, something that you could actually stand on."