The universe is getting just a little bit smaller now that scientists have confirmed the existence of the closest known rocky exoplanet to Earth. HD 219134b is located 21 light-years away, NASA announced Thursday. If Earth were the star of its own sitcom, then HD 219134b would be the weird neighbor who keeps popping up over the fence to zing one-liners.
Telescopes can't see the planet directly, but it transit across the star it orbits, causing a dimming of the star's light. This weakened light is what tipped scientists off to the planet's existence. It was confirmed with observations from NASA's Spitzer Space Telescope, and a study on the findings was just accepted for publication by the Astronomy & Astrophysics journal.
HD 219134b is 1.6 times the size of Earth. It's rocky and falls into the super-Earth category of planets that have a mass greater than our planet, but that are lighter than gas giants like Jupiter.
"Thanks to NASA's Kepler mission, we know super-Earths are ubiquitous in our galaxy, but we still know very little about them," said study co-author and Spitzer scientist Michael Gillon. "Now we have a local specimen to study in greater detail. It can be considered a kind of Rosetta Stone for the study of super-Earths."
Compare the relatively close distance of HD 219134b with the 1,400 light-years between us and, a near-Earth-size planet that made news last week. Scientists don't know if the new Kepler discovery can support life, but they know HD 219134b is too close to its star for us to consider setting up a colony there. It may well have active volcanoes and a partially molten surface.
While you can't look out and spot the exoplanet, you can see its star with the naked eye when conditions are right. Look near the North Star and the Cassiopeia constellation, then follow NASA's map to find it.