Scientists Spot Smallest Planet Ever Seen Exoplanet Kepler-37b is the size of our moon By Matt Cantor, Newser User Posted Feb 21, 2013 6:52 AM CST 37 comments Comments This image provided by NASA shows an artist rendering of the newfound planet known as Kepler-37b. (AP Photo/NASA/Ames/JPL-Caltech) (Newser) – Scientists have discovered the smallest known planet, just a third of the size of the Earth. Mercury, the smallest in our solar system, is two-fifths Earth's size, the AP notes; the new discovery, Kepler-37b, is a far-off exoplanet. "This research shows for the first time that other stellar systems host planets much smaller than anything in our solar system," says a scientist. The ability to spot this planet—via the Kepler telescope—suggests researchers are now capable of finding distant Earth-like planets, Sky News notes. But don't pack your bags just yet: The new planet is pretty close to its sun-esque star, resulting in rather balmy 700-degree temps on its surface. Further making life inhospitable: No atmosphere or water. Still, "this new discovery raises the specter that the universe is jampacked, like jelly beans in a jar, with planets even smaller than Earth," says one expert.