Three new planets found outside our solar system are the smallest exoplanets yet discovered—each of them tinier than Earth, astronomers announced today.
The tiny worlds are clustered around a red M-dwarf star called KOI-961 that is itself among the more diminutive stellar objects in the universe. The star is just a sixth as wide as our sun, or about 70 percent bigger than Jupiter.
"It's almost like you took your shrink gun and set it to seven and zapped the planetary system—the whole thing shrunk," said study co-author John Johnson, a researcher with NASA's Exoplanet Science Institute at the California Institute of Technology.
All three of the KOI-961 planets are thought to be rocky, like Earth and Mars. But they circle fairly close to their star, taking roughly two days to complete their orbits.
That means, even though the host star is dimmer than our sun, the planets are far too hot for liquid water—and thus life as we know it—to exist on their surfaces.
"The surface temperatures of these planets range from 720 Kelvin to 450 Kelvin [836°F to 350°F] ... so the coolest one is almost a factor of two too hot" to be habitable, Johnson said.
Still, the discovery hints that many more small, rocky planets exist across our Milky Way
galaxy.
To read more, click here.