Now Entering The Exoplanet Catalog: Kepler-20e & Kepler-20f
Two Earth-Size Alien Planets, the Smallest Exoplanets Yet
Imaged Above: An artist’s rendering of the newfound alien planet Kepler-20e, which scientists say is smaller than Earth, at about 0.87 times the width of our planet. Credit: NASA/JPL-Caltech/T. Pyle
Two planets orbiting a star 950 light-years from Earth are the smallest, most Earth-size alien worlds known, astronomers announced today (Dec. 20). One of the planets is actually smaller than Earth, scientists say.
These planets, while roughly the size of our planet Earth, are circling very close to their star, giving them fiery temperatures that are most likely too hot to support life, researchers said. The discovery, however, brings scientists one step closer to finding a true twin of Earth that may be habitable.
“We’ve crossed a threshold: For the first time, we’ve been able to detect planets smaller than the Earth around another star,” said lead researcher François Fressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “We proved that Earth-size planets exist around other stars like the sun, and most importantly, we proved that humanity is able to detect them. It’s the beginning of an era.”
To discover the new planets, Fressin and his colleagues used NASA’s Kepler space telescope, which noticed the tiny dips in the parent star’s brightness when the planets passed in front of it, blocking some of its light (this is called the transit method). The researchers then used ground-based observatories to confirm that the planets actually exist by measuring minute wobbles in the star’s position caused by gravitational tugs from its planets.