December 5, 2011: NASA’s Kepler mission has confirmed its first planet ( Kepler-22b ) in the “habitable zone,” the region where liquid water could exist on a planet’s surface
The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our sun. The planet is about 2.4 times the radius of Earth. Scientists don’t yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets.
December 20, 2011: NASA in telephonic conference just announced, Kepler space telescope has found two new Earth-sized planets orbiting a distant sun-like star, and the researchers who made the find say these two are the size of Earth or smaller.
The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet’s surface, but they are the smallest exoplanets ever confirmed around a star like our sun.
This chart compares artist’s concept images of the first Earth-size planets found around a sun-like star to planets in our own solar system, Earth and Venus. Image credit: NASA/Ames/JPL-Caltech
Kepler-20e is slightly smaller than Venus, measuring 0.87 times the radius of Earth. Kepler-20f is a bit larger than Earth, measuring 1.03 times its radius. Both planets reside in a five-planet system called Kepler-20, approximately 1,000 light-years away in the constellation Lyra.
Kepler-20e orbits its parent star every 6.1 days and Kepler-20f every 19.6 days. These short orbital periods mean very hot, inhospitable worlds. Kepler-20f, at 800 degrees Fahrenheit, is similar to an average day on the planet Mercury. The surface temperature of Kepler-20e, at more than 1,400 degrees Fahrenheit, would melt glass. Read entire article nasa.gov/mission