NASA’s planet-hunting Kepler space telescope has delivered another headline-grabbing find: two alien worlds near the size of Earth closely orbiting a star about 950 light-years away. The planets’ surface temperatures are thought to be around 800 degrees Fahrenheit, probably too hot to support life. But scientists say their size is the key factor. "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,” researcher François Fressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., told Space.com. “It's the beginning of an era." Earlier this month, NASA scientists said they found another planet, Kepler-22b, just 600 light-years away where the average temperature may be around 72 degrees. That planet is 2.4 times as wide as Earth.