Seven Earth-like planets found
The search for alien life in our galaxy took a big step forward with the discovery of seven Earth-like planets orbiting a small star just 40 light years away. The seven worlds are rocky like ours, warm enough to have surface water, and are similar in size to our own—ranging from 75_percent as massive as Earth to 10_percent heavier. NASA’s Spitzer Space Telescope detected them orbiting in a tight formation around Trappist-1, a dim, red dwarf star in the constellation Aquarius. Trappist-1 is about 1/12 the mass of the sun and roughly 6,000 degrees Fahrenheit cooler, but its seven planets are closer to the star than Mercury is to the sun. Three are within Trappist-1’s “Goldilocks zone”—the sweet spot where conditions would theoretically be suitable for liquid water and life. “This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life,” NASA astrophysicist Thomas Zurbuchen tells CNN.com. For alien-hunters this may be only the beginning: There are at least 200_billion stars in our galaxy, and this discovery suggests the Milky Way may harbor tens of billions of Earth-like planets—making extraterrestrial life seem quite likely. In coming years, researchers will use the James Webb Space Telescope, to be launched in 2018, to scrutinize Trappist-1’s seven “Earths,” analyzing their atmospheres for oxygen, methane, and other signs of biological activity. “Answering the question ‘Are we alone?’ is a top science priority,” says Zurbuchen.