At Last! First Real Evidence for an Earth-Like Planet Outside our Solar System
Hadley Leggett, WIRED: There’s finally proof that Earth-like planets can exist outside our solar system: Scientists have managed to measure the mass of exoplanet COROT-7b, revealing that it’s the first exoplanet with a confirmed density similar to our own.
“This is a day we’ve been waiting for for a long time,” said exoplanet researcher Sara Seager of the Massachusettes Institute of Technology, who was not involved in the research. “It’s the first definitive rocky world beyond our solar system, and it’s opening a new gate for our research. We’re really, really excited about it.”
When astronomers discovered COROT-7b in February, they couldn’t determine its mass because they didn’t have precise enough measurements of the velocity of its star. Now, using 70 hours of observation data from the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph, scientists from the European Southern Observatory have calculated that the exoplanet is only about five times more massive than Earth.
Combined with the planet’s known radius, which is almost twice that of Earth, the new mass measurement makes COROT-7b the first exoplanet with a known density similar to Earth’s.
Most exoplanets are gaseous giants that resemble Jupiter or Neptune. But if extraterrestrial life exists in the universe, Seager said we’re most likely to find it on a small, rocky exoplanet with a density similar to Earth. “The holy grail in exoplanets, and maybe in all of science, is to find another planet like Earth, a planet that has signs of life on it,” she said.
