For the first time, scientists have discovered Earth-sized planets around a sun-like star using NASA's Kepler space observatory. Although the planets are too hot for life as we know it — temperatures on the two new planets range from 800 to 1,400 degrees Fahrenheit — they are the smallest exoplanets found around a star similar to our own.
Named Kepler-20e and Kepler-20f, the two new planets zip around their parent star in 6.1 and 19.6 days, respectively. The two planets have three bigger sibling planets that orbit the star. Curiously, the more distant planets aren't necessarily larger like in our solar system, and this solar system follows an alternating pattern of big and small planets.
Researchers working on the Kepler observatory look for planets that transit, or move in front of, their stars. When a planet passes in front of a star, there's a small dip in the amount of light that reaches the observatory, allowing researchers to collect data on exoplanets' size and distance from their star. Other telescopes, like Hubble, are looking for exoplanets as well, but the Kepler observatory has the biggest camera ever launched into space. Scientists hope that it's only a matter of time before we find a planet that's not too hot and not too cold to support life.
"In the cosmic game of hide and seek, finding planets with just the right size and just the right temperature seems only a matter of time," said Natalie Batalha, Kepler deputy science team lead and professor of astronomy and physics at San Jose State University in a NASA press release. "We are on the edge of our seats knowing that Kepler's most anticipated discoveries are still to come."
For more information, see this press release from NASA's Jet Propulsion Laboratory.