NASA researchers involved with the Kepler mission to discover Earth-like planets orbiting other stars across the Milky Way Galaxy recently released their third catalog of new planet candidates discovered since the mission began nearly 3 years ago.
The Kepler observatory launched on March 7, 2009 atop a United Launch Alliance (ULA) Delta II rocket from Cape Canaveral Air Force Station (CCAFS) in Florida. Kepler, named after the 17th century German astronomer Johannes Kepler, is designed to survey a portion of our galaxy to detect Earth-sized planets orbiting other stars. More specifically, Kepler’s objective is to determine how common Earth-size planets are within the habitable zone (the region where liquid water could exist) relative to its star and determine whether or not planets similar to Earth are common in other star systems throughout the galaxy.
The Kepler research team recently released their third catalog containing 1,091 new planet candidates – identified from observations which took place from May 2009 to Sept. 2010. Prior to the release of this information, teams had identified 1,235 candidates within that same period of observation, bringing the total thus far - to 2,321. That number does not even include candidates that might be identified by the data from observations performed after Sept. 2010.
Kepler is discovering more and more possible planets every day and is proving that planets are common, very common, throughout our galaxy. The same probably holds true for the more than 170 billion galaxies across the observable universe.
Of the 2,000+ planet candidates identified to date by Kepler, more than 1,100 of them are smaller than twice Earth-size – an increase of 197 percent over the data identified in the second catalog released back in Feb. of 2011. Planets discovered which are larger than twice the size of Earth rose 52 percent. In addition, planet candidates whose orbit’s last longer than 50 days increased by 123 percent, compared to 85 percent for planets whose orbit’s are shorter than 50 days.
Forty-six planet candidates have been found in the habitable zones of their stars, and 10 of those 46 planets have been identified as roughly the same size as our Earth.
“With each new catalog release a clear progression toward smaller planets at longer orbital periods is emerging,” said Natalie Batalha, Kepler deputy science team lead at San jose State University in California. “This suggests that Earth-size planets in the habitable zone are forthcoming if, indeed, such planets are abundant.”
It’s also becoming clear that many stars across the Milky Way exist which host not one individual planet, but entire planetary systems much like our own solar system. Of the 1,790 stars found to date by Kepler with planets orbiting them, 365 of those stars are suns to more than one planet.
Data thus far suggests that 5.4 percent of all stars host Earth-size planets, and 17 percent of all stars host entire planetary systems.
Neighborhoods like our own solar system may not only exist, but are probably very common throughout the galaxy. It is expected that future observations will prove that the same holds true for Earth-size, and possibly Earth-like, planets – orbiting within the habitable zone of their stars and meeting the requirements for a world that could sustain life.
The Kepler mission is managed by NASA’s Ames Research Center in Moffett Field, CA. For more information: Kepler