Astronomers using the Kepler space telescope have detected 219 possible new exoplanets in our galaxy, including 10 relatively small, rocky and possibly habitable planets similar to our own, US space agency NASA announced Monday.
It revealed 10 new rocky, earth-sized planets that could potentially have liquid water and support life.
These are the last additions to the catalogue of exoplanets compiled during the first phase of the Kepler mission, when the space telescope scanned some 200,000 stars in the Cygnus constellation in an effort to find worlds beyond our own.
The Kepler mission team released a survey of 219 potential exoplanets - planets outside of our solar system - that had been detected by the space observatory launched in 2009 to scan the Milky Way galaxy.
Ten of the new discoveries were orbiting their suns at a distance similar to earth's orbit around the sun, the so-called habitable zone that could potentially have liquid water and sustain life.
The official catalogue now contains 4,034 total "candidates" - tiny blips in the data that are thought to signal the presence of a planet around a star. Of these, 49 fit squarely into their star's "habitable zone", that region where liquid water can pool on the surface and life may be able to thrive.
The Kepler space telescope was launched into orbit around the sun in 2009. Its chief mission was to take a census of a small slice of the Milky Way in an effort to understand the "demographics" of our galaxy, and answer questions like: How many stars are like our sun? How many of those host planets? How many planets orbit in the habitable zone? Is there any place else in this vast universe that living beings might call home?
In its first four years, Kepler surveyed just .025 percent of the sky. And for every potential planet detected, NASA estimates that 100 to 200 lurk beyond the telescope's reach. Given a little time and some sophisticated models, scientists will use the Kepler catalogue to estimate how many stars in our galaxy could host an "Earth 2.0."
This is the eighth update of the Kepler planet catalogue and the most thorough survey of the space telescope's data to date. Of the 4,034 candidates, more than half have already been confirmed as exoplanets and not the result of miscalculations or false signals. Kepler research scientist Susan Thompson, the lead author of the catalogue study, said her team is confident about all 10 of the new "earth-like" planets found in their stars' habitable zones.
Several of these planets orbit G dwarfs - the same species of star as our own sun. And one, dubbed KOI 7711 (for Kepler Object of Interest), is a possible "earth twin", a rocky world just 30 times bigger than our own and roughly the same distance from its star.
A second research group combined the Kepler data with measurements from ground-based telescopes to calculate the approximate sizes and compositions of 2,000 exoplanets. They found that smaller worlds, the kind that Kepler was designed to detect, fall into two distinct groups: rocky planets that could be up to 1.75 times the size of our own, called "super-earths," and gaseous "mini-Neptunes", which lack a solid surface and are 2 to 3 times bigger than earth. Nearly every star surveyed hosted a planet in one of these two categories. But, curiously, no planets straddled the divide. Each world was either smaller and rocky, or larger and gassy.
Kepler's original mission ended in 2013 when one of the wheels that helped to keep the spacecraft pointed toward the Cygnus constellation failed, so it could no longer scan the same small slice of sky. But by using pressure from light particles from the sun to stay oriented, the telescope has been refashioned for a second exoplanet search project called K2. NASA estimates the telescope has enough fuel to remain active into 2018.
By then, the space agency hopes to be ready to launch the Transiting Exoplanet Survey Satellite, which will search for small planets around the brightest stars in the sky, and the James Webb Space Telescope, which is designed to detect atmospheres on other planets. The results from Kepler, that new satellite and the Webb will inform the next generation of telescopes - ones that can actually take pictures of planets in motion around distant stars.