Kepler’s final survey has found 50 Earth-like planets

MOFFETT FIELD — What began as a trickle of new planet discoveries from the Kepler Space Telescope a decade ago has turned into a torrent: 2,335 verified sightings, with about 50 our size and shape that may orbit around the warm glow of stars like our own sun.

At a Monday morning news conference at NASA’s Ames Research Center, scientists released the final and most definitive tally from the prolific planet detector Kepler, which gazes into a slice of sky near the constellation Cygnus to detect the subtle dimming that occurs every time a planet passes in front of — or “transits” — its sun.

“Most stars have planets. Many of these planets are earth-like. A fair fraction are in the habitable zone,” said William Borucki, Kepler science principal investigator, recently retired, who devoted two decades to getting the Kepler project launched.

Yet these planetary systems are very diverse, he added.  “While our own solar system is not unique, it is pretty unusual.”

There are 4,034 planet “candidates,” awaiting confirmation.  Of 50 Earth-sized planets in the so-called “goldilocks zone” of habitability, 30 have been verified.

Kepler was launched into an orbit around the sun on March 6, 2009.  Its large survey mission ends on Sept. 30, replaced by a new approach to short-term searching called K2. Next year, a new and improved satellite, called TESS (Transiting Exoplanet Survey Satellite) will be launched.

The final catalog, presented by Susan Thompson of the SETI Institute, uses a new tool called Robovetter that improves accuracy.  Early on in the Kepler mission, each possible planet had to be confirmed manually.

This is the eighth release of the Kepler candidate catalog, gathered by reprocessing the entire set of data from Kepler’s observations during the first four years of its primary mission, according to NASA.  It enables scientists to determine what planetary populations– from rocky bodies the size of Earth, to gas giants the size of Jupiter– make up the galaxy’s planetary demographics.

At the conference, scientists lump the newly discovered planets into five categories: “Hot Jupiters,” “Cold Gas Giants,” “Lava Worlds,” “Ice Giants,” and — most promising — “Rocky Planets” like ours.

Additionally, results using Kepler data suggest two distinct size groupings of small planets. Both results have significant implications for the search for life. The final Kepler catalog will serve as the foundation for more study to determine the prevalence and demographics of planets in the galaxy, while the discovery of the two distinct planetary populations shows that about half the planets we know of in the galaxy either have no surface, or lie beneath a deep, crushing atmosphere– an environment unlikely to host life.

“We like to think of this study as classifying planets in the same way that biologists identify new species of animals,” said Benjamin Fulton, doctoral candidate at the University of Hawaii in Manoa, and lead author of the second study. “Finding two distinct groups of exoplanets is like discovering mammals and lizards make up distinct branches of a family tree.”

While Kepler has offered a pioneering look at the sky, surveying 200,000 stars, this is only a small piece of the celestial landscape, according to the scientists.

To cover the entire sky, 400 Keplers would be needed.

 

via NAIJA Society
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