At least 17 billion Earth-like planets across the Milky Way: study
Associated Press and National Post Staff | Jan 7, 2013 2:55 PM ET | Last Updated: Jan 7, 2013 5:45 PM ET
C. Pulliam & D. Aguilar (CfA)
This artist's illustration
represents the variety of planets being detected by NASA's Kepler
spacecraft. A new analysis has determined the frequencies of planets of
all sizes, from Earths up to gas giants. Key findings include the fact
that one in six stars hosts an Earth-sized planet in an orbit of 85 days
or less, and that almost all sun-like stars have a planetary system of
some sort
LONG BEACH, Calif. — Astronomers
hunting for Earth-like planets now have many places to look. A new
estimate released Monday suggested the Milky Way galaxy is home to at
least 17 billion planets similar in size to our planet.
It doesn’t mean all are potentially habitable, but the sheer number of Earth-size planets is a welcome starting point in the search for worlds like our own.
“Earths and super-Earths aren’t picky. We’re finding them in all kinds of neighbourhoods,” co-author Guillermo Torres of the Harvard-Smithsonian Center for Astrophysics said in a statement. The CfA was one of two teams working on the project.
The scientists determined that at least 50% of stars have an Earth-sized or larger planet in close orbit and that practically all stars have planets. It’s planets that are larger than Earth that are more rare. The teams determined that only about 5% of planets have gas giants, for example.
Scientists have yet to find a twin Earth — one that’s not only the right size, but also located in the so-called Goldilocks zone, a place that’s not too hot and not too cold where water might exist in liquid form.
Two independent groups came up with the new estimate after a fresh analysis of data gathered by NASA’s Kepler spacecraft, launched in 2009 to track down other Earths. The craft spots a planet when it passes in front of its star.
One team led by Francois Fressin of the Harvard-Smithsonian Center for Astrophysics estimated at least one in six stars has an Earth-size planet orbiting it. Using a different method, researchers at the University of California, Berkeley and University of Hawaii determined 17 percent of stars host planets that are one to two times the diameter of Earth.
“There is a list of astrophysical configurations that can mimic planet signals, but altogether, they can only account for one-tenth of the huge number of Kepler candidates. All the other signals are bona-fide planets,” said Fressin in a statement.
The findings were presented at the American Astronomical Society in Long Beach.
It doesn’t mean all are potentially habitable, but the sheer number of Earth-size planets is a welcome starting point in the search for worlds like our own.
“Earths and super-Earths aren’t picky. We’re finding them in all kinds of neighbourhoods,” co-author Guillermo Torres of the Harvard-Smithsonian Center for Astrophysics said in a statement. The CfA was one of two teams working on the project.
The scientists determined that at least 50% of stars have an Earth-sized or larger planet in close orbit and that practically all stars have planets. It’s planets that are larger than Earth that are more rare. The teams determined that only about 5% of planets have gas giants, for example.
Scientists have yet to find a twin Earth — one that’s not only the right size, but also located in the so-called Goldilocks zone, a place that’s not too hot and not too cold where water might exist in liquid form.
Two independent groups came up with the new estimate after a fresh analysis of data gathered by NASA’s Kepler spacecraft, launched in 2009 to track down other Earths. The craft spots a planet when it passes in front of its star.
One team led by Francois Fressin of the Harvard-Smithsonian Center for Astrophysics estimated at least one in six stars has an Earth-size planet orbiting it. Using a different method, researchers at the University of California, Berkeley and University of Hawaii determined 17 percent of stars host planets that are one to two times the diameter of Earth.
“There is a list of astrophysical configurations that can mimic planet signals, but altogether, they can only account for one-tenth of the huge number of Kepler candidates. All the other signals are bona-fide planets,” said Fressin in a statement.
The findings were presented at the American Astronomical Society in Long Beach.
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