The Earth's galaxy is looking far more crowded. NASA has confirmed a “bonanza” of 715 newly discovered planets outside the solar system.
The discoveries, by scientists using the Kepler telescope, pushed the number of known planets in the galaxy to about 1,700. Twenty years ago, astronomers had not found any planets circling stars other than the ones revolving around the sun.
"What we have been able to do with this is strike the mother lode, get a veritable exoplanet bonanza," Jack Lissauer, a planetary scientist at NASA, said.
"We have almost doubled just today the number of planets known to humanity," he said.
The 715 newly verified “exoplanets”, as planets outside our solar system are known, are orbiting 305 different stars. All of them are in systems like ours where multiple planets circle a star. They were nearly all in size closer to Earth than relatively gigantic Jupiter.
Douglas Hudgins, NASA's exoplanet exploration program scientist, called Wednesday's announcement a major step toward Kepler's ultimate goal: "finding Earth 2.0."
The discoveries indicate that "small planets are extremely common in our galaxy,'' said MIT astronomer Sara Seagar. "Nature wants to make small planets."
In general, smaller planets are more likely to be able to harbor life than big ones, Lisa
Kaltenegger, a Harvard and Max Planck Institute astronomer said.
Not much is known about the composition of these planets and whether they would truly have the conditions that would support life, such as a rocky surface, water and a distance from their stars that leaves them neither too hot nor too cold.
Only four of the new exoplanets orbit their stars in "habitable zones" where it is not too hot or not too cold for liquid water to exist. The four are all at least twice as big as Earth so that makes them more likely to be gas planets instead of rocky ones like Earth – and less likely to harbor life.
Planets in the habitable zone are likely to be farther out from their stars because it is hot close in. And planets farther out take more time orbiting, so Kepler has to wait longer to see it again.
So far Kepler has found nine exoplanets in the habitable zone, NASA said. Astronomers expect to find more when they look at all four years of data collected by Kepler. So far, they have looked at two years.
Kepler was launched in March 2009, The discoveries announced Wednesday were all initially detected in the first two years of Kepler's observations, from 2009 to 2011, and confirmed with the new statistical method.
Now crippled, Kepler lost the use of two of the reaction wheels that helped keep it precisely oriented last year.
(FRANCE 24 with AP, AFP)
Date created : 2014-02-27