"Long before it's in the papers"
May 09, 2012

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Light from “super-Earth” reported seen for first time

May 9, 2012
Courtesy of NASA Jet Propulsion Laboratory
and World Science staff

NASA’s Spitzer Space Tel­e­scope has de­tected light from a “su­per-Earth” plan­et be­yond our so­lar sys­tem for the first time, as­tro­no­mers re­port.

While that hefty world isn’t thought to be hab­it­a­ble, sci­ent­ists call the achieve­ment a his­tor­ic step to­ward the search for signs of life on oth­er plan­ets. The Spitzer craft “is pi­o­neer­ing the study of at­mo­spheres of dis­tant plan­ets and pav­ing the way for NASA’s up­com­ing James Webb Space Tel­e­scope to apply a si­m­i­lar tech­nique on po­ten­tially hab­it­a­ble plan­ets,” said Bill Danchi, Spitzer pro­gram sci­ent­ist at NASA Head­quar­ters in Wash­ing­ton.

As this artist's con­cept shows, a plan­et is hard to see in the glare of its par­ent star—when viewed in vis­i­ble light. But viewed in in­fra­red light, the plan­et stands out bet­ter. This is large­ly due to the fact that the plan­et's scorch­ing heat blaz­es with in­fra­red light. Even on our own bod­ies em­a­nate more in­fra­red light than vis­i­ble due to our heat. (Im­age cred­it: NA­SA/JPL-Caltech)

NASA’s Spitzer Space Telescope has detected light emanating from a “super-Earth” planet beyond our solar system for the first time, astronomers report. While the hefty world is not considered habitable, the achievement is seen as a historic step toward the eventual search for signs of life on other planets. The Spitzer craft “is pioneering the study of atmospheres of distant planets and paving the way for NASA’s upcoming James Webb Space Telescope to apply a similar technique on potentially habitable planets,” said Bill Danchi, Spitzer program scientist at NASA Headquarters in Washington. The planet, called 55 Cancri e, falls into a class of planets termed super Earths, which are heavier than our home world but lighter than giant planets like Neptune. It’s about twice as big and eight times as massive as Earth, and hugs its home star—55 Cancri—in such a tight orbit that its year lasts 18 hours. Spitzer and other telescopes previously studied the world by analyzing how the light from 55 Cancri changed as the planet passed in front of the star. In the new work, Spitzer measured how much infrared light comes from the planet itself. Infrared is a type of low-energy light that we feel as heat but cannot see. The results reveal the planet is likely dark, and its sun-facing side is more than 2,000 Kelvin (3,140 degrees Fahrenheit), hot enough to melt metal, researchers said. The new data, they added, fits with a prior theory that 55 Cancri e is a water world: a rocky core surrounded by a layer of water in a “supercritical” state where it is both liquid and gas, and topped by a blanket of steam. “It could be very similar to Neptune, if you pulled Neptune in toward our sun and watched its atmosphere boil away,” said Michaël Gillon of Université de Liège in Belgium, principal investigator of the research, which appears in the Astrophysical Journal. The 55 Cancri system is fairly close to Earth, 41 light-years away (a light-year is the distance light travels in a year). It has five planets, with 55 Cancri e the closest to the star and tidally locked, meaning one side always faces the star, just as the Moon is tidally locked to Earth. “When we conceived of [the Spitzer telescope] more than 40 years ago, exoplanets hadn’t even been discovered,” said Michael Werner, Spitzer project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Because Spitzer was built very well, it’s been able to adapt to this new field and make historic advances such as this.”