Kepler Discovers a System of Tiny Planets   
       
   Feb. 20, 2013:  NASA's Kepler mission scientists have discovered a new   
   planetary system that is home to the smallest planet yet found around a star   
   similar to our sun.   
       
   http://tinyurl.com/b3oa623   
       
   An artist's concept of the new-found planet Kepler-37b. MoreThe planets are   
   located in a system called Kepler-37, about 210 light-years from Earth in the   
   constellation Lyra. The smallest planet, Kepler-37b, is slightly larger than   
   our moon, measuring about one-third the size of Earth. It is smaller than   
   Mercury, which made its detection a challenge.   
       
   The moon-size planet and its two companion planets were found by scientists   
   with NASA's Kepler mission to find Earth-sized planets in or near the   
   "habitable zone," the region in a planetary system where liquid water might   
   exist on the surface of an orbiting planet. However, while the star in   
   Kepler-37 may be similar to our sun, the system appears quite unlike the solar   
   system in which we live.   
       
   Astronomers think Kepler-37b does not have an atmosphere and cannot support   
   life as we know it. The tiny planet almost certainly is rocky in composition.   
   Kepler-37c, the closer neighboring planet, is slightly smaller than Venus,   
   measuring almost three-quarters the size of Earth. Kepler-37d, the farther   
   planet, is twice the size of Earth.   
       
   The first exoplanets found to orbit a normal star were giants. As technologies   
   have advanced, smaller and smaller planets have been found, and Kepler has   
   shown even Earth-size exoplanets are common.   
       
   "Even Kepler can only detect such a tiny world around the brightest stars it   
   observes," said Jack Lissauer, a planetary scientist at NASA's Ames Research   
   Center in Moffett Field, Calif. "The fact we've discovered tiny Kepler-37b   
   suggests such little planets are common, and more planetary wonders await as   
   we continue to gather and analyze additional data."   
       
   Kepler-37's host star belongs to the same class as our sun, although it is   
   slightly cooler and smaller. All three planets orbit the star at less than the   
   distance Mercury is to the sun, suggesting they are very hot, inhospitable   
   worlds. Kepler-37b orbits every 13 days at less than one-third Mercury's   
   distance from the sun. The estimated surface temperature of this smoldering   
   planet, at more than 800 degrees Fahrenheit (700 degrees Kelvin), would be hot   
   enough to melt the zinc in a penny. Kepler-37c and Kepler-37d, orbit every 21   
   days and 40 days, respectively.   
       
   "We uncovered a planet smaller than any in our solar system orbiting one of   
   the few stars that is both bright and quiet, where signal detection was   
   possible," said Thomas Barclay, Kepler scientist at the Bay Area Environmental   
   Research Institute in Sonoma, Calif., and lead author of the new study   
   published in the journal Nature. "This discovery shows close-in planets can be   
   smaller, as well as much larger, than planets orbiting our sun."   
       
   http://tinyurl.com/aexsy5y   
       
   This line up compares artist's concepts of the planets in the Kepler-37 system   
   to the Moon and planets in our own solar system. MoreThe research team used   
   data from NASA's Kepler space telescope, which simultaneously and continuously   
   measures the brightness of more than 150,000 stars every 30 minutes. When a   
   planet candidate transits, or passes, in front of the star from the   
   spacecraft's vantage point, a percentage of light from the star is blocked.   
   This causes a dip in the brightness of the starlight that reveals the   
   transiting planet's size relative to its star.   
       
   The size of the star must be known in order to measure the planet's size   
   accurately. To learn more about the properties of the star Kepler-37,   
   scientists examined sound waves generated by the boiling motion beneath the   
   surface of the star. They probed the interior structure of Kepler-37's star   
   just as geologists use seismic waves generated by earthquakes to probe the   
   interior structure of Earth. The science is called asteroseismology.   
       
   The sound waves travel into the star and bring information back up to the   
   surface. The waves cause oscillations that Kepler observes as a rapid   
   flickering of the star's brightness. Like bells in a steeple, small stars ring   
   at high tones while larger stars boom in lower tones. The barely discernible,   
   high-frequency oscillations in the brightness of small stars are the most   
   difficult to measure. This is why most objects previously subjected to   
   asteroseismic analysis are larger than the sun.   
       
   With the very high precision of the Kepler instrument, astronomers have   
   reached a new milestone. The star Kepler-37, with a radius just three-quarters   
   of the sun, now is the smallest bell in the asteroseismology steeple. The   
   radius of the star is known to 3 percent accuracy, which translates to   
   exceptional accuracy in the planet's size.   
       
   For information about the Kepler Mission, click here   
       
       
   Production editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   More Information   
   Ames is responsible for Kepler's ground system development, mission   
   operations, and science data analysis. NASA's Jet Propulsion Laboratory in   
   Pasadena, Calif., managed Kepler mission development.   
       
   Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler   
   flight system and supports mission operations with the Laboratory for   
   Atmospheric and Space Physics at the University of Colorado in Boulder.   
       
   The Space Telescope Science Institute in Baltimore archives, hosts and   
   distributes Kepler science data. Kepler is NASA's tenth Discovery Mission and   
   was funded by NASA's Science Mission Directorate at the agency's headquarters   
   in Washington.   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.9   
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