Kepler Discovers a Tiny Solar System   
       
   Jan. 11, 2012:  Astronomers using data from NASA's Kepler mission have   
   discovered the three smallest planets yet detected orbiting a star beyond our   
   sun. The planets orbit a single star, called KOI-961, and are 0.78, 0.73 and   
   0.57 times the radius of Earth. The smallest is about the size of Mars.   
       
   "This is the tiniest solar system found so far," said John Johnson, the   
   principal investigator of the research from NASA's Exoplanet Science Institute   
   at the California Institute of Technology in Pasadena. "It's actually more   
   similar to Jupiter and its moons in scale than any other planetary system. The   
   discovery is further proof of the diversity of planetary systems in our   
   galaxy."   
       
   http://www.nasa.gov/mission_pages/kepler/multimedia/images/mini-planetary-sys   
   tem.html   
       
   This artist's concept depicts an itsy bitsy planetary system -- so compact, in   
   fact, that it's more like Jupiter and its moons than a star and its planets.   
   Astronomers using data from NASA's Kepler mission and ground-based telescopes   
   recently confirmed that the system, called KOI-961, hosts the three smallest   
   exoplanets known so far to orbit a star other than our sun.     
   All three planets are thought to be rocky like Earth, but orbit close to their   
   star. That makes them too hot to be in the habitable zone, which is the region   
   where liquid water could exist. Of the more than 700 planets confirmed to   
   orbit other stars -- called exoplanets -- only a handful are known to be rocky.   
       
   "Astronomers are just beginning to confirm thousands of planet candidates   
   uncovered by Kepler so far," said Doug Hudgins, Kepler program scientist at   
   NASA Headquarters in Washington." Finding one as small as Mars is amazing, and   
   hints that there may be a bounty of rocky planets all around us."   
       
   Kepler searches for planets by continuously monitoring more than 150,000   
   stars, looking for telltale dips in their brightness caused by crossing, or   
   transiting, planets. At least three transits are required to verify a signal   
   as a planet. Follow-up observations from ground-based telescopes also are   
   needed to confirm the discoveries.   
       
   The latest discovery comes from a team led by astronomers at the California   
   Institute of Technology in Pasadena. The team used data publicly released by   
   the Kepler mission, along with follow-up observations from the Palomar   
   Observatory, near San Diego, and the W.M. Keck Observatory atop Mauna Kea in   
   Hawaii. Their measurements dramatically revised the sizes of the planets from   
   what originally was estimated.   
       
   The three planets are very close to their star, taking less than two days to   
   orbit around it. The KOI-961 star is a red dwarf with a diameter one-sixth   
   that of our sun, making it just 70 percent bigger than Jupiter.   
       
   http://www.nasa.gov/mission_pages/kepler/multimedia/images/shrunk-planetary-s   
   ystem.html   
       
   'Honey I Shrunk the Planetary System': This artist's concept compares the   
   KOI-961 planetary system to Jupiter and the largest four of its many moons.   
   Image credit: NASA/JPL-Caltech   
       
   Red dwarfs are the most common kind of star in our Milky Way galaxy. The   
   discovery of three rocky planets around one red dwarf suggests that the galaxy   
   could be teeming with similar rocky planets.   
       
   "These types of systems could be ubiquitous in the universe," said Phil   
   Muirhead, lead author of the new study from Caltech. "This is a really   
   exciting time for planet hunters."   
       
   For more information about the Kepler mission, visit: http://www   
   nasa.gov/kepler   
       
       
   Production Editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   More Information   
       
   The discovery reported in this story follows a string of recent milestones for   
   the Kepler mission. In December 2011, scientists announced the mission's first   
   confirmed planet in the habitable zone of a sun-like star: a planet 2.4 times   
   the size of Earth called Kepler-22b. Later in the month, the team announced   
   the discovery of the first Earth-size planets orbiting a sun-like star outside   
   our solar system, called Kepler-20e and Kepler-20f.   
       
   For the latest discovery, the team obtained the sizes of the three planets   
   called KOI-961.01, KOI-961.02 and KOI-961.03 with the help of a well-studied   
   twin star to KOI-961, or Barnard's Star. By better understanding the KOI-961   
   star, they then could determine how big the planets must be to have caused the   
   observed dips in starlight. In addition to the Kepler observations and   
   ground-based telescope measurements, the team used modeling techniques to   
   confirm the planet discoveries.   
       
   Prior to these confirmed planets, only six other planets had been confirmed   
   using the Kepler public data.   
       
   Credits:  NASA's Ames Research Center manages 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 and 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   
   the Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded   
   by NASA's Science Mission Directorate at the agency's headquarters.   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.72   
    * Origin: NCS BBS (1:3828/7)