nov 272012
 
Solar Systems Without Jupiters Mean Massive Comet Belts

  Using ESA’s Herschel space observatory, astronomers have discovered vast comet belts surrounding two nearby planetary systems known to host only Earth-to-Neptune-mass worlds. The comet reservoirs could have delivered life-giving oceans to the innermost planets. Artist impression of the debris disk and planets around the star known as Gliese 581, superimposed on Herschel PACS images [continue reading]