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TY - JOUR AU - Williams, Darren M. AU - Kasting, James F. AU - Wade, Richard A. PY - 1997 DA - 1997/01/01 TI - Habitable moons around extrasolar giant planets JO - Nature SP - 234 EP - 236 VL - 385 IS - 6613 AB - Possible planetary objects have now been discovered1–9 orbiting nine different main-sequence stars. These companion objects (some of which might actually be brown dwarfs) all have a mass at least half that of Jupiter, and are therefore unlikely to be hospitable to Earth-like life: jovian planets and brown dwarfs support neither a solid nor a liquid surface near which organisms might dwell. Here we argue that rocky moons orbiting these companions could be habitable if the planet–moon system orbits the parent star within the so-called 'habitable zone'10, where life-supporting liquid water11 could be present. The companions to the stars 16 Cygni B and 47 Ursae Majoris might satisfy this criterion. Such a moon would, however, need to be large enough (>0.12 Earth masses) to retain a substantial and long-lived atmosphere, and would also need to possess a strong magnetic field in order to prevent its atmosphere from being sputtered away by the constant bombardment of energetic ions from the planet's magnetosphere. SN - 1476-4687 UR - https://doi.org/10.1038/385234a0 DO - 10.1038/385234a0 ID - Williams1997 ER -