Star cluster of White Dwarves, Hubble Telescope, file photo.
Photographer: AP Graphics Bank Copyright 2010 The Associated
Press. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed. International astronomers
say they have detected five possible planets circling a distant
star much like Earth's sun -- and that one of those planets is
apparently in the famed "habitable zone" where water could exist
on its surface. Visible in the evening sky and only 12 light-
years from Earth, the star is called Tau Ceti. The astronomers
reported that they had combined more than 6,000 observations
from three telescopes to detect the system of "exoplanets." The
astronomers estimate that the five planets range from two to six
times the mass of Earth, making it a planetary system with the
lowest mass of any yet detected. The planet inside the habitable
zone -- where, if water exists, life could also be possible --
is only five times the mass of Earth, they calculate. The
telescopes used to