On Sep 1, 9:00*am, Pete Weber wrote:
On Wed, 29 Aug 2012 12:45:19 -0400, Yousuf Khan wrote:
http://www.wired.com/wiredscience/20...t-double-star/

Astronomers have published a study revealing that NASA’s
exoplanet-hunting Kepler telescope has spotted two planets orbiting two
suns for the first time.

The find proves that circumbinary planetary systems can not only form
in, but continue to withstand, the intense pressures exerted by a
binary star system — until now, astronomers had only been able to
identify binary star systems with one planet in orbit, a find that was
confirmed in 2011 when Kepler-16b was spotted.

“The presence of a full-fledged circumbinary planetary system orbiting
Kepler-47 is an amazing discovery,” commented Greg Laughlin, professor
of astrophysics and planetary science at the University of California,
in a press release. “These planets are very difficult to form using the
currently accepted paradigm, and I believe that theorists, myself
included, will be going back to the drawing board to try to improve our
understanding of how planets are assembled in dusty circumbinary
disks.”

They've found single planets orbiting double-stars before, now is the
first time they found two planets orbiting double-stars. Not sure why
the physics of this was considered so onerous before, but there you go.

* *Yousuf Khan

Earth-moon is a double planet

Very good point, as are most captured moons.

Could an existing solar system like ours capture a red dwarf without
causing too much trauma for the existing planets? (seem rather
unlikely, as even capturing another Jupiter mass would likely spell
the demise of most all planets of our inner solar system, although
outer planets [those past Saturn] may do just fine unless hit by
debris from inner planet collisions)