"dreamer" wrote in message
m...
Outer edges of our solar system were disturbed by passing star, may
contain more bodies out there-
http://www.spaceflightnow.com/news/n0412/01passingstar/

Didn't Ahad say something similar in his Oort cloud mission to Alpha
Cen back in August:

"From a dynamical perspective, as predicted by Isaac Newton's well
known gravity equation:

F=G(m1*m2)/r^2

the Sun's sphere of influence reaches well beyond the distance of
Alpha Centauri.

The Sun's gravitational sphere of influence ends when the
infuence of other bodies becomes greater than its own. What's
the density of stars in the neighborhood of the Sun? It's
roughly 25 star systems in a volume of roughly 10,000 cubic
light years. So we have about 13.6 cubic light years per star
on average. Mean distance between stars will be given by the
cube root of the volume per star, or about 7.2 light years.

Assuming an average mass for the stars, then the gravitational
sphere of influence won't extend past the halfway point to the
next star. So in our stellar neighborhood the radius of the
sphere of influence will be about 3.6 ly, which is not quite as
far as Alpha Centauri at 4.3 ly.

Add to this the fact that the Sun has made some 20
revloutions around the Milky Way galaxy since its formation [4,500
million years (age) / 225 million years (galactic rotation period)]
and within that time, it is certain to have passed through dense gas
clouds, star and planet forming regions, brushing the outer edges of
proto-planetary disks of other stars, attracting and shedding swarms
of comets... There is every reason to be hopeful of swarms of comets
existing much further out than those within current detection range of
our instruments. "

The above seems to assume that the rest of the galaxy is motionless
while the Sun sails through it. The stars and other contents of the
local volume of space surrounding the Sun can have similar periods
of revolution around the galactic core, and so it is possible that
the Sun takes its environment with it as it goes. Now, this is not
necessarily true, but it is possible. Declaring that "it is certain
to havbe passed through dense gas clouds, star and planet forming
regions,..." seems to be taking a bit of a leap.


This quote from:
http://uk.geocities.com/aa_spaceagen...ropulsion.html