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. 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. "

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