  Some large trans-Neptunian objects could be formed by the compression of
rarefied dust condensations, but not by the accumulation of smaller
planetesimals. A considerable portion of near-Earth objects could have come
from the trans-Neptunian region. Our runs of the evolution of thousands orbits
of Jupiter-family comets under the gravitational influence of planets showed
that former Jupiter-family comets collide with the terrestrial planets mostly
from orbits with aphelia located deep inside Jupiter's orbit.
