Post by pv+ (PV)The Kuiper belt is also home to Pluto and some dozens of other larger dwarf
planets. There's some comets out there, but comets mostly come from
farther out, as you say. If I remember right, the Kuiper belt objects have
very, very regular orbits - an object there is only going to become a
comet if it interacts with an Oort cloud object as it zips by. *
Actually Kuiper Belt objects (and Oort Cloud objects), while they have
stable orbits, are generally not very regular. That's why Pluto's
atmosphere freezes and falls back to the planet periodically (it
almost becomes a type of comet itself), and while it was still a
planet it would "trade" places with Neptune as being the farthest
planet out - during certain parts of the orbit Pluto's irregular orbit
will dip inside Neptune's regular one :). They still generally stay
out where they need to be though. It's the small interactions with
each other that can send them spinning into the inner solar system.
Both the Kuiper Belt and Oort Cloud are responsible for many comets
though. The Kuiper Belt is the source of "short period" comets (the
ones that swing by every few years), whereas the Oort Cloud, being
much futher out, is the main source of "long period" comets such as
Hale-Bopp. Generally though, the Kuiper Belt will supply numerically
more, as it's comets evaporate more quickly (because of the higher
frequency of their trips close to the sun), so to maintain significant
presence they must be "refreshed" more often. One the flip side, the
more "famous" comets will typically come from the Oort Cloud since
given their longer periods, they typically have not weathered as much
and are much brighter.
The Kuiper Belt is also the most massive (~30 Earth masses compared to
~5 Earth masses for the Oort Cloud), which would explain it's excess
of material to be throwning inward :).
Mike