php require("/home/jeffery/public_html/astro/comet/comet_orbits.html");?>
Caption
:
A cartoon of the
orbits
of
comets
. The
orbits
are all highly
elliptical orbits
.
Features:
Short-period comets
have
orbital periods
less than
200
years
and have
orbital planes
somewhat concentrated near the
ecliptic plane
. It is thought that
short-period comets
originate as
Kuiper Belt objects (KBOs)
that
astronomical perturbations
perturb into highly
elliptical orbits
.
Long-period comets
have
orbital periods
ranging from
200
years
to
thousands
of
years
and their
orbital planes
have a
spherically symmetric
distribution. It is thought that
long-period comets
originate as
Oort Cloud objects (OCOs)
that
astronomical perturbations
perturb into highly
elliptical orbits
.
The
Oort cloud
is a hypothetical
spherically symmetric
population of
rocky-icy bodies
extending from perhaps from
2000
AU
to 200,000
AU
from the
Sun
(see
Wikipedia: Oort cloud: Structure and composition
). No
OCO
has ever been detected since they are very hard to detect: they are very dim, tiny, slow-moving far-off
astronomical objects
.
The
Oort cloud
must exist to resupply
long-period comets
which can't live forever. A
long-period comet
evaporates all its
ices
after a few passes close to the
Sun
(i.e., a few
perihelions
) and eventually
impacts
some other
Solar System
astro-body
or, via a
gravitational assist
, is launched back into an
orbit
entirely beyond the
Neptune orbit
or ejected from the
Solar System
on an
escape trajectory
(AKA
escape orbit
): i.e., a
parabolic trajectory
or
hyperbolic trajectory
.
Credit/Permission:
©
David Jeffery
,
2004
/ Own work.
Image link:
Itself
.
Local file:
local link: comet_orbits.html
.
File:
Comet file
:
comet_orbits.html
.