Comet Orbits
Comets live on highly eccentric orbits in the solar system
-- that's why they are comets!
(What would they be if they didn't live on highly eccentric orbits?)
The orbits (and thus periods) of comets often change significantly.
Why?
They come in two types:
-
Short-period comets (P
< 200 years)
-
Halley (P=76 years, next due 2062)
-
Tempel-Tuttle (P=32.9 years, next due 2030)
-
Enke (P=3.28 years, next due 2000)
Using this definition for short period comets, what is their
maximum distance from the Sun? It turns out to be about 70
AU. How do we get this number?
Short-period comets orbit pretty much in the ecliptic,
and are prograde.
-
Long-period comets (P
> 200 years)
-
Hyakutake (P=8000/14000 years)
-
Hale-Bopp (P=4000/2000 years)
So what is their maximum distance from the Sun?
Long-period comets don't orbit in the ecliptic; their
orbits are isotropic -- in all directions.
These are often the brightest and most impressive comets.
Why?
The orbits of comets suggest two
reservoirs for comets.