[meteorite-list] Stardust Flyby Images of Comet Wild 2

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:00 2004
Message-ID: <200401081610.IAA06329_at_zagami.jpl.nasa.gov>

>
> I know I should research this myself but I hope I can get a relatively brief
> answer upon which I can look further into this question if deemed worthwhile.
> How does a small object like a comet, especially, travel for billions of
> years constantly venting and releasing matter continue to exist? Why doesn't
> it dissipate into virtual nothingness?
>

Some comets have been observed to split apart. SOHO has observed many of the sun grazers
to fall apart entirely. But not all comets will just disappear. They'll eventually
lose all of their volatiles and become a burnt-out comet. At that point they will
resemble an asteroid. There are a few asteroids that we suspect to be former comets -
they are in very elongated orbits, but have not formed a tail.

Comet Wild 2 is considered to be a 'fresh' comet. It has been in the inner
solar system for only about 30 years. Prior to 1974, Comet Wild 2 was in a distant orbit
that crossed the orbits of Jupiter and Uranus. A close flyby of Jupiter in September 1974
radically perturbed its orbit closer to the Sun. Its orbits now
crosses the orbit of Mars at perihelion and the orbit at Jupiter at aphelion.
Being closer to the Sun means it now a much brighter object, and Paul Wild
discovered the comet in 1978.

Ron Baalke
Received on Thu 08 Jan 2004 11:10:02 AM PST