Little Pluto

In message , Tom Kerr
writes
In article , David Knisely
wrote:
You posted:

Comets must approach the Sun to about the distance of Mars' orbital
path (~1.5 AU) before the Sun's heat is enough for sublimation to
begin and a coma and tail to form.

Actually, the comae begin to form at almost twice this distance (inside
of 2.8 A.U.). See INTRODUCTION TO PLANETARY GEOLOGY by Billy Glass.
Clear skies to you.

Although this depends on the amount of volatiles in the comet. For instance,
Hale-Bopp was clearly active (i.e., had a coma and tail) when it was
discovered at ~7 AU, and pre-discovery images showed it had a coma at 13 AU.
This is believed due to volatiles (e.g., CO) trapped in the ice.

Chiron (asteroid 2060 but arguably a comet) has also been seen to show
outgassing.
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In article , wrote:
In message , Tom Kerr
writes
In article , David Knisely
wrote:
You posted:

Comets must approach the Sun to about the distance of Mars' orbital
path (~1.5 AU) before the Sun's heat is enough for sublimation to
begin and a coma and tail to form.

Actually, the comae begin to form at almost twice this distance (inside
of 2.8 A.U.). See INTRODUCTION TO PLANETARY GEOLOGY by Billy Glass.
Clear skies to you.

Although this depends on the amount of volatiles in the comet. For instance,
Hale-Bopp was clearly active (i.e., had a coma and tail) when it was
discovered at ~7 AU, and pre-discovery images showed it had a coma at 13 AU.
This is believed due to volatiles (e.g., CO) trapped in the ice.

Chiron (asteroid 2060 but arguably a comet) has also been seen to show
outgassing.

Absolutely, although I'm sure people will argue that Chiron isn't a good
example of a comet. However, I think comet 46P/Wirtanen also became active
beyond 3 AU from the sun (3 AU being the canonical value for comet
activity).

It's clear that the abundance of more volatile species trapped in water ices
will have an effect on cometary activity, but it's only something we can
start to study these days, given the techniques and equipment required to do
this are recent. What's clear from both observations of comets and ices in
the interstellar medium is that volatiles are often abundant and that you
can't use water ice alone to predict cometary activity.

Hi All Cometary activity(nice term) Did Man copy comets in the way
they sling shot. Does the main ball of the comet spin? I read there is a
comet that swings around the sun every 1500 years. Does this comet come
from the Oort belt? I read in one of these posts the comet has ion type
materials. That means it has a positive charge.The sun's solar wind I
think has positive charged particles(protons) that could make for an
interesting theory,for it could give another reason why comets miss the
sun,and have their tails always facing away from the sun. Coming around
the sun(sling shot) how fast is say "Halley's" comet going? I can see
in about 50 years man making use of comets,even making man made comets.
Bert