Doesn't Pluto have an atmosphere?

I was under the impression that Pluto has a tenuous atmosphere. At
least, I remember back in the 90s when it was inside the orbit of
Neptune, there were Hubble photos of apparent cloud patterns. I
believe the explanation was it was an atmosphere primarily of
sublimation and not in equilibrium as Pluto does not have enough
gravity to sustain it.

It just seems logical to me that a "planet" should have an atmosphere.

1) Round by self-gravity
2) In orbit around the sun
3) Maintains an atmosphere

That would give us nine planets. Perhaps a few more KBOs would
qualify eventually?

"JackPeters" wrote in message
...
I was under the impression that Pluto has a tenuous atmosphere. At
least, I remember back in the 90s when it was inside the orbit of
Neptune, there were Hubble photos of apparent cloud patterns. I
believe the explanation was it was an atmosphere primarily of
sublimation and not in equilibrium as Pluto does not have enough
gravity to sustain it.

It just seems logical to me that a "planet" should have an atmosphere.

1) Round by self-gravity
2) In orbit around the sun
3) Maintains an atmosphere

That would give us nine planets. Perhaps a few more KBOs would
qualify eventually?

But that would probably exclude Mercury
http://sci.esa.int/science-e/www/obj...objectid=31275 as none of
its atmospheric components are 'trapped' as such by its gravity.

Mercury does have a slight Atmosphere composed of helium.

JackPeters wrote:
I was under the impression that Pluto has a tenuous atmosphere. At
least, I remember back in the 90s when it was inside the orbit of
Neptune, there were Hubble photos of apparent cloud patterns. I
believe the explanation was it was an atmosphere primarily of
sublimation and not in equilibrium as Pluto does not have enough
gravity to sustain it.

It just seems logical to me that a "planet" should have an atmosphere.

1) Round by self-gravity
2) In orbit around the sun
3) Maintains an atmosphere

That would give us nine planets. Perhaps a few more KBOs would
qualify eventually?

Unless I'm mistaken, Hubble (or anything else) has never been able to
image Pluto well enough to see cloud patterns. You're probably
referring to occultations of stars where one is able to briefly view a
star through Pluto's atmosphere.

There's lots to learn about Pluto and Charon. 2015 seems a long way
off. I think the IAU made the right decision and that doesn't make
Pluto any less interesting.

On Fri, 25 Aug 2006 19:50:15 +0100, "OG"
wrote:


"JackPeters" wrote in message
.. .

It just seems logical to me that a "planet" should have an atmosphere.

1) Round by self-gravity
2) In orbit around the sun
3) Maintains an atmosphere

That would give us nine planets. Perhaps a few more KBOs would
qualify eventually?

Since the demands of #3 are greater than #1, #1 could be dropped.

a few more KBOs? That is the problem they have already discovered
over 1000 KBOs and 783 of those have known orbits in the Kuiper Belt.
If every Pluto sized object was included as a planet WE WOULD HAVE 53
PLANETS AND CLIMBING. Do we want to include those 44 Plutos + 1
asteroid (Ceres) in the same league as the 8 Major Planets?

But that would probably exclude Mercury
http://sci.esa.int/science-e/www/obj...objectid=31275 as none of
its atmospheric components are 'trapped' as such by its gravity.

Mercury is big enough to have an atmosphere but impacting high-energy
photons and ions from the Sun stripped it away.

I guess is some ways the solar system is kind of like house values:
location, location, location. And I don't want 44+ Plutos to de-value
the other 8 (Major Planets). Dwarf Planets is a good title for them.

Pluto isn't even the largest Dwarf: Xena is.

-- Kevin Heider

West Coast Swing Photos at:
http://www.pbase.com/kheider

Kevin Heider wrote:
On Fri, 25 Aug 2006 19:50:15 +0100, "OG"
wrote:
snip

Do we want to include those 44 Plutos + 1
asteroid (Ceres) in the same league as the 8 Major Planets?

snip

Frankly, I don't care. I don't really care what they call them. They
are there regardless of what we think of them or name them. The whole
idea of "planet" is a cultural concept. What there are are thousands
of bodies of various sizes and compositions in orbit around the sun,
and they are all worthy of study.

This whole fiasco is a tempest in a teapot.

"Ed" wrote in message
ups.com...

Mercury does have a slight Atmosphere composed of helium.


The 'atmosphere' of Mercury is almost entirely a short term effect from
outgassing from surface rocks. I had a quick browse online and read
somewhere that it is so tenuous that the constituents of the atmosphere are
more likely to collide with the surface than other atoms, i.e. most
atomic/molecular paths are ballistic rather than 'random walk'.

A general description of atmospheres would include a requirement that one be
significantly held by the parent planet - but this is not the case for
Mercury. Were it not for outgassing there would not be an atmosphere.

Owen

wrote:

Frankly, I don't care. I don't really care what they call them. They
are there regardless of what we think of them or name them. The whole
idea of "planet" is a cultural concept. What there are are thousands
of bodies of various sizes and compositions in orbit around the sun,
and they are all worthy of study.

This whole fiasco is a tempest in a teapot.

Yes, but that's the primary activity of "pure" science: to discern
differences and then categorize and name things.

Ed T

ED T wrote:
Yes, but that's the primary activity of "pure" science: to discern
differences and then categorize and name things.

No--that is not the primary activity of science. (I don't know what
the term "pure" means in this context--do you mean exclusive of, say,
engineering?) The purpose of science is to find patterns in natural
phenomena, and to relate them to other natural phenomena.

We often call this latter activity "explaining," but in this context it
means something just a little different from what it means in casual
use. In particular, it excludes explanations of the "Just So" variety.
Such a "Just So" statement might be made, but it is not a categorical
statement of truth, rather an admission that we really don't understand
why things seem to act the way they do.

This whole business of categorizing and naming things is only an
ancillary purpose of science, being useful only to the extent that it
facilitates talking about the objects of study.

--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html

On 25 Aug 2006 13:47:04 -0700, "Don't Be Evil"
wrote:


JackPeters wrote:
I was under the impression that Pluto has a tenuous atmosphere. At
least, I remember back in the 90s when it was inside the orbit of
Neptune, there were Hubble photos of apparent cloud patterns. I
believe the explanation was it was an atmosphere primarily of
sublimation and not in equilibrium as Pluto does not have enough
gravity to sustain it.

It just seems logical to me that a "planet" should have an atmosphere.

1) Round by self-gravity
2) In orbit around the sun
3) Maintains an atmosphere

That would give us nine planets. Perhaps a few more KBOs would
qualify eventually?

Unless I'm mistaken, Hubble (or anything else) has never been able to
image Pluto well enough to see cloud patterns. You're probably
referring to occultations of stars where one is able to briefly view a
star through Pluto's atmosphere.

Yes, it probably was the occulation reports that I was remembering.
There were several occultations that set an upper limit on the
atmosphere of both Pluto and Charon in 90s and 00s. Also, Pluto and
Charon eclipsed each other for a while in the 80s.

The Hubble Faint Object Camera did image Pluto back in 1994. A polar
cap, bright and dark rotating features were imaged. Good summary of
the findings he

http://oposite.stsci.edu/pubinfo/edu...ast-facts.html