[meteorite-list] Pluto May Have Comet-Like Tail

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Fri, 22 Apr 2011 19:56:34 -0700
Message-ID: <d47a2225b5b35fc54eada7a14f2c7cdb.squirrel_at_webmail.lpl.arizona.edu>

Richard:

The atmosphere of Pluto has been known since 1985. The reclassification of
Pluto was in 2006 and was based solely on dynamical considerations (a
sphere but has not cleared its orbit, i.e., there are other large things
in similar orbits). Its physical properties were not taken into
consideration.

Oh, Pluto is about 50% rock and 50% ice by mass. So, since rock is denser
than ice, Pluto is more ice than rock by volume. There is still an
uncertainty because of the nature of Pluto's atmosphere. There may be a
haze layer which would mean when Pluto blocks out the light of a star (an
occultation), the measurement may be for the haze layer and not the true
surface. The most recent diameter is about 2320 km, but I do not know the
uncertainty in that measurement

Larry

> Ron et al,
>
> Here are a few more neophyte questions:
>
> Has the term "dwarf" so far and recently been attributed soley to Pluto's
> rocky size with no regard for undiscovered atmosphere anomolies cited
> here?
> And to whit, what about our gas-planets stature in the planet definition?
>
> -Richard Montgomery
>
>
> ----- Original Message -----
> From: "Ron Baalke" <baalke at zagami.jpl.nasa.gov>
> To: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
> Sent: Friday, April 22, 2011 1:24 PM
> Subject: [meteorite-list] Pluto May Have Comet-Like Tail
>
>
>
> http://www.technologyreview.com/blog/arxiv/26667/?ref=rss
>
> Pluto May Have Comet-Like Tail
> The Physics arXiv Blog
> April 20, 2011
>
> The latest measurements of Pluto's tenuous atmosphere indicate that it
> may be shaped into a comet-like tail, say astronomers
>
> Pluto's has a highly elliptical orbit that takes it inside the orbit of
> Neptune and then out into the distant icy reaches of the Solar System.
>
> Astronomers have long believed that this would have important effects on
> the dwarf planet's atmosphere. Their models indicate that Pluto's
> atmosphere is likely to swell as it moves closer to the Sun and the
> poles sublimate. Later, the atmosphere should condense as it cools down.
>
> That should make the surface of Pluto a barren windswept land that
> constantly changes as it is battered by supersonic winds. Indeed, Hubble
> images show that Pluto's surface has a number of interesting features
> that seem to be changing.
>
> In recent years, other evidence has emerged to back up suspicions that
> Pluto is more complex than astronomers initially imagined.
>
> Today, Jan Greaves at the University of St Andrews in Scotland and a
> couple of buddies reveal the details of their own study of Pluto's
> atmosphere using the 15 meter James Clerk Maxwell Telescope in Hawaii.
>
> These guys find clear evidence of gaseous carbon dioxide at altitudes of
> up to four times Pluto's radius. And they say there is significantly
> more of the stuff than the last time CO was detected in 2000.
>
> That's strange. Pluto is currently moving away from the Sun after its
> closest approach in 1989 and ought to be cooling down. One explanation
> is that the south pole has recently come out of shadow for the first
> time in 120 years and for a short time may be evaporating more quickly
> than the north pole is condensing.
>
> But Greaves and co's most interesting discovery is a small red shift in
> the CO spectrum indicating that Pluto's atmosphere must be moving away
> from Earth in an unexpected way.
>
> Their tentative explanation is exciting: "The marginal CO line
> red-shift, if real, could indicate a ??,ow forming into a comet-like tail
> directed away from the Sun," they say.
>
> The thinking is that the expanding atmosphere is interacting with the
> solar wind and being shaped into a tail.
>
> That could throw the cat among the pigeons next time Pluto's status as a
> planet comes up for discussion. It gives ammunition to the naysayers who
> can now claim that far from being a planet or even a dwarf planet, Pluto
> is merely a giant comet.
>
> Astronomers will find out more in the coming years. The world's
> telescopes will be increasingly trained on Pluto as the arrival of the
> New Horizons mission draws near. Its flyby is scheduled for 2105.
>
> Ref: arxiv.org/abs/1104.3014 <http://arxiv.org/abs/1104.3014>: Discovery
> Of Carbon Monoxide In The Upper Atmosphere Of Pluto
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Received on Fri 22 Apr 2011 10:56:34 PM PDT