Pluto shows a change of colour on its surface: NASA + HST

Pluto, the dwarf planet on the outer edge of our solar system, has a dramatically ruddier hue than it did just a few years ago, NASA scientists said Thursday, after examining photos taken by the Hubble Space Telescope.

They said the distant orb appears mottled and molasses-colored in recent pictures, with a markedly redder tone that most likely is the result of surface ice melting on Pluto's sunlit pole and then refreezing on the other pole.

Full article:
uk.news.yahoo.com/18/20100204/tsc-blushi...akes-on-e123fef.html

I wonder if New Horizons will be able to see these changes in colour. I mean, Cassini was able to photograph Saturn in great detail almost 2 years up to its actual arrival in 2004. Considering the Pluto change was also within a 2 to 3 year period, New Horizons could get exciting...

Seanie.

Hi Seanie,

Pluto's atmosphere, just like any atmoshere is a dynamic system which changes over time and astronomers try to monitor these changes.
For those of us who observe occultations, the P-Day is coming: it is 14th February! Pluto will occult a 11mag star in Sagittarius, a rare event, and we are preparing to observe this phenomenon in central and S Europe.
CCD Photometry of the event will hopefully reveal these subtle changes in its atmosphere and perhaps the amount of dust currently near the surface. Also, Video with GPS time (eg Watec cameras) will help timming of the event.

There is an observational campaign for the 14 Feb. Pluto Occultation, see www.iota-es.de/pluto-14feb2010.html

Also see Bruno Sicardy's page: www.lesia.obspm.fr/perso/bruno-sicardy/14_feb_10/

A map with possible observing sites:


I quote from Bruno:
"

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scientific rationale

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The main scientific goal is the study of Pluto's tenuous atmosphere.
Our aim is to monitor Pluto's atmosphere, which underwent a remarkable increase in pressure between 1988 and 2002 (see eg Sicardy et al. Nature, July 2003), see reprint at:
www.lesia.obspm.fr/perso/bruno-sicardy/b...lio/nature_pluto.pdf
See also another paper linked to Pluto's atmosphere (Lellouch et al A&A 2009):
www.lesia.obspm.fr/perso/bruno-sicardy/b..._Pluton_CH4_AA09.pdf
We keep on monitoring Pluto until the NASA flyby by the New Horizons spacecraft in July 2015,
and occultations are the only tool we have right now to probe Pluto's tenuous atmosphere from Earth."

I wish the weather permits observations!
Clear Skies,
Vagelis

Hi Vagelis,
Thanks for the detailed post! How rare is it for Pluto to participate in an occultation? Would I assume correctly that you won't see Pluto, merely just the disappearance (or drop in brightness) of the star (2UCAC 24920649)? If so, what you're intended instrument of choice for this?

Seanie.

Hi Seanie,

You can get an idea here: www.iota-es.de/pluto_system/pluto_predict.html
But these events a. refer to the Globe b. mainly involve faint stars (eg 13 - 16mag) c. contain is an uncertainty factor.
Roughly , I would say, there is one "good" event in any continent every a couple of years or more.

That's correct, during the event Pluto is indistinguishable from the star. "One light source" with the combined magnitude.
What we are supposed to see is just the change of light over time. Light from Pluto contributes 3% to this combined mag, so the star will "dissapear" for 1 - 2 minutes.

My instrument of choice- I wish I was there: www.spartastronomy.gr/astroteams/occults...2010/ccd-pic-du-midi !
But beeing realistic, I will use my humble 10" and ATIK 16-HR CCD and some guys (maybe Yiannis Ef.) a Watec 120+.
With this kind of equipment us amateurs can get smth like this http : // w ww.youtube.com/watch?v=WruS6own5qc
Greece is unfortunately quite east for this event so I plan to drive to the dots (see map) westwards to avoid some twillight.
Weather permitting, of course!

Some more details (I hope it's not too boring for you)

On the above youtube video by Dave Gault, notice the shape of the lightcurve, at the end of the video.
As opposed to asteroid ocultations, where the diminishing of light from the star is instant, since asteroids are just rocks, in the case of Pluto we do have a light curve, meaning that the change of light at both ingress (dissappearance) and egress (reappearance) is gradual, due to differential refraction of the starlight as it passes through different layers of Pluto's -thin- atmospere.
This is exactly what astronomers want to measure. Photometric data wanted!
Hope it was helpful.

Vagelis Tsamis wrote:

Hope it was helpful.

Helpful, and dare I say it (it is Pluto, after all) interesting!

www.spartastronomy.gr/astroteams/occults...2010/ccd-pic-du-midi

I like your choice in 'instrument'...



Seanie.