View Full Version : Discussion: Pluto's Atmosphere is Expanding

2003-Jul-09, 05:37 PM
SUMMARY: A team of astronomers from MIT reported today that Pluto's atmosphere is expanding, even as the planet is getting further away from the Sun on its elliptical orbit. The team made their findings by watching the dimming of a star as Pluto passed in front. Astronomers were expecting to find the opposite situation; that its atmosphere would shrink as it gets further from the Sun, but it's similar to the Earth, where early afternoon is hotter than noon, when the Sun is at its brightest. If all goes well, NASA will launch its New Horizons mission by 2006 to reach Pluto in 2015.

What do you think about this story? Post your comments below.

2003-Jul-09, 11:01 PM
What an interesting story..I wonder how old Clyde Tombaugh (Pluto's discoverer) would think about how "his planet" was being highlighted more and more as the years go by. A mission, the Pluto-Kuiper mission, set down for 2004 will no doubt answer some of the questions raised in the article as Pluto really holds the key in many ways to the formation of the solar system.

Bathed in weak sunlight it's an icy world with pristine conditions, an archaeologically preserved world that probably hasn't changed much since the formation of the solar system almost 5 billion years ago.

Tombaugh discovered Pluto in 1930 and spent the rest of his life lecturing about it, he became famous just for this one discovery but in reality made a lot more contributions to astronomy over the following decades..he was in his late 90's at the time of his death.

You know in planning the Pluto mission NASA sent old Clyde a telegram a year or two before he died, as a mark of respect, asking for "permission" to visit HIS planet..they say the old man had tears in his eyes and remarked that this was the greatest compliment ever paid to him. WHAT A GREAT STORY HUH?


Jafafa Hots
2003-Jul-09, 11:53 PM
Just curious about what photo that is you have for this article.

2003-Jul-10, 12:00 AM
Okay, clue me in. How in the hell does Pluto have an atmosphere? and don't tell me Charon has one.

2003-Jul-10, 12:54 AM
To Trumpdumper

Look, I know it seems strange that a little planet like Pluto (really a moon of Neptune) could have an atmosphere but it does. Small planets we know are inherently difficult to hold atmospheres but Pluto JUST fits in. We know that the moon Titan also posesses an atmosphere as well and it's only small.

Pluto has an atmosphere but not a thick one, it's gravity must be just strong enough to hold onto the lightest elements and we detect this atmosphere as a "haze" around the image of a star seen through it in the distance.

Don't confuse the word atmosphere to mean AIR...it isn't, it can be any of the rarified gases..it's a term for anything "cloudy' around a planet or moon.

See, Venus has an "atmosphere" but it's poisonous to us, mainly carbon dioxide so I think you're wondering how can pluto have 'air', at least that's how I interpret it. Good luck and keep thinking!

By the way, I think the pic Fraser included was just an artistic representation.


2003-Jul-10, 03:24 AM
I think we need to get a great big inferometer out by Jupiter somewhere, or a few of them. Then we could really see some atmospheres!

2003-Jul-10, 04:09 AM
There's a really exciting set of missions from the European Space Agency called Corot, Eddington and Darwin which will launch over the next decade to search for Earthlike planets. Darwin will be able to see Earth-sized planets passing in front of their parent star.

2003-Jul-10, 05:04 AM
Oh, and the picture is an artistic rendition of Pluto and Charon supplied by NASA. Not an actual photo of the planet. Real photos of Pluto are pretty boring.

Tim K.
2003-Jul-10, 07:26 AM
I like those stories of Pluto. Its always special, becuase we don't know much about this little planet. Check my Dutch newssite: www.astrostart.tk (soon: www.astrostart.nl).

2003-Jul-11, 01:26 AM
The observed continued expansion of Pluto's atmosphere may be explained if a greenhouse effect has trapped solar energy. What are the known constituents of Pluto's atmosphere?

2003-Jul-11, 04:49 AM
According to Bill Arnett's "Nine Planets" site...

"Little is known about Pluto's atmosphere, but it probably consists primarily of nitrogen with some carbon monoxide and methane. It is extremely tenuous, the surface pressure being only a few microbars. Pluto's atmosphere may exist as a gas only when Pluto is near its perihelion; for the majority of Pluto's long year, the atmospheric gases are frozen into ice. Near perihelion, it is likely that some of the atmosphere escapes to space perhaps even interacting with Charon. NASA mission planners want to arrive at Pluto while the atmosphere is still unfrozen."


tony greaves
2003-Jul-11, 06:03 AM
Thanks Fraser I didnt think there were photoes that detailed of Pluto.

2003-Jul-11, 05:10 PM
I got taken by that image of Pluto too.

2003-Jul-11, 06:11 PM
There is also a summary article at:

Jafafa Hots
2003-Jul-13, 07:52 AM
Originally posted by CharlesBell@Jul 11 2003, 05:10 PM
I got taken by that image of Pluto too.
well, I didn't get taken by it. I knew it couldn't possibly be real, so that's why I asked.

philip slater
2003-Jul-13, 11:12 PM
For the first few million nanoseconds after seeing the image of Pluto & Charon I too was amazed, delighted, outraged and shocked. Had someone sent out some kit all that way, keeping the mission secret to scoop the picture, and not told me? Or had I been too busy trying to do too many things, and not properly paying attention when I was told? I could believe that. But luckily I got lucky and happened to click on to a handy button alongside saying "visit news source" and was instantly transported to a picture that I could enlarge which said underneath it "An artists concept of Pluto and its moon Charon". :-)

Initially what helped me to buy in to the image was misreading the dark area which filled me with nostalgia for the days when an image of a planet or moon, visualised for the first time, would have strips missing where the camera had packed up or the antenna was pointing the wrong way or someone in the deep space network had plugged in the kettle at the wrong time.

As we press on with getting the first decade of the century filled in, this issue will run and run. Whether an image is a raw photograph or has been processed through a mind, carbon or silicon based, with or without a bit of artistic license, will get harder and harder to read and rely upon. Such thoughts not influenced at all, of course, by reading in UT Issue # 630 July 1st that the adaptive optics of the Gemini observatory in Chile make its image of the galaxies of the Hickson Compact Group 87 as good as Hubble. Of course we believe the evidence of our eyes, but would everyone believe quite as readily in the fine detail if we hadn't had the Hubble pics first? Or should we be sceptical about the stream of digits we get from that as well?

Philip Slater


2003-Jul-14, 05:11 AM
I find it interesting to read Pluto's atmosphere is expanding even though it is quite likely freezing because of it's increasing distance from the Sun.
Then I was reminded it is likely that is exactly what is going on as I poured myself a soft drink and cracked open a tray of ice I filled a few hours before.

Knowing how much I filled the tray and seeing the ice cubes are higher then the water was is a given because ice occupies more space then the same amount of water. In other words ice expands. So an expanding atmosphere as it freezes is natural, unless other substances act differently when they freeze.

2003-Jul-14, 05:52 AM
Unfortunately, water is the anomoly in that department. Pretty much every other substance contracts as it freezes. Why water doesn't, is a whole other subject.


Astronomers are using an analogy to explain why this is happening. It's kind of like how it's hottest around 3:00pm in the afternoon, even through the Sun is well past its brightest point. I guess the planet is still radiating energy and keeping its atmosphere warm for a few more decades. But then the chilly weather will finally take over.

2003-Jul-16, 03:39 AM
Speaking of which, does anyone know what the surface temp is on Pluto at the moment?