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P.A.S. Cruickshank
This artist's impression highlights Pluto's huge atmosphere of carbon monoxide. The source of the gas is erratic evaporation from the dwarf planet's mottled icy surface. The sun appears at the top, as seen in the ultraviolet radiation that is thought to force some of the dramatic atmospheric changes. Pluto's largest moon, Charon, is at lower right.
After nearly two decades of searching, astronomers have detected carbon monoxide in Pluto’s thin atmosphere, as they expected. But they didn’t expect to find so much of it. Pluto's dramatic seasonal changes serve as further evidence that the dwarf planet is one surprising little bugger.
"Everything about Pluto is surprising," Jane Greaves, an astronomer at the University of St. Andrews in Scotland, told me. Greaves presented the new results today at the Royal Astronomical Society's National Astronomy Meeting in Wales.
Five years ago, Pluto was at the center of a controversy over the definition of planethood — which resulted in the creation of the dwarf-planet category, a new class of celestial objects. More recent observations have pointed up still more peculiarities about Pluto. For example, scientists have found that the faraway world's surface features are changing, that its atmosphere contains clouds, and that it might even harbor a pool of liquid beneath its icy shell.
Pluto's thin atmosphere, which was previously known to contain nitrogen and methane, is thought to freeze out and rise up as the world traces its eccentric orbit around the sun. Traces of frozen carbon monoxide have been detected on Pluto's surface, which led astronomers to assume that carbon monoxide gas should be found in the atmosphere as well.
Greaves and her colleagues detected the presence of carbon monoxide in a big way. Previous observations suggested that Pluto's atmosphere extended out to a distance of more than 60 miles (100 kilometers). The new results, obtained by the 15-meter James Clerk Maxwell Telescope in Hawaii, indicate that the atmosphere goes out much farther: more than 1,875 miles (3,000 kilometers), or a quarter of the way out to Charon, the largest of Pluto's three moons.
"Carbon monoxide has been searched for but never before detected," Alan Stern, principal investigator for NASA's New Horizons mission to Pluto, told me in an email. "If confirmed, this is a significant technical achievement, and there will be some interesting scientific implications as well."
Why has the atmosphere grown that much? Greaves speculated that sunlight has been hitting bright patches of frozen material on Pluto's surface, warming up the ice and causing liberal amounts of carbon monoxide and other gases to boil off. "This is now for some reason boiling off more than it was 10 years ago," when scientists in Spain made an extensive study of Pluto's atmosphere, Greaves said.
That may seem counterintuitive, considering that Pluto was at its closest point to the sun back in 1989 and is now moving farther away. But Greaves suggested that Pluto was experiencing thermal inertia — the same phenomenon that explains why the hottest time of year comes in late summer rather than midsummer. Pluto is currently in the late summertime of its full orbital cycle, which lasts for 248 Earth years.
Mark Sykes, director of the Arizona-based Planetary Science Institute, said Pluto's larger atmosphere "is not necessarily a surprise."
"My thought is that we have the sun pushing for higher latitudes on Pluto, and that the net increase in gas production as those polar ices increasingly sublimate is dominating over the freeze-out on the dark pole," he told me in an email.
Carbon monoxide tends to act as a coolant — unlike carbon dioxide or methane. which are greenhouse gases linked to global warming on Earth. The balance between the trace amounts of carbon monoxide and methane is probably a critical factor controlling the ups and downs of Pluto's nitrogen-dominated atmosphere.
"Seeing such an example of extraterrestrial climate change is fascinating," Greaves said in a news release. "This cold simple atmosphere that is strongly driven by the heat from the sun could give us important clues to how some of the basic physics works, and act as a contrasting test bed to help us better understand the earth's atmosphere."
Greaves and other scientists will be tracking what happens to the carbon monoxide and other constituents of Pluto's atmosphere for years to come, but the biggest revelations are expected to come when the New Horizons probe flies past Pluto in 2015.
In the years since New Horizons was launched in 2006, Pluto has been removed from its niche as the "ninth planet" of the solar system — and is now seen instead as one of potentially scores or hundreds of dwarf planets. But Greaves said the icy world has retained its peculiar appeal, no matter what you call it.
"I don't think the name you classify it by is that big a deal," she told me.
More about Pluto:
- Pluto in the spotlight ... dead or alive
- Pluto's rival gets downsized
- Pluto in fact and fiction
- Eight decades of Pluto
- All about "The Case for Pluto"
In addition to Greaves, co-authors of the research paper titled "Discovery of Carbon Monoxide in the Upper Atmosphere of Pluto" include Christiane Helling and Per Friberg. The paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society Letters.
Join the Cosmic Log community by clicking the "like" button on our Facebook page or by following msnbc.com science editor Alan Boyle as b0yle on Twitter. To learn more about my book on Pluto and the search for planets, check out the website for "The Case for Pluto."
Leave a Comment:
I have to disagree. It's classification is a big deal in the sense that this is what we are teaching our kids. If we are teaching them that Pluto is among a large group of celestial bodies called "dwarf planets" there is a possibility it (and others) gets lost in the shuffle. The biggest footnote when teaching about Pluto to our grade school kids is going to be that it was a planet and now it's not. And teachers are going to be asked "why isn't Pluto a planet?".
Personally, I wonder how massive a planet would have to be in order to "clear out it's neighborhood" in the Kuiper Belt region. If you could somehow place Jupiter in Pluto's place with Pluto's eccentric orbit would Jupiter have cleared out it's neighborhood in the 4 and a half billion years it's had a chance to do so??
(Pluto is a planet)
Exactly. I can see the need to reclassify Pluto since it definitely is not a gaseous body and certainly has distinctions from terrestrial bodies as well, but there's no reason we can't have a new name for this class that registers some respect for Pluto at the same time that it recognizes those differences. To lose Pluto in the shuffle of what is, by scientific standards, a fad (there will come a time when science will have moved on from Kuiper Belt objects and it becomes a cottage industry no matter how much is still unknown) is simply irrational. It was the first of its kind to be discovered, thus it should be given some level of recognition and used as an example of the class of bodies.
As for a name for that class, I'm definitely not the first to suggest this but why can't Pluto and its Kuiper Belt cousins be called "the plutonian planets" in the same way that Mercury, Venus, Earth and Mars are the terrestrial planets (all in the class given a name based on the Latin term for Earth) and Jupiter, Saturn, Uranus and Neptune are the jovian planets (all in the class given a name based on the Roman name for Zeus -- Jove, aka Jupiter)?
I think 'clearing out its neighborhood' applies more to Ceres than Pluto.
Pluto (according to the IAU) is not a planet because it has not cleared out it's neighborhood. The point I am trying to make in my comment is that "clearing out your neighborhood" seems like a tall order when your neighborhood is the Kuiper Belt. It may apply to Ceres more or less but it's the reason Pluto was demoted (according to the IAU).
I guess that makes my son's dog a planet. When he releases carbon dioxide (among other things), he most assuredly clears his neighborhood. Even the skunks are filing complaints.
Mob,
"Clearing out its neighborhood" was the arbitrary addition to the definition by the faction that insisted on demoting Pluto. I believe Alan made a point about this in a previous article in the last 6 months or so (unless I'm accidentally attributing someone else's thoughts to him) that if one was to put any rigorous (i.e. mathematical) science to such a claim, one of the jovians (I forget which) would fail such a test if it occupied Pluto's orbit.
Any test of planethood that is passed at one distance in the relevant frame of reference (from the Sun in this case) but failed at another is not scientific. If we were to find a rogue planet in interstellar space, we couldn't call it a planet under this definition because it hasn't attracted all the of the hydrogen gas in between stars. That seems like a definition based on emotion and politics rather than science to me. Five years on, it still shocks me that this came from "scientists."
(Sigh) Children survived re-naming brontosaurus as apatasaurus, they'll survive this.
SO let me get this straight....
Because little bitty Pluto failed to kick-butt at the edge of the Solar system, It get's demoted from planet to "dwarf-planet" and now it has ganged up with Charon (another Dwarf-Planet) and another to try "Clear the area" with bad gas (cM).
And if dinky Jupiter had been magically transported to where Pluto is (and Versa) then Jupiter would probably have failed as well. Sounds like someone had it out for Pluto and wants to keep the Planet count at 8.
Please don't let Gore or the Sierra Club find out about the Global warming issue on Pluto, or he'll make another movie.
We'll all have to endure how he really won in Florida and how he invented the internet - and came up with Global warming - all over again.
@DenverBob - You left out the fact that Gore is also a renowned mathematician. What? You have never heard of an AlGorithm? ;-p
I thought AlGore Rhythm was a form of Democratic birth control?
I don't think he's just democratic birth control. HA!
Lebowski, you cannot call them the 'Plutonian" planets because everyone will think they are radioactive.
Maybe "Hadian" after Hades.
Stygian?
Stygian? I like it. River Styx and dark/gloomy. Sounds like the Oort cloud and Kuiper Belt.
Also, are we now classifying Charon as a dwarf planet rather than a moon of Pluto?
If we change the definition to Stygian planets, what do we call Ceres? Will it become a terrestrial planet or will it become the biggest asteroid? Or maybe a Terrestrial Stygian planet?
@Frank -- If we were simply talking about renaming Pluto rather than reclassifying it entirely by some arbitrarily chosen definition, I'd agree with you. And I'm still waiting for a defense (from anyone here) of why we could call such a body in interstellar space a planet without it having accumulated most of the hydrogen in its "neighborhood."
@Tony -- I don't have much faith in the average American to understand science or our political discourse would be on a completely different level but I do have faith that they would understand the difference between a class of planets and a radioactive element.
Tony, I think Ceres would still be an asteroid, though the entire system is rather arbitrary, at best. It is, after all, based in a system of nomenclature that is now obsolete.
The Big Lebowski Legacy, in defense of why we could call a rogue planet a "planet", I think we could call it a planet because of how it formed. This immediately raises the question of how was it formed. I'm operating under the assumption that it was accreted in a stellar system and then flung out into space. So, it would have been a planet and to me it should keep that title (perhaps simply adding "rogue" to it to classify it as not orbiting a star). And, for all I know, it could accumulate hydrogen from the interstellar space, but it certainly wouldn't clear out it's neighborhood, since it's "neighborhood" is itself and itself is constantly in an unfamiliar place in space, it's not orbiting in it's own "neighborhood".
But this whole rationale is broken (I think) if planets form in different ways.
Tony, how about "Asterian" planets?
I'm no expert on planet formation but I can't see any reason why a planet couldn't form all by its lonesome or nearby a forming star with sufficient velocity to escape it during the formation process.
In either case, since the IAU never qualified "clearing the neighborhood" for rogue planets or specified that it is defined by its neighborhood of origin rather than its current neighborhood (which is like saying I'm defined as a person by the hospital I was born in, anyway, so that addition would fail on two levels), the IAU either must invent another category for rogue planets of either/any type and deny them planethood regardless of their size or reconsider their definition. Since excess granularity in definitions tends to end up overturned by a new, more elegant rule, reconsidering their definition would be the scientific thing to do... but that hasn't stopped them yet.
Your hospital comment got me thinkin'.. IF a person were defined by the hospital they were born in that would be like discarding all of the life experiences that developed that person's personality and character traits. To a certain extent it also does away with understanding certain circumstances that may have totally altered a person's life (such as losing a limb for example).
In that analogy it is undesirable to classify a celestial body as a planet based solely the way it was formed. However, human beings only come to be in one way, sexual reproduction. (let's just exclude dear old Jesus for a moment)
Defining you as a person may not be the best phrasing for it. A better analogy would be classifying you as a human being (as opposed to not being human). In your formation a man and a woman reproduced (intercourse, gestation, birth). That is how a human being is "formed".
If planets all form in one equally simplified way what would it be? And how is that different from how comets, asteroids, moons, or stars are formed? If gravity is our guide then all objects with mass is attracted to all other objects with mass and blammo, accretion is how celestial bodies formed. But that definition does away with all of the circumstances that brought about the characteristics of any given celestial body. For example, one asteroid may be formed through the collision of two other objects resulting in many fragments, one of which is the new asteroid. Another example is our Moon. The most widely accepted formation scheme for how our Moon formed is the giant impact theory whereby the Moon was created "out of the debris left over from a collision between the young Earth and a Mars-sized body" ( http://en.wikipedia.org/wiki/Giant_impact_hypothesis )
Well, that brings up another aspect of the "how-things-were-formed" discussion. Those two examples are fairly similar; two objects collide, fundamentally changing both objects, and actually creating new individual objects in the process. It's somewhat similar to the earlier example of the man and the woman coming together (no pun intended) to create you or me.
I seem to be ranting endlessly. In conclusion, the formation of an object is important in classifying said object. ( <--- thank you captain obvious ) ;-P
I think you forgot coalescing dust in your endless rant.
There's only one question left that I can see.... Does Capt. obvious stand with the same pose as Capt. Morgan?
If it has an atmosphere and isn't a Moon, its a Planet. I have spoken; debate over.;-D
+1!
Mercury?
Mercury does have a very thin atmosphere, but an atmosphere nonetheless, if I'm not mistaken.
What if it's a moon and has an atmosphere? We need a classification for moons without air and those with air. We also need a classification for round moons and irregular moons. Then we need to classify the things in Saturn's rings. Some are called shepharding moons, but what size makes them a shepharding moon and what size is a particle of the rings?
Why don't we classify planets based on their atmospheric pressure? Makes more sense to me than clearing out it's neighborhood of "undesirables". Heck, maybe Pluto did clean up it's neighborhood, but then someone moved in, set up a meth lab, next thing Pluto knew his neighborhood had become a slum. That's not Pluto's fault.
LMAO!
About all I can think to add to that is that shepherd moons are "small moons that orbit near the outer edges of rings or within gaps in the rings. The gravity of shepherd moons serves to maintain a sharply defined edge to the ring; material that drifts closer to the shepherd moon's orbit is either deflected back into the body of the ring, ejected from the system, or accreted onto the moon itself." -from wikipedia
I couldn't think of anything better to add. I'm still stuck thinking about how Pluto is too small to go over and bust up the meth lab on his own. Maybe Pluto needs to call up the neighbors Charon, Nix, and Hydra and go bust a cap and bring order to the vigilante-justice-style.
Pluto, Vigilante Justice, coming to NBC this Fall.
@Tony -- It's quite simple. Any natural body that orbits another is a moon. Perhaps "satellite" is a better word than moon so that Phobos and Demos and the like don't get lumped into one, giant, meaningless category of moons with moons like ours and Jupiters. Actually, I don't think our moon and Jupiter should be lumped into one giant category together since the moons of Jupiter they have atmospheres and geologic activity.
Back on the more general question of planethood, I would say anything which is able to achieve spherical or near-spherical shape and does not orbit another body other than a star is a planet. Welcome, Ceres, Vesta and Eris!
Not trying to be argumentative, but first, you just made my point that they should not be lumped into the same category. Second, if anything that orbits is a moon, then every particle in Saturn's rings is a satellite.
Gotta run
Except that I used the term satellite. I did, however, forget to specify that "moon" should refer to a class of satellites that are near-spherical under their own gravity. We should most likely only use the term moon for such bodies since to use it more broadly would include, as you point out, Phobos, Demos and every ice and rock particle in Saturn and Jupiter's rings (respectively).
Beyond those levels, any more division is actually more descriptive and not so much further division of categories since they no longer refer to the object's position or definition. If we had two moons and one was geologically active, would we refer to them as two different classes of objects? Not likely.
I had to leave earlier and could not complete my thought, but my original description of "moons" was to show the obsurdity we can get into.
Personally, I think we should have planets, then categories of planets (dwarf planet is a category of Planet.)
We already to this with stars (Red Giants, Red Dwarfs, White, Blue, Neutron, etc) and Galaxies (Spiral, Bar, etc.) and sort of do that with planets (Rocky Terrestrial, Gas Giant).
Personally, I think most comets, if they were in a more circular solar orbit rather than a highly eliptical orbit that takes them to the Kuiper Belt and/or Oort Cloud, would be seen as asteroids, and vice versa.
My last statement makes less sense now that it is in my rearview mirror (particularly the first paragraph) but I would tend to agree with you on the need for further classification of planets. Where I believe we differ is in the necessity to define them by their characteristics rather than their context. "Dwarf planet" (if you're supporting the IAU's current definition, which I'm not quite sure you are) is a ridiculously unscientific term that can be applied to Jupiter at sufficient distance from the sun based on the current definition, hence the reason I suggested we rename the class "plutonian planets" (the same way we have the terrestrial and jovian planets) and drop the "clear its neighborhood" condition.
As for whether asteroids and comets would have their names flipped if their types of orbits were... it's possible and certainly a valid question but, since their discovery, we have learned so much more about them that separates them regardless of the shape of their orbits that it's really more of a point of semantics. Additionally, the orbital distinction in this case is more shape than size. I'm sure you can find a long-period comet that has the same area contained by its orbit as an asteroid in the Asteroid Belt and comets are comets regardless of how far out their orbit reaches (Kohoutek and Halley are both comets despite a 4200-year difference in orbital period).
Actually, I just googled comets and found that there are actually comets in the asteroid belt with nearly circular orbits but they're still considered comets. Why can't the definition for planets (with classifications) be that simple?
Sorry. Kohoutek's most recent orbital period was 150,000+ years and its next is calculated to be about 75,000 years. I think I was thinking of Hale-Bopp or Hayakutake with the 4200-year difference. But Kohoutek just accentuates my point.
A while back, in another thread, I had posted how we need a lot more classifications of planets, including that if Jupiter and Saturn are going to be Gas Giants, then Uranus and Neptune should be Dwarf Gas Giants.
I haven't looked up asteroid and comet definitions in a while, so googled as you did, and find the term Centaur for planet like objects that behave as comets and asteroids.
So now we have minor planets and centaurs, which of course are a category of minor planet. My head shall soon explode.
Sounds like a centaur could actually be a dwarf planet since its classification would be independent of time (i.e., no matter how long you give it, it ain't clearing any planets out of its neighborhood). Given enough time, Pluto could theoretically be promoted out of dwarf status by virtue of enough stuff exiting its neighborhood for one reason or another in addition to whatever it can clear. Even though it is a KBO, one cannot reasonably state that its neighborhood is defined as the entire Kuiper Belt. Then again, we're talking about the IAU.
@TonyInDallas - Do you work in marketing? "Dwarf Gas Giants" indeed; right up there with Jumbo Shrimp! ;-D
Yes, Darthdon, it gets more and more ridiculous as time goes on.
If your hovering above Saturn and look for our sun. It looks like any of the other stars so the sun is providing a tiny amount of light to the Saturn system. Pluto is even farther away, there is no way out sun is providing the energy required for what is happening on Pluto. There has to be another energy source on the planet of some sort. Maybe tidal affect from the 3 moons.
I would guess tidal effects, especially considering the size of Charon. But Charon is tidally locked isn't it? I have heard that one could build a bridge between the two if one had the resources to do so. So, perhaps it's the tidal effects of the other moons?
Heavy traffic and global warming.
Why can't it, tachyeon, solar output continues to increase as the sun burns, the sun is gradually expanding as well, and the influence of the solar wind expands well beyond the orbit of Pluto, so is it really so hard believe that there is enough energy received by Pluto to at least some of the external out-gassing? Doubtful that it would have anything to do with any possible internal liquidity, which is most likely tidal effects, the same way Europa may have a liquid interior
Sorry tachyeon, but that's not correct. Here's a link and a partial quote from Wikipedia of the amount of sunlight both of Saturn and Pluto:
Here's the link guys. Pretty interesting...at least to me anyway :) Hope this helps!
http://en.wikipedia.org/wiki/Sunlight
GarrettB, thanks for the link!
Agreed Darthdon.
And I think the cM is leftover from a civilization that was obsessed with lawnmowers.
( But seriously, agreed Darthdon. : )
mmmmm lawnmowers
(Homer Simpson voice)
What is surprises me is how can such a small body attract 3 moons considering asteroids move around 40k per hour, to have one come in at the correct angle and set orbit just does not compute. Makes me think its a base and the EBE's are using it.
I think you should brush up on your moons, its generally thought that planets and moons are formed through accretion. Although, asteroid capture does sound interesting.
Blather, a lot of the moons around our 4 gas giants are most likely captured, plus the two around Mars are widely believe to be captured as well, due to their irregular shapes, and obital patterns(one spiralling out, the other spiraling in)
oh sure - and their lawn mowers are creating the cM -- I see where this is going.
I don't believe for a MINUTE that the sun could possibly have anything to do with Pluto's climate change. There simply MUST be SUVs on Pluto!
There's carbon MOnoxide, not carbon DIoxide. So how else could the atmosphere be warming?
Atmosphere isn't quite the right term for a body that has frozen gasses on its surface that boil off when it approaches the sun. Even at the orbit of Neptune, Pluto's feeble gravity has difficulty holding onto its atmosphere. If Pluto or any of the other Kuiper belt objects are perturbed from their orbits and pass closer to the sun than Jupiter, they would become grand comets. In fact, typical comets are just smaller Kuiper belt objects. Pluto's significance is that it is the second most massive and the first discovered Kuiper belt object. Just as Ceres is the most massive and the first discovered asteroid.
Ceres was the first discovered asteroid??
I hadn't done my homework on Ceres. Interesting how it was thought of as a full-fledged planet for about a half century before itself being demoted.
Yeah, it was the first demotion. I wonder if the internet had been around if everyone would be screaming "Ceres is a planet! I can't believe they demoted it to asteroid!"
Ceres is a planet!
;-P
If it's spherical under its own gravity and orbits the Sun, I would call Ceres and anything like it a planet.
Agreed Dude,
I guess that's the way the whole durned human comedy keeps perpetuatin' itself.
call it whatever...Pluto's not housebroken...just lets out gas anytime, anywhere.
I tend to consider Pluto a planet but haven't really given it much thought beyond that.
as for mobbarleys concerns about what they are teaching kids in school. I'm surprised they
are teaching todays kids anything about astronomy...astrology maybe, but astronomy? The
whole neighborhood clearing thing sounds like a lot of reaching in order to kick Pluto
out of the planetary game.
I think the most interesting argument is when a planet is on it's own, without a star, no moon, nothing. At that point it fails all of the rules that the IAU set up to define a planet.
Alan, a question for you. When speaking about Mars ANY talk of Methane in the atmosphere immediatly spurs talk of possible biological activity since, as my understanding goes, Methane breaks down in the atmosphere unless replenished. I also know that certain geological processes also produce Methane.
However on Pluto, the reports say there is Methane in the atmosphere. Now I don't supose Pluto has active geological processes so what is causing the Methane? Is it left over from plant formation and being so far away from the sun doesn't break down?
Perhaps I'm just missing something, any help would be apprecaited! :)
Methane breaks down in our atmosphere due to the presence of free oxygen. Pluto doesn't seem to have a significant amount of free oxygen in its atmosphere.
Pluto isn't experiencing summer right now. Only part of Pluto is.
No matter how you catagorize it, Pluto is merely a kuiper belt object. For me, its the eccentric orbit that nullifies it. All the other, "regular" planets do not cross paths. ....I.A.U. be damned!!LOL
Pluto is merely a kuiper belt object. Jupiter is merely a gas giant. Earth is merely suitable for sustaining life. No matter how you categorize it, Pluto is still an exceptional celestial object.
If orbit is all that is important than what would you classify Earth if it were suddenly flung out of the solar system? As a rogue planet it would not orbit anything and it would not clear out it's neighborhood. The only thing that would make it a "planet" is the fact that it's rounded by it's own gravity and has not started thermonuclear fusion.
Very low mass brown dwarfs haven't started thermonuclear fusion, are they planets? It's hard to tell hence the term sub-stellar object. Pluto on the other hand has a much clearer path ahead of it (pardon the pun). It's very clearly a KBO and as such should be classified as such, childhood memories be damned. I personally think that makes it a much more attractive target, same as Ceres. Thes "sub-planets" as they were are for me more interesting because of their similarity to larger bodies. I'm really surprised we haven't fast tracked a trip to Ceres to be honest with you.
pw, Ceres will be visited in 2015. A probe was launched in 2007 (Dawn) to go to Vesta in 2011 or 2012 and on to Ceres. Vesta's the second largest asteroid belt object.
The DAWN mission is currently en route to Vesta and Ceres. 2015 is going to be a very notable year for the "dwarf planets". So, I guess that counts as fast tracked.
As for the "sub-brown-dwarf" debate, I'm new to that whole conversation... But in my mind if it is "flickering" at all with thermonuclear fusion then it has "started" thermonuclear fusion. But really my argument is one of semantics. A car that sputters when the key is turned may or may not turn over, and just because the spark plug is sparking doesn't mean the engine has "started". The real issue with brown dwarfs isn't "starting", so much as "sustaining" thermonuclear reactions. But, like I said earlier, I'm new to the conversation about brown dwarfs. But, to me, if Jupiter is a planet then so are low mass brown dwarfs.
dang, Tony, you beat me to it. ;-)
I finally beat somebody ;-P
Who has been driving the gas guzzlers on Pluto?
Someone suggested that moving Jupiter to Pluto's orbit would nullify Jupiter as a planet because the orbit would not be cleared. I suggest that Jupiter would have a lot more satallites. And, a lot more Kuiper stuff would be flung toward us and out into interstellar space.
I have a feeling you are correct. The nature of comets and asteroids in the inner solar system would be vastly different if Jupiter were way out there in Pluto's orbit.
For what it's worth I'm glad we have Jupiter where it is. But, it would be very interesting to see computer simulations of what it would be like if Jupiter were out at Pluto's orbit.
This discussion totally digresses from the point, though. While it would certainly change the dynamic of asteroids, comets, etc., in the Solar System, the point of this thought experiment is that a body such as Jupiter which passes the test for planethood at its current location could be put at a distance where it's gravity would be insufficient to "clear the neighborhood." As one moves away from the sun, the area that must be cleared increases by the square (if, for the sake of simplicity, we consider only the ecliptic plane) while the radius increases by the linear order. In order to have "cleared out" its neighborhood during the life of the Solar System (a preset time which is one of many constants in the technical details of this which the IAU is flagrantly ignoring), the mass of the planet must increase at least by the square.
In other words, there is a radius from the Sun (perhaps not Pluto's) where Jupiter (and every other planet, for that matter) fails this test.
Excellent comment, el Duderino. Quite succinct.
Thanks!
It only "fails" the test based on the time it takes to orbit. The entire Solar System was probably like the Kuiper Belt or Oort Cloud at one time. That's probably where most of Jupiter, Saturn, Uranus and Neptune Satellites came from - They either "ate" the debris, or "adopted" the debris.
Jupiter in the outer Solar System, at its size and gravity, would clear its area in a melinia or two, IMHO. (250+- years to orbit)
Yet another reason why the IAU's definition of a planet is faulty.
P.S. It would take Jupiter way, way, waaaaay more than a couple millenia to clear out Pluto's neighborhoood. It's still not done clearing out its own neighborhood (See: Shoemaker-Levy 9 or that one that hit a few years ago).
Also, without a definitive number to associate with the amount of Kuiper Belt objects it would be hard to guess at how long it would take to clear them out. I have heard some wildly varying numbers from some seemingly credible sources. So, for all I know it may take a few millennia (which is the correct spelling even though in this reply box it is underlined in red, along with Kuiper) or it could take way more than a few millennia. But really, have any planets in our solar system completely cleared out their orbits?
I would agree with your point that no planets in our solar system have (or ever could, really) cleared out their own orbit since there's so much material floating around in perpetuity, not to mention all the stuff that gets replenished by comet and asteroid fly-bys, that a planet's job is never done. However, I'd say Jupiter still has a lot of work to do if, in less than 20 years, we've seen 2 terrestrial killers strike it. For us to have been happening to be looking at two moments when Jupiter happens to have had 2 strikes coincidentally less than 15 years apart that followed an astronomically long period of theoretical quiet would be amazing. If that were actually the case, I'd get my butt to the nearest convenience store to buy $1000 in lottery tickets every day because that's pretty darn lucky.
ShoeMaker Levy was not in Jupiter's orbital area. It was passing by and got caught. There's a difference.
However, I agree with your replenishment, as Earth continues to fly through meteor storms, like the Leonid, that are left over fragments from comets.
It's like vacuuming and dusting, you never quite get through with it. A very flimsy planetary criteria, if you ask me.
Wait till they find something that might or might not be life.
Well, isn't that already classified as an M-class planet?
True, Shoemaker-Levy was caught but what that means is that all the planets failed to clear their orbital area when it came to S-L, not just Jupiter.
TO Tony, I would guess that jupiter's solid(Molten?) core would be larger too.
It's hard to imagine Jupiter having a "rocky" solid core if the temperature and pressure is so great. But I would think we'd have to understand the nature of the liquid metallic hydrogen layer better before we could guess how the core would be affected.
I still think there is some kind of rockiness or metallicness (new words?) in Jupiter, et al. Hard to believe they are all gas, though anything is possible. BTW, it has been "eating" asteroids and comets for a loooong time, so even if it did not start as rocky....
Okay the questions are this??? can we live there?, can we get there if we can live there? and if not then who cares! We need to find a planet to live on not go gaga over because it has carbon monoxide.
I have to disagree. Whether or not we can live there or go there is beside the point. The question is What can we learn from observing and studying this place? From that we can decide whether or not we can live there or if there is a purpose in "going there". Perhaps we wouldn't want to live there but it would be a great place to send robots to mine a specific resource. In any event learning about ALL the places in the solar system is important in understanding OUR place in the solar system.
I will agree that finding habitable planets (or moons) is a worthy endeavor but it is not the end-all-be-all of our study of the solar system.
Too many cars
(sigh)
I know mob, they always blame the cars when we know good and well it's the coal burning electricity plants.
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