What's Going on With Comets?

robnissen · Mar 13, 2006

I amost hate to start this thread because I am really not interested in post after post from the EPH crowd. But it seems to me that our models of comet formation are not being verified by the actual data. We believe comets formed in the cold outer reaches of the solar system and at least on their early passes through the solar system are full of volatiles. But we are not seeing that. We also beleive that comets are dirty snowballs, or snowy dirtballs, but we don't appear to be seeing that either. Last summer, there was very little wator vapor kicked up by the cometary impact, and now with the initial Stardust data instead of seeing volatiles and water, we are seeing minerals that only form in high heat. Plus, it was my understanding that olivene does not form in the presence of water, and yet Stardust is finding large amounts of olivene. Now, don't get me wrong, I am not advocating EPH, or any of the other theories whose proponents generally advance their theories by insulting others. But I think the data we are seeing is demonstrating that our most accepted theories of comet formation are wrong. Thoughts?

mlorrey · Mar 13, 2006

It is absurd to think that Stardust would have captured water. Any water would be evaporated to plasma, not particles. Deep Impact did kick up a fair amount of water, but demonstrated only that comet Tempel has a thick layer of dust, which one would expect for a comet that had spent a long amount of time in the outer solar system. None of the comets that have been visited are young by any stretch of the imagination, so expecting them to have lots of water near or on the surface is the sort of fantasy one would expect of people who had watched too many repeats of Armageddon.

jatslo · Mar 13, 2006

Hi RobNissen, I have access to scholarly works that I can archive through my university, if you are interested in hearing what the Ph. D.'s have to say on the subject. Many things are going to have to change, because comets are the harboror of water on Earth, so the story goes, and many other things will change too. Is there any particular hypothesis we should *REJECT* first. For example, the water on Earth was brought about by comets. <--- Off with its head... <img src="/images/icons/wink.gif" /> Why are we in Phenomena anyway; just curious?

robnissen · Mar 13, 2006

"None of the comets that have been visited are young by any stretch of the imagination." That is just not true. The comet Stardust went to did not enter the inner solar system until 1974 when Jupiter changed its orbit. You can't get much younger than that.

qso1 · Mar 13, 2006

Thats how science works, theories get replaced with new theories when better data is available and then theory can become fact in some cases. Scientists themselves will usually announce they are surprised at some of the research results. <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

dmjspace · Mar 13, 2006

RobNissen said: I amost hate to start this thread because I am really not interested in post after post from the EPH crowd. But it seems to me that our models of comet formation are not being verified by the actual data. And your bias is revealed. Why would anyone start a post saying the standard model is failing miserably, and then in the same breath imply that "I'm not going to consider the alternatives, though!"? You clearly understand that the EPH is, in fact, a superior theory because it has a long record of successful predictions. The snowball model, on the other hand, has been rejected as the null hypothesis. EPH opponents have an emotional bias against the idea of a planetary breakup...fine. Let's all at least be grown-ups about it and admit that this is an emotional bias, not a scientific one. We believe comets formed in the cold outer reaches of the solar system and at least on their early passes through the solar system are full of volatiles. But we are not seeing that. We also beleive that comets are dirty snowballs, or snowy dirtballs, but we don't appear to be seeing that either. Last summer, there was very little wator vapor kicked up by the cometary impact, and now with the initial Stardust data instead of seeing volatiles and water, we are seeing minerals that only form in high heat. Plus, it was my understanding that olivene does not form in the presence of water, and yet Stardust is finding large amounts of olivene. Now, don't get me wrong, I am not advocating EPH, or any of the other theories whose proponents generally advance their theories by insulting others. But I think the data we are seeing is demonstrating that our most accepted theories of comet formation are wrong. Thoughts?

bonzelite · Mar 13, 2006

"...e EPH crowd. But it seems to me that our models of comet formation are not being verified by the actual data. We believe comets formed in the cold outer reaches of the solar system and at least on their early passes through the solar system are full of volatiles. But we are not seeing that. We also beleive that comets are dirty snowballs, or snowy dirtballs, but we don't appear to be seeing that either. Last summer, there was very little wator vapor kicked up by the cometary impact..." i see. a continuation or sequel to the locked wild 2 thread. better be careful there, you're asserting some pretty heavy stuff . not too many here can think about those things you posted there highlighted in yellow. "current theories may be wrong." ----- /> we can't have that here, fella. better have this thread deleted or something. we may have the cartoon riots pretty soon. current models wrong? for comets? how dare you even suggest that. you're not saying they're really dust and dirt are you? maybe even formed close by? nah. blasphemy. next you'll be saying the big bang is wrong, too. golly molly. we can't have that.

dmjspace · Mar 13, 2006

From one of the several articles on Wild 2 samples: Scientists have found minerals formed near the sun or other stars in the samples returned to Earth by NASA's Stardust spacecraft in January. The findings suggest materials from the center of the solar system could have traveled to the outer reaches where comets formed. This may alter the way scientists view the formation and composition of comets. Sometimes rocket scientists can be soooo stupid. The simple solution to the presence in Wild 2 of olivine and other compounds that formed in high heat or in liquid water is that the comet originated from a liquid bearing, terrestrial parent body in the inner solar system. While mission scientists are busy inventing scientific "swidgets" to explain every new and unexpected finding, those of us who favor the EPH can only sit back and shake our heads. Comets are dusty, rocky bodies. They shows signs of intense heating, as if subjected to explosion. There are asteroid-like in composition and terrain. Lots of people--lots of smart people, even--have a real aversion to the idea that a planet-sized body could explode, despite the fact that explosions are a common phenomenon in the universe. Even if you fall into this crowd, isn't it about time to get onboard with a model that makes successful predictions, rather than having to deal with these unexpected surprises all the time?

bad_drawing · Mar 13, 2006

Hi RobNissen I couldn't agree more. I've been reading the stories and following the news and watching the back and forth on these threads. I've always found the dirty snowball model to look good and make sense...but it seems each new discovery and observation by these up close and personal probes kicks another leg out from under that model. I would just like to see a better understanding of comets where prediction gels with observation vs the gasp every time info comes out.... and it seems to this admitted layman that we are approaching the point where we need to stop trying to force the dirty snowball model to work, and look at other real possiblities. Heres the part where I believe we're coming from the same place. Lately on these boards it seems that (with comets) either one has to be pro EU or pro Dirty Snowball. I see no reason why it should come down to just those choices.

robnissen · Mar 13, 2006

Your missing the point. Threads aren't locked because someone challenges orthodox views, threads are locked because of insulting and belittling. When people start talking about conspiracies, or Nasa and its minions, those threads are no longer about "Science and Astronomy," and they are properly locked. I think there are holes in the mainstream theory of comet formation, as do I think there are holes in the big bang --dark enery seems to me to be the ultimate fudge factor. But just because there are things we don't understand, that is no reason to insult those who have spent their lives studying these things, and instead start spouting the drivel from some guy with a web site, like he is the re-incarnation of Einstein. Oh wait, Einstein was also one of the chief conspirators -- give me a break. Newton explained the known universe damn near perfectly, but when problems were found with Mercury's orbit, that didn't make Newton a moron, it just meant his theory was incomplete. Most of our current mainstream theories will still be mainstream science centuries from now, a few will probably join the aesther (sp?) on the scrap heap of science and so it goes. In the meantime, when we get new data, like the data from Stardust, we need to apply it to current theories, and if they support it great, if not we need to explore why it doesn't. Sometimes some guy with a web site might have the right explanation, more often it will be mainstream science. In the meantime, I think the news from the Stardust news conference today was stunning, and I for one, enjoying hearing hypothesis, speculations and theories that try to match the data. To the extent those speculations are outside the mainstream, fine, as long as the discusssion is civil.

robnissen · Mar 14, 2006

We are pretty much in agreement.. The one thing that really surprised me today, was at the news conference, it was just casually mentioned that maybe "the samples formed near a distant star." That seems to me to be a pretty big jump from the standard model of comet formulation. That tells me that the results were even more shocking to the examining scientists, than to us lay people.

bonzelite · Mar 14, 2006

Threads aren't locked because someone challenges orthodox views, think again, buddy.

bonzelite · Mar 14, 2006

We are pretty much in agreement.. The one thing that really surprised me today, was at the news conference, it was just casually mentioned that maybe "the samples formed near a distant star." That seems to me to be a pretty big jump from the standard model of comet formulation. That tells me that the results were even more shocking to the examining scientists, than to us lay people. yeah. i was suggesting in the weird crystals thread that comets may be of extrasolar origin. and guess what? certain mods didn't like my ideas and guess what? they locked the thread. my idea was "irrelevant." who is irrelevant now, sunshine?

bonzelite · Mar 14, 2006

before i knew a damn thing about the recent press release, a day before or so, i posted this that went largely ignored, as is typical of anything radically innovative, or at least interesting: link to post here "more thoughts on comets: comets, in the pristine model, ie, ancient objects, if true, may point to comets being intergalactic, extrasolar, wanderers. often, in edge-on views of galaxies, we are accustomed to seeing obfuscating "dust lanes." these structures are fairly common and observed with regularity. so, then, these dust lanes must be a common component of galaxies. comets are dust. that is basically what science is observing, regardless of what volatiles are present in cometary tails. therefore, an overall composite view, albeit limited to only a handfull of observed comets, is showing us that comets are composed of very super-fine materials, such as dust and ice, compacted into a freeze-dried and very porous object. what i'm getting to is that such objects as comets may originate far and beyond any one solar system. they may be borne out of the pervasive and encircling dust lanes throughout galactic structures. how they accrete is unknown, but they may form in variations upon the basic accretion theme depending on how far or near they are to a star: the longer their journey, the more dust they accumulate over vast distances. because of their wanderlusting ways, so to speak, they accrete only as very porous and loose bodies, picking up superfine dust as they go, never becoming very compacted overall. older coma may be larger, with a more compacted core. in this way, comets may indeed be pristine carriers of matter from the galaxy itself and not only the local solar system. particles, then, may be entirely foreign to this solar system's commonly found e

yevaud · Mar 14, 2006

they may be held together and attract other dust particles electrostatically, like common lint or textiles tumbling in a clothes dryer. You should really take some classes. You say no one discusses this. Guess what? This *is* the mechanism we understand caused fine particles to begin to accrete when the Protoplanetary Disc was coalescing into the Solar System we see today. Look up "Van Der Waals" forces (mind you, we also see that once a certain mass limit is achieved, gravity takes over as the accretion mechanism). No offense, Bonz, but that "no one discusses this" statement shows you haven't really studied this science well. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

bonzelite · Mar 14, 2006

no, charlie. you've left out the thrust of the point ------->extrasolar. your attempt to discredit the whole thing by that one statement is pathetic and useless. your statement shows you haven't really studied this science well.

yevaud · Mar 14, 2006

HAR HAR HAR. I was a double major in two relevant sciences that are germaine to this discussion. You are an illustrator. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

jatslo · Mar 14, 2006

An innovator, and scholar are artistic. It is innovation that will move this world. <img src="/images/icons/smile.gif" />

yevaud · Mar 14, 2006

Do you have any concept just how vast space is? The amount of material you propose is just, well, obscene. It just plain doen't work that way. Remember my analogy about being dropped randomly into the Pacific, and what your probability of landing on an island versus water is? Like that, only multiple magnitudes greater. As to the other point in question. This is verbatim out of one of my texts from school: ...gas and dust were separated as dust sedimented to the midplane disk and accretion of condensates started 4.56 Gyrs ago. This effect is proven by the matrix composition of undifferentiated asteroids, and it occured simultaneously everywhere in the solar nebula. Centimeter sized solids formed in a few thousand years in response to magnetic, electrostatic or van der Waals forces. Within 10^4 years meter to kilometer sized objects were formed in soft low-speed collisions. Gravitational forces were now dominant, and within 10^5 years, objects of 10^2 - 10^3 km in diameters appeared. These will be referred to as planetesimals. Around this time, the dust disk dissipated, but collisions continued to form larger objects, and within 10^6 years Moon to Mars sized objects formed, these objects will be called protoplanets. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

bonzelite · Mar 14, 2006

HAR HAR HAR. I was a double major in two relevant sciences that are germaine to this discussion. "oooohhhh. aaaahhhh. oooooohhhh. aaaaaaahhhh." You are an illustrator. exactly. so was Leonardo daVinci.

yevaud · Mar 14, 2006

Oh, so now you're Leo. Swell. That's not answering me or addressing the points made, now is it? If your experience and schooling was not mine, where do you get the "this isn't discussed" routine? <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

bonzelite · Mar 14, 2006

Do you have any concept just how vast space is? The amount of material you propose is just, well, obscene. It just plain doen't work that way. Remember my analogy about being dropped randomly into the Pacific, and what your probability of landing on an island versus water is? Like that, only multiple magnitudes greater. yes. i read it. and it ignores my entire point. your textbook and YOU PERSONALLY do not know what is possible. that is a fact. not only that, you are myopic to what is possible because of your textbook altar.

yevaud · Mar 14, 2006

What point? That you're trying to state that all cometary material are extrasolar captures, when it utterly ignores all of the physical realities? That you, an amateur, state that a book written by experts in the field, and encompassing decades of work are wrong - based on your uninformed opinion? <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

bonzelite · Mar 14, 2006

the point is extrasolar origin of comets. and that idea is often not suggested, or if it is, it is very seldomly considered --until NOW. beforehand, it was always "Oort Cloud this and that." i suggested that is possibly not correct. how they are actually formed is entirely unknown. and i made guesses as to that, too. that is the point. and that is not written in any text book because it is far out of the bounds of past reason. and yet it is suggested by the recent press release: http://space.com/scienceastronomy/060313_stardust_update.html Pieces of a comet returned to Earth by NASA’s Stardust spacecraft apparently formed near the Sun or around another star altogether before being flung to the outer edges of the Solar System, mission scientists said Monday. i suggested many things in the post. some things may be seeds of genius. some may be way off. but one must begin to entertain seemingly impossible ideas to find what is really possible. rehashing old knowledge does not lead to innovation. so i can check off extrasolar origin as hitting the bullseye when all others stood to ridicule or ignore me. all else must wait. are guesses. are ideas. and this is problematic for you?

jatslo · Mar 14, 2006

Yevaud, "... What point? That you're trying to state that all cometary material are extrasolar captures, when it utterly ignores all of the physical realities? ..." In hypothesis, as in testable hypothesis, a random sample (X) that is less than 30 is treated as "t", as opposed to "z", so a quantity of 1 can be utilized in statistics to predict the outcome of all. The confidence interval (CI), which is probability, can be rather high, and even more so when other sample spaces are tested. Of course, if you find two opposing flavors, then the probability drops to about 50%, and so on. bonzelite can argue within a reasonable degree that all comets are extrasolar captures. NASA did suggest the possibility, right? **out of context quote corrected. Fair warning. If you are going to quote another member, make sure you include enough of the original quote to accurately reflect what they actually said, not a small snippet that makes it “appear” their comment agrees with you.**[/u]

What's Going on With Comets?

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