APOD: Explore Rosetta's Comet (2016 Oct 03)

[MarkBour]

I find Kaarlo's theory interesting ... I believe he is at least pointing out valid Earth-geological patterns to consider and they're worth considering. One of the main things I think he introduced to this discussion is the matter of erosion. Not only erosion by Earth-like processes, but equally relevant, space weathering. We know that comets suffer from this in the extreme. Perhaps someone should coin another term, or extend the list of space-weathering processes listed at: https://en.wikipedia.org/wiki/Space_weathering to include the extreme effects of orbits that cause huge differences in temperature of a cometary nucleus. As I look at the shape of C67P, it does not strike me to be the likely result of simply a binary aggregation, since the central neck region is so off-center. I think it likely that it was either aggregated in a more convex and balanced shape, or was initially monolithic, but that the heating on a trip in towards the sun may have cause an expulsion of a large portion of the middle of the comet, as a very violent "jet" blew a portion out of the middle. Or, perhaps there was simply a chunk of ice, like a glacier, in that region, which all evaporated on such a trip. Either way, it could have had something to do with the rotation that C67P now exhibits.

[Kaarlo]

John,
Thanks for your kind comment.
Someone might consider it quite understandable that an 'untrained geologist' cannot - and consequently refuses to - see apparent geological structures. Someone might call such attitude the 'top of patheticism'.
Someone also - once upon a time - said, after being tried and judged for heresy: "E pur si muove!" - Still it moves.

[Chris Peterson]

One of the main things I think he introduced to this discussion is the matter of erosion. Not only erosion by Earth-like processes, but equally relevant, space weathering. We know that comets suffer from this in the extreme.

Actually, comets are among the least space weathered bodies. Space weathering involves chemical and physical changes, largely at the surface, due to interaction with energetic particles and micrometeorites. Most comets (at least, those with shorter periods or those that are in the inner system) have fairly new surfaces, so there is little evidence of space weathering (which is a slow process).

Erosion on comets is due to the evaporation of volatiles and ejection of particulates while near perihelion.

[rstevenson]

... Someone might consider it quite understandable that an 'untrained geologist' cannot - and consequently refuses to - see apparent geological structures. Someone might call such attitude the 'top of patheticism'.
Someone also - once upon a time - said, after being tried and judged for heresy: "E pur si muove!" - Still it moves.

From Rational Wiki...

The Galileo gambit, or Galileo fallacy, is the notion that if you are vilified for your ideas, you must be right.

An excellent discussion of this syndrome is on this page at Open Parachute.

Rob

[Kaarlo]

Yes, Galileo was tried, judged, vilified and likely even tortured for being right. Right?
Am I right? Well, in a couple of centuries we'll know for sure. At least I was vilified in my time.

[geckzilla]

Yes, Galileo was tried, judged, vilified and likely even tortured for being right. Right?
Am I right? Well, in a couple of centuries we'll know for sure. At least I was vilified in my time.

http://rationalwiki.org/wiki/Galileo_gambit

[Ann]

Yes, Galileo was tried, judged, vilified and likely even tortured for being right. Right?
Am I right? Well, in a couple of centuries we'll know for sure. At least I was vilified in my time.

Wow. Those who are vilified in their time are likely to be hailed as Galileos a couple of centuries from now as a tribute to their vilification.

The number of 21st century Galileos that will be celebrated a couple of centuries from now will be stunning!

Ann

[Kaarlo]

Ann,
Thanks - and congratulations! - for opening your eyes and mind for the very apparent geological evidence: asteroids (comets inluded) derive their origin from Proto-Earth.

[geckzilla]

Did that just happen?

[Chris Peterson]

Yes, Galileo was tried, judged, vilified and likely even tortured for being right. Right?
Am I right? Well, in a couple of centuries we'll know for sure. At least I was vilified in my time.

Galileo expressed scientific views that conflicted with the non-scientific views of non-scientist despots and was imprisoned for that. You have expressed borderline pseudoscientific views that conflict with the scientific views of scientists and have been criticized for your approach and have had your conclusions challenged.

I imagine Galileo would have happily traded his "vilification" for yours.

[JohnD]

This report treats the 'strata' as just that, strata, and uses their planes to show that 67P was originally two objects, as the planes don't line up.
https://www.newscientist.com/article/dn ... t-mash-up/

But they did not explain how strata can form in microgravity. That this can be a part of a planet (why Earth, Kaarlo? Mars fragmnets have landed on Earth) seems so unlikely, but I'm at a loss to explain.

JOhn

[Chris Peterson]

This report treats the 'strata' as just that, strata, and uses their planes to show that 67P was originally two objects, as the planes don't line up.
https://www.newscientist.com/article/dn ... t-mash-up/

But they did not explain how strata can form in microgravity. That this can be a part of a planet (why Earth, Kaarlo? Mars fragmnets have landed on Earth) seems so unlikely, but I'm at a loss to explain.

I have no explanation I'm willing to offer strong support for, but it certainly seems plausible that cometary bodies, which probably form by gravitational accretion, would have stratigraphic structure. On a larger scale that might be onion-like, but any curvature is likely to be invisible (or lost due to metamorphic processes) in smaller fragments.

[MarkBour]

One of the main things I think he introduced to this discussion is the matter of erosion. Not only erosion by Earth-like processes, but equally relevant, space weathering. We know that comets suffer from this in the extreme.

Actually, comets are among the least space weathered bodies. Space weathering involves chemical and physical changes, largely at the surface, due to interaction with energetic particles and micrometeorites. Most comets (at least, those with shorter periods or those that are in the inner system) have fairly new surfaces, so there is little evidence of space weathering (which is a slow process).

Erosion on comets is due to the evaporation of volatiles and ejection of particulates while near perihelion.

Kind of a bad day for me in Starship Asterisk. But I can learn.

First, I offered an opinion that C67P was probably a single body with a blow-out or melt-out creating its overall shape, whereas I now see that the more careful look seems to indicate otherwise, that C67P is most likely a 2-body "mashup". I don't know if there's much confidence in that analysis, but it seems more likely now. (That analysis was done with images of higher resolution than this day's APOD, by the way.)

Second, I was struggling with what word to use for a comet's overall major degradation process. I was thinking by analogy to what happens on Earth, where erosion is mainly a process caused by external materials (wind, water, etc are not part of the object being eroded), whereas if an ice cream cone on earth melts and drips all over the place, I figured "weather" would be a better word, since warm weather would be the cause.

However, I accept the correction above, from Chris. Better, it seems, to think about what the process is doing to the object in question. So, when a comet [or Frosty the snowman] is melted and begins to dissolve [say, Frosty's arm falls off], due to the warmth of the Sun, this is best referred to as "erosion", because the body is wasting away. We would then reserve "weathering" as a term for the modification of the surface of a body, like the development of a patina on a copper penny.

[geckzilla]

Man, being wrong and having someone who knows their stuff actually take the time to correct you is pretty much the easiest way to learn. It's not really a bad day when that happens.

[neufer]

Man, being wrong and having someone who knows their stuff actually take the time to correct you is pretty much the easiest way to learn. It's not really a bad day when that happens.

• I'd say maybe a good way to learn...but not necessarily the easiest.

Click to play embedded YouTube video.

<<On February 4, 2015 Brian Williams apologized for and recanted an Iraq War story he had told on the January 30 Nightly News broadcast, that a military helicopter he was traveling in had been "forced down after being hit by an RPG.” Williams's story was criticized soon after it was aired by Lance Reynolds, a flight engineer on board one of the three Chinook helicopters that had been attacked. Reynolds and other crew members said they were forced to make an emergency landing, and that Williams's Chinook arrived a half-hour to an hour later.

A reference to the fall of the Berlin Wall also received scrutiny. In 2008, Williams said that he was "at the Brandenburg Gate the night the wall came down," while CBS and other sources report that Williams did not arrive until November 10, the day after the gates between the two halves of Berlin were opened. Another statement by Williams, this one regarding the Navy SEALs, also received attention. Williams said he flew into Baghdad with SEAL Team Six, but Special Operations Command spokesman Ken McGraw stated the SEALs do not embed journalists.>>

[geckzilla]

Well, now you've taken it out of the context of a relatively private forum and compared it to flubbing on national television. At Starship Asterisk, no one is really flaying anyone alive for being wrong. I don't even know the real names of a lot of the people here. Who cares if you're wrong once in a while.

[neufer]

Click to play embedded YouTube video.

Well, now you've taken it out of the context of a relatively private forum and compared it to flubbing on national television. At Starship Asterisk, no one is really flaying anyone alive for being wrong. I don't even know the real names of a lot of the people here. Who cares if you're wrong once in a while.

C-3PO: You will therefore be taken to the Dune Sea and cast into the Pit of Carkoon, the nesting place of the all-powerful Sarlacc...In his belly, you will find a new definition of pain and suffering, as you are slowly digested over a thousand years.

[MarkBour]

Those are pretty funny! I just posted my previous note to let you know that at least some of us who post an opinion here are actually capable of realizing when they are wrong ... so it is valuable to reply with corrections (to me at least). Sometimes it seems as though Asterisk posters are quite married to their opinions. But for me, I'll not perform instant floccinaucinihilipilification on my vilifications.

[neufer]

I'll not perform instant floccinaucinihilipilification on my vilifications.

• And The Shenstone of Shame for Sir Walter Scott & the Guinness Book of World Records:

[b][size=150][color=#0000FF]NGC 4414, a flocculent spiral[/color][/size][/b]

---

<<Back in the eighteenth century, Eton College had a grammar book which listed a set of words from Latin which all meant something of little or no value. In order, those were flocci, nauci, nihili, and pili.

Somebody put all four of these together and then stuck –fication on the end to make a noun for the act of deciding that something is totally and utterly valueless (a verb, floccinaucinihilipilificate, to judge a thing to be valueless, can also be constructed, but hardly anybody ever does). The first recorded use is by William Shenstone in a letter in 1741: “I loved him for nothing so much as his flocci-nauci-nihili-pili-fication of money”.

A quick Latin lesson: flocci is derived from floccus, literally a tuft of wool and the source of English words like flocculate, but figuratively in Latin something trivial; pili is likewise the plural of pilus, a hair, which we have inherited in words like depilatory, but which in Latin could mean a whit, jot, trifle or generally a thing that is insignificant; nihili is from nihil, nothing, as in words like nihilism and annihilate; nauci just means worthless.

Floccipaucinihilipilification (with a p in seventh place) also exists. Examples of that form are found online and in some modern books but it isn’t standard. The fault seems to be that of Sir Walter Scott, who misspelled it in his journal in 1829, a mistake perpetuated by the Guinness Book of World Records, which has included it in some editions as the correct form, quoting Scott, while noting the n version only as a variant rather than the original.>>

[Chris Peterson]

Better, it seems, to think about what the process is doing to the object in question. So, when a comet [or Frosty the snowman] is melted and begins to dissolve [say, Frosty's arm falls off], due to the warmth of the Sun, this is best referred to as "erosion", because the body is wasting away. We would then reserve "weathering" as a term for the modification of the surface of a body, like the development of a patina on a copper penny.

Just FYI, from the conventional geology standpoint, "weathering" describes the processes that modify or break down material (e.g. freeze/thaw cycles, acidic chemicals in rain, etc.) and "erosion" is the actual transport of the weathered material to a different location. Erosion pretty much requires some kind of weathering process, but weathering doesn't necessarily lead to erosion (the patina on that penny is pretty robust, as is desert varnish on terrestrial rocks or the space weathered surface of many asteroids).

[JohnD]

To avoid confusing the issue, if we require a word to describe the degradation of objects in space, and those from the discipline of geology are too closely defined, then let us seek another. The closest to astronomy in this application is engineering, and "wear" is a verb and a noun (useful) that means:

Vb: To injure the surface of, partly consume or obliterate, damage, attenuate or alter, by rubbing or stress or use.

N: Damage sustained as the result of ordinary use.
[Both OED definitions or part of]

Substitute "wearing" in place of weathering or erosion, and the meaning is clear and sensible.

JOhn

[Chris Peterson]

To avoid confusing the issue, if we require a word to describe the degradation of objects in space, and those from the discipline of geology are too closely defined, then let us seek another.

Well, I'm all for clarity, and using new words if necessary. Just not sure we need anything here. I don't think there's any confusion, and the geological terminology used in space seems to work just fine, with the same meaning. "Weathering" is the alteration or breakdown of a surface, "erosion" is the transport of material.

In fact, I don't see what "wearing" adds other than a little confusion. Space weathered surfaces aren't reasonably seen as worn, and "eroded" seems much clearer if we're talking about surfaces which have lost material.