Comets - Not What We Expected

[Michael_S]

This video on comets is shocking.

The data suggests they are made out of pure rock.

http://www.youtube.com/view_play_list?p ... 44C0911272

 

[centsworth_II]

This video on comets is shocking....

Sorry, but the presenter lost my respect and my interest right away by opening with a conspiracy theory. NASA, he says, is very good at keeping comet data under wraps. A minute later he tells us that his entire presentation is based on freely available NASA publications. :roll:

 

[MeteorWayne]

Welcome to Space.com.

Unfortunately, much of what is on YouTube is garbage. So far (I have only watched half of the first of 6 videos so far) I have found several factual distortions and errors.

Unless the poster links to the actual articles (which I have) I'm not looking at this anywhere near factual.

I am documanting the assertions, and will back them up with the facts from the peer reviewed articles.

I'd strongly suggest taking ANYTHING posted on YouTube with much skepticism unless you look at the actual data, as pure speculation. Probably distorted for a particular agenda. That's been my experience.

It will take a day or so to go throgh the hour of video, perhaps he posts links to the actual articles. If he does, then we'll see if they say what he says they do.
So far, in the firat 5 minutes, it ain't lookin' good.

 

[Michael_S]

Well he's got a link in the video notes with a page that has every claim made backed up by NASA's own web sites and papers.

http://sites.google.com/site/cosmologyq ... ngs/comets

 

[MeteorWayne]

So he says. So far, halfway through the first part, his assertions do not match what the papers actually state.

 

[xXTheOneRavenXx]

lol, why doesn't that surprise me. Going to Youtube to look for actual facts is like going to a used car salesmen and taking his word for it that the car you wish to buy from him has no problems with it.

 

[3488]

Well he's got a link in the video notes with a page that has every claim made backed up by NASA's own web sites and papers.

http://sites.google.com/site/cosmologyq ... ngs/comets

Hi Michael,

Please take what MeteorWayne says very seriously.

There is a huge amount of distortion & untruths on YouTube as pointed out by MeteorWayne.

There is some genuine good stuff on there also, but the videos that you refer to, as centsworth_II correctly says is woo woo conspiracy nonsense.

It is a known fact that comets are at least part ice & part rock. A truly 'rocky' comet is not a comet, but is instead an asteroid.

There does appear to be a continuum from truly icy comets to rocky & even metallic asteroids, but saying that comets are made from pure rock is total nonsense.

There are indeed part rocky / part icy bodies, as they form part of the continuum of such small bodies.

Also Centsworth_II also directed you to a major inconsistency with the OP on YouTube.

Welcome to SDC & hopefully you will stay around & participate & learn with us.

Andrew Brown.

 

[Michael_S]

Well I'm not taking it at face value.

I'm looking at NASA Deep Impact web site reviewing what he talked about in the video.

http://deepimpact.umd.edu/mission/updat ... #lmcfadden

Since the visible images have a higher spatial resolution, we use those images to calculate the extent of ice on Tempel 1's surface. That turns out to be a small fraction of the surface, only 0.5%...
What is significant is that the extent of this ice on Tempel 1's surface is not sufficient to produce the observed abundance of water and its by-products in the comet's coma.

Now she goes on to say:

The team thus concludes that there are sources of water from beneath the comet's surface that supply the cometary coma as well.

But I can't find the data that supports such a conclusion.

Do you know of some observations that have been published showing images of water ejecting out from deep inside the comet?

All I can find on the deep impact site is the small discharges they claim make up the .5% surface ice, which she just said wasn't enough to explain the coma.

It strikes me as exceedingly odd that a comet giving off a coma millions of miles in diameter that's made up of OH radicals could have only .5% of its surface as visible ice. In the papers I've looked at, the NASA scientists are stating they needed some 200 times the observed ice to account for the coma.

And since they are looking at OH radicals and not actual water, they would then need to explain how photolysis could occur at such incredible rates. How is that much water being broken down so quickly? If astronauts let water go in space, does it break down into OH radicals instantaneously?

 

[Michael_S]

I don't understand this article either.

http://www.skyandtelescope.com/news/330 ... page=1&c=y

Sky and telescope says they didn't find any water on comet borrelly either.

 

[BoJangles2]

This youtube video is just promoting EU obviously

 

[yevaud]

Precisely so. This is a subset of the EU world. They're apparently trying to push EPH ("Exploding Planet Hypothesis"), in which a purported planet located where we now have an asteroid belt (insufficient material present to have been a planet) exploded (mechanism unknown and unexplainable), and left nothing but material "proving" there was a planet once (as Andrew said, Comets run the gamut, they are not 100% rocky at all).

Been there, done that.

 

[kg]

I don't understand this article either.

http://www.skyandtelescope.com/news/330 ... page=1&c=y

Sky and telescope says they didn't find any water on comet borrelly either.

I think this quote from that Sky and Telescope article explains it...

"Because this comet has been trapped in a 7-year-long orbit around the Sun for at least two centuries, scientists believe it has exhausted most of the volatile consituents needed to create an impressive coma and tail."

 

[yevaud]

A far better explanation.

 

[xXTheOneRavenXx]

Now that makes lot more sense, rather then listening to the likes of a "blind-eyed" conspiracy theory.

 

[3488]

Precisely so. This is a subset of the EU world. They're apparently trying to push EPH ("Exploding Planet Hypothesis"), in which a purported planet located where we now have an asteroid belt (insufficient material present to have been a planet) exploded (mechanism unknown and unexplainable), and left nothing but material "proving" there was a planet once (as Andrew said, Comets run the gamut, they are not 100% rocky at all).

Been there, done that.

Thank you very much Yevaud, for backing me up.

I agree that the EPH belongs in woo woo land. As you correctly say there is no mechanism for a planet to explode on its own. Also IIRC the entire mass of the Asteroid Belt amounts to only 4% of our own Moon.

Of that the dwarf planet 1 Ceres accounts for one third, 2 Pallas & 4 Vesta contribute another one sixth between them whilst others like 10 Hygeia, 7 Iris, etc take up a sizable chunk of the rest.

Hardly a substantial planetary mass by any means.

As said, there is a continuum of small bodies, some like Saturn's moons Hyperion, Telesto, Helene appear to be pure ice or very nearly so.

Some hybrids, like 1 Ceres, Enceladus, Phoebe (possible captured KBO by Saturn), Pluto, Eris & the half rock half ice asteroid / comet body 107P/ Harrington - Wilson, to more familiar rocky asteroids, such as 243 Ida & 951 Gaspra, both seen in great detail by the Jupiter bound Galileo spacecraft, then rocky metal hybrids such as the large type M asteroid 21 Lutetia, to be visited by the ESA Rosetta spacecraft in July 2010, just under 14 months from now.

Then truly metallic asteroids like 16 Psyche (very rare, 16 Psyche being the only large example known).

It's a continuum, of small bodies. Hope I'm correct Yevaud.

Andrew Brown.

 

[3488]

I don't understand this article either.

http://www.skyandtelescope.com/news/330 ... page=1&c=y

Sky and telescope says they didn't find any water on comet borrelly either.

I think this quote from that Sky and Telescope article explains it...

"Because this comet has been trapped in a 7-year-long orbit around the Sun for at least two centuries, scientists believe it has exhausted most of the volatile consituents needed to create an impressive coma and tail."

Thank You very much kg.

More likely there are ice encrusted dust particles rather than pure ice in such bodies.

Lets see, 200 years divided by 7 years = 28 orbits into the inner solar system. So yes, for sure much surface ice would have sublimated by now unless the nucleus was gigantic to start with.

That makes sense kg.

Andrew Brown.

 

[yevaud]

Andrew, you ARE correct. Given the number of Meteorites that we have collected worldwide, one would expect them to conform to the "all rocky" hypothesis. were it correct; after all consider that their source is the same reservoir. They simply do not, as you of course know. Carbonaceous Chondrites through Nickel-Iron, they DO range the gamut from soup through nuts.

As to EPH: I have never heard a reasonable explanation from it's proponents as to all of it's glaring defects. They fob them off. There is no know mechanism for a planet to explode, nor is there any explanation where all of the material might have gone. I've even heard it stated that the presence of the Kirkwood Gaps is of no import, regardless of how often I note to them that the perturbative effects of Jupiter - the very reason the gaps exist - would prevent a planet sized body from accreting there in the first place.

It's simply absurd.

 

[Michael_S]

I don't understand this article either.

http://www.skyandtelescope.com/news/330 ... page=1&c=y

Sky and telescope says they didn't find any water on comet borrelly either.

I think this quote from that Sky and Telescope article explains it...

"Because this comet has been trapped in a 7-year-long orbit around the Sun for at least two centuries, scientists believe it has exhausted most of the volatile consituents needed to create an impressive coma and tail."

Well that's an interesting hypothesis, however clearly that's not what McFadden said about Temple 1. "What is significant is that the extent of this ice on Tempel 1's surface is not sufficient to produce the observed abundance of water and its by-products in the comet's coma."

We continue to see Borrelly discharge, its not exhausted. Space.com posted an image from Kitt Peak that clearly shows it to be highly active.

If we see no water on the surface, then I have to wonder how it could possibly discharge given the current theories of photolysis as a mechanism of explaining the OH radicals in comet comas and tails.

I take it no one here is really interested in finding out what is going on with these comets.

Tempel 1, no water.

Borrelly, no water.

Wild 2, no water.

Why?

Then we have comet halley discharging explosively out between Saturn and Uranus, wayyyyy to far for melting. How did that happen?

 

[yevaud]

I take it no one here is really interested in finding out what is going on with these comets.

You're incorrect. We have previously had debates here on this subject that have lasted for months on end. This is a "been there, done that" moment for many of us.

 

[silylene]

I take it no one here is really interested in finding out what is going on with these comets.

You're incorrect. We have previously had debates here on this subject that have lasted for months on end. This is a "been there, done that" moment for many of us.

Precisely. I first opened this thread when it was one post long, got a whiff of 'woo woo', with glimmers of EPH and EU, and became averse to re-open this thread 'til now.

That said, I am quite interested in comets. If the discussion remained more firmly rooted in the mainstream theories of cometary formation and behavior, I'd be more interested.

That said, I sure hope we can place a lander, or better a rover, onto the surface of an active comet before I die of old age !

 

[centsworth_II]

...I sure hope we can place a lander, or better a rover, onto the surface of an active comet before I die of old age !

Hang in there!

Landing on the comet (November 2014)
"Once a suitable landing site is chosen, the lander is released from a height of about one kilometre. Touchdown takes place at walking speed — less than one metre per second.

Once it is anchored to the nucleus, the lander sends back high-resolution pictures and other information on the nature of the comet’s ices and organic crust....

The orbiter continues to orbit Comet 67P/Churyumov-Gerasimenko, observing what happens as the icy nucleus approaches the Sun and then travels away from it."

 

[yevaud]

/Win!

 

[silylene]

Yes, thank you for reminding me about Rosetta !

 

[drwayne]

I take it no one here is really interested in finding out what is going on with these comets.

You're incorrect. We have previously had debates here on this subject that have lasted for months on end. This is a "been there, done that" moment for many of us.

This is also an example of why it is a good idea to take some time and read a forum, and try to understand
some of the forum's history before jumping right into the "lets talk about my favorite topic!" mode.

 

[Michael_S]

I take it no one here is really interested in finding out what is going on with these comets.

You're incorrect. We have previously had debates here on this subject that have lasted for months on end. This is a "been there, done that" moment for many of us.

This is also an example of why it is a good idea to take some time and read a forum, and try to understand
some of the forum's history before jumping right into the "lets talk about my favorite topic!" mode.

GREAT!

If someone could link me the papers that explain all of this I'd love to see them so I could review them.

I haven't been able to find them.

All I've been able to find is the NASA documentation which basically just posts the mission findings and doesn't detail any real explainations for the observations.

I assume all of these questions must have been resolved.

Specifically how the photolysis is occuring without ice on the surface.

That's the real kicker I've been waiting for a good paper on with some experimental data to verify this is really the case.