Blue Collar Scientist

The final video from the Junk Bond Observatory trip is up at YouTube.

If you sent in a question, and haven’t heard it answered yet, it will be covered here. Enjoy!

My previous two videos about Junk Bond Observatory have inspired some Q&A, so I’ve posted part one (of two) of some answers to the questions that have been posted to the blog as comments, and/or e-mailed to me. This is a bit dry, I know, but it is what I do for a living, and I don’t know how to make it interesting unless you are really obsessed with high performance telescopes that aren’t being controlled by grad-student-ware¹. Anyway, here it is:

If you want to keep up with my future videos, you can subscribe to my YouTube channel.

The next two videos coming up will be part two of the Q&A, and a video of a short presentation I gave at a religious school.

1. This is a slightly derogatory term referring to kludged-together software, generally written in some deplorably out of date language or development environment, with many bad architectural choices made, by the graduate students tasked with writing it in return for peanuts and water from the drinking fountain down the hall. In astronomy, grad-student-ware (cf. shareware, freeware) seems to be responsible for more observatory downtime and observational overhead than any other source. [↩]

I’ve finally completed the video about data reduction at Junk Bond Observatory. In this video, we answer the question of how Junk Bond Observatory got its name, and provide a demonstration of what our images look like and how we turn them into scientific results. The demonstration by Dave is followed by a higher-resolution screen recording to show you the details, so stick with it to the end if you are interested in seeing the images up close. (And yes, I know this isn’t the best way - I’ve been learning whole new continents of my computing system doing this, and I am learning, but if I wait to post until I’ve learned everything, I’ll never get around to posting this stuff.)

In the next video, I’ll have answers to the rest of the questions that people asked after the first video was posted, and hopefully it won’t take me so long to get it posted. What can I say - I’m on a working trip. Work comes first, and even though the formal purpose for the visit was fulfilled sometime yesterday, I’ve still been quite busy taking care of loose ends and addressing things that I felt needed to be dealt with before I left.

Tomorrow will be a semi-travel day for me; I’ll be leaving JBO around noon Arizona time and heading up to Tucson, with a long stop to visit some people in between. Then Wednesday is a travel day. Blogging will continue to be light, sporadic, and possibly sub-standard until I’m home and have had a chance to sleep properly. But I’m hoping to get a few things posted from the hotel in Tucson, so stay tuned.

Earlier today I took some time out of my work schedule to record a little tour of the 0.8 meter telescope at Junk Bond Observatory, which is where I’m working for the next six days. This is totally ad-lib, with no script or outline, and it was all done with the iSight camera on my MacBook, so I apologize of the quality is not up to standards.

This is probably going to be a bit more accessible to astronomy types, so if you have questions or want to hear more about something, please leave a comment and let me know.

 

 Junk Bond Observatory tour: Play Now | Play in Popup | Download

Mark Hempsell, the co-author of the book that posits that a copy of an approximately 5,000 year old Sumerian tablet records an observation of an Aten asteroid, prior to its atmospheric entry, which impacted at Köfels, Austria - this being a story which, in the immortal words of The Greenbelt, we “doubt it very much” - has left two comments on this blog, one of them fairly lengthy and, I thought, requiring some reply.

My original takedown is here, and even though I wrote it before I realized that the Bad Astronomer, StumbleUpon, and other internet opinion-makers would make it the most popular post ever on this blog¹, there’s very little I’d retract. It is still a crappy press release that evidences precious little understanding of impact processes or asteroid orbital dynamics, and it is still a wildly implausible hypothesis that the authors actively resist subjecting to peer review.

The comment of Mark Hempsell’s that I am addressing is here. Starting in the second paragraph, Hempsell exhibits either a puzzling unclarity or a lack of understanding of, or poor research within, the field.

It [the impactor] is definitely neither stony nor iron (what Aten is?)…

Asteroids are classified according to their spectral types, which are determined by their compositions. As I read it, Hempsell is here saying that Aten-class asteroids are not stony or iron-rich. There are relatively few known Aten asteroids - hundreds, not thousands - and few of them have been observed spectrally.

As far as I can tell, all Atens so far observed are either stony, or iron:

• (3554) Amun is an M-type - considered to be of mixed iron/stony composition.
• (33342) 1998 WT₂₄ is E-type - stony or rocky, like an achondrite meteorite, or rather like basalt on Earth.
• (99907) 1989 VA is an S-type - of silicaceous rocky composition.
• 1989 UQ is a C-type, which stands for carbonaceous, and is therefore rocky like a carbonaceous chondrite meteorite. In fact, C-type asteroids are (at least in part) where such meteorites are thought to come from.

Oh, and guess what - this list includes (2062) Aten, the first discovered and hence the “type specimen” for the Aten family of asteroids. It is type S, so again, it is made of silicaceous rocks.

A lot of data on this is available in 2008Icar..194..111P (Photometry of Aten asteroids—More than a handful of binaries)², which lists for a large number of Aten asteroids the B-V and V-R color indexes that are used to constrain asteroidal spectral types. (For my lay readers, B-V and V-R provide the asteroid’s color; it is achieved by measuring the brightness of the asteroid in two defined photometric color bands and then taking the difference - hence the minus sign.)

So to Hempsell’s question, ‘what Aten asteroid is stony or iron,’ the answer is, basically, all of them that we’ve ever checked.

…indeed the impact dynamics…

The impact dynamics? There are no impact dynamics to look at. There’s absolutely no evidence of an impact at Köfels. There is no shocked quartz with PDFs, no impact glass, no crater, no microcraters, no remains of an impactor, no local enhancement of elements and isotopes associated with meteoroids, no ejecta….

I believe the problem here is that Hempsell is looking at Köfels, correctly discerning that the geology suggests there was no impact, and is then making ad hoc adjustments to his hypothesis to compensate. It would be more proper to look at Köfels and acknowledge that no impact occurred there - and then stop. Because one adjustment that needs to be made is extremely implausible:

…suggest a density below 1000 kg/m3.

First, let’s convert to the standard units: 1000 kg/m³ is 1 g/cm³. That happens to be the density of water³. Gasoline (petrol for European readers) has a density of about 0.7 g/cm³. Stuff of this density does not exist in inner solar system small bodies for a very good reason - volatiles that have such low densities evaporate or sublimate, and are lost to the parent body. This is a process we see with comets - sublimation creates the comet’s coma and tail. What you are left with after a few centuries of solar heating and mass loss in the inner solar system are the rocky remains - and it is quite possible that many inner solar system asteroids formed in this way.

The problem here is very serious: Hempsell is hypothesizing that the asteroid was an Aten, which by definition spends all its time in the inner solar system. But it couldn’t have had such a low density if it had spent even a few thousand years in the inner solar system, because the fluffy stuff would have long since been lost. If you run integrations on well-observed Aten asteroids, we find they’ve had more-or-less stable orbits for millions of years. (Sources: see here, and here.)

Hempsell seems to hypothesize an asteroid made of something like gasoline, in terms of density, which can’t exist - or can it? Perhaps the asteroid was a rubble-pile. Maybe rubble-pile asteroids have lower densities than water. Shall we check that out?

It is easy to do. The NEAR-Shoemaker spacecraft orbited asteroid (433) Eros, and then landed on it, in 2000-2001. This resulted in very good measurements of its density, which was, indeed far lower than many expected. But the density was still 2.4 g/cm³. If Hempsell is calling for an 0.8 g/cm³ asteroid, this is three times too dense - a massive discrepancy between observation and hypothesis.

The impact effect will be over estimated by Marcus, Melosh, and Collins because of the Alpine terrain.

No, it won’t. Marcus, Melosh, and Collins evaluated different terrain types (PDF). From their abstract:

The program requires six inputs: impactor diameter, impactor density, impact velocity before atmospheric entry, impact angle, the distance from the impact at which the environmental effects are to be calculated, and the target type (sedimentary rock, crystalline rock, or a water layer above rock).

So, unless we believe that Austria is made of feather pillows, it looks like they’ve got the situation covered. In fact, the geology of the area is mixed sedimentary and crystalline rock, and using either target type results in a huge crater, even from an asteroid made the density of gasoline. Go check it out for yourself.

Back to Hempsell:

The way it [ejecta] reaches the south east Mediterranean is the back plume which is deflected by the low pressure region behind the object, an effect well documented during the Shoemaker/Levy 9 impact.

Unfortunately, the SL-9 impact on Jupiter was into a dense gaseous atmosphere with no solid-surface impact, and the dynamics of that impact are thought to be very different from solid-body impacts. Hence, the mechanism that created the Jovian plumes isn’t looked for on Earth. This is for the simple reason that a low-pressure region on Earth cannot achieve as large a pressure difference as on Jupiter⁴. Earth’s atmosphere is significantly less dense to begin with. (Sources: Here, here, here….)

However, suborbital ballistic trajectories of ejecta are expected with large Earth impacts, as happened with the Chicxulub impact (at the K-T boundary - you know, the one that contributed to killing off the dinosaurs). Unfortunately, you don’t get ejecta without a crater. It is the process that forms the crater which causes the ejecta. I’m sure we’ve all noticed that craters are holes in the ground. Ever wonder what happened to all the dirt and rock that used to be where that hole is? Some of it vaporizes, but much of it turns into ejecta.

So, the lack of a Jovian-density atmosphere on Earth means you can’t have SL-9 style plumes, and lack of a crater means you can’t have ejecta. So much for the material supposedly thrown all over Egypt and the Levant, accounting for the destruction of Sodom and Gomorra, and all that.

Hempsell then goes on to suggest that we - the multitudes of asteroid experts, anthropologists, textual critics, and so on, who find all this material laughably amateur, and say so in the comments to my original post - are somehow lacking in integrity and qualification because we haven’t read the book.

…if you want to publically slag it [the book? the hypothesis?] off as delusional pseudo-science please do us the courtesy of finding out what we are actually saying first.

The fact of the matter is that a press release was widely circulated by the home institution of one of the book’s co-authors. It is entirely legitimate to be called to account for false and implausible claims made on one’s behalf in a press release that has the imprimatur of the claimant’s academic institution, and I shall not back down.

In response, apparently, to my offer to read the book and post again, Hempsell says:

A final point on free copies; we have sent around 100 copies to journals and researchers in the field, (and in a strange reversal of the current argument several expressed surprise saying they had expected to buy it). I am sorry if you did not end up on that list, but I hope you can see the problem of sending copies to every anonymous web blogger.

I can indeed see the problem of sending the book to every anonymous “web blogger”⁵. However, I’m not one of them: my real name is disclosed on this blog.

Furthermore, my field of research is asteroids. Let’s not push that too far - I’m not as expert as many, many academics working in the field, and I’d not rate my knowledge equivalent to that of a PhD employed full-time in the field. However, I am not in an entirely unrelated discipline such as astronautics engineering; I’m actually employed in a capacity in which I study these bodies in a scientific way, as a part of a team at an astronomical observatory that has, at this point, thousands of peer-reviewed publications on asteroids, some with my name on them⁶.

I’m also, as commentator “Don Amache” points out, pretty well known as a magazine writer and critic, having been employed to review software and books for several years at Sky and Telescope.

And finally, I’ve also managed to give this particular hypothesis a lot of bad publicity. I’m up to about 20,000 hits on the original posting alone, and there’s still a lot of traffic coming in.

One way to respond to bad publicity, if you have the confidence in the hypothesis that Hempsell claims to have, is to send the work over for reading and further review. And it doesn’t have to be a book - I do all of my reading of scientific papers via PDF these days. The cost to e-mail a PDF is insignificant.

Nevertheless, the authors’ claims, as made in the press release, and as made here, on the blog, are in some cases false, and in all other cases wildly implausible. I predict it won’t bear professional scrutiny, or even a semi-professional fact-checking and inspection. I doubt I shall see the book, and I’m not losing sleep over it. We already have enough to know this crazy idea is all wrong.

1. That’s not necessarily hard to do with a young blog, mind. [↩]
2. Sorry - as far as I know, Icarus prohibits its investigators from participating in arXiv or other free-access solutions. [↩]
3. At 4° C. [↩]
4. Think of it this way - the lowest possible pressure on Earth is zero. Sea level pressure is almost 15psi, making the largest delta 15 psi. On Jupiter, pressures are available that are hundreds of times larger, leading to deltas of many hundreds, or thousands, of psi. Apologies for the SI units. [↩]
5. Are there bloggers who are not on the web? [↩]
6. This is absolutely no reason to believe what I say here, by the way. I raise these matters only to show that I do have some qualifications to review such a book. [↩]

The University of Bristol has a press release out yesterday reporting that a Sumerian clay tablet provides an account of an impact event at Köfels, Austria.

I call bullshit. Here’s why, starting with some background information.

Köfels does not have a crater; it has what looks like a giant landslide, about half a kilometer thick and five kilometers in diameter. In the mid 20th-century, the impact hypothesis was raised to explain the formation. Apparently there is a lot of glass in the formation, which some geologists think could have been formed when rock melted in the landslide, and others think is more plausibly from an impact. There’s no doubt that other impact events have created quite a bit of glass. The age of the Köfels glass has been measured using radiometric methods, so we know the glass was formed between 8,000 years to 16,000 years ago.

Perhaps the strongest evidence for an impact origin of the Köfels structure is the reported presence of planar deformation features in quartz taken from the site. (But see the update at the end of the post!) PDFs, as they are called, are microscopic features of silicate (e.g., quartz, feldspar) grains, and they are basically very thin planes of glass arranged in parallel sets that have particular orientations with respect to the containing crystal’s structure. They are utterly diagnostic of impact events - no other geologic event can form them, not even highly energetic volcanic eruptions¹. They look like this (NASA image):

The presence of shocked quartz - quartz with PDFs - means that this quartz, at some time, was in the neighborhood of an impact event. If the big landslide-looking formation at Köfels was formed by impact, then the shocked quartz could have been formed then. Or it could be from an older impact, and was transported by later geologic events, such as huge landslides. The shocked quartz will survive a lot longer than an impact crater, given the way the Earth covers such structures up relatively quickly, so this may well have happened. However the shocked quartz got where it is found today, we know that it was formed when a meteoritic body impacted the ground. Shocked quartz does not form from a meteoritic airburst - a meteorite that explodes before impact - it requires a ground impact.

Science marches on, and the impact hypothesis to explain the origin of the Köfels formation fell out of favor as we discovered more and more about impacts. The main problem was the lack of parallels between the Köfels features and other known astroblemes - namely, there is no crater at Köfels, and there darn well ought to be if there is 8-16 kiloyear-old glass and shocked quartz from an impact event at the site. Here’s a picture of a smaller impact that is five times that age:

Notice how fresh and recognizable that crater is?

Currently, the consensus of scientific opinion is that Köfels is not from an impact. It is not listed in the Earth Impact Database, not even as a possible impact site. Googling “Köfels impact” turns up a zillion outlets parroting the Bristol press release, but there’s almost nothing else about it on the net.

So, where does this Sumerian tablet come in?

The researchers say the tablet dates from 700 BCE, or about 3,000 years ago. They hypothesize it is a copy of an earlier work:

With modern computer programmes that can simulate trajectories and reconstruct the night sky thousands of years ago the researchers have established what the Planisphere tablet refers to. It is a copy of the night notebook of a Sumerian astronomer as he records the events in the sky before dawn on the 29 June 3123 BC (Julian calendar).

I happen to have some software that can do that. Starry Night, Skymap Pro, or Stellarium, among numerable others, can do the job. So this isn’t rocket science. Anyone know where I can get a high-quality photograph of the tablet that I can use to test their hypothesis from my own reseources?

But a better question might be:

Assuming that the original source is a “night notebook” of a Sumerian astronomer, why is it being copied by a scribe 2,423 years later? No reason is given for this remarkable act in the press release, at least. Already it sounds a little fishy to me.

The press release continues:

Half the tablet records planet positions and cloud cover, the same as any other night….

Wait a second. Do we really know that half the tablet records conditions “the same as any other night?” Because if we do, that means we have a bunch of other examples of this genre of tablet to compare this tablet to. And if so, that’s fine, but then why does the press release say this:

A cuneiform clay tablet that has puzzled scholars for over 150 years has been translated for the first time.

They can either have their cake, or eat it: Either the tablet was mysterious and untranslated; or we can’t really know that this tablet is a typical nightly astronomical report of sky conditions, just like any other.

The problems continue:

…but the other half of the tablet records an object large enough for its shape to be noted even though it is still in space. The astronomers made an accurate note of its trajectory relative to the stars, which to an error better than one degree is consistent with an impact at Köfels.

Okay, I guess - something 500 kilometers away and 1 kilometer in diameter will be a tenth of a degree across, which is just about big enough to determine shape; and it could have been closer and still been in outside the atmosphere. And it is possible to record a trajectory to better than a degree using naked-eye methods.

It is also possible to integrate a bunch of orbits that intersect with Köfels, and it is plausible to believe that some of those orbits might be consistent with the observation of a celestial object that is hypothesized to be recorded in this copy of a hypothesized tablet that existed 5,000 years ago, and it is plausible to believe that some of these orbits would have the object out of Earth’s atmosphere when it was observable over Sumeria.

But really, this is beginning to look a bit like a house of cards, yes? Let’s read on.

The observation suggests the asteroid is over a kilometre in diameter and the original orbit about the Sun was an Aten type, a class of asteroid that orbit close to the earth, that is resonant with the Earth’s orbit.

The bit about the Aten asteroids being resonant is just wrong. Many are resonant, some more strongly than others; but Aten asteroids are defined as those with a semi-major axis of less than one astronomical unit. An AU is, in lay terms, the average distance between the sun and the Earth. A semi-major axis is simply the distance of the long axis of an ellipse, divided by two. Almost all Atens have orbits that cross Earth’s orbit - in other words, most Atens get both closer to the sun than Earth, and farther away from it, depending on what part of its orbit it is in. That’s all - you don’t need the asteroid to be in a resonant orbit to be an Aten.

And a resonant orbit certainly doesn’t lead to a craterless impact, as I initially read the following as claiming:

This trajectory explains why there is no crater at Köfels. The in coming angle was very low (six degrees) and means the asteroid clipped a mountain called Gamskogel above the town of Längenfeld, 11 kilometres from Köfels, and this caused the asteroid to explode before it reached its final impact point. As it travelled down the valley it became a fireball, around five kilometres in diameter (the size of the landslide). When it hit Köfels it created enormous pressures that pulverised the rock and caused the landslide but because it was no longer a solid object it did not create a classic impact crater.

What??

This is just preposterous.

First, you’re going to find plenty of evidence of the impact at Gamskogel if this were true. Any impact significant enough to badly disrupt an asteroid-type impactor, which is what the researchers hypothesize, is going to take out a big chunk of the mountain, cause all sorts of fracturing, landslides, and other highly noticeable effects. The physics of impact are such that, if the impact were truly strong enough to liquify or vaporize a >1 km asteroid, the mountain would have been converted into a crater - much like we see countless times on the moon.

Test of hypothesis number one: Is there a huge crater on the mountain, or has the mountain been obliterated by a huge crater?

The impact of an asteroid with a mountain will result in the classical shock wave in the impact medium and create an ejecta blanket. If the impact hypothesis is true, we should see planar deformation features on the mountain and ejecta more or less symmetrically around it.

Test of hypothesis number two: Is there shocked quartz on the mountain?

Test of hypothesis number three: Is there an ejecta blanket around the mountain?

Next, why would an impactor become a fireball? We all know that meteors in the process of burning up are hot, but they are not, literally, fireballs². The researchers claim that that an asteroidal-type meteorite, after clipping the mountain, was “not a solid object” - but why? And how? How do you get an asteroidal impactor hitting so solidly that it vaporized it, but so softly that it doesn’t shock quartz or create a crater?

Sorry, but you just can’t.

You don’t solve any problems by breaking up an impactor into a million pieces - it still impacts. So you end up with a bunch of smaller craters - the total energy is the same. Here’s an example of either a binary impactor, or disrupted impactor, on the Earth:

and an example on the Moon:

Supposing you can disrupt a 1-km asteroid impactor into pieces no larger than molecular size. What happens then? You still get craters:

That’s a microcrater in glass, too small to be seen by eye.

Maybe the press release is saying that the low angle of impact, supposedly of only six degrees, would not result in the formation of a crater. But that’s wrong too. Highly oblique impacts - thought to be considerably shallower than 6° - produce elongated craters:

So, there’s gonna be a crater, or two, or a billion, no matter what you do to the impactor³. Just because the asteroid “clips” a mountaintop on its way to its final resting place doesn’t mean there will be no crater. There will be one, or many, period.

Test of hypothesis number four: Go find the crater(s).

Test of hypothesis number five: Go find fragments of the impactor. There will be some, even if the main impactor vaporizes.

Let’s read on:

Mark Hempsell, discussing the Köfels event, said: “Another conclusion can be made from the trajectory. The back plume from the explosion (the mushroom cloud) would be bent over the Mediterranean Sea re-entering the atmosphere over the Levant, Sinai, and Northern Egypt.

“The ground heating though very short would be enough to ignite any flammable material – including human hair and clothes. It is probable more people died under the plume than in the Alps due to the impact blast.“

Ok, so there’s no crater because the impactor “wasn’t solid,” but there was enough ejecta - which only comes from craters - to kill people, and cover an area thousands of miles around, including northern Egypt and the Levant, where we should be able to go today and find - ummm, ejecta.

Test of hypothesis number six: Let’s go find ejecta, or evidence of widespread burns, in strata that we can date, using, e.g., pottery shards, to around 3100 BC in multiple archaeological digs in both Egypt and in the Levant. The strata should be iridium-enriched compared to terrestrial facies, ought to include shock products if the impact were powerful enough to spread material over that wide an area, and ought contain impact glass.

Ok, we’re done. Just to sum up, here’s why we can be pretty sure this press release promotes a wrong conclusion.

The researchers hypothesize:

• That Sumerians made regular celestial observations (probably true);
• One of them observed a large body very close to Earth before it had entered the atmosphere (very improbable - whereas seeing a very bright meteor is not only probable, but certain, if you keep looking)
• They recorded the trajectory to an accuracy of +/- one degree or less (plausible)
• The tablet they recorded this on was reproduced by a scribe 2,423 years later (possible, but why?)
• Even though apparently no other nights’ observations were similarly copied (why not? There would have been TONS of interesting stuff, and just as correlated with significant happenings on Earth - not by causation, but by coincidence)
• And this tablet has never been translated before (I’ll stipulate that this is true even though I don’t really know)
• Two researchers - one a space infrastructure engineer, the other a rocket engine engineer, and neither linguists - translated it (huh? how?)
• And the tablet records an impactor (maybe)
• even though the impact glass found at the site is 8,000 to 16,000 years old (not 5,000 years old as the hypothesis says)
• And the impactor was a >1 km Aten asteroid (seriously, people, it requires several hours or days of precise, modern astronomical observations to determine if an asteroid is an Aten - you need either triangulated observations over a short time, or observations over a longer period of time, to extract that kind of data from the observations they say the Sumerians recorded)
• And that impactor landed at Köfels (maybe, but you need triangulated observations of incoming impactors to really determine where and if a possible impactor landed, because you can’t tell celestial distances or radial velocities - motion toward or away from you - by just looking)
• But not before “clipping” a mountain (oh, come ON! can we say “ad hoc hypothesis?”)
• Which turned it into something other than a solid (I’ve heard of shock melting, but turning an entire 1 km impacting asteroid into a liquid with a glancing blow with a mountain is beyond the pale, and turning it all into gas would be even more ludicrous)
• Which then created no craters when it landed (it still should have)
• But which did distribute ejecta all over the eastern Mediterranean (you don’t get ejecta without a crater)
• Which ejecta has not been found anywhere in the eastern Mediterranean (ouch)

I’ll add one more thing: This “research” hasn’t cleared peer review - the authors are trying to sell a direct-to-paperback book for $25 (USD). The press release says it is being published by Alcin Academics, but I can’t find them on the web and I can’t find any other book they’ve published. A quick look at the Amazon page for the book shows that the real publisher is WritersPrintshop - a self-publishing company. I’m thinking if this were a plausible hypothesis supported in a well-written book, they’d have gotten a real publisher to release it.

I’m not buying it - the book or the zany hypothesis. If anyone wants to change my mind, send me a copy of the book, and I’ll read it and reconsider.

Oh - and one more thing: Shame, shame on you, PhysOrg for credulously running this ridiculous story but ignoring the asteroid names announced last week.

Sources for Köfels background information:

• Graham, Bevan and Hutchison, “Catalogue of Meteorites”, 4th Edition, (1985)
• Kurat, Richter; Meteoritics, vol.4, p.192, 1969
• Störzer et al.; Meteoritics, vol.6, p.319, 1971

Update: I’ve been pointed to some additional references regarding the Köfels formation, which somewhat changes what I’ve written above. First, shocked quartz, with PDFs, have not been found at Köfels as some have claimed; quartz with lamellar deformation features typical of tectonic processes were found instead. Also, the Köfels formation was not a single landslide, but a result of several landslides at different times. These are both further blows to the already discredited impact hypothesis for the origins of the Köfels formation, and casts even more doubt onto the conclusions that Sumerians observed a greater than 1 km wide Aten asteroid that impacted at Köfels.

New references:

• Deutsch, Koeberl, Blum, French, Glass, Grieve, Horn, Jessberger, Kurat, Reimold, Smit, Stoffler, Taylor; The impact-flood connection: Does it exist? Terra Nova. vol. 6, 1994, pp. 644-650.
• Hermanns, Blikra, Naumann, Nilsen, Panthi, Stromeyer, Longva; Examples of multiple rock-slope collapses from Köfels (Ötz valley, Austria) and western Norway. Engineering Geology. vol. 83, no. 1-3, 2006, pp. 94-108.

The “French” in the first one is, I’m pretty sure, the same Bevan M. French who has done so much geological work on the moon and terrestrial planets.

There is additional discussion of the geologic findings here, where these two works are also cited among others, and I think the person who brought them to my attention is a member of that forum.

Update #2: Some very specific claims were raised by Mark Hempsell in the comments below; I’ve responded to them here.

1. The can be, and are, formed by nuclear explosions, however. [↩]
2. Amateur astronomers’ slang is to call bright meteors “fireballs,” but this refers to visual appearance, not physical constituency. [↩]
3. It is ridiculous to assert a 100% efficient vaporization of the impactor. The Barringer impactor was vaporized, but fragments of the impacting body remain. [↩]

Tony Dunn, who runs the Gravity Simulator site, has done a long numerical integration of the orbit of (165347) Philplait, outputting this in a diagram with a pseudo-stationary Jupiter and showing how the orbit of Phil’s namesake asteroid changes over time.

The first four rings are our inner planets. The green woven path is (165347) Philplait, and the magenta ring is Jupiter’s average position in a frame of reference designed to be Jupiter-centric.

Awsome, Tony.