Part 56- gifs For Marco Parigi’s Moving Boulder

Gifs 1 and 2 – slow and fast. Red boulder moves much more than small movements in surroundings.


Gifs 3 and 4- as above but these include the big crack in brown in order to show the slight viewpoint perspective change. This is why all parts of the images jump a bit but nothing like as much as for the red boulder. ​


This Part is a follow-on from Part 55. These gifs are compelling but the unequivocal evidence for red boulder movement is in that part. 




Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

To view a copy of this licence please visit:


All dotted annotations by Andrew Cooper

Part 55-Marco Parigi’s Moving Boulder. Close Analysis Proves He’s Right


AFTER- the red dot has moved. Old position marked with a smaller dot. Please ignore the red smudges below the green line.

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

(All photos are from the NAVCAM except one OSIRIS photo which is credited inline. Full credits at bottom). 


In June 2016, Marco Parigi published a blog post in which he suggested that a boulder on Anuket appeared to have moved. Here’s the post.

Whilst the apparent movement looked real and compelling, the various photos of the Anuket neck that I’d seen so far didn’t show enough detail for a detailed analysis. They needed to show the boulder actually sitting on one side of a small, local feature in one photo and then sitting on the opposite side of that feature in a later photo. The feature, whatever it might be (a small crack or ridge or discolouration) would then be acting as a reference point or fiduciary point to betray the boulder’s movement.

Recently, I was browsing another of Marco’s posts on a related change close to the boulder in question. I realised that the photos in that post had sufficient detail to look for fiduciary points that the boulder had slid past. Here’s that post, from which the photos further below were culled.

The two photos from the link above are the two main photos used in this post. Others are added further down for extra evidence. 


Photos 1 and 2- the triangle of boulders. Originals are included where appropriate but not included in the numbering system.

Red- Marco’s boulder that was suggested as having moved. Smudged red is an old artefact. Please ignore.

Light blue- the other two boulders that could be considered to be the base of the triangle. That base stayed the same width but as the triangle appeared to elongate due to the red boulder movement, the base went from looking fairly wide to being comparatively narrow when compared with the height of the triangle. 

Photos 3 and 4- photo 3 shows the position of the red boulder before the movement. Photo 4 shows it after the movement. These are the header photos, reproduced. 

Red- the boulder. Also, in the after photo, the tiny red dot above the actual boulder shows its original location as in the before photo. 

Yellow- a slightly curved feature which leads up to the base of the red boulder before it moves and is marooned above the boulder after it’s moved. This is proof that the red boulder did indeed move. 

Orange- a distinctive ‘W’ shape that’s visible in both photos. It’s useful as a a general fiduciary point. It can then be seen that the yellow feature branches off one end of the W in both the before and after photos. You need to look at the unannotated versions to see the W once the dots have shown you where to look for it. 

Green- this traces the line of a distinctive quasi-triangular feature, part of which collapsed into the main Anuket crack between the before and after pictures. That collapse was documented by Marco in the second blog post linked above. You can see that in the before picture, the red boulder is some distance from the apex of the green triangle. In the after picture, the red boulder is almost kissing the apex. This, along with the marooned yellow feature proves that the red boulder did move.

Photo 5- this is the same as photo 3 but with a single added tiny red dot. This shows the location to which the red boulder would subsequently move.


The lighting in the before photo is similar to that in the after photo. This always makes comparison between features somewhat easier. However, in this case it allows us to check the length of the shadow cast by the red boulder in each case. If we then identify the position of the tip of the shadow for the after shot we can go to the before shot and annotate a shadow from the red boulder in that shot all the way to the known shadow tip in the after shot. 

The reasoning here is that if the comet is static and nothing moved, the boulder/shadow geometry for the after shot would be the same as for the lighting-manipulated before shot. It stands to reason that if the after shot lighting angle is faithfully reconstructed in the before shot, the shadow tip of the red boulder absolutely has to reach the same spot in both cases. So our annotated before shot simply assumes the same lighting angle that pertained in the after shot and casts the drawn shadow to the apex that it would definitely reach under the same lighting conditions as the after shot. The result is a ridiculously long shadow, well over twice as long as it should be. So that proves the red boulder moved too. The shadow reconstruction photos follow. 

Photos 6 and 7- the red boulder and its shadow (6 is the before shot).

Red- the two sides of the boulder in both cases. The side in shadow is estimated. It may be argued that it would be better to measure the visible width and compare it to the shadow length instead but it just so happens that the distance between the red dots is the same as the width at its widest point and this is the case in both photos. So both methods apply with the boulder/shadow ratios we’re about to calculate. 

Yellow- the shadow tip. 
The ratio of shadow to boulder is 1.82 for the before shot and 1.58 for the after shot. There’s obviously an error margin involved but they are both certainly well under a ratio of 2. 

Photo 8- identifying the tip of the shadow in the after shot (yellow dot).

Photo 9- transposing the shadow tip location for the after shot to the before shot (yellow dot). 

Photo 10- this is the annotated shadow set-up. The set-up assumes the red boulder never moved and that it’s lit from exactly the same angle as for the after shot. These two assumptions have to result in the shadow reaching the location of the yellow dot. The shadow is annotated accordingly. The ratio of shadow to boulder is 4.16. That’s well over double what it should be, in fact 2.63 times more than the after shot ratio of 1.58. You can see that even the (real) 1.82 ratio shadow in the photo is dwarfed by the ludicrously long annotation. 

This anomaly is very difficult to explain for a boulder that never moved. The obvious solution for obtaining anything near the required 1.58 ratio is to give the boulder a very noticeable shunt to the left. 


This happens quite often when looking in detail at one particular phenomenon. You suddenly realise something else nearby has also torn, slid, delaminated or collapsed. The right hand light blue boulder also slid (or rolled). 

Interestingly, it slid up the neck in the opposite direction to the red boulder.

Photos 11 and 12- the blue boulder slide. 

Light blue- the sliding boulder. 

Bright green- three dots next to the light blue boulder. These denote an actual line that runs at 90° to the base of the ‘W’. You can see that the blue boulder is below the line in the before shot and above it in the after shot. Please look at the originals to confirm this. The bright green line is obvious and the boulder movement unequivocal but the dots obscure the line itself. 


Photos 13 and 14

There has been a suggestion in the comments on the Rosetta blog that the red boulder might be sitting at the top of a slope so that parallax alone accounts for what is actually just apparent movement. At a low-profile angle and looking from below (as in some of these photos) it would then appear to be closer to its light blue twins than it really is. As you rise up the neck to look vertically down at 90° to the surface, the parallax element would not take effect and the full distance between red and blue would be betrayed. The difference in the two cases would amount to apparent movement of the red boulder. 

The detailed analysis above proves that the two boulders moved anyway, whether such a slope exists or not but it’s as well to address the issue here so that it’s laid to rest.

The simple solution to establish whether there is indeed such a slope is to look at the area from the side and from low down. If it’s there it will be shown up in full. The two photos below show that no such slope exists. Photo 13 is a before shot and photo 14 is an after shot. The before shot has the boulder triangle annotated because it’s so faint and the nearer blue boulder is as good as whited out. Seeing as these are both essentially side views, flat and with no parallax slopes it’s quite clear that the red boulder has moved. The movement is evidenced in the the spaced-out triangle. 


That sub-heading is a quote from Marco’s original post on the boulder, the one that’s linked above. Time and again in the course of working out what the 67P morphology is telling us, we notice something that looks odd but can’t state quite why it looks odd. We might pass over it dozens of times on the way somewhere else, scratching our heads every time, remembering that the paradox is as yet unresolved. 

In this case it was the fact that “the triangle seems more spaced out” and yet the degree of movement of the red boulder didn’t seem to warrant it being quite that spaced out. Then, whilst annotating the photos for this post, the paradox was automatically resolved. The triangle is now more spaced out because the top-right boulder moved upwards. That’s why the triangle is now so long and thin. 

The two light blue boulders remained essentially the same distance apart while the right hand one moved up. Since they constitute the short base of the triangle, the base remained the same width but shunted back a bit on one side. Combining that with the red boulder extending the long tip explains the spaced out triangle.

And, more importantly, we now have two boulders that have moved and they’ve moved in opposite directions: straight up and straight down the neck. 


Since you should now be more familiar with the fiduciary points, these two photos are, for the most part, left unannotated. However the two closest zoom components each have an annotated version. The annotations are the same colours as for the header (reproduced with their key in photos 3 and 4). There are eight photos, four versions of each as follows: original, medium zoom, close zoom, close zoom annotated. They’re presented in pairs for comparison of course. 

Photos 15-22




The reason for the movement of the two boulders and the fact they have moved in opposite directions will probably get its own post when other evidence avails itself, as it usually does. However, as a prelude to such an analysis, one possible reason for the red boulder moving down the neck is the subsidence of material into the neck crack only a short distance away. That’s described in the second link above and it’s placed here as well for convenience:

It would be odd if the two events, collapse and boulder movement, were unrelated when in such close proximity and while such little change has been noticed elsewhere on the comet (notwithstanding Marco’s other Anuket neck change discoveries and the Imhotep slump). It could be argued that the collapse into the crack, being only 100 metres or so away, caused a slight trough between that apex of the subsided material and the boulder, enough for it to affect the gravity gradient and allow the boulder to slide or roll in that direction. 

Slumping in any situation is prone to cause sympathetic ground movement around the slump. Indeed there is some indication in the photos of a slight trough in the after photos but it’s to the right of the slide track and could be the lighting anyway. We await the OSIRIS after photos. 

As for the blue rock moving up the neck, there are delaminations in that direction as a result of stretch. The boulder triangle is sitting right next to the ‘orange tell-tale line’, after all. That line is itself a one-kilometre-long delamination from head rim to body (Part 25 of this blog). 


Another reason for citing delaminations is this. That orange ‘W’ in the pictures above was just a random feature in my mind until I realised that there was a boulder placed neatly at each end and one in the middle. One boulder for each apex. We already know from experience that delaminations often leave boulders behind as they shunt away from a particular position. They tend to shed talus from obviously ragged cliffs (see Part 50) and chunky boulders from squared-off cliffs (e.g. the Hapi boulders and the three Aker boulders). 

The W is very blocky or you might say, squared off, and there are chunky boulders right next to it as if related to it. The knowledge of blocky cliffs shedding large boulders, derived only from stretch theory, prompted me to hunt for another W without even knowing whether one existed at all. 

Stretch theory also told me where to look: one or two hundred metres up the neck, possibly with a circa 45° southerly bias. The upward component is due to the obvious neck stretch vector (Part 25). The southerly bias is because everything was delaminating along the shear line and around the soon-to-be head rim just before head shear. Those delaminations have been identified (not blogged yet but tweeted). The combination of southerly delamination before head shear and easterly (up the neck) delamination during neck stretch results in a circa 45° vector-summed resultant direction. So that’s where I looked first. And sure enough, there it was:

Photo 23

That’s the predictive power of stretch theory and it’s why the boulders got left behind in that ‘W matches the boulder triad’ configuration. 

Photo 24- the same as photo 23 but with the boulder dots depicting the triangle in the ‘before’ configuration. 

This shows how closely related they are to the W. Notice how the right hand end of the newly found W turns 90° to form a chunky rectangle just like its classic twin (whose rectangle is more visible in the header).


This part puts to rest any doubts that Marco Parigi’s boulders moved. His discovery in the first link above is therefore the first documented account of moving boulders on 67P/Churyumov-Gerasimenko. 



Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

To view a copy of this licence please visit:



All dotted annotations by Andrew Cooper

Part 54- Atum Crust Slide Away From the Shear Line. 

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

The header photo is reproduced below with its key. The dots are degrading this image in photos 1-3 for some reason. The original is placed below in all cases and has lost none of its clarity. It’s best to ‘fly solo’ anyway once the dots have told you where to look. Photos 5/6 are unaffected. 


The Anubis/Atum crust slide vectors have been worked out incrementally over time. The term Anubis/Atum was really coined for this one very obvious facet of the diamond-shaped body lobe. This was before Khonsu was added as a named region when it emerged from the winter shadows. Hence the existing page in the menu bar regarding stretch in this area still includes “Anubis/Atum” in the title that largely deals with Khonsu. 

This post shows additional crust slide vectors for southern Atum. It’s telling that the crust slide is in the exact opposite direction from the direction of head lobe rise from the shear line. This is consistent with the behaviour along the entire length of the shear line from this point to Seth, Babi, Aker and Anhur (Parts 26, 32, 35, 40 and the Paleo Rotation Plane Adjustment page). Aker’s slide is not posted yet. 

There will be more explanation and additional, adjacent slides added later in this post and/or a later post. Those slide vectors (and stretch/delamination vectors for Khonsu) complement this particular slide very well and as usual show a tendency to follow the tensile force vectors of stretch. The Khonsu delamination is on the “Anubis/Atum” page already. 


Header reproduced


The keys are narrative keys as is often the case but they are shorter in this post. Some colours are divided into paragraphs but are still part of the key. 

Fuchsia lines- these two wavy lines are the main crust slide match. The upper line is the seating and the lower line is the slid crust that was originally clamped at the seating. The arrows below the bottom line are sitting on the slid crust and show its direction of slide. The arrows above the top line don’t sit on slid crust but are placed where the head rim once sat before it sheared from the body. They show the direction of travel of the head as it rose on the stretching neck. 

The upper fuchsia line is therefore contiguous with the shear line where the head lobe rim once sat. This match for the head lobe seating was presented in Part 17. The Part 17 header is reproduced below to clarify this. It’s of course the reason that this particular crust slide started from this upper fuchsia line- it’s the recoil effect, just like all the other crust slides around the shear line (not only on the body but the head too). 

It should be borne in mind that the upper fuchsia line represents the continuation of the shear line. The shear line/head rim match has been traditionally denoted in red for this side of the comet ever since Part 17 so in this photo, the red-dotted shear line meanders down from top-left, turns sharp right and soon joins this upper fuchsia line. From that point on, the shear line and the fuchsia seating line for the crust slide become contiguous, all the way to the right hand side. 

So the head sat above and to the right of this red/fuchsia line, the head rim’s shear line, and the area both below and to the left of it did not have the head lobe sitting on it. But that area did experience crust slides away from the line. This part is dwelling mainly on the downward fuchsia slide in the header, that is, the slide from along the bottom of the depicted head rim seating. The crust slide from the section to the side will also be shown below but not described in detail. 

Red- the traditional shear line as described above. It should be considered as continuing contiguously with the upper fuchsia line, as also described above. It may look a bit weird as a quasi square when the head rim is fairly straight all round. This is for three reasons. Firstly, it’s a close-up. Secondly, the shadow on the right enhances the squareness. Thirdly, this is the most marked step-down in the head rim on the whole head lobe. The red shear line does a sharp left just off frame at the top and runs along the top of the frame just outside it. This will become clearer when the Part 17 header is shown below. 

Fuchsia dot pairs- these larger fuchsia dots show a matching feature of two adjoining dips. They’ve slid in the same manner and the same distance as the nearby main slide. Notice however, that the slide direction is slightly to the left and that there’s a small lateral gap where there are no matches. The gap signifies a lateral rift which is further evidenced by the highly curved lines between the main fuchsia-dotted crust and its seating. The subtle leftward slide vector for the fuchsia-dotted pair is the very beginnings of the influence of the stretch vector directed towards the long axis tip at Apis (see the Anubis/Atum page). Apis is ~1.5km leftward in this view. 

Yellow- three dips that match from the top line (shear line) to the slid crust (their apparent bled shadows left behind just before the slid crust stopped). 

Small red dots- wavy lines that connect the three yellow features.

Photo 2- this shows the other slide away from the left side of the head rim line.

Fuchsia chunk at left with slide arrows the bright green feature- this is actually just the seating area of the crust which was attached to this part of the shear line and that has now slid in the direction of the three arrows to a point that’s somewhat off-frame, not far off. This chunk will be seen in the zoomed-out overview below. The bright green feature is a mini match to the slid chunk which will help you fit it back when you see the same feature on the chunk. Fuchsia is used again for the crust chunk perimeter because it’s the traditional colour for Anubis. Notice that it’s been drawn as being exactly contiguous with the red shear line because it too tore away from the head rim. 

Photo 3- as photo 2 but with some extra annotations. 

Photo 4- the Part 17 header.

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

Red- the head rim at top and the shear line below which match as described fully in Part 17. 

‘H’- This shows the area where the head sat in the above photos and of course the actual corresponding section of head that has now risen on the stretching neck to a point one kilometre above.

Photo 5- the overview. This was done some time ago so the colours are different. It may get updated so that the colours are consistent with those above. 

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

Yellow- slide vectors. 

Red- the shear line plus the slid crust that was fuchsia above (at bottom right). The slid crust perimeter may follow a slightly different line due to much lower res than the header. But it is close. Also the red line for the head rim seating/fuchsia crust seating isn’t as wavy as the fuchsia seating line in the header. This is only partially due to the lower res but also a higher perspective. The curves of the fuchsia seating in the header are partially stamped on the cliff, a fraction below the red line in this view. 

Fuchsia- chunk plus seating. Notice how the long yellow slide line links the chunk described above to its seating which was all that was shown above. This includes the bright green mini match. 

Dark green- the lower line is the southern rim of the green anchor (Part 24) and the upper one is the chunk that was pulled out of the green anchor tray as the neck stretched. The two dark green wavy lines match because the southern end of the chunk sat on he southern rim of the anchor tray. The yellow line is of course the slide track which was probably more like a ‘transportation within the neck matrix’ track. 

The green chunk is actually just a very big chunk sitting within the green ‘tell-tale line’ that links the green anchor to its head lobe match on the head rim. There are four such tell tale lines. They’re long, fine delaminations running up the neck at Anuket. The delaminations were fine shards, pulled from the shear line crust and dragged up the stretching neck within its matrix. The chunk is the biggest lump, not a fine shard. 

As for the green chunk, thrown in casually here because it happens to be part of an old annotation, it’s the site of one of many spectacular finds by Marco Parigi who has investigated the evolving neck area. He’s found several changes there, either side of perihelion 2015. In other words, these are changes over the last two years or less. Here’s his blog post on the cliff collapse at this green anchor chunk:


Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

To view a copy of this licence please visit:

All dotted annotations by A. Cooper. 

Part 53- A Small Rift in Seth



Yellow- the two perimeters of the rift or tear.

Fuchsia- a mini match showing how there was a bit of overlap. There’s a distinctive rectangle that’s repeated on both sides. It’s between the upper section of the fuchsia line and the yellow line above it.

The resolution in this OSIRIS narrow angle camera (NAC) photo seems to get compressed and slightly degraded by the dotting application. All photos have the original underneath them though and that seems unaffected. If in any doubt about the detail, it’s worth looking at the definitive hi-res version on the OSIRIS site which is here:

And here is the landing page for the photo, showing the meta data that’s also useful (the above link is the ‘full resolution’ link on this page):


The recent OSIRIS NAC camera photo in the header shows a small area of Seth, about 300 metres across. It includes part of the 1.6 km x 200-metre rift outlined in Parts 48 and 49. The header for those parts is here, just for context:

Photo 2- Part 48/49 header.

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0 

This small part of the larger rift is the dusty area at the bottom-left of the header photo for this post. The perimeter of the rift runs diagonally from lower-right to upper-left. The top-right half of the photo is the area beyond the perimeter, which in this blog is called the red triangle. Since the equator runs down the red triangle, to one side, and the paleo equator runs exactly down its middle, we can deduce that the perimeter we see is the southern perimeter of the rift. 

In the middle of the photo there’s a small massif which is the main subject of this part. It borders the dusty area and is therefore part of the perimeter of the rift. It has a curved gouge at its base, much of which is in deep shadow in the header, so it looks like a cave. It has a humped top which hosts another much smaller, shadowed recess. This massif has rifted from the larger massif or ridge to its right and the width of the rift is about 25 metres. This rift of the massif from its perimeter seating is the main reason for this part because it’s a new discovery. However, most of the post is spent putting it context with its surroundings, namely the main 1.6-km rift it’s a part of. For this reason, the small 25-metre rift of the massif is generally called a tear so as not to confuse it with the main rift that’s 200 metres wide. 

The direction of the 25-metre tear (i.e. the tensile force vector doing the tearing) is at around 45° to the main rift perimeter. You might wonder why it isn’t at 90° like the the main rift (see the arrows in part 48, photo 6). Furthermore, you may remember that this perimeter, which is also the perimeter of the red triangle, was supposed to have stretched exactly along its length towards the long-axis tip at Apis. That’s at 90° to the opening rift vector. So why is the tear at 45°? It was most probably responding to the resultant angled force. That’s the vector-summed resultant of the rift-opening vector and the red triangle stretch vector. It has to be at some angle between the two, not necessarily 45°. It looks to be more biased to the red triangle stretch vector meaning that the physical distance moved along the red triangle perimeter by the two parting pieces was greater than the distance the massif was dragged out into the main rift area from the perimeter. It would have been dragged by what is now the opposite perimeter that was tearing away from it as the 200-metre rift started opening up. That initial tearing open of the main rift is the reason the massif has this 25-metre tear between it and the main perimeter. It almost got dragged across the rift to the other side but it resisted the pull vector albeit succumbing temporarily with a small tear. 

Photo 3- the torn massif with matching light blue lines either side of the 25-metre tear. 

Photo 4- with the red perimeter of the main rift. This photo starts to prepare us for the long-distance shots below. 

Red- the 1.6km x 200-metre rift perimeter. It bifurcates just beyond the torn massif because there’s a double match in the long-distance shot further below. 

Mauve- this is just a few dots showing the true perimeter of the other side of the torn massif. They disappear promptly because that perimeter is hidden in this view. This is again in preparation for the long shot which is from above so it shows the other side of the massif in mauve. 

Photo 5- more overlayed additions in preparation for the long shot. 

Orange dot- this is at the bottom of the 25-metre tear. This orange dot is also shown in the long shot as well as another matching orange dot on the other side of the rift, 200 metres away. That twin dot doesn’t show a 25-metre tear match because the matching shape to our massif slid across the main rift without doing the same small 25-metre tear as it broke away from the perimeter. 

Bright green- this is where the next match down the red perimeter was clamped, as per Parts 48 and 49. Since the humped massif and the bright green match below it are small matches along a much longer, matched perimeter of the rift, they would be classed as consecutive mini matches. 

Photo 6- this shows a naive version of the massif’s back perimeter in mauve. The mauve line is shown running over the top of the hump but the perimeter is actually hidden behind the hump, as mentioned above. But the hump itself approximates to the same shape as if it maintains the same profile right round to the back. It’s as if it’s been turned on a lathe. This helps visualise the massif in the long shot. 

Photos 7/8- photo 7 shows the OSIRIS photo with a slightly more naive depiction of the yellow tear i.e. the obvious tear without the subtle overlaps as depicted in the header. This is so as to be able to compare it to the very grainy close up in photo 8, which is a close up of the upcoming long shot. The key is below both photos and the unannotated versions are paired below that. The long shot is a NAVCAM photo. 

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0 

Mauve- the full perimeter of the torn-away massif including the back side that was out of view in the header (at upper-right).

Bright green- part of the bright green seating described above. It’s a ridge, used as a fiduciary point. 

Medium green- the small recess at the top of the hump. 

Photos 9 and 10- the unannotated versions. 

Photo 11- the first long-distance shot, paired with the original.

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

Mauve dot- this is just one dot for now, on the back of the massif so as not to clutter the photo too early on. 

Red- the 200-metre rift perimeter. This isn’t the whole rift length, just the section we’re concerned with here. The whole rift is shown in Parts 48/49. The bifurcation mentioned above isn’t shown here but is shown below. 

Bright green- the next match down the rift perimeter from the mauve massif match.

Photo 12- more overlaid additions.

Mauve- the whole perimeter of the mauve massif. You’ll need to check the unannotated version because the dots obscure the match. It’s admittedly faint, but since it’s straitjacketed by a wealth of matches either side all the way up and down the 1.6-km-long rift, we can be fairly sure it’s genuine. 

Extra red line- this is the double match along the red perimeter of the rift. 

Pale green- at the top and rather faint. This is a continuation of the red perimeter match. It was shown in red in Parts 48 and 49 but it’s pale green here because it’s less important and not strictly part of the red perimeter. It’s a match that tore from beyond the notional right hand perimeter and ended up draped across the 200-metre rift. 

Royal blue- at bottom. This is an obvious match across the rift. And yet it was inexplicably missed in Parts 48/49 with red dots leapfrogging across it with abandon. This is an example of not being focussed enough when there’s clear information hiding in plain sight. This is why the tenets of stretch are being missed. It seems most people won’t slow down enough to take in the necessary detail that’s there in the photos. In this case, I was the one not giving the picture the fullest attention I could. This blue match is certainly worth pointing out as a new mini match but it’s irrelevant to the tearing massif in this post. 

Photo 13- with another overlay.

Yellow- the tear. This is rather crude, given the width of the tear. It certainly doesn’t show the subtle curves that match on either side.



Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

To view a copy of this licence please visit:

All dotted annotations by A. Cooper. 



Part 52- The Body Lobe Match to Rosetta’s Landing Site (Includes suggested flyby track)

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0/ A.COOPER. 

All photos below have the same credit. Full credits at the bottom. Annotations are repeated and overlaid from photo to photo. A blanket key for all of them is provided below.


(All references to up/down/left/right are in ‘upright duck’ mode i.e. with the smaller head lobe at the top and as it’s shown in these photos).

Top red- the September 30th 2016 landing site proposed for the Rosetta orbiter.

Bottom red- the matching point on the body that nested over the landing site. 

Middle red- the point on the shear line where both the landing site and its body match were nested together. The body red dot nested over the landing site red dot. 

Top light blue- the sink hole that Rosetta will presumably fly over just before landing. 

Bottom light blue- the jet on the body that supplied the sink hole mentioned above. Please note that this is therefore the matching point to the sink hole next to the landing site. Its identification is the reason for this post and the suggested low flyby to collect data from it at close quarters. 

Middle light blue- the point where the layer containing the jet and the layer containing the sink hole nested (sink hole over jet source). 

Pale blue- other sink holes on the head that Rosetta will presumably overfly, along with body source (Parts 35 to 37). The body source is effectively one source right on the shear line but is extended back a bit due to the vagaries of the delaminations in this area opening up that small flat area. Apologies for the similar colour- sink holes are always dotted blue but pale blue was used here to differentiate them from the more important, main sink hole match for this post. The mauve flyby track on the body for the source of these pale blue holes runs across the pale blue dot on the body. This is the best theoretical track- I realise it’s impossible to do at very low altitude and would result in a crash into Hathor. A similar argument applies to the other mauve tracks but they become increasingly viable as you move down the body, culminating in the most important one, the jet, being the easiest. But it’s still tricky due to orbiting well off the rotation plane of the comet at such close quarters. 

Mauve- suggested flyby tracks over the areas that would contain residue from layers below and above the sink hole and landing area. 

Orange dot on body- the sweet spot for material that was closest to the landing site level (down through the layers as opposed to left/right/up/down across the surface). It’s almost invisible in the low, side view version as is its mauve slide track. 

Orange dot on head (half hidden under the layer denoted by the green line)- this is where the orange dot on the body was attached. Strictly speaking, the orange dot on the body is a very short delaminated line between the yellow line and bright green line it sits between. That’s because this layer broke from the orange dot on the soon-to-be head and delaminated as it slid from the shear line. 

Yellow- the layers that sheared from each other at the shear line. This happened when the head was still on the body. The line following the bottom of the head lobe is the head rim layer and that sat on the yellow line hosting the middle pair of red and blue dots. The next yellow layer up on the head attached to the second yellow line down on the body- again on the shear line above the middle pair of red and blue dots. These two layers also slid away from the shear line, one up the head and one down the body. 

Bright green- this is the top layer that also tore at the shear line with one layer sliding up the head and one down the body. They both slid further up the head and down the body than the two halves of the layer below (which was the second pair of yellow lines described above). This is because the bright green layer was the first layer to unzip and the other layer was underneath it. 

Dark green- another sink hole on the head with its matching source at the shear line below. The body version should be visualised as being in ‘mid-air’ above its source with its beige chimney curving up from the curved cave which is the source of the gas flow for the hole. 

Beige- the centre of the chimney for the dark green hole. It’s curved because the chimney forms half a bell shape. The bottom perimeter of the bell shape on the head nests over and around the curved source on the body which is often described as a cave. Regular readers will recognise this cave as the fifth ‘gull wing’ set.


This is a short post. There’s a longer draft that’s not complete and that goes into detail on the specific mechanism of sliding layers to prove why the landing site matches to the body as described here. However, since the whole point of the post is to suggest a flyby of the body areas that match the landing site and to have ample time to do so, I’m posting this cut-down version early. 

If you’re familiar with Parts 38 to 41 you won’t need the explanation, you’ll see fairly quickly why all these apparently random layers and mauve flyby tracks are so disjointed and how they all zip up together again. The three red/blue dot pairs nest as one pair at the site of the middle pair. The mauve flyby tracks all nested over the dot pair as one track on the original comet before the head sheared. 

The most interesting match here is that the sink hole next to the landing site matches to a particular jet on the body. Rosetta presumably overflies this and two others nearby just before landing. I say “presumably” because the actual ground track hasn’t been published but the relevant Rosetta blog post says the landing site was chosen so as to get close-up data from several sink holes on approach. The hole and its matching jet on the body are the top and bottom light blue dots as described above in the key. Not to be confused with the extra pale blue ones on the right in the later photo. 

The other interesting match is the actual landing site match and the orange dot on the body which denotes the delaminated material that sat just above the landing site. The most relevant material that was directly on top of the landing site is that material which is kissing the yellow line next to the dot. 

The Capaccioni et al 2015 frost cycle video bears corroborates the sink hole match to the jet. It doesn’t prove it. For the proof, via matching and slide tracks, is laid out in Parts 38-41. Reading parts 31-37 would also be very useful as background information . It’s corroborating evidence that the mechanisms described here were happening at Aswan/Ma’at too and there are similar far-flung matches between the back rim of Aswan and the head lobe. 

I may not get round to publishing the full version of this post before the landing but would still do so at some time because it’s a spectacular match. It might be a new post but it will get added here for sure anyway. 

If the Rosetta mission express an interest in executing one or more of these flyby tracks, I would drop all the other posts currently being researched and hurry the main article through. 


The detailed collecting of data by Rosetta and Philae over the last two years has been a wonderful achievement and it will be available for years to come for refining theories about 67P, comets in general and the formation of the solar system. However, knowing that the comet stretched and how it stretched, points to the most interesting places to collect data. That’s especially the case for analysing and comparing known matches on head and body. 

The landing of Rosetta on 67P is probably the very best opportunity we’ll have: a close flyby of a sink hole on the head, preceded by this suggested close flyby of a known jet and its source material that caused the sink hole to appear in the first place. It’s all the more interesting owing to the exactitude of the match, its small area and the fact that it involves a jet and its sink hole, not just another matching shape.


Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

To view a copy of this licence please visit:

All dotted annotations by A. Cooper

Part 51- The Bastet Pancakes and Their Relationship to Neighbouring slides. 

 Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0/A.COOPER
​Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0/A.COOPER
The gif is an update. It shows nice matching but the matches are fewer and more nuanced than in the descriptions below. Using the unannotated version is far more useful for seeing even more matches. The single red dot and green pair are starter dots for their respective features.


This part is primarily concerned with the morphological evolution of the two quasi-circular pancakes that are side by side at Bastet. In the process of describing the mechanisms that led to their present-day shape and position, other mechanisms in the neighbouring areas of Babi, Anhur, Ma’at and Khepry are invoked. This is to show that the pancake formation and slide mechanism wasn’t isolated but in keeping with and complementary to what was occurring next door on either side and below. 

The global mechanisms of spin-up and the induced tensile stress and Coriolis forces are mentioned too. This is because the evolution of both the pancakes and their neighbouring regions were dictated by those forces. We’ll conclude with the observation that the symmetrical shape of Aker/Khepry and the slid crust material either side of it is effectively the signature of the tensile forces of stretch stamped on today’s comet. The same applies to the two pancakes at Bastet that straddled the rotation plane and the two head lobe crust slides either side of them. 


Photo 1- original for photos 9-21.

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0 

(this credit applies to all unannotated versions of the original, cropped or otherwise until photo 21).

Photo 2- slightly cropped version used for photos 7-21.

Photos 3 to 6- Bastet close-up taken from above photo and 3 annotations with their joint key below.

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0/ A.COOPER

(This credit applies to all annotated versions of the original, cropped as here, or otherwise until photo 21). 


Photo 3- original, cropped from photo 1.

Photo 4- the pancakes in red.

It’s worth noting for later that the top perimeters of the pancakes are zig zagged. In this photo, the red dots along the top are kissing the apex of each zig zag point insofar as they can be discerned with the resolution. There are other zig zag lines too because of extra delaminations of the pancakes so they too belong to them in notional terms. But we’re trying here to discern the most obvious zig zag perimeter. The two top perimeter zig zag lines here correspond to the zig zags that are dotted in a similar manner in the much higher resolution photo 24. The intervening photos don’t attempt to pinpoint the zig zags.

The two pancakes were described in Davidsson et al. 2016 as possibly being cometesimals that had splatted onto Bastet. They cite three such features, the third one being below the left hand one shown here. This shows some signs of matching the one above it but hasn’t been fully investigated yet. Since the objective of this part is to match this annotated pair, the third one will be ignored for now, investigated later and given its own part. Suffice to say, the upper-left pancake shows signs of sliding ‘upwards’ from the supposed pancake below it whether they match or not. 

This matching and sliding behaviour will show that they’re not cometesimals but slid crust. They behaved in the expected manner during spin up: one piece of crust delaminating into two, the two pieces sliding neatly apart either side of the paleo equator or rotation plane. 

Photo 5- the perimeters of the pancakes are dispensed with here and various features are matched between the two using various colours. These are bled matches which means one sat on top of the other before sliding away and the features, having some depth, were duplicated on both delaminations. Bled matches are less obvious than mirrored matches (as in head rim underside to body- Parts 1, 2, 5, 21 to name a few) or translational matches (as in the ‘red’ slide at Imhotep- Part 43). Bled matches have been found in many places especially at Serqet and Maftet (Part 29) and despite being potentially less obvious, they do remain very faithful. 

Photo 6- these are additional matches overlaid on the photo 5 matches. Please ignore the terracotta match (see below). The light blue and two righthandmost yellow features appear to have delaminated along the line of the long, straight dark green line (it’s straight but for its small-scale zig zags). However, the bright green hole, left hand red line and left hand yellow feature seem to have slid with more of an upward component. This is in keeping with the left hand pancake moving up the head lobe more than the right hand one. The matches below the dark green line slid notionally south-north as expected for Coriolis forces during stretch. The left hand pancake then underwent a mini delamination from that neat, expected position and rode up the head a little further. This would probably be due to the vagaries of the Babi and Anhur slide head components tugging slightly differently on their respective pancake (see full explanation of this below). 

Staying with photo 6, the right hand bright green feature is only a vague match placed here for future reference in case it gets forgotten and not subjected to further scrutiny. I don’t think it is a match but it was added in the early days of working out these matches. The main thing to remember is that, although it’s strictly speaking outside the right hand pancake, it’s a feature that matches so strongly to the body, one kilometre below, that it’s continually depicted in bright green in later photos as if it’s a protrusion to the pancake. 

The terracotta match in photo 6 was noticed as being an outright mistake due to a rare error in cross referencing photos and thinking the right hand one was whited out yet visible in a later photo. This occurred just before publishing and so it should be ignored.

Photos 7-10 the head-to-body matches (keys below).

Photo 7- original.

Photo 8- the most obvious matches are of certain features from the right hand head pancake matching to the characteristic right hand ‘dip’ at Aker. The bright green crescent is one of the most obvious of the matches. There are smaller bright green dots on both head and body depicting the interior crescent perimeter that’s a very faithful match. The head lobe component has a northward (rightward) delamination that’s in keeping with the slide vector of the delaminating pancakes. 

The right hand dip at Aker is to the right of the the central ‘prow’ and it has an identical twin dip on the left of the prow. The prow runs down the exact centre line of today’s body lobe long axis. When the head was seated on the body, this prow line was where the paleo equator ran, precisely because the fast-spinning comet was pushing out the end of the long axis into a ‘v’ or prow shape (see Paleo Rotation Plane Adjustment page, photo 8 and text). 

The short length of fuchsia dots on both the pancake and its seating correspond to the short perimeter section along which the pancake was attached to the fourth Babi cuboid (Part 40). This attachment was when the pancake was still in its seating on the body and therefore before head shear. The fourth Babi cuboid was part of the Babi slide in part 40. Its current position is just off-frame from a point towards the bottom right of the frame. An update to part 40 shows a faithful, hi-res match of the cuboid to the seating with the fuchsia dots. In that photo, there’s a slide track that betrays the sliding of the fourth cuboid over the pancake seating, so we know the pancake slid up the soon-to-be head before the cuboid slid down the body. 

Photo 9- some slightly more subtle matches overlaid on photo 8 in light blue and dark green. 

Photo 10- this is the same as photo 8 but shows a new feature in mauve. This is the first sign that the features in the right hand dip at Aker match those in the left dip. And both match to the ones on the two head pancakes. They weren’t annotated on the pancakes in previous photos. This means that the two pancakes on the head once sat in the two dips at Aker.

It also means the two dips delaminated from a single feature. It didn’t necessarily have to be a single dip but it had to have roughly the same shape and exhibit that same mauve feature in its bottom-right corner. It also must have exhibited the other more subtle features annotated further below which are now shared between the dips. 

It would appear that the original feature was roughly the size and circularity of the largest pancake and had enough depth to create all four delaminations, two on the head and two on the body. 

This feature would presumably have been acting like a more bulbous prow, being old crust that wouldn’t be very ductile. So it formed into a spherical cap on the stretching long axis tip. It then delaminated into two at Aker. That delamination would have been the two dips combined with their future pancakes. After this, the top layer i.e. the pancake pair delaminated from the dips and slid up the soon-to-be head lobe. The slightly more rounded seatings of the pancakes are clearly visible inside the dips. 

The central prow then must have formed, as opposed to another spherical cap. This might have been because the next layer down, today’s Aker surface, was previously buried, more ductile and so more responsive to being bent into a prow. The bending would be due to the tensile forces of stretch turning into flexion forces as they rounded the stretching tip, creating a moment on the crust either side of the centre line.

There’s much more on the flexion forces rounding the long axis tips in the Paleo Rotation Plane Adjustment page. It explains the uncanny similarity in width of the two flattened tips at opposite ends of the body lobe diamond shape. Aker was the vestige which resisted tearing due to the flexion force and yielded by bending into a prow instead. It was narrow enough to resist the moment exerted and anything beyond its present-day perimeter couldn’t therefore resist that moment, hence its two snapped-away parallel sides and central prow. The snapped-away sides became the Babi and Anhur slides. They’re perfectly visible, flanking Khepry in the expected symmetrical manner: the Anhur v shape on one side and the fourth Babi cuboid on the other. The Anhur v shape obligingly took its Aker tear delamination with it just to make our matching job easier (photo 27- four blue dots)

The mauve feature in the left hand Aker dip is more obvious in some OSIRIS pictures, proving the match. A relevant photo may be added as an update in due course but the point being made here is that it’s a very clear match. It’s fairly clear here anyway. There are two interesting additional factors regarding this mauve match in the left hand dip. Firstly, there are three large boulders that lie just below the apparently truncated thin end at the bottom, suggesting they were broken off as the Khepry onion layers delaminated and slid eastwards (downwards in this view- see photos 21 and 27). You’ll need to look at the unannotated version to see the truncated end properly. 

Incidentally, the eastward delaminations at Khepry, along the paleo equator were core-directed. Core directed delaminations involved the core stealing matrix material from the short axis and donating it to the stretching long axis. This meant the crust had to yield by delaminating along the line of greatest stretch- the equator. So just like at Imhotep (Part 42), the red triangle (Part 26) and the head lobe layers (Part 29), any core-directed crust stretch was always east-west along the equator. Rather than actually stretching, it took the form of delaminations (Parts 29 and 38 among many) and sometimes rifting. Serqet/Nut is a lower onion layer poking through one such rift (bottom of part 29). As soon as any crust was completely loose or nearly so, Coriolis forces took over (see the Imhotep ‘blue’ slide in Part 42). 

So right/left or north/south delaminations in photo 10 and subsequent photos are loosened crust and Coriolis directed. That’s what happened to the two pancakes when they were on the body. One slid and came to rest north of the paleo equator, in this case the prow, and still kissing it. The other one slid and came to rest south of the paleo equator and still kissing it too. Thus the two pancakes kissed each other with their kissing point right on the paleo equator at the prow. Then, just before the head lobe sheared for good, they recoiled up the soon-to-be head just like (and directly attached to) the head lobe components of the Babi and Anhur crust slides. Part 41 for Babi and the Paleo Rotation Plane Adjustment page for Anhur. The Babi slide’s corresponding head lobe components are the two delaminated layers curving beautifully all the way round from just above the right hand pancake to the so-called cove, one kilometre above the north pole. Between them they host (unsurprising for stretch theory) the much talked about ‘sunset jets’. The head lobe components of the Anhur slide (see below) were attached to the left hand pancake halfway up the south side but they don’t now extend to the corresponding place on the south pole due to material now lost (see photo 27 and Part 20). So it was one head lobe crust slide for each pancake, attached either side, north and south. 

For a more graphic description, it was like a pair of goggles (the pancakes) being slid up onto the forehead of the head at Bastet with thick straps (the head lobe crust slide components) stretching round to the ears which would be the cove for the north side and material now lost on the south side. All completely symmetrical but for the left hand goggle glass rising a tad further up the forehead. Or perhaps one could say that seeing as the goggles were originally below the neck and the right hand goggle glass (from our view) is still near today’s head rim, perhaps the goggles were hanging round the neck and slipped up over the eyes but were skewed up at the left. Returning to photo 27 might now might elicit a smile.  
A second observation regarding the mauve feature in the left hand dip is that it has four further delaminations. They’re spread leftwards (south) across the dip and are not annotated. The wide tops are the most obvious parts. They slid slightly downwards as well as left. If one produces the end of a line joining the delamination tops, that line crosses the Aker perimeter at the corner of the dip and into Anhur. It immediately joins the main Anhur V. That V appears to have pulled and bunched up the bottom of the dip down towards Khepry causing the higher bottom scarp of the dip. This is of course in keeping with what the Babi slide (Part 40) was doing in mirror fashion on its side of Aker. This caused the same effect in the right hand dip and a thicker scarp all the way across the bottom of both dips. 

The two dips, the bottom scarp and the two flanking slides are completely symmetrical because the tensile forces of stretch were symmetrical. So none of this sliding is random. It’s entirely in keeping with the slide vectors that have been described here in many parts over many months. As for Anhur, it deserves its own post but it’s nevertheless described in the Paleo Rotation Plane Adjustment page, along with a short discussion on its mirror relationship to the Babi slide. 

PHOTO UPDATE- the OSIRIS close up of the mauve match on the two dips at Aker (viewed from above the head lobe).


Photos 11 to 14- superimposing the paleo equator and the current equator.


Photo 11- the original reproduced for toggling comparisons. 

Photo 12- the paleo equator is added here in brown. The paleo equator is more often called the paleo rotation plane on this blog because the paleo equator is where the paleo rotation plane emerges at the surface and is therefore the plane in which 67P stretched during spin-up. Calling it the paleo rotation plane constantly reminds us of its stretching influence. It’s being called the paleo equator more in this part because of the Coriolis sliding of the pancakes towards either side (north/south) of the actual equator line. 

The paleo equator line in photo 12 is faithfully represented down the central prow of Aker and on further down Khepry where it bisects the next paleo equator/plane signature. That’s the Khepry flattened tip, one of the 17 paleo plane signatures mentioned in the Paleo Rotation Plane Adjustment page. The brown line isn’t traced up the neck between the lobes because the neck didn’t exist when the paleo plane held sway. It held sway only when the head was attached hence its being traced over the lobes only. After the head sheared, probably immediately after, the paleo plane started precessing. It precessed 12° to 15° anticlockwise to today’s plane (see next photo). Precession was about the long axis so the long axis tips at Hatmehit and Apis acted as gimbals. 

So after head shear, the paleo plane, along with its currently visible 17 signatures, became a fossil plane and no longer held sway. However, the precessing rotation plane would have been close to (only a few degrees off) the paleo plane in the early stages of the head lobe rising on the growing neck. This would be the case even if precession was at play immediately on the commencement of shear and head lobe rise. 

It has to be noted here that the the paleo plane line going up between the pancakes on the head lobe is not truly representative of the paleo plane. This point is rather nuanced. It does show the actual line that was produced by being draped over the prow so it used to be truly representative when it sat there. However, just before head shear, the two pancakes rose up the head and the left hand one rose higher in the process. This in effect means that the pancake pair rotated clockwise by perhaps 40°. This was during (and superimposed on) their translational slide from Aker and up the soon-to-be head lobe at Bastet. The result is that the paleo plane signature we still see today isn’t representative of its former position or orientation anymore. It’s now skewed by the same 40° clockwise because it’s attached to the middle of the two pancakes. It’s nevertheless useful as a guide because we can rotate the pancake pair back anticlockwise by 40° in our mind’s eye. This would be in order to seat the old signature over the paleo plane position. This still wouldn’t be the place the signature originally came from (which was the prow at Aker) but since the translational component of the pancake slide was westward, straight up the paleo plane, the signature line from the prow stayed on the paleo equator line during the slide- but for the rotational component which we’ve accounted for by rotating the pancake pair back again. The result of this operation is shown in photo 26.

Photo 13- the current equator is superimposed in dark blue. The current equator is also the current rotation plane. It’s at an angle of 12°-15° to the paleo plane. The blue line is always an informed guess based on the low resolution shape model. There aren’t many detailed features to relate from the model to the photos so it’s never quite as accurate as the paleo plane based on the 17 signatures of stretch. However, it’s fairly accurate, to within perhaps 50-100 metres, which is enough to show the degree of precession that occurred after head shear. 

Photo 14- with the shear line on the body and the head rim shown in terracotta. This is to show how the left hand pancake is rather further up the head lobe from the rim than the right hand one. Also, notice how the top edge of the pancakes’ seating in the dips at Aker run along the line of circles that denote the shear line across the top of Aker. These circles were noted in Part 21 and match to the cylindrical shapes running along the head rim directly above. The top edges of the pancakes are zig zagged as mentioned for photo 4. There are also zig zags between the shear line circles by virtue of their arrangement in a line. The circle zig zags on the body haven’t been matched one-for-one to the pancake tops on the head in any certain manner yet. However, even in this fairly low resolution photo you can see that there appear to be three triangular shapes between the circles along the top of the right hand seating between the last fuchsia dot and the turn to descend the v-shape to the Aker prow. Similarly on the head version there are three or four similarly sized triangles in the same place depending on which delamination you choose.

It’s telling that we’re even able to discuss these similarly sized, roughly congruent triangles of the same number, arranged in a similarly straight line of the same length and for a tiny run along the perimeter (that’s constrained by larger scale matches either side). That’s as opposed to completely different-sized square shapes or oblongs at different angles or different perimeter lengths of any shape at all. Or an infinite permutational array of amorphous blobs matching nothing anywhere- as one would expect on two lobes that had formed billions of kilometres apart and slowly drifted together. 

Photo 15- the original, reproduced for toggling comparison. 

Photo 16- having matched the right hand pancake to its seating below on Aker and to its left hand partner, it remains to add in the left hand pancake and its seating. 

The left hand seating was also matched to the right hand seating so it’s a physical impossibility for the left pancake not to have been seated in the left hand seating. All other colours are as for previous photos. 

Photo 17- this photo shows the triangle at the top of the Aker prow. 

It’s a flat triangle sitting in front of the line of circles that delineate the shear line along the top rim of Aker. This triangle is the same size as the triangle between the two pancakes along their top perimeter. It’s also exactly where you’d expect such a triangle to be if the two pancakes came from the two dips. It’s better to look at the original, unannotated version because the dots partially obscure the triangle. 

The two pancake seatings shown here don’t quite reach the line of circles at the shear line. This was an experiment, a slight adjustment to the seating. This is because there are clear delaminations above the pancakes (shown in red). These are zig zagged too but arranged along straighter lines on a larger scale. This suggests it was they that sat along the line of circles at the shear line and the pancakes sat just behind them. However the delaminations are so thin, they probably constituted so little volume that they just merged under the pancakes that thus did indeed kiss the circles. This is almost certainly a dud experiment because the pancakes have zig zags anyway. This was dawning on me whilst thinking it through again but the annotation is done and serves to introduce the triangle match and upper delamination lines. 

The experiment was also instigated to help explain the somewhat more circular pancakes fitting to the curved areas in the somewhat squared-off dips. However, the slight anomaly between squared-off and rounded is largely explained via the eye being drawn away from the obvious rounded seating by the prow and a few other straight lines. 

Photo 18- this shows the two pancakes as in photo 16 but with the shear line and head rim added in terracotta.

The shear line is now kissing the pancake seatings as before and is thus not very obvious on the body. The head rim and shear line are shown here to give context regarding visualising the sliding and clockwise rotating of the pancakes. They also aid us in seeing the movement of the head after shear. 

The shear line riding off wildly into the distance on the right isn’t a vague, optimistic guess. It’s been finely matched to the head rim 1 kilometre above it and the Babi cuboid slide 800 metres below it, all explained by and within the constraints of the tensile force vectors at play during stretch. This short section of shear line has many parts dedicated to it including Parts 38 to 41.

Photos 19-20 original reproduced for toggling and additional matches between the left and right pancake seatings (in orange, dark green and light blue).

 It’s advised to fly solo by referring to the original as well rather than relying on the dots. 

Photo 21- The slide delaminations down Khepry (medium green lines and mauve feature slide). Also light blue dots showing tear line matches where the Anhur crust tore away from Aker. The left hand pancake therefore suffered this tear along with its seating tear when seated in the left hand dip. 

In photo 22, below, the blue-dotted matches are very well-defined triangular tear features. For the body, they’re more obvious in photo 27. That photo includes a further delamination down the body of the blue dots. 

Photo 22- original for the Bastet pancake close ups.  ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DyASP/IDA/A.COOPER

The head lobe horizon (not the rim) is shown in small, yellow dots. This was the only relevant Bastet close up in the 2000 OSIRIS photos from MTP 07, taken from about 30km with the narrow angle camera (NAC). There were in fact five almost identical versions sitting together. For this reason the pancakes themselves are so foreshortened that they themselves bear little fruit in terms of showing the matches between them. However, in the foreground (south of the left hand pancake) there are some “off stage” matches which follow the same delamination vector. This is a mirror image (in terms of position and force vector, not shapes) to the bright green delamination that went in the opposite direction, north, from the right hand pancake. Both delaminations are away from the top, outside ‘corner’ of their respective pancake. 

Photo 23- the zoomed-in version used for annotation.  

Photo 24- the delamination from the top-left of the left hand pancake, going in a southwards direction (towards us). Key below.  

Before we describe the delamination, the red perimeters are the actual pancakes as before and the two farthest bright green features are the two obvious holes as before. The red dots along the tops of the pancakes are each placed on a point of a zig zag as was attempted in photo 4. You can see they are very obvious for the right hand pancake (at the top of the picture). There are five points dotted here instead of the supposed three or four suspected earlier. However, if you check photo 22, it looks more as though there are three along the top with one rather stunted one (second one up in this view) and the top one being some way down what was the fuchsia line in other photos. More close-up work on the circles along the shear line is needed to firm up these mini-matches. The upper delaminated lines of zig zags are also visible here. They form lines that sit above their respective pancake tops, especially noticeable for the three (or four) zig zags above the right hand pancake. One faint, long line of zig zags runs across the top of the triangle that fits to the prow triangle. There’s another very vague line above that, which was annotated earlier in the lower res photos but it looks as if it’s not a line of zig zags. 

The delamination, which is the main focus of photo 24, has its seating within the left hand pancake but slides to a point outside it. The features that slide are denoted by mauve, bright green, orange and yellow. Their visibility is in the same order as the colours listed, mauve first, yellow last. You’ll need to refer to the original, especially for the yellow match.

Photo 25- this shows an additional slid feature in red, which delaminated from the red perimeter.

 The red v shape on the perimeter seating is one of the Anhur tear triangles, single-dotted in blue above and in photo 27. The long yellow line with a dog-leg is relevant to photo 27 and not to this delamination. 

Photo 26- this shows the paleo equator or paleo rotation plane adjusted by the imaginary anticlockwise rotation adjustment of the pancake pair. This process was described above.  Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

You can see the paleo plane crosses through the left hand pancake instead of trying to follow the skewed version between today’s pancakes. This adjustment sends the line straight at the centre of the Bastet dip that sits above the Hatmehit cliff. The v apex on the cliff (just over the horizon) is the next paleo plane signature after the prow. This is by far the largest expanse between two signatures on the whole comet. This is precisely because the pancakes slid up Bastet and swivelled in the process. They even carried on delaminating further up. This completely smudged the paleo plane signature. 

The probable reason for the swivel of the pancake pair is the fact that the left hand pancake was and is still firmly attached to its Anhur slide head lobe component. Although the goggles analogy had the Babi slide head lobe component acting as a strap attached to the right hand pancake, it isn’t attached today so it might have pulled on that pancake less or not at all, leaving the sympathetic tensile forces alone to send them up together along with all the vagaries of varying friction. The Anhur head component is a very solid chunk and probably resisted friction somewhat more so it slid higher. 

Photo 27- this shows the pancake pair and their seating from a south pole viewpoint.  Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

You can now see the Anhur slide v shapes and their matching head lobe components. These are also v’s of course. The thick, chunky one is attached to the left hand pancake and the attachment point is denoted by the orange dot. This yellow v-shaped line attachment is shown as the yellow dog-leg line in photo 25. That line doesn’t have an orange dot at its end because it’s a close up. The seating point for the chunky head lobe v shape is denoted by matching its orange dot to the middle orange dot next to the pancake seating. This automatically seats it to the yellow v shape at the seating. However, the seating itself delaminated down the body to the point where the lower orange dot sits with its own delaminated v shape. 

The faint blue dots (this is an old annotation, faded with additions) denote the ragged, torn edge of four points that was annotated in photo 21. This torn edge of the pancake seating also delaminated and slid with the yellow v shape and the orange dot that denotes the v shape’s attachment point to the ragged edge. The four seating dots match to the four dots down the left side of the left pancake in photo 21 (not shown here because they’re whited out). It should be stressed that the four pancake zig zags in photo 21 are not definitively matched to the four main zig zags at the seating but it’s a working hypothesis that they do so because it’s the only place they could have come from and both seating and pancake exhibit the same size, shape and apparent number of zig zags. This is the same argument as for the zig zags along the top of the pancakes matching to the circles along the shear line. 

The Anhur slide is a mirror slide to the Babi slide in terms of its body slide vectors down Anhur towards the base of the comet and its head components sliding up Bastet with the pancakes. This is why the medium green delaminations down Khepry, also in photo 21, are perfectly believable. They were doing what everything on either side of them was doing and they followed suit. 

Similarly, the two pancakes were caught in the middle between the Babi and Anhur head components and drawn up with them by the same slide vector. All this happened when the head was still attached to the body along the shear line as shown in previous photos. It probably happened only shortly before the head actually sheared. From that point onwards, the tensile forces of stretch were transferred to the growing neck and the slides stopped. 

The symmetry of the tensile forces of stretch during this whole scenario is the reason we see Aker with two symmetrical dips either side of a prow and with torn sides of equal length equidistant from the prow. It also explains the pancake pair sitting directly above the symmetrical dips, the two symmetrical slides either side of Aker down the body and their corresponding symmetrical slides up the head. And finally, it explains the neat, flat, symmetrical shape of the Khepry surface below Aker and the fact that its about the same width as Aker too. 


In the process of describing the morphological evolution of the two pancakes on Bastet we have managed to knit that evolutionary scenario seamlessly into the already known processes in neighbouring regions that were brought about by stretch. Therefore the evolution of the pancakes is complementary to that ongoing, internally consistent hypothesis that 67P stretched. 

All the processes described for the pancakes and for the neighbouring regions are constrained by and consistent with the tensile force vectors of stretch as brought about by spin-up of the comet. This has resulted in the symmetrical shape we see at Aker/Khepry and its environs as well as on the head lobe at Bastet and its environs. 

The signatures of the symmetrical tensile forces of stretch are literally stamped on the comet because those symmetrical forces pulled the comet into a symmetrical shape. 



Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

To view a copy of this licence please visit:

All dotted annotations by A.Cooper



Part 50- The Blocky Rectangle Slide at Seth



This is a narrative key with some sections divided into paragraphs. The key ends at the next sub-heading. 

Red arrows- slide directions. The two longer arrows correspond to the same slide. The upper of the two is aligned along the centre of the top surface of the blocky rectangle and depicts its direction of slide i.e. along the same direction as its long axis. The lower of the two is the slide track of the base of the rectangle which is of course in line and in the same direction as its partner arrow on the top surface of the rectangle. The top arrow therefore used to sit directly above the bottom arrow. Both arrows are about 200 metres long perhaps a tad less. The short arrow depicts the sliding of a smaller lump at 90° to the blocky rectangle slide. This is in keeping with the 1.6 km x 200m rift described in Part 49. That rift was described as opening up at 90° to the long fault along which the blocky rectangle slid. 

Bright green- the upper line runs along the top of the blocky rectangle. You can see the other side of the rectangle too but just for clarity to pick it out from the background: it’s an almost mirror image line to the green one (including the central dip) on the other side of the arrow running down the centre. So the arrow is the line of symmetry. The lower bright green line runs along the rim of the very straight, shallow trench that the blocky rectangle once sat in. Since the rectangle slid backwards along the arrow direction, it therefore slid along the trench, hugging the rim as it went. The lower bright green line therefore matches to the base of the rectangle’s cliff, which is in very dark shadow. The cliff base used to sit along this lower line. The cliff of the blocky rectangle itself carries on a little further into the shallow trench and was always hidden behind the trench rim, even as it slid. 

Pale orange- this is the boulder field that relates to the blocky rectangle’s rugged cliff face that’s in complete shadow. The boulder field stops abruptly halfway along the cliff and is therefore staggered from the current position of the cliff face it fell from. This is because the boulders fell away from the cliff when its base was still seated along the lower bright green line. 

There’s an abrupt line between boulders and dust at the far end of the boulder field. This sharp demarcation line is at 90° to the cliff face and alongside the position at which the far end of the cliff used to sit. Since the boulder field is the same length as the cliff, and staggered, it’s clear that the cliff used to sit along the lower bright green line. Ergo the blocky rectangle has to have slid along the direction of the arrows from the seating to its current position. 

The boulder field was almost certainly produced as a result of the 1.6 km x 200m rift in Part 49 yanking the boulders out of the cliff as material tore away at 90° to the cliff. This means we can be sure that the rift happened first and the blocky rectangle happened second and probably as a result of being free to follow its preferred tensile stress vector, along the paleo equator. Please see Part 49 for these differential tensile stress vectors either side of the rift that caused it to open in the first place. 

Mauve- the mauve line in the foreground is part of the ‘mauve anchor’ (Part 24), one of four resilient massifs from which both the head lobe and the red triangle recoil tore away. The mauve line in the background runs along the clifftop of the front face of the blocky rectangle. It then carries on for a short distance. 

The front face the rectangle clamped to the back of the mauve anchor, behind and below the mauve line in the foreground i.e. hidden from our view from this perspective. The head lobe was clamped to the near side of the mauve anchor. This is why the mauve line in the foreground is so ragged: it had material tearing both from behind it and in front of it. The section of the mauve line across the front of the blocky rectangle fits well to the right side of the mauve line in the foreground. The extension to the left doesn’t match for two reasons. Firstly, it was attached to material on Serqet (the head lobe rim component of the mauve anchor). The two sections kissed either side of the ragged foreground line which is now a vestige from inside that violent tear. That’s why it’s ragged and tapers down while the mauve rectangle extension stays high (as does the head rim match). Secondly, the material next to the front cliff of the blocky rectangle recoiled back somewhat like a blanket. That’s not a fudge- there’s plenty of evidence for it, some published, some yet to come. 

Red- this is a nice piece of evidence for the 1.6 km x 200-metre rift in Part 49. The lump on the right was attached to the recess on the left. This match holds up very well in other views too. The small dots denote the far rim of the lump that’s out of view as well as its seating which is in view. So all larger red dots are in view. This lump has a slide vector as denoted by the arrow. You can see that the arrow is at 90° to the blocky rectangle slide. This is because the line along which the rectangle slid (the bright green rim of the trench) is a very straight line and a weak point brought about by the tensile forces of stretch. This line stretches 1.6 km into the distance (off-frame to top-right) and was the cause of the 200-metre-wide rift, to the right in this view. Hence, the little red lump moved to the right. The slide distance of the lump as well as the width of the pale orange boulder field are about 100 metres which is half the width of the 200-metre rift. The opposite perimeter is off-frame to the right. 

Orange- this is what appears to be a nice mini match. It’s the only new discovery in this post. It’s not quite definitive and needs more close-ups from different angles to verify it. In the meantime, it’s up to the readers to ascertain for themselves how likely it is by checking the unannotated version. Of course, if it holds up, it has important implications. The short crack along the far line has been cited in the morphology papers as being a section of cliff that’s cracked because of erosion and on the point of collapse. However, if it did sit on the suggested seating, it simply means that it was wrenched from that position as a ready-made overhang and cracked for that reason. This means that no erosion is necessarily at play in the formation of this overhang. Incidentally no erosion is necessarily at play in any of the rugged cliffs, boulder fields and outcrops in this roughly 500m x 800m view. In fact, stretch theory has already shown that every one of the cliff features in this view has either torn or slid and all boulder fields (including those in the ‘slide trench’) have come about as a result of tears and slides. Athough erosion via sublimation must be happening it’s probably responsible for a fraction of one per cent of what we see in this photo. Hence the need for the obligatory inclusion of the word “necessarily”, above. 


The blocky rectangle slide isn’t a new discovery. It was first published in Part 26, a year ago (see sub-heading ‘signature 6’ in that Part). That sub-heading has a photo showing what is called the ‘red triangle recoil’ which was a 200-metre recoil of the top crust, away from the shear line where the head lobe rim sheared from. 

The direction of the red triangle slide was exactly along the direction of the paleo equator that defines the paleo rotation plane. The paleo equator is quite close to the current equator. So the red recoil slide, including the blocky rectangle in this post, Part 50, slid along the paleo rotation plane. 

Since the tensile force vector induced by spin-up of the comet would act along the paleo rotation plane, in a direction towards the stretching long-axis tip, it means the entire 1-kilometre-wide slide succumbed to that same tensile force vector. This blocky rectangle is just the end section of the red triangle recoil. 

There’s a wealth of additional corroborating matches along the line of the red triangle recoil that extends for a kilometre, all the way from the view in the header photo to Anubis (off-frame, a long way to the left). 

So the evidence presented here is now one year old and the slid blocky rectangle has been referred to on numerous occasions since as a key component in directing us towards other discoveries. These include what is now an intimate understanding of the morphology of the Serqet-Ma’at border. That border used to be clamped against the mauve line in the foreground and therefore to the blocky rectangle when it was seated. This is why the mauve line is so ragged. It had material tearing away from it on both sides. 

The sliding of the blocky rectangle was also key to noticing the 1.6 km x 200-metre rift in Part 49, published recently. 

All the information on the blocky rectangle slide given here was also given in a comment I made on the Rosetta blog some while ago. It was in response to a blog post that contained a very similar close up view of the blocky rectangle, taken from an OSIRIS paper. I made the comment describing the sliding process, the trench and the staggered boulder field in order to show that vast chunks had slid hundreds of metres and that this was evidence for stretch theory. So this part is a second attempt to persuade the Rosetta mission scientists that the blocky rectangle slid 200 metres. This time with a more detailed photo, the argument holds up and is still more compelling with the added red lump slide and the proposed orange crack match.  


Regular readers will know of another ‘blocky rectangle’ part of the red slide on Imhotep. Apologies for the duplication- I forgot about this one when I tentatively named the Imhotep one. This one takes precedence because it was first coined long before the Imhotep one and it’s also more rectangular and blocky. So we’ll have to find another name for the one on Imhotep.