This is the second post which matches features on the two lobes of 67P/C-G in order to prove they were once joined. Some of the text below is a repeat of yesterday’s post since it applies to this post too. However, I would recommend reading yesterday’s too as it will serve to orientate you before moving on to this next section of the shear line. This section’s start point should in fact be yesterday’s end point as it is the continuation of that line. All told, it continues unbroken for the best part of a kilometre.
Below are two photos of comet 67P/Churyumov-Gerasimenko. The first is a close-up of the so called body, the second is a portion of the head. These two areas exhibit an identical wavy line showing that they were once joined together. It therefore follows that 67P/C-G was once a single body that has since been stretched, resulting in the two lobes we see today. This stretching would most likely have happened due to a very close approach to Jupiter, under the Roche limit, or a spin-up due do asymmetrical outgassing.
The colour-coding of the dots in the photos is listed further down. And there are two undotted versions at the bottom of this post which may be easier to work with once you know where to look for the matching lines. You will need to zoom in to see the detail (and please ignore the spurious grey line in the ‘head’ image!)
As with yesterday’s post, the 11 coloured dots trace the same line in both photos. Each colour marks the same twist or turn along both lines. The sequence is:
As the head fits to the body, it follows that 67P/C-G is not a contact binary as has been suggested. Nor is it an unstretched single body that has been eroded to form the separate head and body.
Since the two photos show opposite sections that once fitted together, they are mirror images of each other. They exhibit a geological line formation tracing a convoluted path which is faithfully reproduced in both photos. The shapes of the line in both are topologically identical but due to foreshortening, one is somewhat more squashed than the other. The matches are nevertheless very clear.
These two portions of the head and body of the comet already showed multiple matching features both in the areas shown annotated in close-up and in their immediate vicinity. The dots also match in the third dimension, not just in plan view. For example, the fuchsia dot on the body is at the tip of a pronounced peak. This peak nestles up into the deep recess in the head where its corresponding dot is to be found.
There are many other matches between head and body along the ridge that forms the base of the ‘neck’. The above matches are simply the most compelling ones.
The photos from which the annotated close-ups were taken:
1) ESA Rosetta mission blog
2) Bill Harris who posted the photo of the body portion on the Rosetta blog in the comments on this post:
The original close-up versions of the shots that were used for the purpose of annotating with dots are below. It may be easier to see the matches without the dots once you know where they are.