Sun's Diamond Ring
During a solar eclipse the Moon passes in front of the Sun and just after their centres are both perfectly aligned light starts to break out and form a diamond ring pattern.
I have seen a good picture on Discovery Science TV but unfortunately most photos on the web miss this feature out even though they claim the photos as a "Diamond Ring" pattern. Usually they show a picture slightly afterwards so that the ring appears as a clump of diamonds and oval shaped.
I will have to admit that looking at the video a second time its not clear if I am seeing what I want to see and I would appreciate it if you can endorse what I am suggesting.
The Youtube picture may be slighlty after a diamond shape appears and the structure starts to decay at the corners.
I am including some photos here that I think support the diamond pattern.
I don't know if this effect is caught every eclipse. Perhaps that's why it only occurs once in a blue moon (sorry).
While most of the light is blocked by the moon those rays that are distorted in space around the large mass of the Moon have a chance of making their fleeting appearance. For the briefest moment the 4D phase has been twisted 90 degrees into 3D (just) and we glimpse 4D geometry!
Image 1 (public domain from http://www.racingshadow.com/SEclipse/2002Dec4/Totality_52.jpg) is interesting in that it shows the circular nature of the spatial disotrion being restored. I anticipate this to occur at a low amplitude on the F wave just before the light ray becomes perfectly aligned again with the Sun and earth.
Image 2 showing F wave geometry in a very brief (nearly square state in this particular photo and so nearly in 4D space but not quite. This shows how short lived the event is.

