I'm not sure what you are talking about, but there is no material that has deteriorated between the tiles that would relate to the light shining through. There might me a material between the tiles on the "inner sphere", but the light that we are seeing is not coming from inside the ride, it is coming from the gap between the outer sphere (the tiles that are gray that we see) and not the inner sphere (black and is completely solid like the roof to your house). They probably set lights up as they clean the gutter system as Martin suggested.There is a gasket material between each tile and it appears as if on these particular sections the membrane has deteriorated. This, however, is not a structural issue.
To help people out picturing it, the light was visible in more than just the areas that are showing light in mine and Nakasak's pictures, I think that only the source of the light was showingin the pics, the light could be seen around many more tiles next to the ones showing light in the pics, including coming from the cracks between the 3 smaller tiles that make up the large tile on other tiles (it sounds confusing, but just read it a few times).Couldn't that be a door open, like someone initially pointed out?
or less probable an open inner door with the light inside the building.
Clearly, Disney has hung a glow stick between the outter and inner skin and is sitting back laughing at all of us...
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