Hi, I have discovered an issue (Bug) when my character is underground (cavern / mine-shaft) - When moving around sometimes, (usually panning horizontally), I notice that I can see the sky. Also, if I stop my character, and pan slowly I can keep the sky in view without it disappearing.
It isn't the whole screen, just one or both sides.
Happens quite frequently too (once every 5 mins or so) - I have pictures of this phenomena.

What I expected to happen was...:
I shouldn't be able to see the sky through rocks

What actually happened was...:
I CAN see the sky through any type of underground terrain sometimes.

Steps to Reproduce:
1. Just being underground.
Unsure if its caused by angle of camera or distance from walls or type of terrain i'm standing on or what i'm holding, or if it's a setting in graphics options, or none of the above. It just happens about every 5 mins and can be either side of the screen or both at the same time (rarer) - but never whole screen. Usually disappears if I move away (2 or 3 blocks) or move camera away from the side I can see the sky from.

Of Note: I am forcing Antialiasing (4x AA & 4x Supersampling) from Nvidia Control Panel - But was doing so before 1.8 and had no issues.