After a barrage of tweets from avid fans, Hideo Kojima responded in form on his official Twitter page.
According to Kojima-san, the grey hair that Snake sported after removing his goggle was because of the game engine's effects. Specifically, it was due to the rim-lighting.
"Saw many tweet about Snake in grey hair after taking off the goggle. This is due to the rim-lighting."
Included with the tweet was a big picture of Snake with half of his face in the effect and the other half out of it. So, he's not so old after all. With this in mind, where do you think Ground Zeroes actually takes place in the series? Or, more specifically, when?