Believe it or not but today (23rd April) marks the 4 year anniversary of The Impossible Astronaut and Day of the Moon, the momentous two-part adventure that opened NuWho's sixth series back in 2011. It was a much anticipated story since it marked the triumphant return of the Eleventh Doctor, Amy and Rory and it had earned a fair amount of fame even before its broadcast due to the location filming in Utah. What really made it stand out, however, was that it was the first time in the history of the modern show that a series opened with a two-part storyline. The two-episode story format really paid off for this explosive opener as, all in the course of 45 minutes, everything fans thought they knew about the Doctor and his companions changed to give them more questions than answers. By the time the ending credits rolled for Day of the Moon, Whovians everywhere were desperate to know the truth behind the web of secrets that had now ensnared the heroic TARDIS crew. There were numerous moments during The Impossible Astronaut/Day of the Moon that left the audience's jaw on the floor, and here are just 10 of them.