I've always been fascinated with the Apollo missions and I think in large part it's down to this picture.

Its official NASA designation is AS8-14-2383HR but it's more commonly known as Earthrise. It was taken by Bill Anders on Apollo 8, the first manned spacecraft to go around the moon in December of 1968 and became famous for Anders, Jim Lovell (Who was later to command the ill-fated Apollo 13) and Frank Boorman broadcasting a Christmas Eve message from the book of Genesis.
I believe the picture has actually gone on to become one of the most reproduced images in history although it's almost always rotated ninety degrees to the right, presumably so its fits more comfortably with our Earth-bound perceptions of gravity.
I don't know why I love the image so much, possibly its because they were the first people to ever see it, possibly because its something I know I'll never see myself or possibly because the three Astronauts have jokingly spent forty years arguing over which of them actually took it. If you were to ask most people about the Apollo missions (Arguably aviation and aerospace's greatest achievements) they could probably tell you that Neil Armstrong was the first man on the moon on Apollo 11 and that'd be about it but for me the Apollo mission's finest hour was the first lunar orbit and that picture above.
My wings are like a shield of steel.