National Geographic

It was visible for just five seconds or so, gliding between the buildings on L Street here in Washington, D.C., but I still managed to raise my camera and snap one last shot of the Space Shuttle Discovery as it headed toward its final home at Dulles International Airport this morning.

I am a Titanic junkie. And I'm not just talking about the movie, which I've seen like, 786 times. (Okay I'm slightly exaggerating, but I did spend several hours waffling over the perfect headline for this blog using a quote from the movie. Since I can pretty much recite the whole flick, it took…