With the theme being "A Small World" I immediately thought of that famous quote from Neil Armstrong,

"It suddenly struck me that that tiny pea, pretty and blue, was the Earth. I put up my thumb and shut one eye, and my thumb blotted out the planet Earth. I didn’t feel like a giant. I felt very, very small."

My idea is to do a lunar lander type game, where you land on the surface of the moon then get out, plant the flag, and then look up at the Earth and stick your thumb over it.