Spot the Difference

Don Pettit was the first astronaut to use a yo-yo in space. On board the International Space Station, he was able to demonstrate several tricks because yo-yos rely on the laws of conservation of angular momentum, which work in micro-gravity as well.

Much like cats and dogs, foxes can be both friendly and interested in humans. Archeologists have found a 16,500-year-old grave in Jordan in which a man is buried with his pet fox. This is 4000 years before the earliest known grave of a human and their dog!

With a total length of 21,196 kilometres, the Great Wall of China is the longest man-made structure in the world. The mighty bulwark was constructed over the course of five centuries and was intended to fend off nomadic tribes, most notably the Mongols. It did so with moderate success.