1) The ozone layer, located in the Earth's stratosphere, protects us from harmful ultraviolet (UV) radiation.

2) The oldest known musical instrument is a flute made from a bird bone, estimated to be around 43,000 years old.

3) The world's first paper money was created in China over 1,000 years ago.

4) The world's largest desert is the Antarctic Desert, covering around 5.5 million square miles.