1) J.K. Rowling's "Harry Potter" series of books has sold over 500 million copies worldwide and has been translated into 80 languages.

2) In Norse mythology, Valhalla is a majestic hall located in Asgard, the realm of the gods. It is the afterlife destination for brave warriors who die in battle, where they are greeted by the Valkyries and engage in feasting, drinking, and preparing for the final battle of Ragnarok.

3) The Amazon rainforest produces more than 20% of the world's oxygen.

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