1) The name "Bluetooth" comes from the 10th-century Danish king, Harald Bluetooth, who united Denmark and Norway.

2) The Earth's core is primarily composed of iron and nickel and is as hot as the surface of the sun.

3) In Aztec mythology, Quetzalcoatl is a prominent deity often depicted as a feathered serpent. He is associated with creation, fertility, and wind, and is considered a cultural hero and patron of priests and rulers. The arrival of Spanish conquistadors was interpreted by some as the return of Quetzalcoatl.

4) The Andes, stretching along the western coast of South America, is the longest mountain range in the world, spanning over 4,300 miles (7,000 kilometers).