1) The world's largest volcano, Mauna Loa in Hawaii, is also one of the most active. It stands over 13,000 feet (4,000 meters) above sea level.

2) The process of nuclear fusion powers the sun and other stars, fusing hydrogen atoms together to form helium and releasing vast amounts of energy in the process.

3) The French Revolution, which began in 1789, marked a major turning point in European history, leading to the overthrow of the monarchy and the rise of republicanism.

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