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 world's oldest known recipe is for beer and is over 4,000 years old.

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

4) Michael Phelps, an American swimmer, has won a total of 28 Olympic medals, including 23 gold medals, making him the most decorated Olympian of all time.