1) In Norse mythology, Ragnarok is a cataclysmic event that signifies the end of the world. It involves a series of apocalyptic battles and natural disasters, leading to the destruction of the gods and the world as it is known. From the ashes, a new world and a new generation of gods emerge.

2) The Great Barrier Reef in Australia is the largest coral reef system in the world and is visible from space.

3) The Federal Reserve System, often referred to as the Fed, is the central banking system of the United States.

4) The International Cricket Council (ICC) is the governing body for the sport of cricket and oversees international tournaments and rankings.