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 coldest known temperature in the universe was achieved in a laboratory in 2019, reaching a fraction of a degree above absolute zero (-273.15 degrees Celsius).

3) The study of fossils is called paleontology, and it helps us understand the history of life on Earth and the process of evolution.

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