1) Norse mythology, originating from the Scandinavian region, features gods and mythical creatures like Odin, Thor, Loki, and Valkyries. It explores themes of heroism, destiny, and the battle between gods and giants, with intricate tales recorded in texts such as the Prose Edda and Poetic Edda.

2) DNA, the building block of life, can store incredible amounts of data. It is estimated that one gram of DNA could potentially store about 215 petabytes of data.

3) The ozone layer, located in the Earth's stratosphere, protects us from harmful ultraviolet (UV) radiation.

4) The abolition of slavery in the United States was officially proclaimed with the ratification of the 13th Amendment to the Constitution in 1865.