1) The discovery of the Americas by Christopher Columbus in 1492 opened up new trade routes and had a profound impact on world history.

2) Marilyn Monroe, born Norma Jeane Mortenson, was an iconic American actress, model, and singer, known for her beauty, charisma, and tragic personal life.

3) The Northern Lights, also known as the Aurora Borealis, are natural light displays that occur in the polar regions due to interactions between the Earth's magnetic field and solar particles.

4) In Norse mythology, the Valkyries are divine maidens who serve Odin, the chief god. They are responsible for selecting warriors worthy of entering Valhalla and escorting them to the afterlife. They are often depicted as powerful and beautiful figures, riding winged horses and wielding spears.