1) 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.

2) The world's first car radio was invented in 1929.

3) The ocean covers about 71% of the Earth's surface and contains roughly 97% of the planet's water.

4) The concept of sovereignty refers to the supreme authority and power of a state to govern itself, make decisions, and control its own territory without interference from external forces.