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 word "orange" contains three vowels: O, A, and E.

3) The novel "To Kill a Mockingbird" by Harper Lee has been translated into more than 40 languages and has sold over 40 million copies worldwide.

4) The Great Wall of China is not visible from space without aid, contrary to popular belief.