1) The process of nuclear fusion powers the sun and other stars, fusing hydrogen atoms together to form helium and releasing vast amounts of energy in the process.

2) The Great Wall of China is a UNESCO World Heritage site and one of the most iconic man-made structures in the world. It stretches over 21,196 kilometers (13,171 miles) and was constructed to protect the Chinese empire from invasions during ancient times.

3) The word "oxygen" contains two vowels: O and E.

4) The world's oldest known living tree is a bristlecone pine named "Methuselah" in California, estimated to be over 4,800 years old.