1) Robert Downey Jr. is an American actor known for his portrayal of Iron Man in the Marvel Cinematic Universe. He has also starred in films such as "Sherlock Holmes," "Chaplin," and "Tropic Thunder," and has received critical acclaim and commercial success for his performances.

2) The world's largest desert is the Sahara Desert in Africa, covering an area of about 3.6 million square miles (9.4 million square kilometers).

3) The Age of Exploration, during the 15th and 16th centuries, saw European explorers such as Christopher Columbus and Vasco da Gama reach new lands and establish trade routes.

4) George Clooney is an American actor, filmmaker, and activist. He gained fame for his role in the television series "ER" and has since starred in successful films such as the "Ocean's" trilogy, "Syriana," and "Up in the Air," winning several awards for his performances.