Billy A

Before becoming the head of the Catholic Church in 2013, Pope Francis lived a much simpler life back in Argentina. In fact, he held an unusual job for a future pope - he worked as a bouncer at a nightclub.

If you've ever told a knock-knock joke or groaned at a corny one, you can thank William Shakespeare for this timeless and beloved form of humor. The Bard is renowned for pioneering over 1,700 words and phrases in the English language through his celebrated plays and sonnets. But he also may have invented one of the world's simplest — yet most entertaining — comedic setups: the knock-knock joke.

At $410 million, Pirates of the Caribbean: On Stranger Tides holds the record for the most expensive movie ever made. But that lofty price tag is pocket change compared to the over $100 billion spent on constructing the International Space Station (ISS)—the most expensive object ever built by humans.

In 1997, the chess world experienced a historic sea change. World champion Garry Kasparov resigned in defeat against IBM's Deep Blue supercomputer. For the first time, a machine had officially defeated a top human player under tournament conditions. Since then, computers have only extended their supremacy at the royal game. No human has managed to beat a computer opponent in a major chess match since 2005.

Towering into the rust-hued Martian sky, Olympus Mons dominates the horizon, dwarfing even Earth's tallest peaks. This towering volcanic mountain rises 16 miles high - nearly three times taller than Mount Everest.

Deep in the world's oceans thrives a photosynthetic powerhouse you can't even see. The tiny microbe Prochlorococcus measures just 0.6 micrometers wide—half the size of the thinnest human hair. Yet this unassuming organism pulls off an astounding chemical feat: producing up to 80% of the oxygen in Earth's atmosphere.