There are up to 100 trillion microbes in the gut, and maintaining the relative balance in this ecosystem is important for our health.

The Berlin Wall physically separated East and West Berlin for nearly three decades, preventing East Germans from fleeing to the West and earning the nickname 'the Iron Curtain.'

Humans may have as many as 100,000 to 150,000 individual hairs on our scalps, growing at a rate of roughly 1 centimeter per month.

On a cruise ship, the average person uses about 50 gallons of water a day, which is treated by bacteria and onboard filtration systems, then stored until the ship can legally discharge the wastewater.

On planets in systems with two stars, such as the fictional Tatooine from 'Star Wars,' observers would see overlapping rainbows and double rainbows.

Plato's famous allegory of the cave is a metaphor exploring the value of truth over ignorance.

Explore a detailed map of Odysseus' fictional journey from 'The Odyssey.'

Watch the many different civilizations around the Mediterranean shift power from the year 2500 BCE to 0 BCE in this animated map.

If a source of music traveled past someone at twice the speed of sound, assuming sufficiently sensitive hearing and powerful equipment, they would hear the music backward.

Listen to audio clips from Hoover, a harbor seal named after its insatiable appetite, who learned to say English phrases such as 'hello there' and 'come over here.'

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

Robert Smalls escaped slavery by piloting a stolen Confederate ship to freedom, then became an influential Black political leader during Reconstruction.

Male pattern baldness accounts for more than 95% of hair loss in men and is characterized by thinning hair, hair loss, and a receding hairline.

Watch footage from the moments the Titanic wreck was discovered by a joint US-French research team in 1985.

Between 2002 and 2012, at least 12 people were killed in the Philippines in incidents related to off-key karaoke singing of Frank Sinatra's 'My Way.'

See where your state ranked in an analysis of the best public school systems in the US.

Explore an interactive forecast of the future of the universe, from the return of Halley's Comet to the last light in the cosmos.

The animatronic shark from 'Jaws' was a complex machine called 'Bruce.'

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

The final shots of the Civil War were fired in the Arctic over 2 months after the South's surrender.

'Bibliotherapy' is of increasing interest as a way to improve mental health and help navigate complex life situations—with people immersing themselves in the experiences of fictional characters or nonfiction and self-help books to find relief and gain personal insights.

Rapid intensification is the increase in a hurricane's sustained wind speed by at least 35 miles per hour within 24 hours, which can strengthen it by up to two categories.

In 1962, the US detonated a nuclear weapon in space, which produced an electromagnetic pulse that disabled three low Earth orbit satellites and damaged electrical equipment in Hawaii.

This interactive website features nearly 40,000 photos from Wikipedia for you to create visual mosaics with.

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

Fecal transplants can help treat infections by transplanting healthy gut bacteria from a donor into a patient's gastrointestinal tract using samples of human waste, which are turned into a liquid mixture and often delivered via a colonoscopy procedure.

Emanuel Leutze's painting 'Washington Crossing the Delaware' is one of the defining images of the Revolutionary War.

One of the most famous portraits ever taken is 'Afghan Girl' (1984) by Steve McCurry, yet the subject Sharbat Gula went much of her life without being identified or benefitting from the image's success.

One of the most famous portraits ever taken is "Afghan Girl" by Steve McCurry. Sharbat Gula, the subject of the photo, was not credited until 2002 for her role in the famous National Geographic cover, and continued to live in poverty after the photo was taken.

Metamorphosis evolved over millions of years as species that hatched as smaller versions of adults started exhibiting genetic mutations that differentiated juvenile and adult bodies.

See a 3D reconstruction of Tenochtitlan, the Aztec capital

Hear 50 years of iconic hip-hop samples, the genre's foundational looped tracks.

Streaming service Netflix's sound logo 'Tudum' was designed as a key sonic differentiator.

Computer scientists first started trying to optimize dating using computers in the 1950s.

Explore the history of American restaurants through an archive of menus dating back to the early 1800s.

Explore Lewis and Clark's 8,000-mile journey in Google Earth.

Cats have a mutation that prevents them from tasting sweetness, and goldfish rank among the world's supertasters.

Author David Foster Wallace's 'This Is Water' speech provides guidance for adulthood.

'Golden blood' is the rarest blood type in the world—fewer than 50 people are known to have it.

The world's largest waterfall is in the ocean and is more than three times the height of Angel Falls, the largest waterfall on land.

The tallest tsunami in recorded history was 524 meters (1,720 feet) high—taller than the Empire State Building—and occurred in Lituya Bay, Alaska, in 1958 after an earthquake dislodged a rockface into the water.