Ayatollah Khomeini returned to Iran on Feb. 1, 1979, after 14 years in exile

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

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.

Although the moon passes between the sun and Earth each month, its orbit is tilted by five degrees, preventing Earth from experiencing a solar eclipse each month.

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

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

Pregnancy makes someone more attractive to the mosquito species that transmits malaria.

See a breakdown of how some of the most common food items are traded across the globe, including the key trade relationships for each item.

Humans tend to imagine aliens as humanlike, but that's probably unlikely. Three different hypothetical planets show how aliens' bodies could take many forms.

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 collapse of gas bubbles in the joint synovial fluid causes 'cracking' knuckles.

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

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

'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.

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.

Explore (and debunk) the world's most contagious misconceptions—from the 5-second rule to sugar rushes—on this interactive site. Click on each misconception for further evidence.

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.

Apeirophobia is the fear of everlasting life and may stem from the human brain's inability to conceptualize the concept of anything happening beyond what it can project out, such as the concept of an infinite life.

Explore 3D models of some of the most dangerous viruses, allowing us to understand these and other pathogens in new ways.

A dog's nose can be up to 100,000 times more sensitive than a human's, and each possesses a secondary organ for smelling, which helps learn about other dogs when they sniff each other's butts.

Use this tool to calculate the dollar value of your parental mental load, from meal planning to coordinating after-school care, then see resources that help generate solutions.

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

There are 'YouTube camps' that teach children how to create content for the video platform.

Watch 4-plus decades of Pixar's opening logos.

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

Watch a visualization of what it would look like to move along Earth's surface as fast as the International Space Station, or about 23 times the speed of sound.

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.

As part of the up to 15 pounds of seafood they consume daily, sea otters eat urchins that feed on kelp forests—sources of shelter and food to over 800 species—thereby making the marine mammal a keystone species.

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

Watch Bruce Springsteen's 1985 performance of Woody Guthrie's 'This Land Is Your Land,' which he calls 'the greatest song ever written about America.'

Here are some tips from Pew Research to help you distinguish between a good poll and an unreliable one.

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

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.

The US jobs projected to shrink the fastest over the next decade include typists and word processors.

Watch President John F. Kennedy's speech on going to the moon

Washing dishware before putting it in a dishwasher may reduce the appliance's effectiveness because it dynamically adjusts wash time and temperature based on a sensor that detects dirtiness.

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

Researchers generally group gut bacteria into six different categories, with varying amounts of these microbes residing in different parts of the digestive tract.

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

Examine this captivating animation 'building' a human—illustrating the roughly 40 weeks of fetal development.

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