Food
Why Do Onions Make You Cry?
Cutting onion cells triggers enzyme reactions that release a volatile irritant. Your eyes produce tears to dilute and wash it away.
FACTOSBRAIN KNOWLEDGE DESK
One remarkable fact can open a wider view of the world.
We turn passing curiosities into concise stories with enough context to make them stick.
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Technology
The First Computer "Bug" Was an Actual Moth
The term "bug," used today to describe a software error, is famously traced back to an actual moth found inside a computer in 1947.
Human Body
Why the Stomach Does Not Digest Itself
A constantly renewed mucus-and-bicarbonate barrier protects the stomach lining from the acid and enzymes used to digest food.
Animals
Polar Bear Fur Isn't Actually White — It's Transparent
The seemingly white fur of polar bears is actually colorless and transparent, while their skin underneath is closer to black.
Psychology
Why We Value Things More When We Build Them Ourselves
The IKEA effect describes our tendency to assign extra value to objects we helped create or assemble.
Space
Bigger Than Earth: Jupiter's Great Red Spot
Jupiter's Great Red Spot, a massive swirling storm, is larger than Earth's diameter and has been raging for hundreds of years without dying down.
History
Cleopatra Lived Closer to the Moon Landing Than to the Pyramids
The Great Pyramid was already ancient in Cleopatra's time; fewer years separate her from Apollo 11 than from its construction.
SECTIONS
Explore by subject
05ScienceThe principles and discoveries behind the phenomena all around us.02HistoryUnexpected links between people, events, and the timelines we take for granted.02SpaceBig and small questions that help us understand planets, stars, and the universe.03AnimalsThe anatomy, behavior, and remarkable adaptations of the animal world.02Human BodyHow the human body works—and the familiar claims we often get wrong.03FoodThe science, history, and culture hidden inside everyday food.01PsychologyThe mechanisms that shape thought, emotion, memory, and choice.02LanguageThe many ways speech and writing divide, describe, and reshape the world.01GeographyScale, distance, and the ways places shape the lives lived within them.01TechnologyThe inventions, mistakes, and language behind the tools we use today.
SCIENCE
Science
Science
Why Does Ice Float on Water?
When water freezes, its molecules form an open crystal structure and expand by roughly 9 percent. The resulting lower density keeps ice afloat.
Science
A Puffy Cumulus Cloud Can Hold About 500 Tonnes of Water
In a standard example, the tiny droplets spread through a cumulus cloud add up to about 500 tonnes of water. A simple calculation explains the estimate—and why the cloud still floats.
Science
A Rainbow Is Actually a Full Circle
Rainbows are circular optical phenomena, but the horizon usually hides the lower half from observers on the ground.
HISTORY
History
History
Cleopatra Lived Closer to the Moon Landing Than to the Pyramids
The Great Pyramid was already ancient in Cleopatra's time; fewer years separate her from Apollo 11 than from its construction.
History
Oxford University Is Older Than the Aztec Empire
England's University of Oxford had already been teaching students for centuries before the Aztec Empire was even founded — a surprisingly old institution.
SPACE
Space
Space
Bigger Than Earth: Jupiter's Great Red Spot
Jupiter's Great Red Spot, a massive swirling storm, is larger than Earth's diameter and has been raging for hundreds of years without dying down.
Space
On Venus, the Sun Rises in the West
Venus rotates in the opposite direction from most planets, so the Sun would appear to rise in the west and set in the east.
ANIMALS
Animals
Animals
Why Do Cats Have Vertical Pupils?
A cat's vertical pupils do more than control light. Research connects their shape with judging distance while ambushing prey close to the ground.
Animals
Polar Bear Fur Isn't Actually White — It's Transparent
The seemingly white fur of polar bears is actually colorless and transparent, while their skin underneath is closer to black.
Animals
Octopuses Have Three Hearts and Blue Blood
Octopuses are mysterious creatures with three hearts and blue blood, a unique physiology that helps them survive in the cold depths of the ocean.