Some ideas get repeated so often that they start to feel like settled science. They turn up in cartoons, classroom trivia, dinner-table arguments, and the occasional game show, and almost nobody stops to check them. Yet a surprising number of these “facts” fall apart the moment you look at the evidence.

Below are twelve of the most persistent misconceptions, along with what scientists and historians actually know. Some are harmless. A few can lead to bad decisions. All of them make for better conversation once you know the real story.

1. Goldfish Have a Three-Second Memory
   The joke that a goldfish forgets everything before it finishes a lap of its bowl has no basis in biology. Goldfish can be trained to respond to sounds, colors, and light signals, and they can hold on to those associations for weeks or even months. Many owners notice their fish crowding to the front of the tank at feeding time. That is learned behavior, not coincidence.
2. Blood Is Blue Until It Touches Oxygen
   Human blood is always red. Blood carrying plenty of oxygen is bright red, and blood that has already delivered its oxygen is a darker, deeper red. It never turns blue inside the body.
   The myth comes from the way veins look through skin. Skin and tissue scatter and absorb light in a way that makes veins near the surface appear bluish or greenish. Anatomy diagrams that color veins blue have not helped.
3. You Can See the Great Wall of China From Space
   The Great Wall is extraordinarily long, but it is also narrow, and much of it is built from materials that blend into the surrounding landscape. That combination makes it very hard to pick out with the naked eye from orbit. Astronauts have described it as difficult or impossible to spot unaided, while cities, major highways, and airports are far easier to see. From the Moon, no individual human structure is visible at all.
4. Bulls Get Angry When They See Red
   Cattle have more limited color vision than humans and are not thought to perceive red the way we do. What provokes a bull in the ring is movement. The cape is waved and snapped, and a stressed animal charges at the motion. The red itself is mostly tradition, aimed at the crowd rather than the bull.
5. Lightning Never Strikes the Same Place Twice
   Lightning tends to hit the tallest, most conductive object in an area, and that object doesn’t move between storms. Skyscrapers, radio towers, and lone trees on hilltops can be struck again and again, sometimes during a single storm. The Empire State Building is hit many times in a typical year.
   This one matters for safety. Believing a spot is protected because it was already struck can put people at risk. If you can hear thunder, you are close enough to be struck, and the safest shelter is a substantial building or a hard-topped vehicle.
6. Humans Use Only 10 Percent of Their Brains
   This idea has fueled movie plots and self-improvement pitches for decades. Brain imaging tells a different story. Over the course of a day, virtually every region of the brain shows activity. Different tasks engage different areas, but there is no large, dormant reserve waiting to be switched on.
   Damage to almost any part of the brain produces some kind of effect, which would not be true if nine-tenths of it sat idle.
7. Different Parts of the Tongue Detect Different Tastes
   Many people learned in school that sweetness is sensed at the tip of the tongue, bitterness at the back, and salty and sour flavors along the sides. That “tongue map” grew out of a misreading of early research on taste sensitivity. In reality, taste buds that can detect all of the basic tastes are spread across the tongue. Some areas may be slightly more sensitive than others, but the differences are small.
8. Earth Has Seasons Because It Moves Closer to the Sun
   Earth’s orbit is slightly oval, but the change in distance is not what drives the seasons. If it were, both hemispheres would have summer at the same time.
   The real cause is the tilt of Earth’s axis. As the planet travels around the Sun, each hemisphere spends part of the year tilted toward it, receiving more direct sunlight and longer days, and part of the year tilted away. Earth is actually closest to the Sun in early January, right in the middle of the Northern Hemisphere’s winter.
9. Shaving Makes Hair Grow Back Thicker and Darker
   A razor cuts hair at the surface. It doesn’t touch the follicle beneath the skin, so it cannot change how thick, dark, or fast hair grows. The confusion comes from what happens next. A shaved hair has a blunt tip instead of a naturally tapered one, so stubble feels coarser. Regrowth can also look darker simply because it hasn’t yet been lightened by sun exposure.
10. Bats Are Blind
    “Blind as a bat” is a catchy phrase, but no bat species is blind. Many bats use echolocation to hunt insects in the dark, sending out high-pitched calls and listening for the echoes. That ability works alongside their eyesight rather than replacing it. Large fruit bats, many of which don’t echolocate at all, depend heavily on vision and smell to find food.
11. Napoleon Was Unusually Short
    Napoleon Bonaparte is often remembered as a tiny man with an outsized ego, but he was roughly average height for a Frenchman of his era. Part of the mix-up comes from measurement. French inches of the period were longer than British inches, so his recorded height seemed shorter when read using British units. British cartoonists also loved drawing him as small, and his nickname, “the little corporal,” was a term of affection from his soldiers rather than a comment on his stature.
12. Sugar Makes Children Hyperactive
    Ask a room full of parents, and many will swear that birthday cake turns kids into tiny tornadoes. Yet controlled research has repeatedly failed to show that sugar itself causes hyperactivity. When neither the parents nor the children know whether a snack contains sugar or a substitute, behavior looks much the same.
    Expectation and setting play a large role. Parents who think their child has eaten sugar are more likely to see hyperactive behavior, and the parties where sweets appear are already loud and exciting.

See also: The Role of Technology in Scientific Research

Why These Myths Refuse to Die

Misconceptions survive for a few predictable reasons. They are usually simple and memorable, while the truth involves more detail. And many of them feel right because they match something we have seen with our own eyes, like bluish veins or a wired child at a party.

Repetition is powerful on its own. The more often we hear a claim, the more familiar it feels, and familiarity is easy to mistake for accuracy. Psychologists call this the illusory truth effect.

How to Check a “Fact” Before You Share It

• Trace it to a source. If a claim leads back to a cartoon, an old advertisement, or “everyone knows,” treat it with suspicion.
• Watch for tidy numbers and absolute words. Phrases like “only 10 percent” or “never” are often warning signs.
• Use references that cite their evidence. Encyclopedias, university websites, and government science agencies are good places to start.

If this kind of myth-busting appeals to you, the list of common misconceptions on Wikipedia is a deep rabbit hole, with sources cited for each entry.

Keep the Curiosity Going

Facts like these are most fun in collections, where one surprising correction leads straight to the next. For more curated lists on science, history, and the odd details of daily life, Lists Resource gathers themed roundups that are easy to browse in a spare few minutes. Reading widely is one of the best defenses against the next catchy myth.

The next time someone at the table insists that goldfish forget everything or that bulls hate red, you’ll have the real answer ready. Just be kind about it, since most of us believed a few of these once.