One hundred science facts, checked and grouped so you can actually find your way around them. Twenty each on space, the human body, biology, physics and chemistry, and the planet you are standing on.
A few of these are here specifically because the popular version is wrong. Where that is the case, the correction is the fact.
Space and astronomy
- A day on Venus is longer than its year. Venus takes about 243 Earth days to rotate once and about 225 to orbit the Sun.
- Venus also rotates backwards compared with almost every other planet, so the Sun there rises in the west.
- There is no sound in space in the ordinary sense, because sound needs a medium to travel through and the vacuum has almost nothing to carry it.
- The Sun accounts for about 99.8% of all the mass in the solar system. Everything else, including Jupiter, is rounding error.
- Light from the Sun takes roughly eight minutes and twenty seconds to reach Earth.
- Jupiter has no solid surface to land on. It gets denser with depth until the distinction between atmosphere and interior stops being meaningful.
- Saturn's average density is lower than water's, so given a bathtub large enough it would float.
- The Moon is drifting away from Earth by about 3.8 centimetres a year.
- Because of that drift, total solar eclipses will eventually stop happening. The Moon will appear too small to cover the Sun.
- Footprints left on the Moon will last millions of years, because there is no wind or liquid water to erase them.
- Olympus Mons on Mars is roughly two and a half times the height of Mount Everest above sea level.
- A neutron star is so dense that a sugar-cube-sized piece would weigh about as much as a mountain.
- Neutron stars can spin hundreds of times per second.
- Space is not silent to instruments. Charged particles produce electromagnetic waves that can be converted into audio, which is where those eerie NASA recordings come from.
- The observable universe is about 93 billion light years across, even though it is only about 13.8 billion years old, because space itself has expanded.
- The cosmic microwave background is leftover heat from the early universe, and it fills all of space at about 2.7 degrees above absolute zero.
- Most of the matter in the universe is not the kind we are made of. Ordinary matter is roughly 5% of the total energy content.
- If you fell into a black hole feet first, the difference in gravity between your head and feet would stretch you. Physicists call this spaghettification, unironically.
- The Milky Way and the Andromeda galaxy are on a collision course, expected to merge in about 4.5 billion years.
- There are more stars in the observable universe than grains of sand on all of Earth's beaches, by most estimates.
The human body
- Your body contains roughly as many bacterial cells as human cells. The old claim of ten to one was an overestimate.
- The human brain uses about 20% of the body's energy while making up about 2% of its weight.
- You are never using only 10% of your brain. Brain imaging shows activity across essentially the whole organ over the course of a day.
- Bone is stronger than concrete under compression, weight for weight.
- The human stomach lining replaces itself every few days, because it would otherwise digest itself.
- Your body produces about 1 to 1.5 litres of saliva a day.
- The acid in your stomach is strong enough to dissolve some metals.
- Red blood cells have no nucleus in humans, which is part of why they can carry so much haemoglobin.
- A red blood cell completes a full circuit of your body in about 60 seconds.
- You blink roughly 15 to 20 times a minute, which adds up to hours of closed eyes per year.
- Your eyes have a blind spot where the optic nerve leaves the retina, and your brain fills it in without telling you.
- The cornea is one of the few tissues in the body with no blood supply. It takes oxygen directly from the air.
- Humans can distinguish somewhere on the order of a trillion different smells, far more than the 10,000 long quoted.
- The strongest muscle in the body by force relative to size is the masseter, the jaw muscle.
- Your femur is the longest and strongest bone you have.
- Babies are born with about 300 bones. Adults have 206, because many fuse during growth.
- The small intestine is around 6 metres long in adults, several times longer than the large intestine.
- You lose most of your body heat through whatever is uncovered, not specifically your head. The head myth came from a study where subjects were dressed except for their heads.
- Your sense of taste depends heavily on smell, which is why food tastes flat when you have a blocked nose.
- Goosebumps are a leftover reflex from ancestors with more body hair, where raised hair trapped warmth or made them look bigger.
Animals and biology
- Octopuses have three hearts and blue blood, because they carry oxygen with copper-based haemocyanin rather than iron-based haemoglobin.
- Two of an octopus's hearts stop beating when it swims, which is part of why they prefer to crawl.
- Tardigrades can survive the vacuum of space, extreme radiation and near absolute zero by entering a dormant state.
- The immortal jellyfish can revert to an earlier life stage, which in principle allows it to avoid death by ageing.
- Honey does not spoil. Edible honey has been recovered from ancient Egyptian tombs.
- Bananas are berries in the botanical sense. Strawberries are not.
- Trees communicate through underground fungal networks that move nutrients and chemical signals between them.
- Sharks predate trees. Sharks have existed for roughly 400 million years, trees for around 350 million.
- A blue whale's heart is roughly the size of a small car, and its arteries are wide enough for a human to crawl through.
- Blue whales are the largest animals known to have ever lived, larger than any dinosaur we have found.
- Cows have best friends and show measurable stress when separated from them.
- Crows can recognise individual human faces and hold grudges for years.
- Some crows and other corvids make and use tools, and can solve multi-step puzzles.
- Axolotls can regenerate limbs, parts of the heart and portions of the brain.
- Starfish have no brain and no blood. They move water through their bodies instead.
- A single strand of spider silk is stronger than steel of the same thickness by weight.
- Ants do not have lungs. They breathe through small openings along their bodies.
- There are more trees on Earth than stars in the Milky Way, roughly three trillion against a few hundred billion.
- Mushrooms are genetically closer to animals than to plants.
- The mantis shrimp has one of the fastest strikes in the animal kingdom, fast enough to briefly boil the water around it.
Physics and chemistry
- Water expands when it freezes, which is why ice floats and why pipes burst.
- Hot water can freeze faster than cold water under certain conditions, an effect named after Erasto Mbemba.
- Glass is not a slow-flowing liquid. Old window panes are thicker at the bottom because of how they were made, not because they sagged.
- Absolute zero, at minus 273.15 degrees Celsius, cannot be reached, only approached.
- Lightning is roughly five times hotter than the surface of the Sun.
- A bolt of lightning contains enough energy to toast about 100,000 slices of bread.
- Diamonds and graphite are both pure carbon. The difference is entirely how the atoms are arranged.
- Helium is the only element that was discovered in space before it was found on Earth, identified in the Sun's spectrum.
- Gold is so unreactive that essentially all the gold ever mined still exists in some form.
- The element with the highest melting point is tungsten, at about 3,422 degrees Celsius.
- Atoms are mostly empty space. If an atom were the size of a stadium, the nucleus would be about the size of a pea.
- Nothing with mass can reach the speed of light, because the energy required would be infinite.
- Time runs measurably slower in stronger gravity, which is why GPS satellites need relativistic corrections to stay accurate.
- Uncooked rice, sand and many powders behave like fluids when vibrated, a state called fluidisation.
- The Sun converts about 4 million tonnes of mass into energy every second.
- Sound travels roughly four times faster in water than in air, and faster still in steel.
- A teaspoon of a white dwarf would weigh several tonnes.
- Electrons do not orbit the nucleus like planets. They exist as probability distributions called orbitals.
- Quantum entanglement means measuring one particle instantly tells you about its partner, but it cannot be used to send information faster than light.
- Superfluid helium can climb the walls of its container and flow with zero viscosity.
Earth and nature
- Earth's inner core is solid despite being hotter than the surface of the Sun, because the pressure is immense.
- The Earth is not a perfect sphere. It bulges at the equator, which makes the summit of Chimborazo the point furthest from Earth's centre.
- Mount Everest grows a few millimetres a year as the Indian plate pushes into Asia.
- The Atlantic Ocean widens by roughly 2.5 centimetres a year, about the rate fingernails grow.
- More than 80% of the ocean has never been mapped in detail or explored.
- The Mariana Trench is deep enough to swallow Mount Everest with over a kilometre to spare.
- The Sahara was green grassland with lakes as recently as about 6,000 years ago.
- Antarctica is technically a desert, because it receives very little precipitation.
- Lake Baikal holds around 20% of the world's unfrozen fresh surface water.
- The oldest known living individual trees are bristlecone pines over 4,800 years old.
- Earth's magnetic field has reversed many times, and the poles have swapped hundreds of times over geological history.
- There is more water vapour in the atmosphere than in all the rivers on Earth combined.
- About 70% of Earth's oxygen comes from marine organisms, not from rainforests.
- Diamonds form deep in the mantle and reach the surface through violent volcanic eruptions.
- The largest known single organism is a fungus in Oregon spanning several square kilometres.
- Earth is the only planet not named after a Greek or Roman deity.
- Rain smells because of a compound called petrichor, released from soil and produced partly by bacteria.
- A year is not exactly 365 days, which is why leap years exist and why some centuries skip them.
- The deepest hole ever drilled reached about 12 kilometres, barely scratching the crust.
- Volcanic lightning happens when ash particles rub together and build up charge.
Why some "science facts" are wrong
Several entries above exist to correct something you have probably been told. The 10% brain myth, the ten-to-one bacteria ratio, glass flowing in old windows, heat loss through your head. All of these circulate widely, all of them appear on fact lists, and none of them survive contact with the source.
The pattern is worth knowing because it will help you spot the next one. Bad facts tend to be memorable, tidy, and slightly flattering to whoever repeats them. Real ones are often messier and come with a range rather than a round number. When a fact has a suspiciously clean figure attached, that figure is usually the part that was invented.
If you want more of this, our 47 mind blowing science facts goes deeper on fewer items, and 27 brain facts stays with neuroscience. For the general-knowledge version rather than the science one, try facts that will blow your mind.
How to actually remember any of this
Reading a hundred facts in one sitting and retaining them are different activities. You will remember perhaps five of the above tomorrow, and that is normal rather than a failure of attention.
What moves a fact from read to known is retrieval. Trying to recall something, and struggling slightly before you get it, does far more for memory than reading the same line again. It is why testing yourself beats rereading, and why the effort is the point rather than an obstacle.
The other half is spacing. A fact you meet once today and again in three days will outlast one you read five times this afternoon. That effect is one of the most reliably replicated findings in learning research, and it is the thing almost nobody does on purpose.
Frequently Asked Questions
What are some good science facts?
The ones that reliably land are the ones that overturn something you assumed. A day on Venus is longer than its year. Sharks are older than trees. Bananas are berries and strawberries are not. Your body contains roughly as many bacterial cells as human cells. Each is short enough to repeat and surprising enough to be worth repeating.
What is the most surprising science fact?
For most people it is the scale ones, because intuition has nothing to compare them to. A sugar-cube-sized piece of a neutron star would weigh about as much as a mountain. The observable universe is 93 billion light years across despite being 13.8 billion years old, because space itself expanded. Atoms are mostly empty space, so a nucleus in a stadium-sized atom would be about the size of a pea.
Are all science facts on the internet true?
No, and several very popular ones are not. You use far more than 10% of your brain. The ten-to-one bacteria-to-human-cell ratio was an overestimate. Glass in old windows is thicker at the bottom because of how it was made, not because it flowed. Bad facts tend to be tidy, memorable and slightly flattering, and the suspiciously round number is usually the invented part.
What is a science fact that sounds fake but is true?
Honey recovered from ancient Egyptian tombs is still edible, because honey does not spoil. Wombat droppings are cube-shaped. Superfluid helium climbs the walls of its container. The mantis shrimp strikes fast enough to briefly boil the water around it. All four are real and all four get flagged as made up.
What are good science facts for kids?
The animal ones travel best because they are concrete. Octopuses have three hearts and blue blood. Starfish have no brain. Sea otters hold hands while sleeping so they do not drift apart. Footprints on the Moon will last millions of years because there is no wind to erase them.
How do I remember facts I read?
Retrieval and spacing. Trying to recall a fact, and struggling slightly before you get it, builds memory far better than reading it again. And meeting it once today and again in three days beats reading it five times in one sitting. Both effects are among the best-replicated findings in learning research, and almost nobody applies them deliberately.
Is it true that we only use 10% of our brains?
No. It is one of the most persistent myths in popular science. Brain imaging shows activity across essentially the entire brain over the course of a day, and damage to almost any region produces some deficit. There is no dormant 90% waiting to be unlocked.
How many science facts are in this list?
One hundred, grouped into five sections of twenty: space and astronomy, the human body, animals and biology, physics and chemistry, and Earth and nature. They are numbered continuously so you can point someone at a specific one.
Every NerdSip course clears a four-layer fact-checking pipeline before it reaches the app: grounded in live sources, scored nightly, gated on failure, and reviewable by a person at one tap. Articles on this blog are drafted with AI assistance, then researched, verified, and edited by our team.
Editorial responsibility: ai51 UG (haftungsbeschränkt). Responsible editor named in the imprint.
📚 Keep Learning
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