99 Fun Facts About Science and Nature

Iron oxide, better known as rust, gives which planet its famous colour?

Mars. Its rusty dust is so fine that winds can whip it into storms covering the whole planet; one in 2018 blotted out the Sun and ended the solar-powered Opportunity rover's mission.

What gas do plants absorb from the atmosphere during photosynthesis?

Carbon dioxide. Light energy drives the plant to build sugars from carbon dioxide and water, and the oxygen is given off as a by-product.

Which household antiseptic fizzes on a cut as an enzyme in blood breaks it down?

Hydrogen peroxide, H2O2, is water's formula plus one oxygen atom; the enzyme catalase, found in blood and most living cells, splits it back into water and oxygen gas, and those bubbles are the fizz.

How many bones are in the adult human body?

206 is the usual adult count. A newborn has around 270 bones, and the number falls because many of them fuse together as the skeleton grows.

Which is the only mammal capable of true, powered flight?

Bat. Its wing is a modified hand, a thin membrane stretched between very long finger bones that it can flap; flying squirrels, sugar gliders and colugos can only glide.

What is the largest planet in our solar system?

Jupiter. More than twice as massive as all the other planets combined, it tore comet Shoemaker-Levy 9 apart in 1992 and swallowed the fragments in a string of impacts in July 1994.

What is the powerhouse of the cell?

Mitochondria. They descend from free-living bacteria that took up residence inside an ancestral cell, which is why they still carry their own small ring of DNA, passed down from the mother.

What type of animal is a dolphin?

Mammal. Dolphins descend from hoofed land animals that took to the water about 50 million years ago, which is why they still have to surface and breathe air through a blowhole.

At which of these places does water boil at only about 70°C instead of 100°C?

Mount Everest's summit. The air pressure there is only about a third of that at sea level, and the less the air presses down on water, the lower the temperature at which it boils.

Which scientist developed the theory of general relativity?

Albert Einstein. In 1919 astronomers photographing a solar eclipse found starlight bending around the Sun just as his theory predicted, and the headlines made him an international celebrity.

What is the hardest natural substance on Earth?

Diamond. It is pure carbon, the same element as the soft graphite in a pencil; the difference is that its atoms lock into a rigid three-dimensional lattice while graphite's lie in loose layers.

What does DNA stand for?

Deoxyribonucleic acid. Friedrich Miescher first isolated it in 1869 from the pus on used hospital bandages, and called it nuclein because it came from the nuclei of cells.

Which element has the atomic number 1?

Hydrogen. Its name comes from the French hydrogène, 'water-former', because burning the gas produces water.

The giant sequoia is the most massive tree, but which species grows tallest?

Coast redwood. The record holder, a tree named Hyperion, grows in California's Redwood National Park, which has closed the area around it because off-trail visitors were trampling the forest floor.

What layer of Earth's atmosphere do we live in?

Troposphere. The lowest layer holds most of the atmosphere's mass and about 99% of its water vapour, which is why almost all weather happens inside it.

What is the speed of light in a vacuum, approximately?

Light travels 299,792,458 metres per second, about 300,000 km/s; the figure is exact by definition because the metre is defined as the distance light covers in 1/299,792,458 of a second.

Which organ in the human body produces insulin?

The pancreas. Insulin is made there in clusters of cells called the islets of Langerhans, and it takes its name from insula, the Latin for island.

Which gas makes up nearly four-fifths of the air?

Nitrogen. Its atoms pair up with a triple bond so strong that plants cannot use the gas directly; lightning and soil bacteria must first 'fix' it into compounds that roots can absorb.

Which scientist is known as the father of evolution?

Charles Darwin. He had worked on the theory for some twenty years without publishing, until an 1858 essay from Alfred Russel Wallace outlining the same idea spurred him into print.

Which scale was introduced in 1935 to rate the magnitude of earthquakes?

Richter scale. Charles Richter devised it in 1935, but it measures the very largest quakes poorly, so seismologists now report moment magnitude instead.

Which ocean trench holds the deepest known point on Earth?

The Mariana Trench. Its Challenger Deep lies nearly 11 km down, and people first reached the bottom in January 1960, when Jacques Piccard and Don Walsh descended in the bathyscaphe Trieste.

What type of rock is formed from cooled lava or magma?

Igneous. The speed of cooling sets the texture: magma trapped underground cools slowly and grows large crystals, while lava chilled quickly at the surface turns fine-grained or even glassy.

What phenomenon causes the Northern Lights (Aurora Borealis)?

Charged solar particles hitting gas. The particles follow Earth's magnetic field down toward the polar regions, which is why the glow forms rings around the Arctic and Antarctic.

An extra chromosome 21 causes which genetic condition?

Down syndrome. Most people have 46 chromosomes; the extra one usually arises by chance, when a chromosome pair fails to separate as an egg or sperm cell forms, so most cases are not inherited.

What is the chemical symbol for gold?

Gold's symbol Au comes from the Latin aurum; silver's Ag likewise comes from the Latin argentum.

In March 2025, astronomers announced 128 new moons for which planet?

Saturn. The newcomers are irregular moons only a few kilometres across, probably the fragments of captured moons smashed apart in collisions, and they left every other planet far behind.

What is the process by which a caterpillar transforms into a butterfly called?

Metamorphosis. Inside the chrysalis the caterpillar digests most of its own body, and clusters of cells called imaginal discs, carried since it was in the egg, use the soup to build the butterfly.

What is Newton's First Law of Motion also known as?

Law of inertia. Galileo deduced it from balls rolling down inclined planes, overturning the old Aristotelian view that an object comes to rest unless something keeps pushing it.

Which blood type is known as the universal donor?

O negative. Its red cells carry none of the A, B or Rh markers that another person's immune system might attack, so hospitals reach for it in emergencies when a patient's blood type is unknown.

What particle in an atom has a negative charge?

Electron. J. J. Thomson found it in 1897 while studying cathode rays; it was the first particle smaller than an atom ever discovered, proof that atoms are built from smaller parts.

What is the pH of pure water at room temperature?

7 is neutral, neither acid nor base. Each step on the scale is a tenfold change, so a liquid at pH 4 is a thousand times more acidic than pure water.

What is the largest organ in the human body?

Skin. Besides keeping germs out and body heat steady, it constantly rebuilds itself from below, shedding and replacing its whole outer layer every few weeks.

Which element, more familiar as a gas, makes up almost half of Earth's crust by mass?

Oxygen makes up nearly half of the crust by mass, not as a gas but bound into the minerals of ordinary rock; silicon, the stuff of sand, comes second.

Which faint red dwarf, about 4.2 light-years away, is the nearest star to the Sun?

Proxima Centauri. Although it is the Sun's nearest neighbour, it is too faint to see with the unaided eye, unlike the bright pair of stars, Alpha Centauri A and B, that it accompanies.

What type of chemical bond involves two atoms sharing electron pairs, rather than transferring electrons?

Covalent bond. Gilbert Lewis came up with the shared pair in 1916 and Irving Langmuir gave it the name 'covalent'; Lewis was nominated for a Nobel Prize dozens of times and never won.

Which natural disaster is measured using the Saffir-Simpson scale?

Hurricanes. The scale rates only a storm's sustained wind speed, from Category 1 to 5, so a storm with a low number can still bring deadly storm surge and flooding.

What is the main function of white blood cells?

Fighting infection. Some white blood cells swallow invading germs whole, while others make antibodies that lock onto a germ so that it can be destroyed.

Big Bang nucleosynthesis made helium and a small amount of which other light element?

Lithium. Besides hydrogen and helium, the Big Bang left only traces of it, all forged within the first few minutes; heavier elements such as carbon were made much later, inside stars.

What is the term for an organism that makes its own food using sunlight?

Autotroph. Sunlight is not the only option: some autotrophs, such as bacteria at deep-sea hydrothermal vents, make their food by chemosynthesis, drawing energy from chemicals instead of the Sun.

What is the Heisenberg Uncertainty Principle about?

Limits on knowing position and momentum: the more precisely one is pinned down, the fuzzier the other becomes. It is no flaw of the instruments; anything that behaves like a wave has the same trade-off.

What is the Coriolis effect responsible for?

Deflection of moving air and water. Earth's spin makes big storm systems turn counter-clockwise north of the equator and clockwise south of it, but it is far too weak to steer the water draining from a bathtub.

What organelle is responsible for protein synthesis in cells?

Ribosome. Bacterial ribosomes differ enough from ours that many antibiotics work by jamming them, halting the germ's protein production while leaving human cells unharmed.

Which physicist won a Nobel Prize in 1901, the award's first year, for discovering X-rays?

Wilhelm Röntgen. One of the first X-ray photographs he took, weeks after noticing the mysterious rays in 1895, showed the bones of his wife's hand.

What is the term for the point in an orbit where a planet is closest to the Sun?

Perihelion. Earth reaches it in early January, in the depth of the northern winter, because the seasons come from the tilt of the planet's axis and not from its distance to the Sun.

What phenomenon explains why ice floats on water?

Ice is less dense than the liquid because freezing locks its molecules into an open hexagonal lattice, expanding it by about 9%; most substances do the opposite and get denser when they freeze.

What is CRISPR-Cas9 primarily used for in science?

Gene editing. The tool was borrowed from bacteria, which use it as an immune system: it recognises the DNA of an invading virus and cuts it apart.

Which isotope, with a half-life of about 5,700 years, lets scientists date ancient bones, wood and cloth?

Carbon-14. Living things take it in until they die, after which it decays at a steady rate; in 1988 the method showed that the linen of the Shroud of Turin dates from the Middle Ages.

What is the primary cause of ocean tides?

The Moon's gravitational pull; the Sun pulls too, but its tidal effect is roughly half the Moon's because it is so much further away.

In the electromagnetic spectrum, which type of radiation has the shortest wavelength?

Gamma rays. Cosmic bursts of them were discovered by accident in the late 1960s by American military satellites that were watching for secret Soviet nuclear tests.

What is the Chandrasekhar limit?

The maximum mass of a stable white dwarf, about 1.4 times the Sun's. Chandrasekhar worked it out in 1930, aged 19, on the ship taking him from India to study at Cambridge.

What is the Miller-Urey experiment (1953) famous for demonstrating?

Amino acids form from simple inorganic gases. Stanley Miller sent sparks, standing in for lightning, through a flask of early-Earth gases; vials he saved, retested after his death, held even more amino acids than he reported.

What is the Mpemba effect?

Hot liquids can freeze faster than cold. Tanzanian schoolboy Erasto Mpemba noticed it making ice cream, when he put his mixture in the freezer still hot; a 2016 study questioned whether the effect is real at all.

What do astronomers call a massive star collapsing into a black hole without exploding?

Failed supernova. The star fades out instead of blowing up: the best-known candidate, N6946-BH1, about 25 times the Sun's mass, flared for a few months in 2009 and then seemed to vanish from view.

A 2015 study found the strongest known biological material, stronger than spider silk, in the teeth of which seashore animal?

Limpet. It feeds by scraping algae off bare rock with a tongue of tiny teeth, and their strength comes from fibres of the iron mineral goethite, packed tightly and extremely thin.

What does the Pauli exclusion principle assert?

No two identical fermions share a quantum state, so the electrons in an atom cannot all crowd into the lowest level; they stack into separate shells, which is what gives each element its own chemistry.

What is the rarest naturally occurring element in Earth's crust?

Astatine, with under 30 grams in the whole crust at any moment, exists only as a fleeting decay product of heavier elements; its most stable isotope, astatine-210, lasts about eight hours.

What is the Great Oxygenation Event?

Cyanobacteria flooding the air with oxygen, more than two billion years ago. The gas was a waste product of their photosynthesis, and it is thought to have poisoned much of the anaerobic life that then dominated Earth.

What is a tardigrade's most remarkable ability?

Surviving vacuum, radiation and extreme cold. In 2007 a satellite carried tardigrades into orbit, and some survived direct exposure to open space, reviving afterwards from a dried-out dormant state.

What did the Michelson-Morley experiment (1887) famously fail to detect?

Michelson and Morley found no change in light's speed between perpendicular directions, so no luminiferous aether wind could be detected; the null result cleared the ground for special relativity.

Which tiny nectar-drinking birds can hover like a helicopter, beating their wings dozens of times a second?

Hummingbirds are named for the hum of their beating wings, and their flight muscles let them fly in any direction. The fastest wings, on a tiny woodstar, beat 99 times a second.

Which woody grass, used across Asia as scaffolding, can grow almost a metre in a single day?

Bamboo is a grass, not a tree, and some species have been measured growing 91 cm in 24 hours. The largest stalks reach 46 metres, and giant pandas eat almost nothing else.

In which small fish, which swims upright, does the male carry the eggs in a pouch and give birth?

The seahorse female places up to 1,500 eggs in the male's brood pouch, and he gives birth, usually at night. He can be ready for the next batch by morning.

Which African animal has the same number of neck vertebrae as a human, each one over 28 cm long?

The giraffe has just seven neck vertebrae, as people do: its neck is long because each bone is stretched, not because there are more of them. Its tongue is about 45 cm long.

Which sea animal has three hearts, blue copper-based blood and most of its neurons in its arms?

The octopus pumps blood with one main heart and two gill hearts, and two-thirds of its neurons sit in its arms. The copper-rich protein haemocyanin is what turns the blood blue.

Which comet, seen from Earth roughly every 76 years, is next due to return in 2061?

Halley is the only short-period comet regularly visible to the naked eye. Edmond Halley worked out in 1705 that sightings centuries apart were one object coming back.

Which two elements, a soft reactive metal and a poisonous yellow-green gas, combine to make table salt?

Sodium and chlorine are each dangerous alone: the metal can explode in water and the gas was a First World War weapon. Joined as salt, they are safe to eat.

Which Australian marsupial, which sleeps up to twenty hours a day, has fingerprints remarkably similar to a human's?

The koala has fingerprints so human-like that the two are hard to tell apart even under a powerful microscope. Prints help animals that climb and grasp, so gorillas and chimpanzees have them too.

Which bird of prey becomes the fastest animal on Earth when it dives on prey at over 320 km/h?

The peregrine falcon climbs high, then drops in a steep dive called a stoop; one was clocked at 242 mph. It thrives in cities, nesting on tall buildings and hunting pigeons.

Which planet takes longer to turn once on its axis than it takes to orbit the Sun?

Venus takes 243 Earth days to turn once but only about 225 to circle the Sun. It also spins backwards, so the Sun would rise in the west.

Which continent receives so little precipitation that it ranks as the largest desert on Earth, ahead of the Sahara?

Antarctica is a polar desert: its interior gets less than 50 mm of precipitation a year. Even so, about 70% of the world's fresh water is frozen there.

Which human organ, the heaviest inside the body, can regrow to full size from as little as a quarter?

The liver is the only human internal organ that can naturally regrow lost tissue, which is why a living donor can give part of one away. It is also the body's largest gland.

Which insect performs a waggle dance that tells its nestmates the direction and distance of food?

The honey bee angles its dance against the Sun: a run straight up the comb means fly towards the Sun. Karl von Frisch, who decoded it, shared a Nobel Prize in 1973.

Which egg-laying Australian animal hunts underwater with its eyes shut, sensing the electric signals of its prey?

The platypus closes its eyes, ears and nose when it dives and finds prey by the tiny electric currents of their muscles. British scientists first suspected the animal was a hoax.

Which space telescope, launched in 1990 with a wrongly ground mirror, was repaired in orbit by astronauts in 1993?

Hubble sent back blurred images until astronauts fitted corrective optics that worked like a pair of spectacles. Its mirror had been ground very precisely, but to the wrong shape.

Which Scottish scientist discovered penicillin in 1928 after a mould contaminated one of his bacterial culture plates?

Alexander Fleming called his find mould juice for months before naming it penicillin. He shared the 1945 Nobel Prize with Howard Florey and Ernst Chain.

Which substance, the hardest in the human body, forms the thin outer coating on the crown of every tooth?

Enamel is 96% mineral, the highest share of any tissue in the body. Unlike bone, it has no way to regenerate, so damage beyond a certain point is permanent.

Which alloy of copper and tin was the hardest metal in widespread use before iron tools took over?

Bronze is copper hardened with roughly 12% tin, while brass swaps the tin for zinc. It mattered so much that a whole age of prehistory is named after it.

Which Indonesian volcano's 1883 eruption made the loudest sound in recorded history, heard nearly 5,000 km away?

Krakatoa's blast sent a pressure wave around the globe more than three times. On the island of Rodrigues, 4,800 km away, people took the noise for cannon fire from a ship.

Which supercontinent, proposed by Alfred Wegener, joined nearly all of Earth's land before splitting in the Jurassic?

Pangaea was ringed by a single superocean, Panthalassa. Geologists rejected Wegener's idea of drifting continents until the 1960s, when evidence for plate tectonics piled up.

Which heavyweight of Africa's rivers, despite looking like a giant pig, is the closest living relative of whales?

The hippopotamus and the whales split from a shared ancestor about 55 million years ago. Blood proteins gave the first clue, later backed up by DNA and fossils.

Which Arctic whale carries a spiral tusk up to three metres long that is really an overgrown canine tooth?

The narwhal's tusk grows from the left side of the male's upper jaw. Nobody is sure what it is for: display, a weapon, a feeding tool and a sense organ have all been proposed.

Which Italian scientist was tried by the Inquisition in 1633 for defending the idea that Earth circles the Sun?

Galileo Galilei was found vehemently suspect of heresy and forced to recant. He spent the rest of his life under house arrest.

Which primatologist's fieldwork at Gombe, begun in 1960, showed that wild chimpanzees make and use tools?

Jane Goodall overturned two beliefs of her day: that only humans use tools and that chimpanzees are vegetarians. Her mentor, the fossil hunter Louis Leakey, raised the money to send her to Tanzania.

Which bending of light, as it passes between air and water, makes a half-submerged pencil look broken?

Refraction happens because light changes speed when it enters a new material. The same bending makes a pool look shallower than it is and splits sunlight into a rainbow.

Which Russian chemist's periodic table of 1869 left gaps for elements that had not yet been discovered?

Dmitri Mendeleev predicted the properties of three missing elements, later found and named gallium, scandium and germanium. Element 101, mendelevium, is named after him.

Which metal, with the highest melting point of any, was the standard choice for light-bulb filaments?

Tungsten melts at 3,422 °C, hotter than any other metal can stand. Its symbol, W, comes from its other name, wolfram, after the ore wolframite.

Which spiral galaxy, the nearest major one to the Milky Way, can be seen with the naked eye?

Andromeda lies about 2.5 million light-years away, so the faint smudge seen on a dark night is light that set out long before our species existed.

Which mineral, ranked softest on the Mohs hardness scale, is ground up to make baby powder?

Talc sets the value of 1 on the Mohs scale, the bottom rung of ten. It is also the main ingredient of soapstone.

Which Swedish botanist formalised the two-part Latin naming system that labels humans as Homo sapiens?

Carl Linnaeus bore a surname his father coined from a giant lime tree on the family homestead. He is also the type specimen for the human species, the individual the name is pinned to.

Which Mexican salamander keeps its external gills for life and can regrow lost limbs and parts of its brain?

The axolotl stays in its larval, water-living body even as a breeding adult. Its home lakes were largely drained over the centuries to make way for Mexico City.

Which tree, the last living species of an order over 290 million years old, is called a living fossil?

Ginkgo vanished from the fossil record everywhere except a small area of central China, where it hung on. Some trees even lived through the Hiroshima atomic bomb.

Which parasitic Southeast Asian plant produces the largest single flower on Earth, which stinks of rotting flesh?

Rafflesia has no visible leaves, stems or roots: it lives hidden inside a jungle vine until its bloom, which can be over a metre wide, bursts out.

Which crater buried beneath Mexico's Yucatán Peninsula marks the asteroid strike blamed for wiping out the dinosaurs?

Chicxulub is about 200 km across and was found by geophysicists prospecting for oil in the late 1970s. The asteroid that dug it was only about ten kilometres wide.

Which stirrup-shaped bone in the middle ear is the smallest and lightest in the human body?

The stapes is the last in a chain of three tiny bones that carry sound vibrations to the inner ear. Its name is simply the Latin word for a stirrup.

Which chemist led the X-ray work at King's College London that produced Photo 51, the key image of DNA?

Rosalind Franklin's student Raymond Gosling took the picture, the 51st in his series. Watson, Crick and Wilkins shared a Nobel Prize for the double helix in 1962, four years after her death.

Which Augustinian friar worked out the basic rules of heredity by cross-breeding pea plants in the 1850s and 1860s?

Gregor Mendel saw his results go largely unnoticed in his lifetime. Three botanists independently confirmed them in 1900, sixteen years after his death.

Which effect makes a passing ambulance siren drop in pitch and lets astronomers measure how fast stars are moving?

Doppler shifts arise because waves bunch up ahead of an approaching source and stretch out behind it. The effect is named after Christian Doppler, who described it in 1842.

Which part of the human brain fine-tunes balance and movement and holds more neurons than all the rest combined?

The cerebellum packs in those neurons while taking up only 10% of the brain's volume. Its name is Latin for little brain.

Which blood vessel, the largest artery in the human body, carries blood out of the heart's left ventricle?

The aorta leaves the heart heading upwards, then bends and runs down to the abdomen, where it splits into two smaller arteries bound for the legs.