150 Fun Facts About Science

What is the chemical symbol for gold?

Au comes from the Latin 'aurum'; gold is so unreactive that it is one of the few metals found in nature as nuggets of pure metal.

Which planet in our Solar System is less dense than water?

Saturn has a mean density of about 0.69 g/cm³, the only planet below water's 1 g/cm³, so it would float in a large enough ocean; Jupiter is roughly twice as dense.

Which organelle is nicknamed the 'powerhouse of the cell'?

Mitochondria carry their own small genome because they descend from free-living bacteria that fused with an ancient cell; Philip Siekevitz popularised the 'powerhouse' nickname in 1957.

About how fast does light travel through a vacuum?

About 300,000 km/s, so a laser pulse bounced off mirrors that Apollo astronauts left on the Moon comes back in about 2.5 seconds.

Which physicist imagined a cat that is both alive and dead inside a sealed box?

Erwin Schrödinger devised the cat in 1935, not as a real experiment but to show how strange quantum rules look when applied to something as big as a cat.

What is the hardest natural substance on Earth?

Diamond, which is hard but not tough: hardness is resistance to scratching, and a hammer blow along a cleavage plane will split it. It is pure carbon, the same stuff as pencil graphite, arranged differently.

What gas makes up approximately 78% of Earth's atmosphere?

Nitrogen makes up about 78% of the air, yet plants and animals can't use the gas until bacteria, lightning or industry 'fix' it.

What is the largest organ in the human body?

Skin is the largest organ, yet the surface you touch is dead: its outer layer is flattened, keratin-filled cells that are constantly shed.

Which element has the atomic number 1?

Hydrogen's name means 'water-former' because the gas makes water when it burns, the property Henry Cavendish discovered.

What phenomenon causes the Northern Lights?

Solar particles exciting gases in the upper atmosphere make them glow, and auroras hug the polar regions because Earth's magnetic field steers those particles there.

What is the chemical formula for table salt?

NaCl, sodium chloride, joins sodium, a metal that reacts vigorously with water, to chlorine, a First World War poison gas, yet together they season dinner.

Which blood type is considered the universal donor?

Only about 7% of Americans are O negative, so blood banks prize it for emergencies when there is no time to type a patient.

What is the most abundant protein in the human body?

Collagen can't be made properly without vitamin C, which is why scurvy, a vitamin C shortage, brings gum disease and wounds that heal poorly.

Who discovered penicillin?

Alexander Fleming found penicillin by accident in 1928, when mould that had landed on a staphylococcus culture plate cleared a bacteria-free ring around itself.

What is the unit of electrical resistance?

The ohm honours Georg Ohm, whose law was received so coolly that he resigned his teaching post; in 1841 Britain's Royal Society gave him its Copley Medal.

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

Igneous rock can even float: pumice forms when frothy, gas-filled lava cools so fast that it traps countless bubbles, leaving it lighter than water.

What is the closest star to Earth after the Sun?

Proxima Centauri, just over four light-years away, is the nearest star after the Sun, yet it is so small and dim that you can't see it with the naked eye.

Which vitamin is produced when human skin is exposed to sunlight?

Vitamin D forms when sunlight hits the skin and helps the body absorb calcium, so a shortage can leave children with the soft, bowed bones of rickets.

What is the process by which plants convert sunlight into energy?

Photosynthesis happens as much at sea as on land: tiny ocean phytoplankton carry out roughly half of all the photosynthesis on Earth.

What is the Heisenberg Uncertainty Principle about?

Position and momentum cannot both be known exactly because particles behave like waves, not because instruments are clumsy; Werner Heisenberg introduced the idea in 1927.

What is the pH of pure water at room temperature?

Pure water has a pH of 7 at 25 °C, yet boiling-hot pure water reads below 7 while staying neutral, because heat splits more molecules into equal numbers of hydrogen and hydroxide ions.

On which planet do sunsets glow blue?

Mars gets its rusty colour from iron minerals in its dirt, yet fine dust in its air lets blue light through near the Sun, so Martian sunsets glow blue.

What is the function of white blood cells?

Fight infections: pus is largely the remains of white blood cells that died at the site, along with dead tissue and germs.

What force keeps planets in orbit around the Sun?

Gravity, and an orbit is really a fall: a planet is always dropping toward the Sun, but it moves sideways fast enough that it keeps missing.

What is the most common element in the Earth's crust?

Nearly half the crust's mass is oxygen locked up in silicate and oxide minerals; silicon comes second at roughly 28%.

Whose 1543 book set out the Sun-centred model that Galileo defended?

Nicolaus Copernicus died the year his book came out, and in 1616 the Catholic Church suspended it until it was corrected.

Which part of the eye controls how much light gets in?

Iris patterns are as distinctive as fingerprints, which is why iris scanners can be used to confirm who a person is.

Which supercontinent joined all of today's continents together about 250 million years ago?

Pangaea's breakup is why fossils of the same small aquatic reptile, Mesosaurus, turn up in both Brazil and South Africa, now an ocean apart.

What do honeybees collect from flowers and turn into honey?

Nectar is passed from bee to bee and mixed with their enzymes, then stored in the wax cells of the honeycomb, where it becomes honey.

Which athletes often have a resting heart rate in the 40s?

Marathon runners and other well-trained endurance athletes can rest at 40 to 60 beats a minute, below the usual adult range, because a trained heart pumps more blood with each beat.

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

The law of inertia: Galileo had already reasoned that moving objects stop because friction acts on them, not because rest is their natural state.

Which organ in the human body produces insulin?

The pancreas makes insulin, and early attempts to treat diabetes by feeding patients pancreas failed, probably because the gland's own digestive enzymes broke the hormone down.

Which theory says the universe has been expanding ever since an extremely hot, dense early state?

The Big Bang Theory got its name from rival astronomer Fred Hoyle, who backed the Steady State theory and coined the phrase in the late 1940s.

What is the chemical symbol for iron?

Fe is from the Latin ferrum, and molten iron swirling in Earth's outer core is what generates the planet's magnetic field.

About how long does sunlight take to reach Earth?

About 8 minutes, so the Sun you see in the sky is really the Sun as it looked about 8 minutes earlier.

What type of bond involves the sharing of electron pairs between atoms?

A covalent bond holds a water molecule's atoms together, while much weaker hydrogen bonds between molecules are what give water its unusually high boiling point.

What is the largest planet in our solar system?

Jupiter: the four moons Galileo spotted circling it in 1610 were the first objects seen orbiting another planet, a serious blow to the belief that everything orbits Earth.

What is the double helix structure associated with?

DNA's double helix model drew on Photo 51, an X-ray image from Rosalind Franklin's lab that Watson was shown without her knowledge; she died in 1958, four years before the Nobel.

What is the Richter scale used to measure?

Earthquake strength: Charles Richter devised the scale in the 1930s for southern California quakes, and seismologists now rate big quakes on the moment magnitude scale instead.

NASA's planet-hunting telescope honours which astronomer, who found that planets orbit in ellipses?

Johannes Kepler personally defended his mother when she was accused of witchcraft, and she was eventually released.

What is absolute zero in Celsius?

Absolute zero, −273.15 °C or 0 K, is where classical physics says motion stops, yet quantum physics says particles still keep a tiny zero-point jiggle there.

Roughly what share of an adult human body's weight is water?

About 60%, but it varies: fat holds much less water than lean tissue, so people with more body fat carry a smaller share of water.

What did Marie Curie discover?

She discovered radium and polonium in 1898 with Pierre Curie, naming polonium after her native Poland; her 1903 Physics and 1911 Chemistry prizes made her the first person to win Nobels in two different sciences.

What is the Doppler effect?

A wave's frequency shifting with motion is why a passing ambulance siren drops in pitch, and how police radar guns clock a car's speed.

Which condition does an extra chromosome 21 cause?

Down syndrome grows likelier as mothers get older, yet most babies with it are born to younger mothers, simply because younger women have more babies.

Which group contains the most reactive metals in the periodic table?

Alkali metals have a single outer electron they give away easily, which is why caesium, one of them, explodes even in cold water.

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

The troposphere holds almost all our weather, and its air gets colder as you climb, which is why tall mountain peaks can stay snowy even in summer.

Roughly how long is the half-life of carbon-14, the basis of radiocarbon dating?

About 5,700 years, so after roughly 50,000 years too little carbon-14 is left to measure, which is as far back as the method can reach.

Which famous physicist spent his last three decades running Britain's Royal Mint, chasing counterfeiters?

Isaac Newton ran the Royal Mint from 1696 until his death in 1727 and made bringing clippers and counterfeiters to justice one of his main jobs.

Which animals make up the order Chiroptera, Greek for hand-wing?

Bats aren't blind, despite the saying: they can see, though many rely more on echolocation.

Which of the four fundamental interactions holds atomic nuclei together?

The strong interaction, about 100 times stronger than electromagnetism at nuclear distances, is what overcomes the mutual repulsion of the protons and binds the nucleus together.

Which metal has the highest melting point of any pure metal?

Tungsten has the highest melting point of any metal, which is why it was chosen for the glowing filaments of old incandescent light bulbs.

Which planet spins with its axis tilted about 98 degrees, almost on its side?

Uranus rolls around the Sun on its side, so each pole gets about 42 years of continuous sunlight and then 42 years of darkness; a collision with an Earth-sized object may have tipped it.

What are the two main products of photosynthesis?

Sugar and oxygen: the oxygen comes from water molecules that the plant splits apart using light energy.

What is the SI unit for electric current?

The ampere honours André-Marie Ampère, who within weeks of hearing of Ørsted's compass-needle discovery in 1820 showed that two current-carrying wires attract or repel.

The number of particles in one mole, about 6 × 10^23, is named after which scientist?

Amedeo Avogadro's 1811 idea that equal volumes of gas at the same temperature and pressure hold equal numbers of molecules was neglected until after his death.

Which element has the highest electronegativity on the Pauling scale?

Fluorine tops the Pauling scale at 3.98; it pulls electrons so strongly that it reacts with almost every other element, including noble gases such as xenon.

Which meteorologist and polar explorer proposed in 1912 that the continents slowly drift?

Alfred Wegener's drifting continents were widely ridiculed, and he died on a Greenland ice-cap expedition in 1930, decades before plate tectonics proved him right.

The ozone layer protects life on Earth by absorbing most of the Sun's what?

Ultraviolet light: the ozone layer soaks up most of the Sun's medium-frequency UV, which would otherwise damage living things near the surface.

Which tiny cell fragments in the blood help stop bleeding by clumping into a clot?

Platelets: low-dose aspirin makes them less able to clump, which is why doctors use it to lower the risk of heart attacks and strokes.

Mercury is closest to the Sun, but which planet has the hottest surface in the Solar System?

Venus's thick atmosphere traps heat in a runaway greenhouse effect, making its surface hot enough to melt lead.

Besides mercury, which element is a liquid at standard room conditions?

Bromine is a fuming reddish-brown liquid, discovered independently by Carl Jacob Löwig and Antoine Balard in the 1820s; gallium and caesium melt only above 28 °C, so they stay solid in a normal room.

Which mineral sits at 1, the softest point, on the Mohs hardness scale?

Talc is the softest mineral, so easily crushed that it has long been sold as talcum powder.

Which is the largest moon in the solar system?

Ganymede is wider than the planet Mercury yet less than half as massive, because it is a low-density mix of rock and water ice.

Which element is named after the US city where it was first made?

Berkelium was first made in December 1949 by a Berkeley team including Glenn Seaborg, who bombarded americium with alpha particles in a cyclotron.

The chemical symbol Sb belongs to which element?

Antimony's symbol Sb comes from the Latin stibium, the name of its sulfide ore used as the eye cosmetic kohl in antiquity; the metalloid is alloyed with lead to harden bullets and type metal.

Which scientist coined the biological term 'cell' in the 1665 book Micrographia?

Robert Hooke, looking at cork under a microscope, thought the tiny compartments resembled honeycomb or monks' cells, and published the drawings in Micrographia in 1665.

Which 1859 Darwin book explained natural selection?

The Origin of Species came out as an abstract of a much bigger book, because another naturalist, Wallace, had reached almost the same conclusions.

Edward Jenner's 1796 smallpox vaccine used material from which disease?

Jenner took cowpox matter from the hand of milkmaid Sarah Nelmes and inoculated eight-year-old James Phipps, who then resisted smallpox.

What is the smallest bone in the human body?

The stapes passes sound vibrations into the inner ear, so when bone growth locks it in place, as in otosclerosis, hearing slowly fades.

Who discovered the neutron in 1932?

James Chadwick, who had trained under Ernest Rutherford, proved in 1932 that neutrons exist, a discovery that paved the way to splitting uranium.

Which German scientist discovered X-rays in 1895?

Wilhelm Röntgen's famous early X-ray photograph showed every bone in his wife's hand, along with her wedding ring.

What is the SI unit of frequency?

The hertz honours Heinrich Hertz, who proved that the electromagnetic waves James Clerk Maxwell predicted really exist, and then died in 1894 at just 36.

What is the SI unit of pressure?

The pascal honours Blaise Pascal, who showed in 1648, with a barometer carried up a mountain, that air pressure falls as you go higher.

Which SI unit of energy is named after an English physicist?

James Prescott Joule's careful measurements showed that heat and mechanical work are equivalent, which helped establish the law of conservation of energy.

Who discovered Pluto in 1930?

Clyde Tombaugh, a 24-year-old assistant at Lowell Observatory, spotted Pluto on photographic plates in February 1930; the IAU reclassified it as a dwarf planet in 2006.

Which comet did Mark Twain predict he would go out with?

Halley's Comet: Twain said he came in with it in 1835, and as he predicted, he died in April 1910, a day after it swung closest to the Sun.

Dry ice is the solid form of which gas?

Dry ice is frozen carbon dioxide; it skips the liquid phase entirely, subliming straight to gas at about −78.5 °C at normal pressure.

'Laughing gas' is the common name for which compound?

Nitrous oxide was tested by Humphry Davy, who inhaled large amounts of it himself, and it was soon called laughing gas.

Which element, made artificially in 1937 from irradiated molybdenum, is now widely used in medical scans?

Technetium's name comes from the Greek for 'artificial', because it was made in a lab rather than found, and technetium-99m is widely used in medical imaging.

Albert Einstein's 1921 Nobel Prize in Physics was awarded mainly for explaining which phenomenon?

The photoelectric effect was named in Albert Einstein's citation while relativity went unmentioned, and he received the 1921 prize a year late, in 1922.

Rutherford's gold-foil experiments showed an atom's positive charge is concentrated where?

In a tiny nucleus: Hans Geiger and Ernest Marsden, working under Rutherford, fired alpha particles at gold foil, and the rare ones that bounced sharply back revealed a dense core.

Which chemist's 1869 periodic table left gaps for undiscovered elements?

Dmitri Mendeleev's gaps paid off: he predicted an element he called ekasilicon, and germanium, found in 1886, matched his forecast.

Which element was first spotted in the Sun's light in 1868, decades before anyone found it on Earth?

Helium takes its name from helios, Greek for the Sun, after a yellow line in the 1868 eclipse spectrum; William Ramsay found it on Earth in 1895.

About how fast does sound travel through air at room temperature?

About 340 m/s, roughly a kilometre every three seconds, which is why counting the seconds between lightning and thunder tells you how far away a storm is.

The kelvin temperature unit honours a physicist with what birth name?

William Thomson was ennobled as Baron Kelvin in 1892, taking the title from the River Kelvin that runs past the University of Glasgow, where he was professor for more than fifty years.

Which temperature scale puts water's freezing point at 32 degrees?

Fahrenheit's zero came from a freezing mix of ice, water and salt, so plain water freezes higher up the scale, at 32 degrees.

Gregor Mendel worked out the laws of heredity using which plant?

Peas: Gregor Mendel worked out the rules of heredity from pea plants before anyone knew genes existed, and won recognition only after his death.

Jonas Salk developed one of the first successful vaccines against which disease?

Jonas Salk was hailed as a miracle worker when his polio vaccine was declared safe and effective in April 1955, after years of epidemics that paralysed children.

What is the hardest substance in the human body?

Tooth enamel is the body's hardest substance, yet it contains no living cells, so once it wears or chips away the body cannot grow it back.

Why do adults have fewer bones than newborns?

Bones fuse together as a child grows, and a newborn's skull is still separate plates joined by flexible seams, which let the head squeeze through the birth canal.

Which colour of visible light has the longest wavelength?

Red has the longest waves of visible light, and because long waves scatter least, red and orange are what survive sunlight's long path through the atmosphere at sunset.

Which pigment gives most plants their green colour?

Chlorophyll absorbs mostly blue and red light, so the green in between is reflected back to our eyes.

What is the largest animal known to have ever existed?

The blue whale, the largest of all known animals, feeds almost entirely on krill, tiny shrimp-like animals it strains from the water through its baleen.

Which Swedish scientist formalised the two-part Latin naming system for species?

Carl Linnaeus set out two-part Latin names in his Systema Naturae, and he is the reason humans are called Homo sapiens.

Which state of matter makes up lightning, neon signs and the Sun?

Plasma forms when atoms lose electrons to heat or electricity, and because stars are almost pure plasma, it makes up most of the visible matter in the universe.

What is the estimated age of the Earth?

About 4.5 billion years, a figure Clair Patterson fixed in 1956 from lead in a meteorite; his later fight against lead pollution helped get lead banned from petrol.

The Challenger Deep, the ocean's deepest point, lies in a trench named for which islands?

The Mariana Trench's Challenger Deep, about 10,935 metres down, is named after HMS Challenger, whose crew first sounded the trench in 1875.

Tardigrades are better known by which nickname?

Water bears can dry out into a lifeless husk for years and revive when water returns, and they have even survived exposure to outer space.

A light-year is a unit of what?

Distance: despite the 'year' in its name, a light-year is how far light travels in one year, about 9.46 trillion kilometres.

Which sea animal pumps blue, copper-based blood around its body using three separate hearts?

An octopus has blue blood because it carries a copper-rich protein called haemocyanin. Two of its three hearts do nothing but push blood through the gills.

Which human organ can grow back to full size from as little as a quarter of its original tissue?

The liver is the only human internal organ that can regrow lost tissue. That is why a living donor can give away more than half of theirs and still end up with normal function.

Which Australian marsupial's fingerprints are hard to tell from a human's, even under a microscope?

The koala evolved fingerprints of its own, as have other animals that climb and grasp for a living, such as gorillas and chimpanzees.

Laika, the first animal to orbit the Earth aboard Sputnik 2 in 1957, was what kind of animal?

Laika was a stray dog found wandering the streets of Moscow. Soviet scientists chose strays because they assumed such animals had already learned to endure extreme cold and hunger.

Which small birds can hover in mid-air and are the only ones able to fly backwards?

Hummingbirds are named for the hum of their wings, which beat up to 99 times a second in the smallest kinds.

Archimedes reputedly boasted he could move the Earth with a place to stand and which simple machine?

A lever turns a small push on its long arm into a much bigger force on its short one. Archimedes proved the law that says just how much.

Alfred Nobel, who left his fortune to fund the Nobel Prizes, got rich by inventing which explosive?

Dynamite made unstable nitroglycerin safe enough to handle, and it was soon used widely in mining and in building transport networks. Nobel patented it in 1867.

Which giant member of the grass family can shoot up almost a metre in a single day?

Bamboo includes some of the fastest-growing plants on Earth, with certain kinds adding 91 centimetres in 24 hours. That works out at about a millimetre every 90 seconds.

Which golden gem is really fossilised tree resin, sometimes with ancient insects trapped inside?

Amber begins as soft, sticky resin, which is how insects, spiders and even their webs end up sealed inside. People have worked it as a gemstone since classical antiquity.

Which flexible tissue, also found in human ears and noses, makes up the entire skeleton of a shark?

Cartilage is about half as dense as bone, which helps a shark stay buoyant without the gas-filled swim bladder that bony fish have.

Which ocean is rimmed by the Ring of Fire, a belt that holds most of the world's active volcanoes?

The Pacific is edged by plate boundaries where one slab of crust dives beneath another. The chain of volcanoes this feeds is about 40,000 kilometres long.

Which French rabies-vaccine pioneer gave his name to the heat treatment that makes milk safe?

Louis Pasteur first patented the gentle heating to fight the 'diseases' of wine, and it was soon applied to beer and milk. His vaccines are credited with saving millions of lives.

Which galaxy contains the Solar System and shows up from Earth as a hazy band across the night sky?

The Milky Way and Andromeda are the two largest galaxies in the Local Group. A 2025 simulation study gave them only about an even chance of merging within the next 10 billion years.

Which precious metal is the best conductor of electricity of all, beating even copper?

Silver has the highest electrical conductivity of any metal, and the highest reflectivity too. It is rarely used in wiring simply because it costs so much.

Dolly, the first mammal ever cloned from an adult body cell, was which kind of farm animal?

Dolly the sheep was named after Dolly Parton, because the cell she was cloned from came from a mammary gland. She lived her whole life at the Roslin Institute in Scotland.

Which heavy metal has the chemical symbol Pb, taken from its Latin name plumbum?

Lead was the favourite metal for water pipes for so many centuries that plumbum, its Latin name, gave English the word plumbing.

Which element, plentiful in bananas, takes its chemical symbol K from the Neo-Latin name kalium?

Potassium gets its English name from potash, the plant ashes it was first isolated from. Humphry Davy freed the pure metal in 1807 by passing electricity through molten potash.

What gives Earth its seasons, so that the two hemispheres have summer at opposite times of year?

A tilted axis leans each hemisphere toward the Sun for part of the year, giving it a higher Sun and longer days. Earth is actually closest to the Sun in January, during the northern winter.

Which physicist, diagnosed with motor neurone disease at 21, wrote A Brief History of Time?

Stephen Hawking saw the book spend a record 237 weeks on the Sunday Times bestseller list. His synthesised voice later featured in a Pink Floyd song and an episode of The Simpsons.

Mushrooms and yeasts belong to which kingdom of life, a closer relative of animals than of plants?

Fungi build their cell walls with chitin, the tough material of insect and crab shells, which is one of the traits that sets them apart from plants.

Which British primatologist found at Gombe in Tanzania that wild chimpanzees make and use tools?

Jane Goodall watched a chimpanzee push grass stalks into a termite mound to 'fish' for the insects. Until then, people had assumed that only humans could make and use tools.

Which flightless bird has the biggest eyes of any land vertebrate, each about 5 cm across?

The ostrich uses those eyes to spot predators such as lions from far away. It is also the largest living bird and the fastest animal on two legs, sprinting at about 70 km/h.

Which egg-laying Australian mammal is armed, in males, with a venomous spur on each hind foot?

The platypus looked so unlikely, with its duck bill and beaver tail, that British scientists first suspected a hoax. The male's venom is powerful enough to cause humans severe pain.

Bronze, the alloy that named a whole prehistoric age, is mostly copper mixed with which other metal?

Tin makes up about 12 percent of a typical bronze and leaves it harder than copper alone. Swap the tin for zinc and the result is brass instead.

In Albert Einstein's famous equation E = mc², what does the letter c stand for?

The speed of light is such a large number that, once squared, it makes a small amount of mass equal to an enormous amount of energy.

Which effect bends light passing from air into water, making a half-dipped pencil look bent?

Refraction happens because light slows down when it enters water or glass. The same effect makes a swimming pool look shallower than it really is.

Which force resists one surface sliding over another and warms your hands when you rub them?

Friction turns motion into heat, which is how rubbing two pieces of wood together can start a fire and how a struck match ignites.

Which waves pass almost unnoticed at sea as a slight swell while racing along at around 800 km/h?

Tsunamis take their name from the Japanese for 'harbour wave'. Fishermen who met nothing unusual out at sea would sail home to find their village devastated.

Which star barely moves as the night sky turns, because it lies almost exactly in line with Earth's axis?

Polaris is often assumed to be the brightest star in the night sky, but it ranks only 47th. Its fame comes from holding still while every other star circles around it.

Which corrosive acid does the human stomach make to help digest food and kill swallowed microbes?

Hydrochloric acid keeps the stomach's contents at a pH of about 1 to 2. The stomach wall protects itself from the acid with a thick barrier of mucus.

Which layer of Earth, about 2,900 kilometres thick, makes up 84 percent of its volume?

The mantle is almost entirely solid rock, yet over geological time it flows like a very thick liquid, sometimes compared to caramel.

Which objects, formed when giant stars collapse, are so compact that not even light can escape them?

Black holes owe their catchy name to physicist John Wheeler, who took up the phrase in 1967 after someone in his lecture audience reportedly suggested it. It had already appeared in print a few years earlier.

Charles Darwin spent almost five years circling the globe aboard which Royal Navy ship?

HMS Beagle was meant to be away for only two years. Darwin had joined at 22, hoping to see the tropics before settling down as a country parson.

Who became the first human in space, circling Earth once aboard Vostok 1 in a 108-minute flight?

Yuri Gagarin made the flight on 12 April 1961, and it turned out to be his only trip to space. His call sign was Kedr, the Russian for Siberian pine or cedar.

Which space telescope reached orbit in 1990 with a misshapen mirror that astronauts later corrected?

Hubble is named after Edwin Hubble, the astronomer who confirmed that the universe is expanding. A servicing mission in 1993 finally sharpened its blurred view.

Scurvy, the disease that once killed sailors on long voyages, is caused by a lack of which nutrient?

Vitamin C is made by almost all animals and plants, but humans have to get it from food. British sailors were issued so much lime juice against scurvy that they were nicknamed 'limeys'.

Which dome-shaped muscle below the lungs drives breathing and causes hiccups when it spasms?

The diaphragm flattens as it contracts, enlarging the chest so that the lungs expand and draw in air. A hiccup is the same muscle jerking of its own accord.

Spiders, scorpions and ticks all belong to which class of eight-legged animals?

Arachnids take their name from arachne, the Greek for spider and also the name of the boastful weaver of myth who was turned into one. Unlike insects, they have no antennae or wings.

Which tough protein makes up human hair and fingernails as well as the horns of a rhinoceros?

Keratin also forms feathers, claws, hooves and the scales of reptiles. A rhino's horn is the same stuff as a fingernail, and there is no good evidence that it has any health benefits.

Which geological period, the final chapter of the dinosaur age, ended in a mass extinction?

The Cretaceous takes its name from creta, the Latin for chalk, because so much chalk was laid down in the seas of its later half.

Which type of electromagnetic wave has the shortest wavelength and the highest energy of all?

Gamma rays can cause cancer, yet concentrated beams of them are used to kill cancer cells, and gamma radiation also sterilises medical equipment.

Which towering cloud, often flat-topped like an anvil, brings thunderstorms, hail and tornadoes?

Cumulonimbus joins the Latin words for 'heap' and 'rain cloud'. When one of these clouds brews up a thunderstorm, it is often called a thunderhead.

Which NASA probe, launched in 1977, became the first spacecraft to enter interstellar space?

Voyager 1 crossed into interstellar space in 2012. It carries a golden phonograph record with greetings in 55 languages and music by Chuck Berry, among others.

Which buried crater, some 200 km wide, marks the asteroid strike blamed for killing the dinosaurs?

Chicxulub lies beneath Mexico's Yucatán Peninsula. It was found in the late 1970s by geophysicists who were actually prospecting for oil.

Which 'living fossil' fish, thought long extinct, turned up in a catch off South Africa in 1938?

The coelacanth was believed to have died out around 66 million years ago. The expert who identified it cabled back: 'Most Important Preserve Skeleton and Gills'.

Pluto is the largest known object in which region of icy bodies beyond the orbit of Neptune?

The Kuiper belt is named after the Dutch astronomer Gerard Kuiper, who speculated about such a disc in 1951. Apart from Pluto and its moon Charon, nothing was found there until 1992.

Which English bookbinder's apprentice went on to discover electromagnetic induction in 1831?

Michael Faraday had little formal education, yet his work made electricity practical to use. Albert Einstein kept a portrait of him on his study wall.

Uranium-235 and uranium-238 are atoms of one element with different neutron counts, known as what?

Isotopes get their name from the Greek for 'at the same place', because they share one square of the periodic table. A Scottish doctor, Margaret Todd, suggested the word in 1913.

Which process turns a solid straight into a gas without melting first, as mothballs slowly do?

Sublimation is also how freeze-drying works: food is frozen, then the pressure is lowered so its ice leaves as vapour. The reverse change, gas straight to solid, is called deposition.

Which unreactive gas, the third most plentiful in Earth's air, fills incandescent light bulbs?

Argon takes its name from the Greek for 'lazy' or 'inactive', because it undergoes almost no chemical reactions. Inside a bulb, that stops the hot filament from burning away.