138 Fun Facts About Interesting

Teaching at which university, the oldest in the English-speaking world, is recorded as early as 1096?

Oxford had teaching by 1096 and grew fast after 1167, when Henry II banned English students from attending the University of Paris.

Cleopatra lived closest in time to which of these events?

Apollo 11 in 1969 came about 2,000 years after Cleopatra died in 30 BC, yet the pyramid-builders of Giza had lived some 2,500 years before she was born.

Which of these appeared on Earth first?

Sharks go back more than 400 million years, before the first trees appeared, and have since survived five mass extinctions, including the one that ended the dinosaurs' reign.

Which planet has the hottest surface in the Solar System?

Venus is hotter than Mercury despite orbiting almost twice as far from the Sun, because its dense carbon dioxide atmosphere traps heat in a runaway greenhouse effect.

Claude Shannon's famous estimate of 10 to the power of 120 is a lower bound on what?

Possible games of chess number at least 10 to the power of 120 by Claude Shannon's 1950 estimate, which he made to show that no computer could ever play by checking every line.

Laser ranging to Apollo reflectors shows the Moon drifting away from Earth by about how much per year?

3.8 centimetres a year is the rate at which tides push the Moon outward, and the same tidal drag is slowing Earth's spin, so our days are very gradually getting longer.

Which animal's skin secretes 'blood sweat', a red fluid that works as sunscreen and antibiotic?

Hippopotamus 'blood sweat' contains no blood: it oozes out colourless and turns red within minutes thanks to two pigments, then slowly darkens to brown.

What saved the Eiffel Tower from demolition when its 20-year permit expired in 1909?

Its use as a radio antenna made the tower too valuable to scrap, a reprieve for a structure that Paris artists had denounced in an 1887 protest letter as useless and monstrous.

Lightning heats nearby air to about what temperature, several times hotter than the Sun's surface?

30,000 C is about five times as hot as the Sun's surface, and air heated that fast expands explosively, sending out the shock wave we hear as thunder.

For thousands of years up to about 5,000 years ago, which desert was covered in grasses, trees and lakes?

The Sahara turned green when a slow wobble in Earth's axis strengthened the African monsoon, and rock paintings from those wetter times show people who appear to be swimming.

Measured from its base on the sea floor rather than sea level, which mountain is taller than Everest?

Mauna Kea is a volcano that grew up from the Pacific floor, so more than half of its 10,000-plus metres is hidden underwater and Everest keeps the title of highest summit above sea level.

Vanilla flavouring comes from the cured seed pods of what kind of plant?

An orchid from Mexico, vanilla could not be farmed elsewhere until 1841, when Edmond Albius, an enslaved 12-year-old on Réunion, worked out the quick hand-pollination method still used today.

Before the Spanish conquest, what did Mesoamerican peoples commonly use cocoa beans as?

Currency in cacao beans bought everyday goods, with a turkey hen costing about 100 beans in one 16th-century price list, and rulers even collected the beans as tribute.

Which giant volcano on Mars is the tallest known in the Solar System?

Olympus Mons could grow so tall because the crust of Mars does not move: it sat still over one hot spot, so lava kept piling up in the same place, helped by the planet's weak gravity.

With the Sun holding over 99% of the Solar System's mass, which planet accounts for most of the rest?

Jupiter is more than twice as massive as all the other planets put together, yet it still amounts to less than a thousandth of the Sun's mass.

Astronauts grow taller in orbit because weightlessness lets which part of the body stretch out?

The spine relaxes and its vertebrae spread apart once gravity stops compressing them, adding a few centimetres of height that disappear within months of returning to Earth.

Which part of the human body has no blood vessels and gets its oxygen from the air via tears?

The cornea has no blood vessels because they would cloud the eye's clear window, so oxygen from the air dissolves in the tear film and soaks in instead.

Which Ice Age animal was still alive when the Great Pyramid was built?

Woolly mammoth herds isolated on Wrangel Island, off Siberia, outlasted most of their mainland kin by thousands of years, dying out only about 4,000 years ago, centuries after the Great Pyramid went up.

France last used the guillotine in the same year that which blockbuster film opened?

Star Wars opened in May 1977, and that September Hamida Djandoubi was guillotined in a Marseille prison, the last execution before France abolished the death penalty in 1981.

Which American civil rights leader was born in 1929, the same year as Anne Frank?

Martin Luther King Jr. was born in Atlanta five months before Anne Frank; they seem to belong to different eras because she died at 15, a decade before he came to prominence.

Alexander Bain patented an early version of which device in 1843, over 30 years before the telephone?

The fax grew out of Bain's work on electric clocks: his design used a stylus on a swinging pendulum to scan a message line by line, with a second pendulum kept in step to copy it at the far end.

Tsutomu Yamaguchi is the only person officially recognised by Japan as having survived what?

Both atomic bombings caught him three days apart: burned in Hiroshima on a business trip, he went home to Nagasaki and was telling his boss about the blast when the second bomb exploded.

Which country's Althing, founded in 930, is called the world's oldest legislature?

Iceland's Althing began as a yearly gathering of chieftains, and around the year 1000 it settled whether the island would turn Christian by handing the decision to its pagan lawspeaker.

Which language is written with just 13 letters, including a glottal-stop mark called the okina?

Hawaiian was first written down in the 1820s by American missionaries, who settled on five vowels and a handful of consonants; letters such as B, R and T now appear only in borrowed words.

Which country has around 840 living languages, more than any other on Earth?

Papua New Guinea's languages average only about ten thousand speakers each, so people from different villages talk to one another in Tok Pisin, an English-based creole.

Which microscopic animals, nicknamed water bears, have survived the vacuum of space?

Tardigrades survive by drying out into a dormant state called a tun; in 2007 dried specimens were flown on a satellite, exposed to open space and revived once back on Earth.

Which Mexican salamander can regrow lost limbs, gills and even parts of its brain?

The axolotl never grows up, keeping its feathery gills and larval form for life; it is common in labs and pet shops yet critically endangered in the wild.

What lets a cockroach keep breathing for weeks after losing its head?

Air holes along its body, called spiracles, pipe oxygen straight to the tissues without any help from the brain, so a headless cockroach can carry on for weeks.

The dark colour of a giraffe's 45 cm tongue is thought to protect it from what?

Sunburn is the likely threat, because the tongue spends much of the day out in the open, reaching around the thorns of acacia trees to strip their leaves.

What colour is a polar bear's skin beneath its fur?

Black skin soaks up the sun's warmth, and the fur above it is not really white: each guard hair is a clear, hollow tube that scatters the light.

What did William Morgan call volleyball when he invented it in 1895?

Mintonette nodded to badminton, but at a demonstration in 1896 a professor remarked on how the players volleyed the ball back and forth, and the game was renamed volley ball.

What did Douglas Engelbart show the public for the first time at 1968's 'Mother of All Demos'?

The computer mouse he showed was a wooden block on wheels, and its patent never used the word: it was filed as an 'X-Y position indicator for a display system'.

What did the world's first text message, sent on 3 December 1992, say?

Merry Christmas was typed on a computer rather than a phone: engineer Neil Papworth sent it over Vodafone's network to a colleague's handset, three weeks before the holiday.

Which composer wrote As Slow as Possible, an organ piece now being played in Germany over 639 years?

John Cage gave no tempo beyond the title, so Halberstadt chose 639 years, the age of its first organ in 2000; the performance began in 2001 with a long pause before any note sounded.

Which band failed an audition for Decca Records on New Year's Day 1962, months before signing with EMI?

The Beatles lost out to Brian Poole and the Tremeloes, a band from nearer London; Decca's Dick Rowe, ever after the man who turned them down, later signed the Rolling Stones on George Harrison's advice.

Vincenzo Peruggia, a former Louvre workman, is remembered for stealing which artwork in August 1911?

The Mona Lisa owes much of its fame to the theft, which kept it in the headlines for more than two years; Pablo Picasso was among those questioned by police.

What colour was the Statue of Liberty when it was unveiled in 1886?

Copper brown was its colour for barely two decades: by the early 1900s rain and sea air had turned the metal skin the green we know today.

Strictly speaking, what is 'Big Ben' the nickname of?

The Great Bell cracked within months of first chiming in 1859 and stayed silent until it was repaired; it was already the second attempt, the first casting having cracked beyond use in testing.

Which country has the only national flag that does not have four sides?

Nepal's flag is two stacked pennants that once flew separately for rival branches of the ruling dynasty; they were later joined into one, and the present design was adopted in 1962.

Most of Canada's estimated two million lakes were created by what?

Glaciers scoured basins out of the rock during the last ice age and left a scrambled drainage system behind them, so water pools in hollows instead of running off.

Which sovereign state is the world's second-smallest after Vatican City, at about 2 sq km?

Monaco levies no income tax on its residents, which has made the tiny principality a haven for the wealthy and a major banking centre.

The Mpemba effect is the surprising observation that, under some conditions, what freezes faster?

Hot water than cold water: Erasto Mpemba, a Tanzanian schoolboy, saw his hot ice-cream mix freeze before his classmates' cooled ones; a teacher called it impossible, but physicist Denis Osborne tested it and the pair published in 1969.

What did NASA fix to both Voyager probes in 1977 as a message for extraterrestrials?

A gold-plated phonograph record rode on each probe with its own needle and cartridge, and symbols etched on the cover show how to play its music and greetings in 55 languages.

Which galaxy, about 2.5 million light-years away, is the most distant object easily seen with the naked eye?

Andromeda's light takes about 2.5 million years to reach us, so the faint smudge visible on a dark night left the galaxy long before our own species existed.

Some species of which plant can grow 91 cm in a single day, roughly a millimetre every 90 seconds?

Bamboo is not a tree but a giant member of the grass family, so those towering canes are, botanically speaking, oversized grass stems.

A bristlecone pine in California, more than 4,600 years old, is named after which biblical figure?

Methuselah lived 969 years in Genesis; his namesake's exact spot is kept secret to protect it, and an even older bristlecone, Prometheus, was cut down by a researcher in Nevada in 1964.

Which everyday word did chemist Gilbert Lewis propose as a unit for the time light takes to cross one centimetre?

A jiffy, in Lewis's sense, lasts about 33 trillionths of a second; computer engineers later borrowed the word for one tick of a system clock, a far longer stretch.

Research in 2023 suggested that Roman concrete lasts so long partly because it can do what?

Roman concrete can heal its own cracks because lumps of lime in the mix, long dismissed as poor workmanship, dissolve in seeping water and recrystallise to plug the gap.

The horned 'Viking' helmet was popularised in the 1870s by costumes made for which composer's operas?

Richard Wagner staged his Ring cycle in the 1870s with horned helmets by costume designer Carl Emil Doepler; the few helmets actually found from the Viking Age have no horns at all.

Which frozen treat did Frank Epperson patent in 1924 and first call the Epsicle?

The Popsicle got its lasting name, the story goes, when Epperson's children pressed him to change it; by his own telling he had invented it at 11, in 1905, when a cup of soda powder and water froze overnight around its stirring stick.

Why do owls have to swivel their heads so far round?

Their eyes are fixed in their sockets because they are not balls but long tubes held rigid by rings of bone, so an owl swivels its head as much as 270 degrees to look around.

Which reptile is physically unable to stick out its tongue?

A membrane holds the tongue in place; the salt glands on it are one thing that separates crocodiles from alligators.

Male gentoo penguins traditionally court a female by offering her what?

A pebble is a serious gift because gentoos build their nests from piles of stones, guard them jealously and fight neighbours who try to make off with them.

The tiny pocket inside the front pocket of Levi's jeans was added in the 1870s to hold what?

A watch on a chain was what the little riveted pocket was made for; the second back pocket arrived in 1901 and turned the design into the five-pocket jeans still made today.

A 3M chemist's failed attempt at a super-strong glue in 1968 produced the weak adhesive behind which product?

Post-it notes took years to arrive: Spencer Silver's weak glue had no use until colleague Art Fry, tired of bookmarks slipping out of his hymn book at choir practice, tried it on paper.

Percy Spencer discovered the heating effect that led to the microwave oven in 1945 while working on what?

Radar equipment gave it away: the story goes that a chocolate bar melted in his pocket as he stood by a working magnetron, so he held popcorn kernels near it and saw them burst.

Which household product grew out of a crepe paper developed as a gas mask filter in the First World War?

Kleenex tissues went on sale in 1924 as a way to wipe off cold cream, and only later were they advertised as throwaway handkerchiefs, the use that made the name.

What does the 40 in WD-40 stand for?

The 40th formula attempted was the one that worked: in 1953 the three-man Rocket Chemical Company wanted a water-displacing spray to keep Atlas missiles from rusting, and Water Displacement, 40th try, stuck.

Which US state is both the westernmost and, by longitude, the easternmost?

Alaska's Aleutian Islands stretch so far west that they cross the 180th meridian into the Eastern Hemisphere, so by longitude the state holds both the westernmost and the easternmost points in the country.

Where was the highest air temperature ever recorded on Earth, 56.7 C, measured in 1913?

Death Valley, California took the title only in 2012, when the World Meteorological Organization struck off a 1922 reading of 58 C from Libya as unreliable.

Which of the world's great rivers has no bridges across its main stem along its entire length?

The Amazon could be bridged, but it runs mostly through thinly peopled rainforest with few roads to join up, ferries already do the job, and its soft, marshy banks would make any crossing very costly.

Which animal is the loudest on Earth, producing clicks of about 236 decibels underwater?

Sperm whale clicks work as sonar: the animal hunts squid in the dark of the deep sea, so it finds its prey by sound rather than by sight.

Which flavour can domestic cats not taste, thanks to a broken taste-receptor gene?

Sweet is lost on cats because one of the two genes that build the sweet receptor is broken, a defect shared by lions and tigers, all of them committed meat-eaters.

Research since 2014 suggests a zebra's stripes evolved mainly to deter what?

Biting flies approach stripes too fast and fail to slow down for a landing, so horses dressed in striped coats were landed on far less often than horses in plain ones.

Which of these is a real ability of some turtles?

Breathing through their rear end lets some turtles sit out the winter under ice: the blood-rich lining of the cloaca draws enough oxygen from pond water to keep them going for months.

Which is the only element that will not solidify at atmospheric pressure, no matter how cold it gets?

Helium stays liquid all the way down to absolute zero because of a quantum effect: its atoms never settle enough to lock into place, and only about 25 atmospheres of pressure will freeze it.

Observations since 2017 point to which cosmic events as the forge of much of Earth's gold?

Neutron star collisions were caught in the act in 2017, when telescopes tracked the afterglow of the merger GW170817 and found freshly made gold and platinum, settling a decades-old puzzle.

The blue whale, the largest animal known to have lived, feeds almost entirely on which small creatures?

Krill, tiny shrimp-like animals, make up nearly all of its diet; a blue whale strains them from great mouthfuls of sea through its baleen and can eat about four tons in a day.

Which of these is an elephant physically unable to do?

Jump is beyond an elephant because its ankles are stiff and its lower-leg muscles weak for its bulk; even at full speed it keeps at least one foot on the ground.

By a 2006 count, the Lego factory was turning out about 306 million of which item a year, besides bricks?

Tyres leave Lego's moulds in such numbers that, counted by units rather than by size, the toy maker has been called the world's number-one tyre manufacturer.

Which board game grew out of one that Lizzie Magie patented in 1904?

Monopoly began as Magie's Landlord's Game, a warning about concentrated wealth with one rule set where everyone prospered and one where a single owner took all; the cut-throat version is what spread, and she earned about $500 from it.

Roughly how many possible arrangements does a standard Rubik's Cube have?

43 quintillion arrangements, yet every one of them can be solved in 20 moves or fewer, a limit that took about 35 CPU-years of computing donated by Google to prove in 2010.

Scrabble's inventor Alfred Butts worked out how many of each tile to include partly by counting letters in which newspaper?

The New York Times was among the pages the out-of-work architect combed during the Depression, tallying letters by hand to settle how many of each tile to make and what each should score.

Which party game took off in 1966 after Johnny Carson played it with Eva Gabor on The Tonight Show?

Twister was about to be dropped as too racy, with Sears refusing to list it, when the broadcast aired; shoppers queued the next day and it went on to sell three million copies within a year.

The teddy bear was named after President Theodore Roosevelt did what on a 1902 hunt?

He refused to shoot a captive bear that his guides had tied to a tree, calling it unsporting; a newspaper cartoon of the scene inspired a Brooklyn shopkeeper to sell 'Teddy's bear'.

Playing cards were most likely invented in which country around the 9th century?

China's cards are thought to have followed the spread of woodblock printing, then travelled west through Persia and Mamluk Egypt to reach Europe in the 1370s.

Chess descends from chaturanga, a board game played around 1,400 years ago in which country?

India's chaturanga spread across Asia and into Europe, changing as it travelled, and only settled into the modern rules of chess about 500 years ago.

Uranus is unique among the planets because it rotates how?

Almost on its side, Uranus is tilted about 98 degrees, possibly knocked over by a collision with an Earth-sized body long ago, so each pole gets decades of sunlight and then decades of darkness.

Why do identical twins, who share their DNA, have different fingerprints?

Womb conditions shape the ridges: prints form between the third and sixth months of pregnancy, and each twin's surroundings in the womb nudge the pattern a different way.

Roughly how long does a human red blood cell circulate before it is recycled?

About 120 days is the limit because red cells give up their nucleus to make room for oxygen-carrying haemoglobin, so they cannot repair the wear of squeezing through tiny vessels and are finally recycled.

Which Australian marsupial produces cube-shaped droppings, which it stacks to mark territory?

Wombat droppings are squared off inside the intestine, where stiffer and softer bands of gut wall squeeze at different speeds, and the flat sides stop them rolling off the rocks they mark.

Which sea creature has three hearts and blue blood?

The octopus has one heart for the body and one for each gill, and its blood is blue because it carries oxygen with a copper-based protein that works well in cold, oxygen-poor water.

The Bluetooth wireless standard is named after a 10th-century king of which country?

Denmark's Harald Bluetooth was famed for uniting Scandinavian lands, so Intel's Jim Kardach borrowed his nickname as the codename for a link meant to unite PCs and phones; the logo joins his runic initials.

Botanically speaking, a banana is what kind of fruit?

A berry, to a botanist, is a fleshy fruit grown from a flower with a single ovary, so bananas, grapes and aubergines qualify while strawberries and raspberries do not.

Sea otters have no blubber, so how do they keep warm in cold Pacific waters?

Their exceptionally dense fur, with up to a million hairs per square inch, traps a layer of air against the skin, which is why otters spend hours a day grooming to keep it fluffed and waterproof.

Which video game giant was founded in Kyoto in 1889 to make hanafuda playing cards?

Nintendo spent its first seven decades as a card maker, handcrafting hanafuda and from 1902 producing Japan's first Western-style playing cards, before it turned to toys and video games.

Ketchup was made for over a century before which now-standard ingredient first appeared in a recipe, in 1812?

Tomatoes only joined in 1812, in a recipe by the scientist James Mease; before that, ketchup meant a thin dark sauce made from mushrooms, walnuts, oysters or anchovies.

Why are adult flamingos pink or red when their chicks hatch greyish?

Pigments in their plankton diet, the same carotenoids that colour carrots, are broken down in the gut, absorbed by fats in the liver and laid down in the growing feathers and skin.

In 1932, Australian soldiers armed with machine guns were sent to Western Australia to cull which birds?

Emus scattered so quickly that the guns were withdrawn within a week of the first attempt, and the fiasco became known as the Emu War.

The shortest recorded war in history lasted at most 45 minutes in 1896, between Britain and which sultanate?

Zanzibar's royal palace was set on fire by a British naval bombardment that opened at 9:02 in the morning and was over within about 40 minutes.

In 1893's Nix v. Hedden, the US Supreme Court ruled that which fruit counts as a vegetable for import tariffs?

Tomato importers argued for the botanical definition, but the court said tomatoes are vegetables because they are eaten with the main course, not as dessert.

Which soft drink was created in Nazi Germany after a wartime embargo cut off imports of Coca-Cola syrup?

Fanta was first made from whatever was available in wartime Germany, including sugar beet, whey and apple pomace.

Which natural food never spoils if stored properly, because its sugar and acidity stop microbes growing?

Honey keeps so well that it, and objects immersed in it, have been preserved for centuries. Bees make it for the same reason, as long-term food storage.

Scottish doctor John Aitken pioneered which saw in the 1780s for use in difficult childbirths?

The chainsaw began as a fine serrated chain held between two wooden handles, designed to widen the pelvis during an obstructed labour.

Which mythical creature is Scotland's national animal and appears on the United Kingdom's royal arms?

Unicorn lore cast the beast as the natural enemy of the lion, so the United Kingdom's royal arms pair a Scottish unicorn with an English lion. Two unicorns held Scotland's own royal arms before 1603.

Which dwarf planet, discovered in 1930, will not complete its first full orbit since that discovery until 2178?

Pluto takes about 248 Earth years to circle the Sun, so nobody who was alive for its discovery will see it return to the same point in its orbit.

Olympic gold medals must contain at least six grams of gold but are made mostly of which metal?

Silver must make up at least 92.5% of each Olympic gold medal; the last solid gold ones were awarded at the 1912 Games in Stockholm.

Which Dr. Seuss book was written after his editor bet $50 that he could not use only 50 different words?

Green Eggs and Ham won Dr. Seuss the bet, which was a response to The Cat in the Hat and the 236 different words it had needed.

Which animal named Wojtek was enlisted in the Polish army during World War II, with his own rank and paybook?

A brown bear bought as a cub by Polish soldiers in Iran, Wojtek rose from private to corporal and is said to have carried ammunition crates at Monte Cassino.

In 1919, a burst storage tank sent a deadly 25-foot wave of which sticky liquid through Boston?

Molasses surged through the streets at about 35 miles per hour, killing 21 people, and residents said the area smelled of it on hot summer days for decades.

In 1518, a mysterious 'plague' in Strasbourg made as many as 400 people do what for weeks on end?

Dance was all the victims could do: the outbreak began in July 1518 with one woman, Frau Troffea, who kept going in the street for a week.

Which crime novelist vanished for eleven days in 1926 before turning up at a hotel in Harrogate?

Agatha Christie had registered under the surname of her husband's lover, while more than 1,000 police officers and 15,000 volunteers searched for her.

Which fairground treat, a hit at the 1904 World's Fair, was co-invented by a dentist, William Morrison?

Cotton candy made its debut under the name Fairy Floss, selling 68,655 boxes at the fair for 25 cents each.

Swiss engineer George de Mestral invented which fastener after burrs stuck to his dog's fur on an Alpine hunting trip?

Velcro copies the tiny hooks on burdock burrs, and its name joins the French words velours and crochet, meaning velvet and hook.

Which planet has a six-sided cloud pattern circling its north pole, each side longer than Earth's diameter?

Saturn's hexagon was discovered by the Voyager mission in 1981 and was still there when the Cassini probe returned in 2006, so it is no passing storm.

Which Italian supercar brand was founded by a man who first built tractors out of discarded war materials?

Lamborghini's founder Ferruccio started his tractor company in 1948 and also made boilers and air conditioners before turning to cars in 1963.

Which Thames crossing was sold to an American entrepreneur in 1968 and rebuilt in Lake Havasu City, Arizona?

London Bridge travelled as 10,000 tons of granite blocks via the Panama Canal, and the councillor behind the sale denied that the buyer expected Tower Bridge.

Italian-born restaurateur Caesar Cardini created the Caesar salad in 1924 at his restaurant in which country?

Mexico got the salad because Cardini, who lived in San Diego, ran his Tijuana restaurant just over the border to serve Americans dodging Prohibition.

Which African country has about 220 surviving pyramids, the most in the world and well ahead of Egypt?

Sudan's Nubian pyramids were built as tombs for the kings and queens of Napata and Meroë. They are smaller and far steeper than Egypt's, with sides rising at about 70 degrees.

Which Pacific nation skipped 30 December 2011 entirely by jumping across the International Date Line?

Samoa went straight from Thursday 29 December to Saturday 31 December, a switch meant to make business easier with Australia and New Zealand.

Which sea in the North Atlantic is the only one on Earth bounded by ocean currents instead of land?

Sargasso Sea takes its name from the brown sargassum seaweed floating on its surface, and it is where European eels travel to breed.

Which lake, the deepest in the world, holds more water than all five North American Great Lakes combined?

Lake Baikal in Siberia holds 22–23% of the world's fresh surface water, even though it ranks only seventh among lakes by surface area.

Which horseshoe-shaped bone is the only one in the human body that is not connected to any other bone?

Hyoid bone sits in the front of the neck, held in place only by muscles and ligaments, where it helps the tongue move and the throat swallow.

Which bone is still soft cartilage when a human baby is born and only starts to harden at about age three?

The kneecap, or patella, starts turning to bone from a single centre and is not fully hardened until around puberty.

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

Liver tissue is the only kind among human internal organs that regenerates naturally, though it regrows as extra mass rather than restoring its original shape.

Bananas are very slightly radioactive because they are rich in which element?

Potassium includes a tiny share of the unstable isotope potassium-40, but one banana's dose is only about 1% of the radiation a person is exposed to on an average day.

Apollo 14 commander Alan Shepard brought his own equipment in 1971 to play which sport on the Moon?

Golf on the Moon took a six-iron head fixed to the handle of a sampling tool, and one of Shepard's two balls ended up in a crater.

Which playground contest was a medal event at every Summer Olympics from 1900 to 1920?

Tug of war gold in 1908 went to a team from the City of London Police, and the event was cut after 1920 when the Olympic programme was streamlined.

Fredric Baur had some of his ashes buried in the tube-shaped can he designed for which snack?

Pringles' can designer asked for the send-off himself, so in 2008 his children placed part of his cremated remains in an Original flavour tube in his grave.

Which symbol did freelance artist Harvey Ball draw in about ten minutes in 1963 for a fee of just $45?

The smiley face was commissioned by an insurance company in Worcester, Massachusetts, which wanted to lift staff morale after a merger.

Which word, from the Old French for 'needle', names the small sheath on the end of a shoelace?

Aglet tips are now fitted by machines that wrap plastic tape around the end of the lace and bond it on with heat or chemicals.

Which German company sold heroin from 1898 as an over-the-counter cough suppressant, having trademarked the name?

Bayer marketed heroin as a non-addictive substitute for morphine, and its research chief reputedly based the name on the German word for heroic.

Which stock sound effect from the 1951 film Distant Drums became an in-joke reused in Star Wars and Indiana Jones?

Wilhelm scream takes its name from Private Wilhelm, a minor character who seems to let it out when an arrow hits his thigh in a 1953 western.

Which animals flew around the Moon aboard the Soviet probe Zond 5 in 1968, months before any human did?

Tortoises were chosen because they were easy to secure tightly, and the pair came back safely, having lost about a tenth of their body weight.

Which moon of Jupiter is the largest in the Solar System, bigger even than the planet Mercury?

Ganymede is wider than Mercury but has only 45 percent of the planet's mass, because it is about half water ice rather than solid rock and metal.

Which seabird sees two summers a year by making the longest migration of any animal, to Antarctica and back?

Arctic tern round trips can top 70,000 km a year, and the long journey means the bird sees more daylight than any other creature on the planet.

Turritopsis dohrnii, which can revert to an immature stage instead of dying of old age, is what kind of animal?

A jellyfish found in temperate and tropical seas worldwide, it is nicknamed the immortal jellyfish and is one of the few animals known to grow young again.

NASA's Mars Climate Orbiter was lost in 1999 because its builder and the space agency failed to use the same what?

Units of measurement sank the probe: Lockheed Martin's software reported thruster impulse in pound-force seconds, while NASA's expected newton-seconds.

Bell Labs workers coined which name in the 1960s for the # symbol on the new touch-tone telephone keypad?

Octothorpe was invented because the engineers needed names for the two extra keys they were adding; 'octo' means eight, and where the rest came from is still a mystery.

Which word names the dot over a lowercase i or j, and pairs with 'jot' in a phrase meaning every small detail?

Tittle and jot appear side by side in the King James Bible, in a verse promising that not even the tiniest mark of the law will pass away.

Benjamin Franklin invented which instrument in 1761, played by touching the rims of bowls spun by a foot pedal?

Glass armonica music won over Mozart and Beethoven, who both wrote for the instrument; Franklin took its name from armonia, the Italian word for harmony.

Which sea creature scrapes algae off rocks with teeth that are the strongest known biological material?

Limpet teeth are reinforced with iron minerals and can reach a tensile strength of 6.5 gigapascals, against a best of 4.5 for spider silk.

Which metal melts at just under 30 C, letting chemists prank guests with spoons that vanish in hot tea?

Gallium looks much like aluminium, which is what makes the spoon trick work, and a lump of it will even melt in the warmth of a person's hand.

Which Central Asian nation joins Liechtenstein as one of just two countries ringed entirely by landlocked neighbours?

Uzbekistan is also the only Central Asian state that borders all four of the others, so reaching any ocean from it means crossing at least two frontiers.

Whose nine-month-old corpse was dug up, propped on a throne and put on trial in Rome in 897?

A pope's corpse was the defendant at what became known as the Cadaver Synod: Formosus was judged by Pope Stephen VI, stripped of his papal vestments and later thrown into the Tiber.

Because of a metal shortage during World War II, Oscar statuettes were made for three years from which material?

Painted plaster Oscars were only a stopgap: after the war, the Academy invited winners to trade them in for gold-plated metal statuettes.

Which Arctic animal's eyes change from gold in summer to blue in winter to see better in the polar darkness?

Reindeer owe the change to a reflective layer behind the retina, and they can also see ultraviolet light, which makes urine and fur stand out against snow.

Which country's calendar included a 30 February in 1712, the only known real use of that date?

Sweden added a second leap day that year to get back onto the Julian calendar after earlier mistakes, which gave 1712 a total of 367 days.