96 Fun Facts About Color

In the mnemonic ROYGBIV for the colours of the rainbow, what does the I stand for?

Indigo: Isaac Newton spelled it 'indico', and it was one of two colours he added to his original five.

Isaac Newton gave the rainbow seven colours rather than five to match what?

Seven notes of a major scale: yet Newton admitted that his own eyes were not very good at telling colours apart.

Which astronomer discovered infrared radiation in 1800 by testing a spectrum's colours with thermometers?

William Herschel: the warmest reading of all came from just beyond the red end of the spectrum, where no light could be seen.

The daytime sky looks blue mainly because of which physical effect?

Rayleigh scattering: air scatters the short blue waves of sunlight far more than longer red ones, so blue light reaches our eyes from all over the sky.

In the CMYK printing model, what does the K stand for?

Key: black can be mixed from cyan, magenta and yellow inks, but printers usually add black ink instead for crisper text and less ink.

How many types of colour-sensing cone cell does a typical human retina have?

Three: matching those three kinds, screens can mix most of the colours we see from just red, green and blue light.

Which animal's eyes contain 12 to 16 types of photoreceptor cell and can detect circularly polarised light?

Mantis shrimp: despite all those receptors, experiments show they are remarkably poor at telling similar colours apart.

Which is the most common form of colour blindness in humans?

Red–green: it affects about 1 in 12 men of Northern European descent but only 1 in 200 women, because the genes sit on the X chromosome.

Which colour-blind chemist described the condition to a Manchester society?

John Dalton: he guessed that a tinted fluid inside his eyes was to blame, though the cause turned out to lie in the cones.

Which pigment, with brown-black and red-yellow forms, is the primary determinant of human skin colour?

Melanin: red hair gets its colour from mostly the red-yellow form, pheomelanin, with only a little of the dark eumelanin.

Chlorophyll makes leaves green by absorbing light most strongly in which two colours?

Blue and red: it absorbs green only weakly, and that green light is scattered back out by leaf structures such as cell walls.

Tyrian purple, the imperial dye prized by Roman emperors, was extracted from what?

Sea snails: thousands of them yielded only about a gram of dye, which made purple cloth a mark of power and wealth.

In 1856, William Henry Perkin discovered the dye mauveine while trying to make what?

Quinine: he was an 18-year-old working in his home laboratory over the Easter holidays, and his accidental dye founded a new chemical industry.

Renaissance ultramarine was ground from lapis lazuli mined mainly in which modern country?

Afghanistan: its lapis mines had been sending stone to ancient Egypt thousands of years before Renaissance painters ground it into blue.

A yellow painters' pigment reportedly came from the urine of cows fed on what?

Mango leaves: an 1883 investigation described the cows' urine being collected, dried and sold as balls of raw pigment.

The red dye carmine, still used in food and cosmetics, is made from which creature?

A cactus-dwelling scale insect: the bugs are so tiny they were long mistaken for something else, and about 70,000 dried ones make a pound of dye.

Which paint did Edward Burne-Jones bury once he learned what it was made from?

Mummy brown: his wife recalled that he thought the name only described a shade, until he was assured it held real mummy.

Prussian blue, the first modern synthetic pigment, was made by accident around 1706 in which city?

Taken orally, the same compound is a WHO essential medicine, used as an antidote to thallium and radioactive caesium poisoning.

Scheele's green, a popular Victorian pigment, was dangerous because it contained which element?

Arsenic: an 1808 attempt to improve the pigment produced emerald green, which proved just as poisonous.

The word for the dye that colours blue jeans comes from a Greek word meaning what?

The plant-based dye was largely replaced after BASF industrialised a synthetic version in 1897, building on Adolf von Baeyer's chemistry.

Which French artist registered his signature ultramarine paint in 1960?

Yves Klein: he suspended the pigment in a synthetic resin instead of oil, which kept the ultramarine from dulling.

Vantablack, one of the darkest substances ever made, absorbs up to 99.965% of visible light using what?

Vertically aligned carbon nanotubes: the artist Anish Kapoor later struck a deal with the maker for exclusive rights to use it in art.

YInMn Blue is named for yttrium, indium and which third element?

Manganese: its ions are what give the pigment its intense blue, and changing their share shifts the colour.

Picasso's Blue Period, from 1901 to 1904, was directly followed by which of his periods?

Rose: the warmer period began after he settled among poets and writers at the Bateau-Lavoir in Paris.

The name Crayola was coined by Alice Binney from 'ola', for oily, and 'craie', the French word for what?

Chalk: the everyday word crayon grew from the same French root, craie, through a word that first meant a chalk pencil.

Which sky-blue shade was Pantone's very first Color of the Year, for 2000?

Cerulean: Pantone started the yearly pick to get designers and colour fans talking about colour.

Which warm brown shade did Pantone name its Color of the Year for 2025?

Mocha Mousse: Pantone said its hint of chocolate and coffee answered a desire for comfort.

Since Mauritania's 2017 flag change, which is the only sovereign country whose flag has no red, white or blue?

Jamaica: its black first stood for hardships, until a 1996 review recast it as the people's strength and creativity.

Which country's national flag was plain green, with no emblem, from 1977 to 2011?

Libya: after Gaddafi's fall in 2011, the country brought back the tricolour it had flown before 1969.

The Pan-African colours of green, yellow and red were borrowed from which country's flag?

Ethiopia: apart from a brief Italian occupation it kept its independence, so many African nations took up its colours on becoming independent.

Which British prime minister's 1858 study found no blue in Homer's descriptions of nature?

William Gladstone: he argued that Homer's colour words described light and dark more than hue.

In which language can the word ao describe both blue and green, including a 'go' traffic light?

Japanese: teaching green apart from blue only began after World War II, so green vegetables are still called ao.

Which shade of pink, 'drunk-tank pink', has been painted in prison cells to calm aggression?

Baker-Miller: some football teams even painted visitors' locker rooms pink, yet the balance of evidence suggests the colour has no simple calming effect.

What paint scheme did the US Navy suggest for the Golden Gate Bridge instead of 'international orange'?

Black and yellow stripes: the Navy wanted passing ships to see the bridge, but architect Irving Morrow picked a colour to suit its natural setting.

What colour is an aircraft's 'black box' flight recorder actually painted?

Bright orange: the colour helps investigators find the recorder in wreckage, so 'black box' is really a misnomer.

What turns greyish young flamingos pink?

Carotenoid pigments in their food: flamingos cannot make these pigments themselves, so the algae and other plankton they eat supply them.

Why does a bull charge a matador's red cape?

Like most mammals, cattle are red–green colour blind, so the cape's colour is for the audience, not the animal.

Chameleons are famed for camouflage, but what do their colour changes most commonly serve?

Social signalling and temperature: panther chameleons, for example, change colour rapidly during contests between males or during courtship.

A polar bear's fur looks white, but what are its guard hairs actually like?

Transparent and hollow: the hollow guard hairs help trap heat, and beneath the fur its skin is black.

Which explanation for zebra stripes is the most strongly supported by evidence?

They deter blood-sucking flies: horseflies are far less likely to land on striped surfaces, though exactly why is still being tested.

The vivid blues on peacock feathers and Morpho butterfly wings are produced not by pigment but by what?

Microscopic surface structures: Robert Hooke found that wetting a peacock feather's coloured parts destroyed their colours.

The idiom 'blue blood' for aristocracy was translated from which language?

Spanish: old Castilian families claiming no Moorish ancestry supposedly showed blue veins through their pale skin.

What was a 'red herring' before the phrase came to mean a false clue?

A smoked herring: curing turned the fish red, and its strong smell was supposedly used to throw hounds off a scent.

The popular 'second full moon in a month' definition of a blue moon traces to a 1946 misreading in which magazine?

Sky & Telescope: the slip spread after the radio show StarDate used it in 1980 and a 1986 edition of Trivial Pursuit repeated it.

'The Dress' of 2015 looked white and gold to many, but what colours was it really?

Blue and black: the photo's lighting split viewers so sharply that vision scientists went on to study why people saw it differently.

Frank Cyr standardised school-bus yellow at a 1939 conference held at which institution?

Teachers College, Columbia University: the colour was chosen because lettering on it was easiest to read in semi-darkness.

The Statue of Liberty was a shiny reddish-brown until weather turned its thin sheets of which metal green?

Copper reacts with air, water and pollution to form verdigris, and the statue went fully green within about twenty years. That crust now shields the metal from further corrosion.

Which office product is canary yellow only because the lab next door had yellow scrap paper?

Post-it Notes got their colour by chance, and 3M later registered that canary yellow as a trademark. Their weak glue was itself an accident, the result of a failed attempt at a super-strong adhesive.

Which African animal oozes a red 'blood sweat' that works as both sunscreen and antibiotic?

A hippopotamus secretes two acidic pigments that absorb ultraviolet light and slow the growth of bacteria. The fluid is neither blood nor sweat.

Tennis balls switched from white to fluorescent yellow in 1972 so they would show up better on what?

Television research showed that 'optic yellow' balls were easier to see than white ones. Polls still split on whether the ball is really yellow or green.

Before MGM's The Wizard of Oz made them ruby, Dorothy's magic shoes in L. Frank Baum's novel were what?

Silver Shoes are what Dorothy wears in the 1900 book, but the film-makers turned them red to make the most of the Technicolor process.

Moscow's Red Square is not named after communism: its name 'Krasnaya' once also meant what?

Beautiful was the old meaning of 'krasnaya', which only later came to mean red. A tsar formally adopted the name centuries before the Soviet Union existed.

Which British monarch made the white wedding dress fashionable by wearing one trimmed with Honiton lace?

Queen Victoria chose white to marry Prince Albert, and widely published pictures set the trend among wealthy brides. Before that, a bride married in any colour she liked.

What did Pierre de Coubertin say the Olympic rings' five hues plus a white background represented?

Every nation's flag of the day could be made from those six, he wrote in 1913. The idea that each ring stands for one continent came later.

Mars looks red from Earth because its surface is covered in fine dust of which compound?

Iron oxide, the same compound as rust, coats much of the planet as fine dust. Enough of it hangs in the thin Martian air to tint that pink as well.

Film studios favour green screens for visual effects mainly because green is furthest from what?

Actors' complexions differ most from green and blue, so software can strip either backdrop cleanly without erasing the cast. Red is avoided because every face contains it.

Which Shakespeare tragedy gave English the phrase 'green-eyed monster' as a warning against jealousy?

Othello contains the warning that jealousy 'is the green-eyed monster which doth mock the meat it feeds on'. Shakespeare also wrote of 'green-eyed jealousy' in The Merchant of Venice.

According to the sagas, which Norse explorer gave icy Greenland an inviting name to attract settlers?

Erik the Red reasoned that people would be drawn to a land with a favourable name, his saga says. Of the 25 ships that then sailed from Iceland, only 14 arrived.

Puce, a brownish purple said to be Marie Antoinette's favourite, is the French word for which insect?

Flea is the literal meaning of 'puce', and the full French name, couleur puce, means flea colour. The shade became fashionable at the court of Louis XVI.

Turquoise takes its name from an Old French word linking the gemstone to which country?

Turkey gave the stone its name through the Old French 'turquois', meaning Turkish, because it reached Europe through Ottoman lands. The gems themselves were mined in Persia.

The brown tone sepia, familiar from antique photographs, is named after the ink of which sea animal?

Cuttlefish ink sacs supplied the rich brown pigment, and 'sepia' is simply the ancient Greek word for the animal.

The dark brownish-red colour maroon takes its name from the French word for which nut?

Chestnut is 'marron' in French, borrowed from the Italian 'marrone', which means both the nut and the colour brown.

Which yellow-green colour is named after a liqueur that French monks began making in the 1700s?

Chartreuse the colour copies the green liqueur of the same name. Its makers, the Carthusian monks, took their own name from the Chartreuse Mountains, where their order began.

Khaki entered English through Britain's colonial army from a Hindustani word meaning the colour of what?

Soil is 'khak' in Persian, so khaki means soil-coloured. Armies adopted it because it blends into sandy and dusty terrain.

The purplish-red dye magenta was renamed in 1860 to celebrate what kind of event the year before?

A battle near the town of Magenta, where French and Sardinian troops beat a larger Austrian army in 1859, gave the dye its name. The new label made it a commercial success.

Blue-chip shares, the stock market's safest big names, are named after the highest-value token in which game?

Poker sets traditionally come with white, red and blue chips, and American custom makes the blue ones worth the most.

The phrase 'red tape' for needless bureaucracy comes from ribbon once used to tie up what?

Official documents were tied up with red ribbon, and Thomas Carlyle and Charles Dickens turned the tape into a byword for delay.

The phrase 'white elephant' for a costly burden comes from sacred animals kept by monarchs in which region?

Southeast Asia's kings prized the rare pale animals as sacred, so a gift of one could never be put to work. Receiving it was both a blessing and a curse.

US paper money earned the nickname 'greenbacks' as emergency currency printed during which war?

The Civil War drove the United States to issue emergency paper money, and the public named it for the green ink on the back. Until then its official currency was gold and silver coin, with paper notes left to private banks.

Manfred von Richthofen, the Red Baron, is most associated with a red-painted triplane built by which company?

Fokker built the Dr.I triplane he made famous, yet only 19 of his 80 victories came in it. He had first painted an Albatros red on becoming a squadron commander.

Rubies are red and emeralds are green thanks to traces of which same metallic element?

Chromium colours both gems, and its name comes from the Greek word for colour because so many of its compounds are intensely coloured.

Which element did Humphry Davy name in 1810 after the Greek word for the pale green of its gas?

Chlorine comes from the Greek khloros, a name Davy chose once it was confirmed that the choking gas was an element and not a compound of oxygen.

Which element, named after a Scottish village, gives red fireworks and emergency flares their colour?

Strontium takes its name from Strontian, where its ore was found in 1790, and it was recognised as new by the crimson of its flame.

Which gas high in the atmospheres of Uranus and Neptune gives both planets their blue-green tint?

Methane has strong absorption bands in visible light, leaving Uranus aquamarine and Neptune faintly blue. Deep inside Uranus, pressure may crush the same gas into a hail of diamonds.

What do astronomers call the stretching of light from receding galaxies toward longer wavelengths?

Redshift measurements of distant galaxies had shown by 1930 that the universe is expanding. The opposite change, toward shorter wavelengths, marks a source that is approaching.

Which space probe took the 'Pale Blue Dot' photograph of Earth in 1990, at Carl Sagan's urging?

Voyager 1 turned its camera homeward for one last picture as it left the Solar System, and Earth fills less than a single pixel of the frame.

Which pigment, named after an old tomato genus, also colours watermelon and pink grapefruit red?

Lycopene is bright red, yet the body does not need it as a nutrient. Most of what people eat comes from tomato dishes and products such as ketchup.

Saffron, the spice that dyes food golden yellow, is the dried crimson stigmas of which flower?

Crocus sativus, the saffron crocus, is sterile and unknown in the wild, so every plant alive has been propagated by people.

Which pigments, made actively by leaves as their green fades, give autumn foliage its reds and purples?

Anthocyanins are newly made in autumn, unlike the yellows, which sit in the leaf all year and show only once the green fades.

Which pigment, a breakdown product of the heme in red blood cells, turns the skin yellow in jaundice?

Bilirubin is named from the Latin for bile and red, and light therapy treats jaundiced newborns by turning it into a form that dissolves more easily.

What is the term for one iris being a different colour from the other, common in some cat and dog breeds?

Heterochromia can be complete, with two differently coloured eyes, or sectoral, where part of one iris differs from the rest. It is uncommon in people.

The brilliant red pigment vermilion was traditionally ground from cinnabar, an ore of which toxic metal?

Mercury made vermilion costly as well as poisonous, because mining cinnabar was difficult, expensive and dangerous.

China's Yellow River gets its colour from which fine-grained sediment, washed off a vast plateau upstream?

Loess settles along the riverbed and keeps raising it, which is the cause of the river's notorious floods.

Which language treats light blue and dark blue as two separate basic colours, each with its own word?

Russian places goluboy and siniy side by side in the spectrum as separate colours, where English treats azure and cyan as mere shades of blue.

Which country's flag is a red disc on a green field, set slightly towards the hoist side?

Bangladesh offsets the disc so that it appears centred when the flag is flying. The red is widely read as the blood shed in the 1971 war of independence.

Which delivery company chose 'Pullman brown' for its vans because the railway-car colour hides dirt?

UPS founder Jim Casey wanted yellow vehicles until a partner argued they would be hard to keep clean. The firm later advertised with the line 'What can Brown do for you?'

Which Dutch painter limited his grid compositions to red, blue and yellow with black, white and grey?

Piet Mondrian restricted himself just as strictly in direction, allowing only horizontal and vertical lines.

The 1871 painting 'Arrangement in Grey and Black No. 1' is far better known by which colloquial name?

Whistler's Mother gained an explanatory subtitle because viewers of the day would not accept a portrait exhibited as an 'arrangement'.

Which author became the first Black woman to win the Pulitzer Prize for Fiction with The Color Purple?

Alice Walker wrote the 1982 novel as a series of letters, and it also won the National Book Award for Fiction.

Which singer took the ballad 'True Colors' to number one on the US Billboard Hot 100 in 1986?

Cyndi Lauper held the top spot for two weeks with it, her second and last single to reach number one.

Which 1998 film traps twin teenagers in a black-and-white 1950s sitcom that gradually turns to colour?

Pleasantville is also the name of the sitcom inside the film, and colour spreads through its town as the two visitors change how the residents live.

In the arcade game Pac-Man, which of the four ghosts is red and programmed to chase the player directly?

Blinky was first named Oikake, or 'chaser', and each ghost was given its own behaviour so the game would be neither impossible nor boring.

Which tennis tournament enforces an almost all-white dress code for players, a long-standing tradition?

Wimbledon allows small colour accents on players' whites, provided they do not form the scheme of a recognisable commercial logo.

Which cycling Grand Tour gives its leader a pink jersey, matching the paper of the newspaper that founded it?

Giro d'Italia was launched in 1909 to boost sales of La Gazzetta dello Sport, whose pink pages gave the leader's jersey its colour.

The colour pink takes its name from frilly garden flowers called pinks, members of which genus alongside carnations?

Dianthus flowers were called pinks long before the shade was, and the name may come from their frilled edges, which look as if they were cut with pinking shears.

Which golf major awards its champion a green jacket that must go back to the clubhouse after one year?

The Masters has awarded the jacket since 1949, and a golfer who wins again keeps using the one from his first victory.