Blue Trivia
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100 free Blue trivia questions with answers — trivia quiz, new questions added Oct 2026.
This blue trivia quiz is built around one colour and everything named after it. There are questions on the science of blue (why the sky is blue, why blue eyes have no blue pigment, the first synthetic pigment), on the great blues of art and history (lapis lazuli, ultramarine, Prussian blue, Picasso's Blue Period, Miles Davis's Kind of Blue), on blue animals (the blue whale, the blue-ringed octopus, the blue-footed booby, the blue jay) and on the many things that borrowed the name: Bluetooth, blue jeans, blue cheese, blue chips, blue plaques, blue laws, Blue Peter, Blue Monday, Blue (Da Ba Dee), Blue Man Group, IBM's Big Blue and the blue screen of death. It works as a themed round for a baby shower, a colour-themed party or a pub quiz. Difficulty runs from easy questions about the sky to hard ones about Viking kings and 12-inch singles. Every answer is checked against Wikipedia and cited on the question, so you can see where each fact comes from.
30 of 100 questions with answers and explanations. Play the quiz
Q 01Which optical effect makes the clear daytime sky look blue?
Rayleigh scattering
Rayleigh scattering. Air molecules scatter short blue wavelengths far more than long red ones, and at sunset the light crosses so much air that the blue is scattered away and the reds are left.
Q 02Which colour of visible light has a shorter wavelength than blue?
Violet
Violet. Blue light runs from roughly 450 to 495 nanometres and violet is shorter still, so the 405-nanometre 'blue' laser that reads a Blu-ray disc really sits in the violet range.
Q 03What was the first artificial pigment, made more than 4,000 years ago by heating sand with ground minerals?
Egyptian blue
Egyptian blue. It glows strongly in infrared when lit, so museums can now photograph traces of it on ancient statues that look bare to the naked eye.
Q 04Which organisation's flag shows a world map wreathed in olive branches on a light blue field?
The United Nations
The United Nations. Its designers in 1945 chose blue to stand for peace, as the opposite of red, which they called the colour of war.
Q 05Ultramarine, the most expensive Renaissance pigment, was ground from which stone?
Lapis lazuli
Lapis lazuli. Ground and washed into ultramarine, it could cost as much as gold, so Renaissance painters often saved it for the robes of the Virgin Mary.
Q 06The pigment name 'ultramarine' comes from Latin words meaning what?
Beyond the sea
Beyond the sea, from the medieval Latin ultramarinus. The name is said to describe the journey rather than the colour, because the stone it was made from reached Europe by ship from Asia.
Q 07Which pharaoh's funeral mask is inlaid with the blue stone from which ultramarine was later made?
Tutankhamun
Tutankhamun. The stone rims the eyes and eyebrows of his gold mask, and it had been traded all the way from mines in what is now Afghanistan.
Q 08Prussian blue, the first modern synthetic pigment, is the traditional 'blue' in what?
Blueprints
Blueprints. The copying paper turns Prussian blue wherever light strikes it, so the lines of the drawing, which block the light, stay white on a blue sheet.
Q 09Which artist's Blue Period, from 1901 to 1904, followed the suicide of his friend Carles Casagemas?
Pablo Picasso
Pablo Picasso. He was so short of money in those years that he painted over used canvases, which is why scans keep finding hidden pictures beneath his Blue Period works.
Q 10Blue eyes have no blue pigment: their irises are just low in which other pigment?
Melanin
Melanin. Blue-eyed people share a genetic switch that turns down production of the brown pigment in the front of the iris, so the blue is an effect of light rather than a dye.
Q 11The blue whale is the largest animal ever known: roughly how much can the biggest weigh?
About 200 tonnes
About 200 tonnes. Whalers after its oil drove the species to the brink of extinction in the 20th century, until an international ban in 1966 protected it.
Q 12A blue whale's diet consists almost entirely of what?
Krill
Krill. The largest animal ever known lives on tiny shrimp-like creatures, gulping a huge mouthful of sea and then straining the water out through its baleen plates.
Q 13A blue whale's heart can slow to just two beats a minute when the animal does what?
Dives deep to feed
Q 21The Bluetooth logo is made by merging two what?
Norse runes
Norse runes. They are Hagall and Bjarkan, the initials of the king the technology is named after, who is said to have earned his nickname from a dead tooth that looked dark blue.
Q 22The 1873 patent that gave birth to blue jeans protected which feature?
Copper rivets
Copper rivets. Reno tailor Jacob Davis used them to stop the pockets of work trousers tearing, then asked Levi Strauss, who sold him the cloth, to share the patent.
Q 23Until factories began making it in the 1890s, where did the world's indigo dye come from?
Plants
Plants. Indigofera shrubs supplied most of the dye until factory-made indigo went on sale in the late 1890s, and within two decades the plant trade had all but collapsed.
Dives deep to feed. The slow beat stretches the whale's oxygen supply underwater, and once it is back at the surface its heart races at up to 37 beats a minute.
Q 14The blue-ringed octopus carries tetrodotoxin, the same nerve poison found in which fish?
Pufferfish
Pufferfish. The octopus does not make the poison itself: bacteria living in its salivary glands produce it, and its rings flash bright blue as a warning only when it feels threatened.
Q 15About half of all breeding pairs of blue-footed boobies nest on which islands?
The Galápagos
The Galápagos. Males court with a high-stepping strut that shows off their feet, and the bluer the feet, the better a male's chances with a female.
Q 16The clever, acorn-hoarding blue jay belongs to which family of birds?
The crow family
The crow family. Like other members it is a talented mimic, and a blue jay can copy a hawk's scream well enough that it may frighten other birds away from their food.
Q 17Under the popular definition, when is a full moon called 'blue'?
It is the second in one calendar month
It is the second in one calendar month. The rule began as a slip, when a 1946 magazine article misread an old farmers' almanac, and a radio show and Trivial Pursuit later spread it.
Q 18After which 1883 volcanic eruption did the Moon really look blue for months?
Krakatoa
Krakatoa. Its ash filled the upper air with particles just the right size to filter out red light, so the Moon shone blue, and sometimes green, through the haze.
Q 19Bluetooth technology is named after a 10th-century king of which country?
Denmark
Denmark. The king's nickname was only meant as a placeholder: the names lined up to replace it, RadioWire and PAN, fell through before launch, so the codename stuck.
Q 20Bluetooth is named after a medieval king who was famed for doing what?
Uniting Scandinavian lands
Uniting Scandinavian lands. Intel engineer Jim Kardach proposed the name because the new radio link was meant to unite the PC and mobile phone industries in the same way.
Q 24By legend, which blue cheese was born when a shepherd left his lunch in a cave to chase a girl?
Roquefort
Roquefort. In the tale he came back months later to find his cheese veined with blue mould, and the real thing is still ripened in the caves of Roquefort-sur-Soulzon.
Q 25The 'blue chip' stock term comes from which game, where blue chips are traditionally worth most?
Poker
Poker. Dow Jones lore credits an employee, Oliver Gingold, with borrowing the gambler's term in the 1920s after watching shares change hands at $200 or more.
Q 26'Blue blood' translates a boast that old Iberian noble families made in which language?
Spanish
Spanish. The phrase is sangre azul, claimed by old families of Castile, and the idea was probably that fair-skinned nobles could point to the blue veins showing through their skin.
Q 27London's blue plaques honour notable people, but only once the person has been what?
Dead for 20 years
Dead for 20 years. The wait is meant to give the judges hindsight, though the oldest surviving plaque breaks the rule: it went up in 1867 to Napoleon III, who was still alive.
Q 28The BBC children's show Blue Peter is named after a flag that ships fly when about to do what?
Leave port
Leave port. The name was chosen to cast the programme as a ship setting out on a voyage of adventure, with new things for its young viewers to discover along the way.
Q 29The sleeve of New Order's 1983 single 'Blue Monday' was designed to look like what?
A floppy disk
A floppy disk. Designer Peter Saville had just seen one for the first time, and the die-cut copy was so costly that, as the story goes, Factory Records lost money on every single sold.
Q 30Which Italian group had a worldwide hit in 1999 with 'Blue (Da Ba Dee)'?
Eiffel 65
Eiffel 65. The name was half an accident: 'Eiffel' came off a ready-made list of band names, and the 65 was two digits of a phone number jotted across the single's label copy.