Sundials Trivia
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55 free Sundials trivia questions with answers — technology quiz, new questions added Sep 2026.
Sundials are the oldest clocks humans ever built, and this quiz covers them from the shadow clocks of Egypt and Babylon to a bridge in California whose mast is a gnomon. The easy questions ask what a gnomon is, why the shadow moves 15 degrees an hour, why a dial made for one hemisphere runs backwards in the other, and why a garden sundial rarely agrees with your phone. From there it moves into the mechanics that make a good dial work: the style angle that must equal your latitude, the equation of time and its 16-minute swing, the figure-eight analemma printed on globes, and the three corrections needed to turn sundial time into clock time. The harder end is for history and astronomy fans: Vitruvius's catalogue of Greek dials, the scaphe of Aristarchus, Augustus's obelisk in the Campus Martius, the tide dial on the Bewcastle Cross, Ibn al-Shatir's equal-hours dial in Damascus, the Vrihat Samrat Yantra at Jaipur, sundial cannons that fire at noon, Newton's ceiling dial, the Benoy and bifilar dials, and the mottoes carved on dials for centuries. Every answer was checked against encyclopaedia entries on sundials, their history and their most famous examples, and the supporting sentence is stored with each question. If you enjoy this one, try our astronomy, ancient Egypt and inventions quizzes next.
30 of 55 questions with answers and explanations. Play the quiz
Q 01In which US state can a sundial's upright pointer cast no shadow at noon on two days a year?
Hawaii
Hawaii is the only state south of the Tropic of Cancer, so the noon Sun can stand straight overhead there twice a year, a moment named Lahaina Noon.
Q 02By what angle does the Sun appear to swing around the sky each hour?
15°
15°, near enough: a full 360° circuit takes 24 hours, which is also why each ideal time zone spans 15 degrees of longitude.
Q 03For a sundial to be accurate all year, its style must be parallel to what?
Earth's rotational axis
Earth's rotational axis: set that way, the style's shadow turns at the same rate in every season, so the dial can mark equal hours all year.
Q 04What must a horizontal sundial's style angle above the horizontal equal?
The local latitude
The local latitude, so a dial built for London keeps poor time in Cairo until it is tilted by the difference between the two latitudes.
Q 05What is a sundial's single time-telling point, such as a style's tip, called?
Nodus
Nodus: its shadow falls on a different curve in each season, so a dial with one can show the date as well as the hour.
Q 06Which ancient civilisation left the oldest known shadow clocks, from about 1500 BC?
Ancient Egypt
Ancient Egypt: Egyptians were apparently among the first to divide the day into parts much like our hours, and shadow clocks measured them.
Q 07Which Greek thinker from Miletus is credited with bringing the sundial to Greece?
Anaximander
Anaximander is said to have set up a gnomon at Sparta to mark the solstices and equinoxes, though Herodotus says the Greeks learned the device from Babylon.
Q 08Which Roman author listed the sundial types known in his day, naming their Greek inventors?
Vitruvius
Vitruvius wrote about dials because he counted the making of timepieces as one of architecture's three departments, beside building and machinery.
Q 09Which Greek astronomer is credited with inventing the scaphe, a bowl-shaped sundial?
Aristarchus
Aristarchus of Samos also put the Sun at the centre of the cosmos, but the Greeks did not accept the idea and Earth-centred models prevailed.
Q 10Pliny says Rome's first public sundial, set up in the First Punic War, was taken from which island?
Sicily
Sicily: the dial was laid out for Catania, about 4 degrees further south, so it never quite matched Rome's hours, yet it kept the city's time for about a century.
Q 11The word 'dial', once meaning a sundial, traces back to the Latin word for what?
Day
Day: it apparently came through Medieval Latin 'dialis', meaning 'daily', and the same word now names clock faces and telephone dials.
Q 12Which emperor set up an obelisk as a shadow-caster in Rome's Campus Martius?
Augustus
Augustus's obelisk cast its shadow on lines of brass, but by Pliny's day the readings had stopped agreeing, and he wondered whether the Sun or the Earth had shifted.
Q 13Which TV science educator helped design the sundials carried by NASA's Spirit and Opportunity rovers?
Bill Nye
Bill Nye helped create the MarsDials, inscribed 'Two Worlds, One Sun', which doubled as targets for calibrating the rovers' cameras.
Q 21German astronomer Nicolaus Kratzer made sundials as royal astronomer to which king?
Henry VIII
Henry VIII's astronomer Kratzer also teamed up with Hans Holbein to devise a painted ceiling of planets for a banqueting house at Greenwich Palace.
Q 22What is the year-varying gap of up to 16 minutes between a sundial and a clock called?
Equation of time
The equation of time was once used the other way round: early clocks were corrected with it to match sundial time.
Q 23Before sundials reached Rome, how did the city learn that it was midday?
An official announced it
An official announced it: the consuls' attendant called out midday when, from the Senate house, he saw the Sun between the Rostra and the Graecostasis.
Q 14The obelisk that served as a giant shadow pointer in ancient Rome now stands before which building?
The Chamber of Deputies
The Chamber of Deputies meets in Palazzo Montecitorio, where the obelisk, fallen and buried for centuries, was raised again by Pope Pius VI.
Q 15Which octagonal marble monument in Athens bore sundials outside and housed a water clock?
Tower of the Winds
The Tower of the Winds is named for its frieze of wind gods, and a bronze Triton on top is said to have turned to point at whichever wind was blowing.
Q 16In the Bible, which king was given the sign of a shadow moving backwards on the dial of Ahaz?
Hezekiah
Hezekiah, ill and promised fifteen more years, asked for the harder sign, and the shadow went back ten degrees on his father Ahaz's dial.
Q 17Which motto shares the sundial side of the 1787 Fugio cent, an early US coin?
Mind Your Business
Mind Your Business: set beside the sundial and the word 'Fugio', 'I fly', it read as a rebus: time flies, so mind your business.
Q 18Which English monk promoted canonical sundials for fixing the times of prayer?
The Venerable Bede
The Venerable Bede also helped popularise counting years from the birth of Christ, using AD dates in his Ecclesiastical History of the English People.
Q 19Which Damascus timekeeper built a sundial for a minaret of the Umayyad Mosque?
Ibn al-Shatir
Ibn al-Shatir's dial was later taken down, and a replica now stands in its place on the minaret.
Q 20Which Holbein painting shows a celestial globe, a polyhedral sundial and a torquetum on a shelf?
The Ambassadors
The Ambassadors also hides a stretched skull between the two men that only snaps into shape when you view the painting from the side.
Q 24Which Shakespeare king wishes he could sit on a hill carving out dials?
Henry VI
Henry VI says it sitting on a molehill at Towton, then watches a son who has killed his father and a father who has killed his son.
Q 25If you photographed the Sun at the same clock time all year, what shape would it trace?
A figure eight
A figure eight: Earth's tilt makes the two loops, while its slightly oval orbit makes one loop larger than the other.
Q 26Varro judged which Roman playwright wrote the comedy in which a hungry parasite curses whoever set up a sundial?
Plautus
Plautus, Varro was sure: the parasite of The Boeotian Woman grumbles that the sundial cuts and hacks his days into small portions.
Q 27In which country do sundials in the far west read noon when clocks there show about three in the afternoon?
China
China: Beijing time covers the whole country, so in Xinjiang many people also keep a local Xinjiang Time that runs two hours behind.
Q 28In which city do the hour numbers on a horizontal sundial run anticlockwise?
Sydney
Sydney: in the Southern Hemisphere a dial's gnomon points south and its shadow turns the other way, while clock hands copied northern sundials.
Q 29Which sundial type has a plate at right angles to the style, with evenly spaced hour lines?
Equatorial
Equatorial: the Sun lights its plate from above in summer and from below in winter, so an opaque dial needs hour lines on both faces.
Q 30Which sundial type has a vertical rod moved daily and hour markers set out in an ellipse?
Analemmatic dial
Analemmatic dial: some are laid out on the ground so that a person standing on the date scale becomes the shadow-casting gnomon.