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60 free Sundials trivia questions with answers — technology quiz, new questions added Aug 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 60 questions with answers and explanations. Play the quiz
Q 01What is the shadow-casting part of a sundial called?
Gnomon
The word comes from Ancient Greek for 'one that knows or examines'; only its time-telling edge is called the style.
Q 02How many degrees does the Sun appear to move around Earth's axis each hour?
15°
That is why the hour lines on a dial whose plate faces the celestial pole are evenly spaced.
Q 03For a sundial to be accurate all year, its style must be parallel to what?
Earth's rotational axis
That alignment is what makes the shadow sweep round at a constant rate whatever the season.
Q 04What must a horizontal sundial's style angle above the horizontal equal?
The local latitude
A dial built for London therefore does not keep good time in Cairo unless it is tilted.
Q 05What is the single time-telling point, such as a style tip, on a sundial called?
Nodus
The path traced by a nodus over a day is a conic section such as a hyperbola.
Q 06From roughly what date do the earliest known Egyptian and Babylonian shadow clocks survive?
1500 BC
Egyptian obelisks were long assumed to be sundials too but are now thought to have been purely memorials.
Q 07Which Greek thinker is credited with bringing the sundial to Greece around 560 BC?
Anaximander
He was a pupil of Thales in Miletus and also drew one of the first maps of the known world.
Q 08Which Roman author catalogued the known sundial types in Book IX of De Architectura?
Vitruvius
He wrote around 25 BC, and every dial on his list was a shadow-tip type that differed mainly in the shape of its receiving surface.
Q 09Which Sun-centred-model astronomer is credited with the bowl-shaped scaphe dial?
Aristarchus
None of his original works survive; the dial was a hemispherical bowl with a vertical pin whose tip was level with the rim.
Q 10According to Pliny, in what year was a sundial first recorded in Rome?
293 BC
A character in a Plautus comedy later complained that his day was 'chopped into pieces' by the ubiquitous dials.
Q 11What did the Greeks call the axe-shaped pattern of hyperbolae traced by a shadow tip?
Pelekinon
The curves are narrow near the noon line and flare out toward the early morning and evening hours.
Q 12Which emperor set up an Egyptian obelisk as a shadow-caster in the Campus Martius in 10 BC?
Augustus
The obelisk had originally been erected under the pharaoh Psamtik II and now stands in Piazza di Montecitorio.
Q 13On which date did the Solarium Augusti's shadow fall across the centre of the Ara Pacis?
23 September
That was the emperor's own birthday, linking his birth to the arrival of peace.
Q 21The villages around which French Alpine town were famed for painted sundials in the 1800s?
Briançon
The Hautes-Alpes department has at least 400 painted dials, a hundred of them by Giovanni Francesco Zarbula.
Q 22What is the up-to-16-minute correction between a sundial and an ordinary clock called?
Equation of time
It arises from Earth's elliptical orbit and tilted axis, and it is the same everywhere on Earth.
Q 23Around which date is a sundial furthest ahead of clock time, by 16 min 33 s?
3 November
The dial runs slowest, roughly a quarter of an hour behind, around 11 February.
Q 14Which pope re-erected the Montecitorio obelisk in Rome in 1789?
Pius VI
The obelisk had been thrown down after the 8th century and lay buried until it was rediscovered in 1512.
Q 15Which octagonal marble monument in Athens carried eight sundials and a water clock?
Tower of the Winds
It is the only surviving horologium from classical antiquity and was completed by about 50 BC.
Q 16What bronze figure originally topped Athens' octagonal clock tower as a weather vane?
A Triton
The figure held a rod that pointed out the wind direction; it has completely disappeared.
Q 17Which Anglo-Saxon cross in Cumbria carries the earliest surviving English sundial?
Bewcastle
The dial is a canonical one divided into the 'tides' that governed the medieval working day.
Q 18Which English monk promoted canonical sundials for fixing the times of prayer?
The Venerable Bede
His shadow table assumed a monk's height was six times the length of his foot.
Q 19Which Damascus timekeeper built a sundial for the Umayyad Mosque minaret in 1371?
Ibn al-Shatir
His dial used hours of equal length all year, unlike the seasonal hours of the old Greek dials.
Q 20Which Italian astronomer's 1570 treatise explained how to lay out wall and horizontal dials?
Giovanni Padovani
Sundials have been in common use in Europe since that century.
Q 24How many times a year does a sundial agree exactly with mean clock time?
Four
The zeros fall near 15 April, 13 June, 1 September and 25 December.
Q 25What shape does the analemma, the Sun's yearly path at a fixed clock time, resemble?
A figure eight
The long axis spans about 47 degrees, twice the tilt of Earth's axis.
Q 26Where on a terrestrial globe is the analemma usually printed?
The eastern Pacific
It is the only large tropical region with very little land to obscure.
Q 27How many minutes of time does one degree of longitude represent when correcting a sundial?
4 min
A dial 5 degrees west of its zone's reference meridian therefore reads 20 minutes slow all year.
Q 28Which way do the hour numbers run on a horizontal sundial in the Southern Hemisphere?
Anticlockwise
A dial made for one hemisphere has to be reversed to work at the same latitude in the other.
Q 29Which sundial type has its plate perpendicular to the style and evenly spaced hour lines?
Equatorial
It is also called an equinoctial dial because the plate is parallel to Earth's equator.
Q 30Which sundial type has a vertical rod moved daily and hour markers set out in an ellipse?
Analemmatic dial
Some are built so that a person standing on the date scale becomes the shadow-caster.