Aristarchus of Samos
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40 free Aristarchus of Samos trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Aristarchus of Samos is the ancient Greek astronomer who argued, in the third century BC, that the Earth is a planet in motion around the Sun. The idea found few takers in his own day and waited many centuries for its comeback. These questions gather the fun facts about Aristarchus that people go looking for: how he tried to measure the heavens with nothing but geometry and patience, who taught him, who argued with him, how his lost theory reached us at all, and what on the Moon now carries his name. The quiz suits students meeting Greek astronomy for the first time, teachers after a quick classroom round, and anyone who enjoys the story of a good idea that arrived far too early. Every answer comes with a short explanation.
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Q 01Aristarchus is called the ancient version of which astronomer, who revived his Sun-centred idea in 1543?
Nicolaus Copernicus
Nicolaus Copernicus published the same basic idea some eighteen centuries after Aristarchus, and probably arrived at it independently.
Q 02Which Greek mathematician preserved the outline of Aristarchus's lost Sun-centred theory?
Archimedes
Archimedes summarised the theory in a short treatise written for his king, and that summary is the main reason anyone knows Aristarchus proposed it.
Q 03A famous Greek treatise estimated how many grains of what would fill the vast universe of Aristarchus?
Sand
Sand, at most 10 to the 63rd power grains of it, was the estimate, and the author had to invent a new way of naming huge numbers just to state it.
Q 04Aristarchus put the Sun 18 to 20 times farther away than the Moon; what is the true multiple?
About 400
About 400 times is the true figure, because the angle he measured as 87° is really close to 89° 50′, far too fine a difference for the instruments of his day.
Q 05The lunar crater named after Aristarchus, about 40 km wide, is deeper than which famous chasm?
Grand Canyon
The Grand Canyon is shallower than this crater, which spans almost 25 miles and sinks more than 2 miles (3.5 km) deep.
Q 06Which famous Greek thinker, born around 570 BC, shares his home island with Aristarchus?
Pythagoras
Pythagoras was born on Samos roughly 260 years before Aristarchus, and is said to have left the island at about 40 during the rule of the tyrant Polycrates.
Q 07To compare the distances of the Sun and Moon, Aristarchus measured an angle at which lunar phase?
Half
At half phase the Moon sits at the corner of a right triangle with Earth and Sun, so one measured angle, which he took as 87°, fixes the ratio of the two distances.
Q 08In the model of Aristarchus, what does the Earth do once every day?
Spins on its axis
The Earth spins on its axis once a day in his model, which explains why the stars seem to wheel overhead; the yearly trip around the Sun is a separate motion.
Q 09Aristarchus's figure for the Sun's distance was accepted for some 2,000 years, until which invention?
The telescope
The telescope finally let astronomers measure the Sun's distance precisely, replacing a value close to his that had been repeated for two millennia.
Q 10Aristarchus worked out the Moon's size relative to Earth by studying which kind of event?
A lunar eclipse
A lunar eclipse showed him how wide the Earth's shadow is compared with the Moon, from which he judged the Moon to be roughly a third as wide as the Earth.
Q 11Aristarchus built his estimates on the fact that the Sun and Moon share nearly the same what?
Apparent size
Apparent size was his starting point: because the two discs look equal, their true widths must be in the same proportion as their distances from us.
Q 12The home island of Aristarchus lies in which sea, about a mile off the coast of modern Turkey?
The Aegean Sea
The Aegean Sea surrounds Samos, which the Mycale Strait, only about a mile wide, separates from the Turkish mainland.
Q 13Aristarchus probably studied in which city, where his teacher also tutored the future Ptolemy II?
Alexandria
Alexandria is the likely place, because his teacher spent years in Egypt as tutor to the young prince before returning to Athens to lead a famous school.
Q 21Which Greek writer's work about the face seen in the Moon tells of Aristarchus and an impiety charge?
Plutarch
Plutarch also records that Aristarchus offered his moving Earth only as a hypothesis, while a later follower asserted it as fact.
Q 22The crater right beside Aristarchus on the Moon bears the name of which ancient Greek historian?
Herodotus
Herodotus is the lava-flooded neighbour just to the west, darker and slightly smaller than Aristarchus, so the two craters make a striking pair.
Q 23Apollo 15 detected signs of which gas seeping from the Moon near the crater Aristarchus?
Radon
Radon gave itself away through a rise in alpha particles as the spacecraft passed 110 km overhead in 1971, and a later orbiter confirmed the leak.
Q 14The Roman architect Vitruvius credited Aristarchus with a bowl-shaped version of which instrument?
A sundial
A sundial shaped like a hollow hemisphere, with a pointer in the middle to cast the shadow, is the invention Vitruvius describes, along with a flat disc version.
Q 15Besides a lunar crater, which kind of Solar System body carries the name 3999 Aristarchus?
An asteroid
An asteroid in the main belt between Mars and Jupiter carries his name; it was discovered in January 1989 and given the number 3999.
Q 16The lunar crater Aristarchus is the brightest large feature on the Moon mainly for which reason?
It is relatively young
It is relatively young, so the solar wind has not yet had time to darken the rock that the impact dug up.
Q 17The teacher of Aristarchus went on to lead which Athenian school, founded by Aristotle?
The Lyceum
The Lyceum made him its third head in about 287 BC, following Aristotle himself and Theophrastus.
Q 18According to Ptolemy, Aristarchus observed which annual astronomical event in the year 280 BC?
The summer solstice
The summer solstice he timed in 280 BC followed a Greek tradition: Meton had made the same observation at Athens about 150 years earlier, in 432 BC.
Q 19The ideas of Aristarchus lost out to the Earth-centred system later set down in which work by Ptolemy?
The Almagest
The Almagest, written in the 2nd century AD, fixed the Earth at the centre so convincingly that its model was inherited by medieval astronomy.
Q 20Aristarchus placed the stars immensely far away to explain the absence of which annual shift?
Parallax
Parallax is real but tiny: the first successful measurements of a star's shift came only in the 1830s, about two thousand years after Aristarchus.
Q 24The crater Aristarchus stands out even on the Moon's unlit part when it glows faintly with what?
Earthshine
Earthshine, sunlight reflected from our planet onto the Moon's unlit portion, is enough to pick out this crater, whose surface reflects nearly twice as much light as most lunar features.
Q 25A later Aristarchus, the most influential ancient scholar of Homer, came from which Greek island?
Samothrace
Samothrace produced the other Aristarchus, who was born about a decade after the astronomer died and rose to run the great royal library in Egypt.
Q 26Which is the only work of Aristarchus to survive, though it never mentions his Sun-centred theory?
On the Sizes and Distances
On the Sizes and Distances of the Sun and Moon keeps the Earth at the centre throughout, which suggests it was written early in his career.
Q 27A rule of trigonometry comparing sines and tangents of acute angles is known as Aristarchus's what?
Inequality
Inequality is the word, and Ptolemy later relied on the same rule while constructing his table of chords.
Q 28Which philosopher, born on Samos about thirty years before Aristarchus, founded a school in Athens?
Epicurus
Epicurus was born on Samos to Athenian settlers in 341 BC and later taught in a garden he owned, about halfway between two rival schools.
Q 29Which later astronomer reused the geometry of Aristarchus and put the Moon 67 Earth radii away?
Hipparchus
Hipparchus followed the same procedure in the 2nd century BC, and Ptolemy later used it again to put the Moon 59 Earth radii away.
Q 30Long before Aristarchus, which philosopher taught that the stars are fiery bodies of the same nature as the Sun?
Anaxagoras
Anaxagoras had pictured both Sun and stars as red-hot masses, with the stars simply too far away for their heat to be felt.