Halley's Comet Trivia
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45 free Halley's Comet trivia questions with answers — science & nature quiz, new questions added Sep 2026.
This Halley's Comet trivia quiz covers the only short-period comet you can reliably see with the naked eye. The easy questions handle the basics: how often it comes round, when it last visited, when it is due back, the man who worked out it was the same object returning, and the tapestry that shows it hanging over King Harold in 1066. From there it digs into the science and the strange history: the retrograde orbit, the two meteor showers it feeds, the peanut-shaped nucleus that turned out to be blacker than coal, the 1910 scare over cyanogen gas and the anti-comet pills sold to worried buyers, Mark Twain coming in and going out with it, the Babylonian tablets found in the British Museum, the pope who supposedly excommunicated it, and the fleet of spacecraft that met it in 1986. Every answer was checked against the comet's encyclopaedia entry before publishing and the supporting sentence is stored with each question. If you enjoy this one, our astronomy and space exploration quizzes are the natural next stop.
30 of 45 questions with answers and explanations. Play the quiz
Q 01Roughly how often does Halley's Comet return to the inner Solar System?
Every 74-79 years
Every 74-79 years: that steady beat has let astronomers match the comet to old sky records of its visits going back more than 2,000 years.
Q 02Why was Halley's Comet so faint in 1986?
Behind the Sun
Behind the Sun: at its brightest in February 1986 the comet sat on the far side of the Sun from Earth, and it never came nearer to us than 63 million km.
Q 03What does 1P in 1P/Halley record?
First shown to return
First shown to return: when it came back in 1758 as forecast it proved that comets can circle the Sun, so it heads the list of periodic comets as number 1.
Q 04What convinced Edmond Halley that three past comets were one?
Similar orbits
Similar orbits: the comets of 1531, 1607 and 1682 followed nearly the same path, so in 1705 he forecast a return in 1758.
Q 05Why did Halley never see his comet's 1758 return?
He had died
He had died in 1742, aged 85, sixteen years before the comet came back on schedule and was given his name.
Q 06The comet's on-time return in 1758 was hailed as proof of which scientist's theories?
Isaac Newton
Isaac Newton: Halley had used Newton's gravity to forecast the return, so when a German amateur spotted the comet on Christmas night 1758 it was cheered as a triumph for Newtonian physics.
Q 07French mathematicians warned the comet would run late in 1758 because of what?
The pull of Jupiter and Saturn
The pull of Jupiter and Saturn: Alexis Clairaut, Joseph Lalande and Nicole-Reine Lepaute worked out that the giant planets would hold the comet back until spring 1759, and came within a month of the true date.
Q 08Whose 1577 measurements showed comets fly beyond the Moon, not in Earth's air as Aristotle taught?
Tycho Brahe
Tycho Brahe: he found the great comet of 1577 showed no parallax shift against the stars, so it had to lie far beyond the Moon.
Q 09What shape is Halley's Comet's orbit?
A long ellipse
A long ellipse: the stretched loop keeps it far out in the cold for most of each lap, which is why it disappears for decades and then sweeps back past the Sun.
Q 10At its closest to the Sun, Halley's Comet passes between the orbits of which two planets?
Mercury and Venus
Mercury and Venus: at about 88 million km from the Sun it is racing along at roughly 54 km/s, and its ices boil off to form the coma and tail.
Q 11At its farthest, about 35 times Earth's distance from the Sun, Halley's Comet is roughly as far out as which body?
Pluto
Pluto: Halley turns back about 5 billion km out, beyond Neptune and roughly where Pluto orbits, slowing to under 1 km/s before it falls sunward again.
Q 12What is unusual about the direction Halley's Comet travels around the Sun?
It orbits opposite to the planets
It orbits opposite to the planets: anything launched from Earth meets it nearly head-on, which is why the 1986 probes flew past at around 70 km/s, some 250,000 km/h.
Q 13Twice a year Earth crosses the trail of dust shed by Halley's Comet, producing what?
Meteor showers
Q 21Spacecraft found the gas streaming off Halley's nucleus was mostly which substance?
Water vapour
Water vapour: about 80% of the gas, because under the crust of dust lies water ice that the Sun turns straight into vapour.
Q 22Why is the water in comets like Halley a poor match for Earth's oceans?
It holds too much heavy hydrogen
It holds too much heavy hydrogen: Halley's water carries far more deuterium than seawater does, so comets of its kind probably did not fill Earth's oceans.
Q 23Which spacecraft made the closest pass of Halley's nucleus, on 14 March 1986?
Giotto
Giotto: the European probe swept within about 600 km of the nucleus, far closer than any other craft in the fleet, and sent back close-up pictures of a comet's core.
Meteor showers: the Eta Aquariids each May and the Orionids each October are both grains of Halley's Comet burning up in Earth's atmosphere.
Q 14Halley's 1910 visit was the first time anyone managed to do what to the comet?
Photograph it
Photograph it: photography was only unveiled in 1839, four years after the comet's previous visit, so 1910 was the first chance, and astronomers also split its light that year to read its chemistry.
Q 15If Halley was once a long-period comet, where is it thought to have originated?
The Oort cloud
The Oort cloud: this distant shell of icy bodies feeds long-period comets, and the giant planets' gravity is thought to have pulled Halley into its present short orbit.
Q 16What nudges Halley's Comet off the schedule that gravity alone would set?
Jets of gas from its surface
Jets of gas from its surface: as ice boils off the sunlit side the jets act like small rocket engines, a push Fred Whipple explained in 1950 and forecasters now allow for.
Q 17Halley's tail can stretch millions of kilometres, but roughly how long is its solid nucleus?
About 15 km
About 15 km: probes found only about a tenth of the peanut-shaped nucleus was giving off gas, yet that small patch feeds the whole vast tail.
Q 18Halley's nucleus has an average density of about 0.55 g/cm3. What does that suggest about its structure?
It is a loosely bound rubble pile
The nucleus is many small pieces held together very weakly, which is why comets so often break apart.
Q 19Halley's icy nucleus reflects about as much sunlight as which material?
Coal
Coal: the nucleus reflects only a few percent of the sunlight that hits it, because a crust of dark dust covers the ice and leaves it pitch black.
Q 20The 1986 flybys broadly confirmed Fred Whipple's famous model of a comet as a what?
Dirty snowball
Dirty snowball: Whipple proposed in 1950 that a comet is ice mixed with dust, though Halley proved so dusty that some now call it a snowy dirtball instead.
Q 24Which nation's probe captured the first-ever image of Halley's nucleus, in March 1986?
The Soviet Union
The Soviet Union: Vega 1 and its twin flew in first as pathfinders, and their fix on the nucleus let Europe's probe aim far closer days later.
Q 25Japan's first deep-space probe, sent toward Halley in 1985, was named Sakigake, meaning what?
Pioneer
Pioneer: Sakigake was Japan's first craft to leave Earth's pull, and it watched Halley from 7 million km while its twin Suisei went in to about 150,000 km.
Q 26What informal nickname was given to the fleet of spacecraft that studied the comet in 1986?
The Halley Armada
The Halley Armada: five probes from three space agencies met the comet in March 1986, while other spacecraft watched from a distance.
Q 27Which Space Shuttle was carrying an instrument to study Halley's Comet when it was lost with its crew?
Challenger
Challenger: its final flight in January 1986 carried Spartan Halley, a small satellite meant to record the comet in ultraviolet light.
Q 28The first certain record of Halley's Comet, a 'broom star' seen in 240 BC, comes from which country?
China
China: Greek writers may have seen the same comet around 466 BC, but the Chinese entry for 240 BC is the first that astronomers can tie to Halley for certain.
Q 29Halley's visit in 164 BC was recorded on clay tablets, now in the British Museum, by which ancient people?
The Babylonians
The Babylonians: their astronomical diaries hold the only surviving record of that visit, and two thousand years on they let astronomers check the orbit computed for the comet.
Q 30In AD 66 Josephus described a sword-shaped star, often taken to be Halley, hanging over which doomed city?
Jerusalem
Jerusalem: Josephus wrote of a star resembling a sword standing over the city, read afterwards as an omen of its destruction by the Romans.