50 free Halley's Comet trivia questions with answers — science & nature quiz, new questions added Aug 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 50 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
The period drifts because Jupiter and Saturn tug on the orbit; it has run anywhere from 72 to 80 years since 240 BC.
Q 02In which year did Halley's Comet last visit the inner Solar System?
1986
It was the worst-placed apparition in 2,000 years, with the comet and Earth on opposite sides of the Sun.
Q 03When is Halley's Comet next expected to reach perihelion?
2061
Perihelion is predicted for 28 July 2061, and this time Earth will be on the same side of the Sun, so the show should be far better than 1986.
Q 04What is the comet's official designation in the periodic-comet catalogue?
1P/Halley
The 'P' means periodic and the '1' means it was the first periodic comet ever recognised.
Q 05In which year did Edmond Halley publish the work that showed the comet was periodic?
1705
His Synopsis of the Astronomy of Comets used Newton's new laws to compare the comets of 1531, 1607 and 1682.
Q 06Edmond Halley never saw his prediction come true. In what year did he die?
1742
He had personally watched the comet near perihelion in September 1682, decades before he worked out it would return.
Q 07Who first spotted the comet on its predicted 1758 return?
Johann Georg Palitzsch, a German farmer
He caught it on Christmas Day 1758; the return was the first proof that anything other than planets orbits the Sun.
Q 08Which French astronomer first named the comet in Halley's honour, in 1759?
Nicolas-Louis de Lacaille
Lacaille is better known for naming 14 southern constellations after scientific instruments.
Q 09Which of these people was on the three-person French team that calculated the delayed 1759 return?
Nicole-Reine Lepaute
Working with Clairaut and Lalande, Lepaute helped compute a 618-day delay caused by Jupiter and Saturn, and got the perihelion date within a month.
Q 10Which observation disproved Aristotle's idea that comets were disturbances in Earth's atmosphere?
Tycho Brahe's parallax measurements in 1577
Parallax showed the comet had to lie beyond the Moon, though many still assumed comets flew in straight lines through the Solar System.
Q 11What is the orbital eccentricity of Halley's Comet?
0.967
Zero would be a circle and 1 a parabola, so its path is a long, thin ellipse stretching out past Neptune.
Q 12Halley's perihelion lies between the orbits of which two planets?
Mercury and Venus
At 0.59 au from the Sun the comet's ices sublimate furiously, producing the coma and tail.
Q 13Halley's aphelion, about 35 au from the Sun, is roughly the orbital distance of which body?
Pluto
Out there it crawls along at under 1 km/s; it reached that farthest, slowest point most recently on 9 December 2023.
Q 21Halley's Comet reflects only about 4% of sunlight. What common material has roughly the same albedo?
Coal
Astronomers had expected something more like bare soil at 0.17; instead the nucleus turned out to be pitch black.
Q 22Whose 'dirty snowball' model of comets did the 1986 flybys broadly confirm?
Fred Whipple
The twist was that so much of the surface is dark dust that Halley is arguably a 'snowy dirtball' instead.
Q 23Spacecraft found the gas streaming off Halley's nucleus was mostly which substance?
Water vapour
About 80% water vapour, with carbon monoxide and carbon dioxide making up most of the rest.
Q 14What is unusual about the direction Halley's Comet travels around the Sun?
It orbits retrograde, opposite to the planets
Seen from above the Sun's north pole it moves clockwise, and its orbit is tilted 18 degrees to the ecliptic.
Q 15Which two meteor showers are associated with debris from Halley's Comet?
The Eta Aquariids and the Orionids
Earth crosses the comet's path twice a year, in early May and again in late October.
Q 16How many Halley-type comets (periods of 20-200 years, steep inclinations) had been observed as of 2024?
105
That compares with 816 Jupiter-family comets, which have shorter periods and shallow orbits.
Q 17If Halley was once a long-period comet, where is it thought to have originated?
The Oort cloud
Jupiter-family comets are instead thought to come from the flatter Kuiper belt just beyond Neptune.
Q 18On average, how much do jets of sublimating gas delay Halley's perihelion passage each orbit?
About four days
These non-gravitational kicks are why the orbit cannot be integrated accurately much further back than 837 AD.
Q 19Roughly how long is the nucleus of Halley's Comet?
About 15 km
For a body that can throw a tail 100 million km long, the nucleus is tiny: about 15 by 8 by 8 km, shaped like a peanut or potato.
Q 20Halley'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 24Why did later measurements rule out Halley-type comets as the main source of Earth's oceans?
Their water has far more deuterium than seawater
The deuterium-to-hydrogen ratio was at first thought to match Earth's oceans, then found to be far higher.
Q 25Which spacecraft made the closest pass of Halley's nucleus, on 14 March 1986?
Giotto
The European Space Agency probe was named after a 14th-century Italian painter who put the comet into a nativity fresco.
Q 26Which nation's probe captured the first-ever image of Halley's nucleus, in March 1986?
The Soviet Union
Vega 1 began returning pictures on 4 March and flew past on 6 March, three days before its twin Vega 2.
Q 27What were the two Japanese probes sent to Halley in 1986 called?
Suisei and Sakigake
Suisei means 'comet' and Sakigake 'pioneer'; they joined the European and Soviet probes at the comet in March 1986.
Q 28What informal nickname was given to the fleet of spacecraft that studied the comet in 1986?
The Halley Armada
Astron, an ultraviolet space telescope, and the International Cometary Explorer also joined in from a distance.
Q 29Which Space Shuttle mission carrying a Halley ultraviolet experiment ended in disaster in 1986?
STS-51-L, Challenger
A second comet mission, STS-61-E, was cancelled afterwards and its ASTRO-1 platform did not fly until 1990.
Q 30Which instrument first picked up the incoming comet on 16 October 1982?
The 5.1 m Hale Telescope at Palomar
David Jewitt and G. Edward Danielson used a CCD camera, then a novel instrument, to pick it up.