EVERY YEAR the world celebrates the anniversaries of masterworks and maestros. In 2020 there will be a host of events and publications commemorating the lives of Ludwig van Beethoven, Raphael, Charles Dickens, Anne Brontë and William Wordsworth. Such milestones usually come in neat multiples of 50. The 42nd anniversary of anything is rarely observed.

Yet on March 8th fans of “The Hitchhiker’s Guide to the Galaxy” (“HHGTTG”) will pay tribute to the comedy science-fiction series, which had its radio premiere on that day in 1978 and was subsequently adapted into novels, TV series, video games and a film. To mark the occasion, Pan Macmillan has reprinted the scripts and novels in colourful new editions (“HHGTTG” was the first book published under their “Pan Original” imprint to sell more than 1m copies). The British Library will host a day of “celebrations, conversation and performance”. BBC Radio 4 has aired the original episodes; Radio 4 Extra will put on a “five-hour Hitchhiker’s spectacular” including archival material and specially commissioned programmes. Such is the enduring interest in Douglas Adams’s story that it is due to be adapted into a new television series by Hulu, a streaming service.

The number 42 is the tale’s signature joke. It is the response that Deep Thought, a supercomputer, has taken millions of years to deliver to a race of “hyper-intelligent pan-dimensional beings” who seek “the Answer to the Ultimate Question of Life, the Universe, and Everything”. (In a risqué throwaway gag typical of Adams, the name “Deep Thought” evokes a notorious pornographic film of 1972; later it inspired IBM's chess computers, including the grandmaster-vanquishing Deep Blue.) When the machine unveils its nonsensical answer, the hyper-intelligent beings are livid. What they really want to know, Deep Thought muses, is the wording of the “Ultimate Question” itself. It turns out that the planet Earth is a very complicated simulation designed to reveal that question, with the hyper-intelligent beings secretly keeping tabs on it while disguised as mice. Unfortunately, a tribe of hideous aliens blow the planet up five minutes before the simulation is due to finish.

The series’ protagonist is Arthur Dent, a denizen of a small West Country town who narrowly escapes the Earth's destruction and is fated to wander the universe, bewildered, in a dressing gown as improbable events take place around him. This droll application of the quotidian to the wonders of the universe is at the heart of Adams’s appeal. He strips away sci-fi’s more portentous attributes without depriving it of either its sweep or its potential profundity. He is often so deliciously funny that readers may find themselves dwelling on the insights he has offered only when they close the books. The Total Perspective Vortex, a notional machine designed to extrapolate the enormity of “Life, the Universe, and Everything” from a single mundane but agreeable object—a slice of fairy cake—serves as a metaphor for his own work.

If Adams’s themes are universal, his reach has proved almost as wide. “HHGTTG” has sold more than 14m copies worldwide and been translated into dozens of languages, including Korean, Hebrew and Japanese—apt for a series which gave Babel Fish, an early online translation site, its name. (Your correspondent was fascinated by the English original as a teenager in Nairobi in the 1980s.) Every year May 25th is observed by Adams fans across the globe as “Towel Day”, named for “the most massively useful thing an interstellar hitchhiker can have”. On Towel Day in 2013, Norway’s Kolumbus public-transport company gave away towels which allowed passengers to ride for free. Two years later Samantha Cristoforetti, an Italian astronaut, delivered a “HHGTTG” reading from the International Space Station. Elon Musk, the boss of Tesla, has described Adams as his “favourite philosopher”. “What Adams was essentially saying,” Mr Musk has said, “is, ‘The universe is the answer; what are the questions?’...A lot of times the question is harder than the answer.”

Adams was an imperfect writer. His plotting was lax, partly a result of a notorious procrastination habit which required him to rush at the last moment, but which helped make him an imaginative improviser. (“I love deadlines,” he wrote. “I like the whooshing sound they make as they fly by.”) His female characters are flimsy. But he excelled at bringing a human scale and sensibility to the vastness of the cosmos, and vice-versa, often via a deftly executed one-liner. God, in the world of Arthur Dent, has only one message for his creations: “We apologise for the inconvenience.” This wry approach to serious subjects is now a recognisable idiom in sci-fi. His late rival Terry Pratchett might not have cared to acknowledge it, but “HHGTTG” opened up the door for Pratchett’s “Discworld”.

The success of “HHGTTG” was a wonderfully unintended consequence for a writer who treated unintended consequences as the stuff of both life and literature. “I may not have gone where I intended to go,” Adams wrote, “but I think I have ended up where I needed to be.”