Sir Patrick Moore, who has died aged 89, had the air of a crusty, uncompromising bachelor and slightly dotty boffin who could have walked straight out of a Victorian or Edwardian novel. An amateur but distinguished astronomer, star of television programmes including GamesMaster, prolific author, composer and manic xylophone player, he was a true, quite unselfconscious British eccentric – and a populariser of science without equal in an era of great but often abstruse discovery.

In his capacity as an astronomer, he helped map the moon and was for more than half a century until his death the presenter of BBC TV's The Sky at Night, missing only a single episode through illness, in July 2004. The following year the programme spawned a monthly magazine.

The Sky at Night appealed hugely to laymen as well as experts. This was largely because of Moore's ability to make inspired connections and analogies: linking the Milky Way to a fried egg, a solar eclipse to a Spanish taxi-driver and the moon to a dog walking uphill. Few people with degrees in science – he had no degrees in anything except many honorary doctorates – could have held the audience so imaginatively and with so little self-importance.

Moore was interested in astronomy from the age of six, and became a member of the British Astronomical Association at 11. In his old age he became a more broadly based television personality, complete with eyeglass, bushy brows, enormous bulk and a liking for mustard tweed suits that would have been looked upon with caution by an old-fashioned bookmaker.

As a musician, his output included operas, and once, at the Theatre Royal Bath, he played 21 xylophone pieces, 19 of which he had written himself. In evening dress with his shirt-front threatening to take off at any moment, he played the same instrument on the Room 101 "pet hates" television programme in 2002 after telling Paul Merton that he hated plastic food wrappers, "too many female teachers" and the Archbishop of Canterbury for not denouncing hunting.

It was one of the ironies of Moore's altogether strange life that, while he was quite comfortable thinking in cosmic terms as an astronomer, and could envisage forms of life similar to our own out there in space, he was in political thinking a Little Englander, always harking back to 1940 and Britain's finest hour as the yardstick by which to judge contemporary happenings.

But Moore was never a stereotype rightwinger or anything else, as his strong denunciation of hunting as an unnecessary cruelty ("but you can't argue with these filthy people") demonstrated. He was in several respects simply the archetypal cocksure small boy who never grew up, typing his more than 100 books, including many editions of the Guinness Book of Astronomy Facts & Feats, on the 1908 typewriter he had been given as a boy of eight. He also harboured the cuckoo clock he was given for his seventh birthday, the telescope he bought for seven shillings at ten, and the boy's bike he rode until his late 70s, when he had to have a replacement knee and his bicycle was not in first-rate form either.

About his personal life he was always reticent. When TV Astronomer: Thirty Years of the Sky at Night, was published in 1987, readers were told: "This book is in no way meant to be an autobiography, if only because nobody would be in the slightest degree interested."

This emphatic choice of words was characteristic of his machine-gun delivery – he could talk at 300 words a minute (and type at 89.6 words a minute). But it did not put off media interviewers who dug for explanations of why he had never married. Moore would say that his fiancee had been killed in the war and he would not settle for second best.

Until the mid-1960s he lived with his mother in East Grinstead, mid-Sussex, where he was a leading light in the chess club, and then in a handsome house made from several cottages in Selsey, on the West Sussex coast, until she died at 94 in 1981. He lived alone for many years after that, but then shared his home with a godson.

If Moore had an unusual life – ultimately relenting on his suspicion of autobiographies, so that his Eighty Not Out, with paring personal details, appeared in 2003, and as a paperback in 2005 under the title Patrick Moore the Autobiography – he also had an unusual background. Born in Pinner, west London, he was the son of Captain Charles Caldwell-Moore, MC, who died when the boy was very young, leaving him in a tenacious relationship with an ex-opera singer mother, Gertrude, whom he adored and felt to be his only security. She was also an accomplished artist, as was evident from her amusing illustrations, such as a Christmas card showing Martians on canals.

Because of a heart condition, he was largely educated at home by tutors and his mother. Possessed of perfect pitch, he played and composed for the xylophone from the age of 12, but was even more precocious in astronomy. When he was six, his mother gave him George F Chambers's 1898 Story of the Solar System, which he read curled up on a dining room chair – and kept all his life.

In 1936, at 13, he published Small Craterlets in the Mare Crisium, his first scientific paper on the moon. Even his small telescope could show up a great deal of detail on the moon's surface, making it especially attractive to amateur astronomers at a time when professionals tended to neglect it.

But for the second world war, he had intended to go to Cambridge University. In order to enter the RAF, he not only lied about his age, but also got someone else to impersonate him and take the medical for him, so that he could conceal his heart problem. He trained as a navigator on bombers, later sometimes reminiscing about flying over Germany on Pathfinder flights.

He maintained that though he had been compelled to learn how to fly, he was not acceptable to the RAF as a pilot because he always flew with one wing lower than the other. While he was in hospital after an injury, his heart condition was discovered: he relinquished his commission in 1944 and took up the defusing of bombs.

Later he became an air training corps officer in the voluntary reserves, reaching the rank of squadron leader. Some of the sights of suffering he had witnessed sickened him and fuelled his hatred of Germans; and he returned to civilian life in a robust, even bellicose, state of mind.

Unlike many servicemen colleagues, he refused to accept a grant to go to university, protesting, "Either I do a thing myself or I don't do it at all." He turned to teaching, but in 1952 gave that up to become a freelance author, writing children's novels.

On the subject of flying saucers, then very much in vogue, Moore maintained that he kept an open mind, though he may have said this purely to provoke discussion: he was involved in at least one hoax to show how easy it was to get the public to believe they had seen one. At any rate, his friend Douglas Leslie felt that Moore would have enough to say on the subject to put him forward for a discussion programme on BBC television dealing with UFOs. The producer Paul Johnstone was then looking for an astronomer-presenter, and so in April 1957 Moore appeared on the first edition of The Sky at Night.

Johnstone had found both the right presenter and the right moment. The Russians were about to launch Sputnik 1, the first artificial satellite. Moore's programme recorded most of the rapid developments in the space field. The Russian Lunik 3's first pictures of the far side of the moon were quickly on the air, and when Lunik 4 missed the moon by 5,000 miles and all the British astronomers delegated to watch it were defeated by bad weather, Moore had "one of my first experiences of what is known in broadcasting jargon as padding". His ability to think on his feet, and to talk so fast that critics were never quite sure of what they heard, was vital.

With one exception after his teaching days – his directorship of Armagh Planetarium in Northern Ireland (1965-68) – Moore was never an employee. Often hard-up, dependent on battered old cars and bicycles, he gave his time readily to a large number of international organisations including his honorary membership of the Astronomic Society of the USSR. He maintained loose links with Russian astronomers, in spite of many obstacles when the cold war was still on.

He was appointed OBE in 1968, CBE in 1989, and knighted in 2001.

He captained the local cricket team, and was a formidable bowler until he had to have an artificial knee. One explanation for his use of a monocle in later life was the eye injury he suffered when fielding in the slips at too great an age.

In the late 1980s he formed his own political party, the United Country Party, for those who had "common sense" and who wanted an end to inflation, rubbish rotting in the streets and immigration. He was a friend of Norris McWhirter and his rightwing Freedom Association.

In the 1990s he announced that he would not back the Tories again because they were in favour of hunting. He founded the Halley Club (after the comet), which had no subscription, no rules, no aims or objects. He described it himself as the "most useless club in the world – after the European Parliament, of course", and went on to support Ukip.

Though his opposition to immigration and, latterly, Britain becoming "a dumping ground" for economic as distinct from political refugees, alienated many leftwingers, he was too patently against human or animal suffering and too scatter-gun in his beliefs to make such critics more than mildly uncomfortable.

His attitude to party politics in general was indicated by his flirtation with the Monster Raving Loony Party on the grounds that they "had one advantage over all the other parties – they knew they were loonies". His highly individualistic attitude to organisations in general was well summed up when he once observed, "I'm thinking of starting the Politically Incorrect School of Sociology – and the acronym says it all." The initials were indeed just what he thought applied to so much of the modern world.

His tireless work explaining the wonders of the universe - punctuated by his mantra of scientific inquiry, "We just don't know" – was altogether more creditable and important.

Brian Warner, emeritus professor of astronomy, University of Cape Town, writes: There are many individuals in successive generations of professional astronomers who owe a great deal to the books and personal support of Patrick Moore. He introduced children of all ages to astronomy, and some of them became prominent professionals in astrophysics and planetary sciences.

Having, as a schoolboy, lived within bicycling distance of Patrick's house in East Grinstead, I benefited from his encouragement and generosity of time and, indeed, from his introduction to those who were later to become my teachers and mentors. And I still value the inscribed books he gave me during those years. The scope of his books went well beyond introductory and popular texts – his early lunar and planetary publications were well-rounded reviews that included much from the professional literature. Some books, such as the one on Neptune (1989), were useful contributions to the history of astronomy.

Patrick's eccentric presence and encylopedic knowledge, as a radio voice and TV personality present at many of the significant astronomical and space related events over more than half a century, steadily maintained public interest in the subject and helped encourage the large increase in entrants to university astronomy courses. Other sciences should have been so lucky.

• Patrick Moore (Patrick Alfred Caldwell-Moore), astronomer, television presenter and writer, born 4 March 1923; died 9 December 2012

• This article was amended on 10 December 2012. The original said The Sky at Night was first broadcast in April 1947. The year has been corrected to 1957.