British astronomer and broadcaster Sir Patrick Moore has died, aged 89.
He "passed away peacefully at 12:25 this afternoon" at his home in Selsey, West Sussex, friends and colleagues said in a statement.
Sir Patrick presented the BBC programme The Sky At Night for over 50 years, making him the longest-running host of the same television show ever.
He wrote dozens of books on astronomy and his research was used by the US and the Russians in their space programmes.
Described by one of his close friends as "fearlessly eccentric", Sir Patrick was notable for his habit of wearing a monocle on screen and his idiosyncratic style.
Sir Patrick presented the first edition of The Sky at Night on 24 April 1957. He last appeared in an episode broadcast on Monday.
A statement by his friends and staff said: "After a short spell in hospital last week, it was determined that no further treatment would benefit him, and it was his wish to spend his last days in his own home, Farthings, where he today passed on, in the company of close friends and carers and his cat Ptolemy.
"Over the past few years, Patrick, an inspiration to generations of astronomers, fought his way back from many serious spells of illness and continued to work and write at a great rate, but this time his body was too weak to overcome the infection which set in, a few weeks ago.
"He was able to perform on his world record-holding TV programme The Sky at Night right up until the most recent episode .
"His executors and close friends plan to fulfil his wishes for a quiet ceremony of interment, but a farewell event is planned for what would have been Patrick's 90th birthday in March 2013."
Patrick Alfred Caldwell-Moore was born at Pinner, Middlesex on 4 Mar 1923.
Heart problems meant he spent much of his childhood being educated at home and he became an avid reader. His mother gave him a copy of GF Chambers' book, The Story of the Solar System, and this sparked his lifelong passion for astronomy.
When war came he turned down a place at Cambridge and lied about his age to join the RAF, serving as a navigator with Bomber Command and rising to the rank of Flight Lieutenant.
But the war brought him a personal tragedy after his fiancee, Lorna, was killed when an ambulance she was driving was hit by a bomb. He never married.
Sir Patrick, who had a pacemaker fitted in 2006 and received a knighthood in 2001, won a Bafta for services to television and was a honorary fellow of the Royal Society.
His other TV credits include the role of Gamesmaster in the 1990s computer games show of the same name.
BBC science correspondent Pallab Ghosh said Sir Patrick's appearance sometimes aroused as much comment as his astronomy: "He was six-foot-three, and was once described as having 'an air of donnish dishevelment', with his raised eyebrow, scarcely-brushed hair and poorly-fitting suits.
"His enthusiasm was unstoppable, and on occasions he would talk at 300 words a minute."
Queen guitarist Brian May, who published a book on astronomy written with Sir Patrick, described him as a "dear friend, and a kind of father figure to me".
He said: "Patrick will be mourned by the many to whom he was a caring uncle, and by all who loved the delightful wit and clarity of his writings, or enjoyed his fearlessly eccentric persona in public life.
"Patrick is irreplaceable. There will never be another Patrick Moore. But we were lucky enough to get one."
Television presenter and physicist Professor Brian Cox posted a message on Twitter saying: "Very sad news about Sir Patrick. Helped inspire my love of astronomy. I will miss him!"
The acting director general of the BBC, Tim Davie, said his achievements at the corporation "were unmatched", adding that Sir Patrick will be missed by his "countless fans".
UKIP leader Nigel Farage said: "Since I first met Sir Patrick when he dominated a UKIP stage in 1999, he has been a friend and an inspiration - not only to us in UKIP, but across the country and around the world. Today we have seen the passing of a true great, and a true Englishman."
And Dr Marek Kakula, public astronomer at Royal Observatory in Greenwich, described him as a "very charming and hospitable man".
"When you came to his home he would always make sure you had enough to eat and drink. He was full of really entertaining and amusing stories.
"There are many many professional astronomers like me who can actually date their interest in astronomy to watching Patrick on TV, so his impact on the world of professional astronomy as well as amateur is hard to overstate."