Dec. 8 (UPI) -- For millions of people around the world, it's a moment they will always remember -- where they were, what they were doing and how they felt about it -- when they heard the news that music superstar and former Beatle John Lennon had been gunned down outside his New York City home 40 years ago Tuesday.
The date, Dec. 8, 1980, was a momentous one in the history of music and the annals of crime. Now, four decades later, Lennon's murder and his life are the subject of much focus.
Julian Lennon, John's first son with wife Cynthia, acknowledged Tuesday's anniversary by posting a photo of his father and the words, "As Time Goes By..."
"We all had to say goodbye to John peace and love John," former Beatles drummer and musician Ringo Starr said in a tweet Tuesday, with a photo of him and Lennon. "I'm asking every music radio station in the world sometime today play 'Strawberry Fields Forever.' Peace and love."
"'Imagine all the people living life in peace,' tweeted Lennon's official Twitter account. "Please share your tributes for John using the hashtag #JohnLennon."
Mourners will pay tribute to Lennon on Tuesday at his former home, the Dakota in Manhattan, which is also where he was shot by assassin Mark David Chapman. A few hours before he was shot, Lennon signed a copy of his album Double Fantasy for Chapman, a former fan who grew disillusioned with the singer over his perceived materialism and lack of religious faith.
That album, in fact, to which Lennon signed his name, and the year "1980" -- something fans and historians say he rarely ever included on his autographs -- will soon sell at auction and is expected to fetch more than $1 million.
New York City's WABC-TV is streaming a new documentary about Lennon's death, called Eyewitness to the Death of John Lennon. It is available to stream now and will air on WABC this weekend.
Before he was killed, Lennon had greeted Chapman outside his apartment building earlier in the evening on his way to a recording studio. Later when Lennon returned, Chapman was still there -- waiting for just the right moment to strike. As Lennon was walking several feet behind Ono on the way through the security area of the Dakota, Chapman produced the .38-caliber revolver and opened fire.
The shooting was described then by some as a "premeditated execution," as Chapman, visiting New York from Hawaii, had been lurking outside Lennon's home for three days.
"The gunman's motives remained a mystery, but reports Tuesday painted Chapman as a quiet, suicidal young man who had trouble keeping a job and identified obsessively with Lennon," UPI reported at the time.
"When Chapman left his last job as a security guard-maintenance man, he signed out as 'John Lennon,'" said Mike Bird, who replaced the suspect at the job in a Waikiki vacation apartment. In another job as a guard for a utility, Chapman reportedly taped Lennon's name over his identification badge.
Legendary sportscaster Howard Cosell famously announced Lennon's death during Monday Night Football.
"We have to say it. Remember this is just a football game, no matter who wins or loses. An unspeakable tragedy confirmed to us by ABC News in New York City. John Lennon, outside of his apartment building on the West Side of New York City -- the most famous, perhaps, of all of the Beatles -- shot twice in the back, rushed to Roosevelt Hospital -- dead on arrival."
Ono, whose social media accounts are filled with photos and words about Lennon, paid tribute on Oct. 9, what would have been his 80th birthday. It's also Sean Lennon's birthday.
"Happy Birthday John! Happy Birthday Sean! Yes, you are my angels. I love you!"
After the shooting, Ono declared there would be no funeral for Lennon but millions of people around the world paid tribute to Lennon in the days and weeks that followed, including more than 100,000 at a vigil at nearby Central Park.
"John loved and prayed for the human race. Please pray the same for him," she said at the time.
"By far the biggest crowd gathered at Central Park in New York. More than 100,000 people, including actress-activist Jane Fonda and Mayor Edward Koch, braved stinging cold to listen to recorded music and pray in silence," UPI's Mark Mooney reported on Dec. 14, 1980.
"Though Central Park is renowned as a haven for muggers, [one attendee] said none of them were afraid. 'We felt John's spirit was with us.'"
Born Oct. 9, 1940 in Liverpool, Britain, Lennon went on to form the band that would eventually become The Beatles in 1960, with Starr, Paul McCartney and George Harrison. Within a few years, the group had achieved international fame.
In an interview last weekend, McCartney recalled the impact that mega stardom had on the mental health of every member in the band.
"You know, John [wrote] 'Help! I need somebody.' And I thought, 'Well, it's just a song,' but it turned out to be a cry for help," he said.
After The Beatles disbanded in the early 1970s, Lennon moved to New York City with Ono and launched a solo career, which produced one of his most popular songs, "Imagine."
On Tuesday, the New York Adventure Club is hosting a live webinar titled "John Lennon: Liverpool x New York" to explore Lennon's "life and legacy," with a focus on his nearly 10 years living in New York City -- which virtually became his adopted home after he left Britain in the 1960s.
In one of his final interviews, Lennon expressed a great deal of love for the city and its people.
Additionally, Indiana University provost professor Glenn Gass will host "Remembering John Lennon 40 Years Later", an online event reflecting on Lennon's career and death.
Now 65, Chapman pleaded guilty to Lennon's murder and was sentenced to 20 years to life in prison. Now housed at a prison in upstate New York, he's been eligible for parole every two years since 2000. He's so far been denied parole 11 times, his most recent denial in August. He will have another parole hearing in 2022.