(CNN) Oh, how the world mourned for the Purple One, pop superstar Prince. Social media exploded with shock, disbelief and grief. Monuments around the globe were tinted purple.
Fans gathered at the First Avenue club in Minneapolis and New York's Apollo Theater for all-night dance parties in his honor.
Radio stations interrupted their lineups to play "When Doves Cry" and "Cream," while his albums shot to the top of iTunes. MTV began a music video marathon, just as it did in 2009, when Michael Jackson died, and in 2012, when Whitney Houston died.
It was an outpouring of communal grief that we reserve especially for our music superstars.
"Do people mourn celebrities differently than other people? Yes. And then we mourn singers even more differently," said David Kaplan, chief professional officer at the American Counseling Association. "We identify with them. They become a part of us in a sense, a part of our family."
"The singers that become the subjects of 'mourn-a-thons' are those who have been around for a while and are quite famous," said sociologist Jacque Lynn Foltyn, who teaches at National University in California. "These are our 'intimate strangers.' We may have been following them for decades, grown up with them. When they die, we mourn as if we knew them, because they have been part of our lives."
It was a similar scene in 2009. Huge crowds watched the story unfold in Times Square, gasping and sobbing as Michael Jackson's death was announced in a news banner: "King of Pop, Dead at 50." Fans gathered at the Apollo, where the Jackson 5 often performed, and masses gathered outside UCLA Medical Center in Los Angeles, watching the ascent of the helicopter taking Jackson's body to autopsy while "Thriller" and "Beat It" played in the background.
"Music and emotion are connected, and music evokes emotion," Foltyn said. "Singers are connected deeply to our emotional life, and the popular music that tends to mean the most to us is the music of our youth. That's the time of our romantic and sexual awakening, so singers become part of our coming of age."
"That's what we call classical conditioning," Kaplan said. "When the song gets paired with specific memories and specific times you may not have thought of for years. Then the singer dies, and all of a sudden, those memories come flooding back."
For many of our musical icons, that grief is slow to die. That's certainly the case for the King of Rock 'n' Roll.
Holding candles, hundreds of mourners walk slowly past Elvis Presley's gravesite every August 16, marking the anniversary of his death in 1977. His Memphis home, Graceland, draws about a half-million fans annually.
"One of the issues is, when we identify with a famous person and they die, it makes us think about our own successes, our failures and our own mortality," Kaplan said.
"We remember hearing Prince's 'When Doves Cry' when we were hurt by our lover or Whitney Houston's 'I Will Always Love You' when we were married, and when that artist dies, we are taken back to that time, and we then start to think about what we have or haven't accomplished in our lives. And there are folks who can get caught up in that."
Another factor that might earn our collective, long-term grief is the age and cause of death.
"That's important to their mythology," Foltyn said. "If they die young and beautiful, it's more tragic. Or was it a sudden, unexpected death? If celebrities die in their 80s and 90s, it's not such a big deal. We expect it."
And if the cause was "careless, stupid, illegal or immoral," she said, the death can become a sort of morality play.
"Amy Winehouse and Whitney Houston -- their mythology is that they were cut down before their time, as a result of poor choices," Foltyn said. "So part of the allure of their death is that they died tragically and young, as tortured artists.
"In a way, they become blamed for their own death, and their legacy is that they become educational tools for how you can avoid becoming like them."
Not everyone is lucky enough to be close to a meaningful symbol of our sadness, such as Graceland or the Apollo. But today we can still join in via social media. It's a sort of cultural connective "tissue" that we can all share.
"My view of social media is that it's no different from old days of standing around the water cooler or over the fence or at church," said Kaplan. "It's the same phenomenon."
Foltyn disagrees. She believes social media creates a global community of mourners, a sort of "social contagion" that can affect even those of us who aren't emotionally attached to the singer who has just passed away.
" 'Oh, David Bowie died. I don't know his music. Let me go check him out. Oh, wow, he was really good,' and before you know it, you're caught up in the public grief," Foltyn said. "Then you can gather online and lay a virtual flower or light a virtual candle, and suddenly you are defining yourself by that community, even if you didn't originally feel that much grief."
For the youth of our world, intimately connected to social media, grief might become even stronger because of the nature of today's interactions with our pop icons.
"Some of us pay more attention to the details of singers' and celebrity lives than we do our own friends," Foltyn said. "It's so easy to do, because the stars are on social media all the time, posting about what they eat, what they are doing that weekend, when they work and sleep. And we can tweet back, and some of them even respond to us with a tweet!"
It's what she calls "the paradox of the intimate stranger": "We don't know them, but we feel like we do.
"And when they die, it feels like a close, personal death to us, because this person has become part of our lives," she said. "And they encourage this strong emotion, this strong attachment, and that moves along with them after their death."