The most impactful television events of the last 50 years, as measured in a survey conducted by Nielsen and Sony Electronics. The rankings are based on a questionnaire of consumers about events they had watched, if they remember where they were and if they discussed the events with others. 
 
 1. Sept. 11 terrorist attacks (2001). 
 
 2. Hurricane Katrina (2005). 
 
 3. The O.J. Simpson verdict (1995). 
 
 4. The Challenger space shuttle explodes (1986). 
 
 5. Death of Osama bin Laden (2011). 
 
 6. The O.J. Simpson White Bronco chase (1994). 
 
 7. The Japanese earthquake and tsunami (2011). 
 
 8. Columbine school shooting (1999). 
 
 9. BP oil spill in Gulf of Mexico (2010). 
 
 10. Princess Diana’s funeral (1997). 
 
 11. Death of Whitney Houston (2012). 
 
 12. Capture and execution of Saddam Hussein (2006). 
 
 13. Barack Obama Election Night speech (2008) 
 
 14. Wedding of Prince William and Kate Middleton (2011). 
 
 15. John F. Kennedy assassination (1963). 
 
 16. Oklahoma City bombing (1995). 
 
 17. Bush/Gore disputed election (2000). 
 
 18. Los Angeles riots, Rodney King beating (1992). 
 
 19. Casey Anthony murder trial verdict (2011). 
 
 20. John F. Kennedy funeral (1963). ||||| FILE - In this Sept. 11, 2001, file photo, the twin towers of the World Trade Center burn behind the Empire State Building in New York. The Sept. 11, 2001 terrorist attack is by far the most memorable... (Associated Press) 
 
 The Sept. 11, 2001 terrorist attack is by far the most memorable moment shared by television viewers during the past 50 years, a study released on Wednesday concluded. 
 
 The only thing that came close was President John F. Kennedy's assassination and its aftermath in 1963, but that was only for the people aged 55 and over who experienced those events as they happened instead of replayed as an historical artifact. 
 
 Sony Electronics and the Nielsen television research company collaborated on the survey. They ranked TV moments for their impact not just by asking people if they remembered watching them, but if they recalled where they watched it, who they were with and whether they talked to other people about what they had seen. 
 
 By that measure, the Sept. 11 tragedy was nearly twice as impactful as the second-ranked moment, which was the coverage of Hurricane Katrina in 2005. Minutes after the first airplane struck New York's World Trade Center on a late summer morning, television networks began covering the events continuously and stayed with them for days. 
 
 The other biggest TV events, in order, were the 1995 verdict in O.J. Simpson's murder trial, the Challenger space shuttle explosion in 1986 and the death of Osama bin Laden last year, the survey found. 
 
 Sony was interested in the study for clues on consumer interests and behaviors and found "that television is really the grandmother of all the social devices," said Brian Siegel, vice president of television business for the company. 
 
 Going into the study, Siegel said he had anticipated that entertainment events like the final episode of "M-A-S-H" (ranked No. 42), the Beatles' appearance on "The Ed Sullivan Show" (No. 43) and the "Who shot J.R.?" episode of "Dallas" (No. 44) would rank higher. Instead, television coverage of news events made the biggest difference in viewers' lives. 
 
 The Super Bowl is annually the most-watched TV event, with this year's game between the N.Y. Giants and New England Patriots setting an all-time record with 111 million viewers. The memories don't seem to linger, however: the top-ranked Super Bowl Sunday event in Sony's study came in 2004 and had nothing to do with football. It was Janet Jackson's wardrobe malfunction (No. 26). 
 
 Men and women agreed on the three most impactful television events _ Sept. 11, Katrina and Simpson. After that, some of the interests diverged. 
 
 For example, women ranked the 1997 funeral of Princess Diana as the fourth most memorable event, while men put that at No. 23. Women ranked last year's death of Whitney Houston at No. 5, with men judging it No. 21. 
 
 Similarly, the 2003 bombing of Baghdad at the start of the Iraq War was seen as the No. 14 most impactful moment by men, and No. 37 among women. Men were also far more struck by boxer Mike Tyson biting off a piece of Evander Holyfield's ear. 
 
 The passage of time has also diluted some moments once thought as unforgettable, simply because succeeding generations have no personal memory of them. Man's first moon landing in 1969 ranked No. 21. 
 
 Age also made a big difference in the survey. JFK's assassination was the second-most impactful TV event among people 55 and over, while for those between 18 and 34, it was the death of Osama bin Laden. 
 
 Young people also ranked Barack Obama's Election Night speech in 2008 at No. 3, while that didn't move older viewers quite as much (No. 24). 
 
 Simply because of their age, events like the JFK assassination, President Nixon's resignation and the moon landing didn't register at all among viewers 18 to 34. The oldest event to appear in their rankings was the 1980 shooting of John Lennon. 
 
 The study was based on an online questionnaire of 1,077 adults selected as a scientific sample from among Nielsen's panel of people measured for television ratings. It was conducted between Feb. 15-17 this year. 
 
 The study could be a good baseline for future looks at how television impacts viewers, said Paul Lindstrom, senior vice president for custom research at Nielsen. 
 
 "I'd like to see these done on a periodic basis going forward," he said. ||||| A knife was found on the old property of OJ Simpson is likely not connected to the murders of Nicole Brown Simpson and Ronald Goldman. Patrick Healy reports for the NBC4 News at 6 on Friday, March 4, 2016. (Published Friday, March 4, 2016) 
 
 Los Angeles police confirmed Friday morning a knife was found on the former Brentwood property of O.J. Simpson and said they are investigating a report that it was discovered years ago by a construction worker who handed it over to authorities. 
 
 A report, published Friday by TMZ and citing unidentified law enforcement sources, said a construction worker found a knife several years ago buried on the perimeter of the former Simpson home and gave it to a police officer working security for a nearby film shoot. 
 
 Archive: The O.J. Simpson Slow-Speed Chase On June 17, 1994, an apparently suicidal Orenthal "OJ" Simpson and his friend Al Cowlings led police on a 60 mile slow-speed car chase through Los Angeles and Orange counties, captivating viewers glued to television sets. Simpson had failed to surrender to police earlier in the day, when he was slated to be charged in the murders of his ex-wife and her male friend. As police closed down the freeways and 20 cruisers followed Simpson, spectators filled the freeway overpasses, many cheering him on with signs reading "Go O.J." (Published Friday, March 4, 2016) 
 
 The officer, now retired, was recently ordered to surrender the knife for testing by authorities after he contacted a friend at the department for information about the 1994 murder case for which Simpson stood trial, according to the report. 
 
 LAPD Capt. Andrew Neiman told NBC4 Friday morning that police are investigating the report. 
 
 The mansion on Rockingham Avenue in Brentwood, where Simpson lived when his ex-wife and her friend were stabbed to death in June 1994, was demolished by a new owner in 1998. TMZ reported, citing law enforcement sources, that the knife was found sometime from "several years ago to 1998." 
 
 The Great White Bronco Chase 
 
 "We still don't know if that's an accurate account," Neiman said. 
 
 Neiman confirmed at a Friday morning news conference that an individual identified by the officer as a construction worker gave the knife to him when he was working security at a film shoot near the former Simpson estate. The officer retired in the late 1990s, but it's not clear whether the officer was retired at the time the knife was found, Neiman said. 
 
 "If this story is accurate, I would think an LAPD officer would know that anytime you come into contact with evidence you should submit that to investigators," Neiman said. 
 
 The officer will likely not face administrative charges because he is retired, Neiman said, adding that an investigation will determine whether criminal charges are possible. 
 
 Life and Times: OJ Simpson 
 
 Police became aware of the knife within the last month, but authorities did not discuss details about how they obtained the item. It has been submitted to an LAPD forensics team for examination. 
 
 It was not clear to whom the knife belonged and authorities are attempting to determine the identity of the individual who turned it over to the officer, Neiman said. 
 
 "With all cases that remain open, unless there's an actual arrest or conviction to prove we've actually closed the case, the case remains open," Neiman said of the killings of Nicole Brown Simpson and Ron Goldman. 
 
 Neiman did not provide a description of the knife at the Friday news conference, but multiple law enforcement sources familiar with the investigation told NBC News that the knife undergoing tests is a relatively inexpensive, smaller-bladed utility blade typically used by construction workers, gardeners, landscapers or other laborers. 
 
 The murder weapon in the case has remained a mystery. A 15-inch retractable-blade knife that Simpson bought at Ross Cutlery in downtown Los Angeles drew the interest of murder trial prosecutors, but the defense presented the knife in a preliminary hearing. Tests later showed the knife in pristine condition with no signs it had been used in the double killing. 
 
 LAPD Discusses Knife Found at Ex-OJ Simpson Home (Published Friday, March 4, 2016) 
 
 In 1998, a residential construction crew found a folding-blade knife in Simpson's former neighborhood but police said there was no evidence to show it was related to any crime. 
 
 The mansion, where Simpson married Brown in 1985, was one of the landmarks of the murder trial. The infamous white Ford Bronco pursuit from Orange County ended in the mansion's driveway. It's also where Det. Mark Fuhrman said he found a bloody glove during the investigation into the slayings of Brown and Goldman. 
 
 Simpson was forced to sell the Rockingham Avenue estate to comply with requirements of the civil court judgment after the criminal trial. An investment banker hired a demolition crew to raze the house and clear the way for a new mansion four years later. 
 
 "It's not my house and I could care less," Simpson told The Associated Press in a telephone interview at the time the house was demolished. "I am a sentimental guy, but there's things you've got to compartmentalize." 
 
 The former NFL and USC football star was acquitted of murder in the slayings of ex-wife and Goldman, but a civil jury found him liable. In September 2007, Simpson was arrested in Las Vegas and charged with several felonies after an armed robbery and kidnapping at a hotel in an attempt to recover sports memorabilia. 
 
 He was sentenced to 33 years in prison. 
 
 OJ Trial: Key Players Then and Now 
 
 No matter what is determined through the knife investigation, Simpson cannot be tried again in the Brown-Goldman murders because of the Double Jeopardy Clause of the Fifth Amendment. Attorney Carl Douglas, a member of Simpson's legal team that secured the 1995 acquittal, said an investigation involving the knife would be a waste of time and money. 
 
 "I am amazed at the latest frenzy surrounding this ridiculous frenzy about some knife found on OJ's former property," Douglas said. "As a proud citizen of Los Angeles, I will be offended if the Los Angeles Police Department spends one minute of city time or one dollar of the city's limited resources chasing this ridiculous, supposed lead. I hope there are other investigations more deserving of the city's resources than this failed attempt, now 22 years old. 
 
 "OJ left the house two days after the murders and never returned until October 3rd, 1995. I certainly hope the LAPD used all of the resources then to scour every inch of his property looking for relevant evidence. It is pure fantasy to believe that there's anything relevant with this knife that has now been turned over. I'd rather talk about the Easter Bunny instead."
– What moments are engraved most profoundly into the minds of television viewers in the past 50 years? Sony Electronics and Nielsen surveyed more than 1,000 adults and found that the 9/11 attacks are the easy No. 1, though OJ Simpson has the distinction of cracking the top 10 twice. The top vote-getters, from AP and the New York Post. 9/11 attacks Hurricane Katrina (2005) OJ Simpson verdict (1995) Challenger shuttle explosion (1986) Death of Osama bin Laden (2011) OJ Simpson's white Bronco chase (1994) Japan's earthquake and tsunami (2011) Columbine school shooting (1999) BP oil spill (2010) Princess Diana's funeral (1997)