The Sept. 11, 2001, terrorist attacks are the most memorable moment shared by TV viewers of the past 50 years, according to a new study.

View Photo Gallery: Reuters reports that a new survey shows the Sept. 11, 2001, terrorist attacks are by far the most memorable TV moment shared by viewers in the past 50 years.

Hurricane Katrina is ranked No. 2, according to a study conducted by Nielsen Research, in collaboration with Sony Electronics which, the study announcement noted, is “a company that knows a thing or two about television.”

Not surprisingly, there are almost no 50-year-old events in the Top 20 list. This could be because Nielsen fielded a national sample of people aged 18 years and older, so a mess of respondents weren’t, you know, alive in the 1960s.

And, in order to “to elevate the list into something more than just a simple ranking by viewership,” the two companies said they instead created a Custom Impact Score, taking into account things such as whether respondents viewed the event on TV live as it happened and remember where they were when they did. Study participants not born by 1963 would naturally have had a harder time watching live-TV coverage of the assassination of President John F. Kennedy than those born before the assassination occurred.

All things considered, it seems practically a miracle that both JFK’s assassination and his funeral made the Top 20 list, at No. 15 and 20, respectively.

Kennedy’s funeral did, however, finish behind the Casey Anthony murder-trial verdict, at No. 19.

In fairness, Kennedy’s assassination did rank high — coming close to 9/11 — among people 55 and older.

Apparently you missed nothing in the ’70s, and the ’80s were a bit of a washout too, because only one event from those decades made the Top 20 List.

Things pick up in the 90’s, starting with 1992’s “Los Angeles riots, Rodney King beating,” as the study calls that horrific chapter in Los Angeles history.

The mesmerizing slow-mo “chase” by police of the white Bronco containing O.J. Simpson, just days after his ex-wife Nicole had turned up dead, is ranked No. 6, though Nielsen and Sony called it a “high speed” chase.

Not surprisingly, 19 of the Top 20 Most Impactful Events were news-related. The only entry not listed by Nielsen as a news event is Whitney Houston’s death, which is ranked No. 11.

Yes, while Nielsen deemed the 2011 “Wedding of Princess William and Kate Middleton” (No. 14) to be “news,” the event Nielsen itself referred to as “news coverage of the death of Whitney Houston” earlier this year (No. 11) has been listed as an “entertainment event.”

In the study, this puts Houston’s sudden death, at the Beverly Hilton hotel on the eve of this year’s Grammy Awards, in company with the 1977 ABC miniseries “Roots” (No. 36), and the “Who Shot JR” episode of “Dallas” (No. 44).

And just in case you were wondering whether this study is something for pundits to navel-lint-pick over in the years to come — or more a pretext for Brian Siegel, vice president of TV set-selling Sony Electronics Television Business to be quoted in the study’s news release, consider his saying:

“Whether the conversations happen over the back fence or on Twitter®, people turn to TV to learn about what’s happening”

We should note that, among the options for most impactful TV moments of the past 50 years in this study was Chaz Bono participating on “Dancing With the Stars,” which came in at No. 59) and the Kim Kardashian/Kris Humphries wedding (No. 76).

Here are the Top 20:

1) September 11th tragedy (2001)

2) Hurricane Katrina — the levees break (2005)

3) The OJ Simpson verdict (1995)

4) The Challenger space shuttle disaster (1986)

5) Death of Osama bin Laden (2011)

6) The OJ Simpson white Bronco high-speed chase (1994)

7) The Earthquake in Japan (2011)

8) Columbine school shooting (1999)

9) Oil spill in the Gulf (2010)

10) Princess Diana's funeral (1997)

11) News coverage of the death of Whitney Houston (2012)

12) Capture and execution of Saddam Hussein (2006)

13) Barack Obama acceptance speech (2008)

14) Wedding of Prince William and Kate Middleton (2011)

15) Assassination of JFK (1963)

16) Oklahoma City bombing (1995)

17) Bush/Gore election debacle (2000)

18) Los Angeles riots, Rodney King beating (1992)

19) The Casey Anthony murder trial verdict (2011)

20) The funeral of JFK (1963)