In taking the time over this past weekend to remember the victims of 9/11 on the ten-year anniversary of the horrific terrorist attacks, there had to have been several twinges of “I can’t believe it’s really been ten years.”

Here’s another (less depressing) one from the “I can’t believe” files: Pearl Jam has been a band for 20 years.

Feel old yet? 20 years.

How many parents yelling “turn that (insert expletive) down” at their kids in 1991 while they were playing “Even Flow” ever thought that would happen? To them, that song that probably sounds like it’s trying to eat itself.

Has it really been that long since we first watched the gut-wrenching music video for “Jeremy,” mouth agape?

But here we are in 2011. “Ten” is destined to be one of those albums reissued more times than the concept of “American Idol,” their career album sales are north of 60 million, and nearly the same original lineup remains in tact.

Leave it to director Cameron Crowe (“Almost Famous,” “Vanilla Sky,” “Jerry Maguire”) to take over 1,200 hours of footage spanning Pearl Jam’s two decade career and condense it into “Pearl Jam Twenty,” a commemorative documentary that is “part concert film, part intimate insider-hang, part testimonial to the power of music and uncompromising artists.”

As of now, you only have one chance to see it in Sacramento (see below). Check out a trailer for the film here.

In considering 20 years of longevity in a continually disjoined music industry, there are a couple of lessons that hopefully we have all learned from a band that’s had the guts to last that long.

One, there’s no such thing as grunge.

It was a style of clothing, not music. If someone can explain how the “Big Three” of grunge (Pearl Jam, Nirvana, Soundgarden) sound anything alike, then you’re smarter than I am. If hair metal was hair metal because of the hair, then grunge had to be grunge because of the clothes, right? Grunge was a fad, and fads don’t last 20 years.

Two, everyone was quick to tag Pearl Jam as a hard rock band, but truth be told, they are merely the new generation version of Neil Young & Crazy Horse, with a little more meat behind the “boom-boom-thack” and much deeper vocals. Seriously, if you can’t hear the roots of Pearl Jam in “Everybody Knows This is Nowhere,” then you’re not paying close enough attention. Do they have what it takes to tack on 20 more, or maybe even to last as long as Neil Young has...?

Happy Anniversary, Pearl Jam.

“Pearl Jam Twenty” is slated for one showing only at The Crest Theatre (1013 K St.) in their courtyard cinema on Tuesday, September 20 at 8:15 p.m. (doors open at 7:45). Tickets are $9.50.

The showing of “Pearl Jam Twenty” is one of several one-time showings at theatres around the world, all happening on September 20. Limited releases are planned in select cities, but as of now, Tuesday’s showing is the only scheduled Sacramento screening.

UPDATE: The 8:15 p.m. showing of "Pearl Jam Twenty" is sold out. A 10:30 p.m. show has been added, tickets will be available at the theatre's Tickets.com page in the afternoon on Wednesday, September 14.

Click here for more information on “Pearl Jam Twenty.”