By Beth Johnson
Updated March 17, 1995 at 05:00 AM EST

When Pink Floyd’s Dark Side of the Moon first hit the record charts, it was March of 1973 and Richard Nixon was President of the United States. By March 22, 1980, Nixon had been out of the Oval Office for six years, Gerald Ford had come and gone there, Jimmy Carter had only 10 months left in it, but Pink Floyd’s head-trippy disk was still flying high. On that date, after 303 weeks on Billboard’s 200 top album chart, Dark Side of the Moon became the longest- charting rock album of all time. It didn’t stop there. Rock & rolling on, Dark Side zoomed past Johnny Mathis’ Johnny’s Greatest Hits after 490 weeks to become the longest-charting album of any kind. And when it finally tumbled off the list on Oct. 8, 1988, Pink Floyd had set a record that’s almost untouchable: It had been on the charts for a staggering total of 741 weeks. Written mostly by bassist-songwriter Roger Waters and recorded on then- cutting-edge 24-track equipment, Dark Side’s run is all the more remarkable in light of the achievements it didn’t rack up. Its only Grammy nomination went to Abbey Road engineer Alan Parsons who, years before digital sampling, created a sound that’s fresh today. And although more than 500,000 copies of Dark Side of the Moon (an occult term for the subconscious) are sold each year, it ranks only fifth in sales (Thriller is No. 1) and produced only one hit, ”Money.” Pink Floyd began in mid-’60s London as Pink Floyd Sound (in homage to Southern bluesmen Pink Anderson and Floyd Council) and consisted of Waters, guitarist-songwriter Syd Barrett, drummer Nick Mason, and keyboardist Rick Wright. By 1968, Barrett’s mind was an acid casualty, and he was replaced by his friend David Gilmour. The band kept recording and performing its mind- blowing stage shows into the early ’80s, with growing acrimony: Gilmour felt that Waters was a megalomaniac, and Waters said ”nobody else in the band could write lyrics” and quit after 1983’s The Final Cut. He and Pink Floyd record separately and have continued to perform music from Dark Side. Just why did their album so far outlast all others? ”It’s inexplicable to me,” Gilmour has said. ”It’s a very good record and I’m very fond of it but I must confess I can’t put my finger on what separates it from the other great records of all time.” Waters has at least hazarded a guess. ”Maybe,” he’s said, ”its humanity has caused Dark Side to last as long as it has.”