In 1989, Russian cosmonauts took a Pink Floyd album with them to the MIR space station. Sadly, it wasn't The Dark Side of the Moon. It was their 1988 live album Delicate Sound of Thunder, which was the only one of their albums that was officially released in Russia.

Syd Barrett was the group leader until he gradually lost his mind due to excessive drug use and had to be kicked out of the band. Once described as joyful, friendly, and extroverted, he became increasingly depressed and socially withdrawn, and experienced hallucinations, disorganized speech, memory lapses, intense mood swings, and periods of catatonia. It got to the point where he would stand on stage and refuse to play his guitar. When Barrett couldn't contribute musically, the remaining members hoped he could stay on as a songwriter, similar to what Brian Wilson did for The Beach Boys, but he was too far gone.

When I was a child
I caught a fleeting glimpse
Out of the corner of my eye
I turned to look but it was gone
I cannot put my finger on it now
The child is grown
The dream is gone
I have become comfortably numb

One of the most critically acclaimed records in history. The Dark Side of the Moon reached number one on the US Billboard Top LPs & Tape chart (now known as the Billboard 200), and has charted for 950 weeks in total. That's more than 18 years.

The rock opera explores the life of Pink, a jaded rock star whose eventual self-imposed isolation from society is symbolized by a wall. Bassist Roger Waters conceived The Wall during Pink Floyd's 1977 In The Flesh tour, modeling the character of Pink after himself and former bandmate Syd Barrett.

On Ummagumma, Pink Floyd album cover designer Hipgnosis altered the concept of the Droste Effect (image inside an image that repeats infinitely) by rearranging the band members inside each repeated window.

We're just two lost souls
Swimming in a fish bowl
Year after year
Running over the same old ground
And how we found
The same old fears
Wish you were here

In mid-1966, road manager Peter Wynne-Willson joined their road crew, and updated the band's lighting rig with some innovative ideas including the use of polarisers, mirrors and colored condoms stretched over lights.

The Dark Side of the Moon is said to sync perfectly with The Wizard of Oz and led to conspiracy theories that the band had written it with that purpose in mind. Pink Floyd drummer Nick Mason told MTV in 1997, "It's absolute nonsense. It has nothing to do with The Wizard of Oz. It was all based on The Sound of Music."

The album's cover shows an inflatable pig floating between two chimneys of the Battersea Power Station. As Photoshop didn't exist at the time (1977) the band commissioned German company Ballon Fabrik (who had previously constructed Zeppelin airships) to build a 12-metre (40 ft) porcine balloon (known as Algie). On the second day of photography, the balloon broke free of its moorings and disappeared from view. The pig flew over Heathrow, resulting in panic and canceled flights. Pilots also spotted the pig in the air. It eventually landed in Kent and was recovered by a local farmer, who was apparently furious that it had scared his cows.