Phenomenon is the third studio album by English hard rock band UFO, released in May 1974. It was the band's first album to feature lead guitarist Michael Schenker, who replaced Mick Bolton.
Their third studio album, Phenomenon was UFO's debut with major label Chrysalis Records and their first to be released in the United States. With the arrival of ex-Scorpions lead guitarist Michael Schenker, Phenomenon saw UFO begin to leave their blues-based "space rock" sound behind and transition to a more straightforward hard rock sound.
"With the Scorpions, I had recorded [the title track of]Lonesome Crow, but 'Rock Bottom' was the continuation of that. I needed to have a song in which I could improvise and go on an adventure. The version that we recorded for Phenomenon had begun in rehearsals as a riff, and we kept adding more riffs to it. And then Phil [Mogg, singer] leapt up and said, 'This is how we'll make it into a song'… I still think of 'Rock Bottom' as a work in progress. When I play it live now, I use the most memorable parts of the solo, and keep a space to represent my latest frame of mind." – Michael Schenker[7]
The album was produced by Leo Lyons, bassist of British rock group Ten Years After. All tracks were recorded at Morgan Studios in London. The original cover design and photos were by Hipgnosis.