Phenomenon is the third studio album by English rock band UFO, released in May 1974. It was the band's first album after guitarist Michael Schenker joined them, replacing 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 former Scorpions guitarist Michael Schenker, Phenomenon saw UFO 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 English rock group Ten Years After. All tracks were recorded at Morgan Studios in London. The original cover design and photos were by Hipgnosis.