While camping in Glastonbury in 1968 with then-girlfriend Marianne Faithful, Jagger spotted what he described as a "cigar-shaped mothership" floating amongst the stars. A year later, the Rolling Stones' frontman saw a second UFO during the infamous concert at Altamont. The sightings left such an impression on the singer that he installed a "UFO detector" at his English estate. The most mysterious part of this story? Mick Jagger goes camping.