Some observers called police, others quickly hit the Internet to broadcast tweets about what they saw, The Sunday Telegraph reported.
"UFO invasion?! Ball of fire flew past my window!" one woman posted on Twitter.
David Konstantinou of Glasgow tweeted he had seen "a huge meteorite heading south."
"Huge white tail. Flashed green and red. Amazing sight. Made the hairs on my neck stand up," he added.
One Greater Manchester police officer joined in the fun, tweeting: "Sounds like we are being invaded by martians. Several sightings of a bright orange light over Salford!"
The most likely explanation for the phenomenon was that a meteor, probably about the size of a person's fist, had hit the Earth's atmosphere 60-70 miles up about 10 p.m. Saturday, the British newspaper said.