Reports came in of a large white flash in the sky around 7pm on Monday, with Twitter users across the Highlands, Aberdeenshire and Perth saying they had witnessed the phenomenon.
Some speculated the flashes and noises had been caused by a meteor. Others reported feeling buildings shake as a result of the bang.
Police Scotland said they had been unable to ascertain the cause of the noise.
The Met Office said there were no lightning or thunderstorms in the area.
STV News weather presenter Sean Batty said the flash appeared to be from a meteor burning up in the atmosphere, lighting up a sheet of cloud.
A spokesman for Police Scotland said: "We've had reports of a very loud bang but we've been unable to establish what it is.
"Some people were saying their houses were shaking."
He said there had been no reports of aircraft in distress in the area from air traffic control.
@STVNews was that a meteor hit heard all over scotland!— joanne pittendreigh (@jojopittbear) February 29, 2016
Proper massive rumble, ground shaking, folk seeing the sky flash blue and sirens going off everywhere....is this the end?!— Kim Paterson (@kp_x_) February 29, 2016
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