Was it a bird? Was it a plane? Or was it, goodness gracious, great balls of fire?

To be honest, no one is entirely sure, but police were inundated with calls from Warana and Kawana residents who heard "some sort of explosion" just before 10.30pm on Wednesday.

Some reported seeing a bright flash in the sky at the time of the bang, with others claiming their house shook from the noise.

Kawana's Island Keys resident manager Chris Hobart and her husband Bob likened the noise to an explosion.

"We were working inside and heard it, and being a manager of a complex, we thought the gas bottles had exploded or something," she said.

"We went outside but we couldn't see anything. It was pretty loud. We had the television on and the computer on. It was like a big clap of thunder."

Other residents as far away as Marcoola reported hearing the bang.

The usual suspects were quickly eliminated yesterday, with the air force denying they had any jets in the area, no reports of power outages and no sign of an earth tremor.

Which left people looking to the skies and those in the know guessing that the Coast's big bang was more a case of small rocks.

University of Queensland astro physics lecturer Michael Drinkwater said it sounded like "what we call a fireball".

"Very high energy, very fast tiny meteors in the upper atmosphere," he said.

"They create a big effect because of the high speed they come in on. They are dumping a lot of energy, which can create the big bang and flashes of light."

Wappa Falls astronomer Owen Bennedick agreed.

"It sounds like the meteor was going so fast it broke the sound barrier and exploded. Anyone who saw it would have seen a very spectacular sight.

"When you have something with a tremendous amount of energy coming out of the atmosphere something has to go bang. Even something the size of a pea will make a spectacular entry."