Residents of Carroll, Haralson and Douglas counties heard the boom Friday, but investigators in all three counties said they couldn't determine the source, The Atlanta Journal-Constitution reported.
"There was no catastrophe, we know that," said Douglas County Communications Director Wes Tallon. He said the 911 calls "lit up" the switchboard about 9:45 p.m. Friday.
"People all over the city heard the boom, but we couldn't find anything," a Villa Rica Police Department receptionist said.
The National Weather Service had no natural explanation for the boom, and there were no obvious signs of damage in the area. An amateur astronomer said a meteorite probably didn't cause the boom.
"A really big meteor can make a sonic boom, but if it did it would make a big flash of light," said Michael Covington, who helps run a computer research program at the University of Georgia when he's not star-gazing.
Even a sonic boom seems unlikely, officials said.
A sonic boom only happens when an airplane breaks the sound barrier, but no civilian planes can fly that fast, and there were no military planes in the region when the boom was reported.