Mystery sonic boom in California

Residents of California's Central Coast experienced a sonic boom Wednesday morning but nobody knows the source. The Federal Aviation Administration reviewed their data and came back empty-handed. According to FAA spokesman Ian Gregor, it's possible their system may have missed a plane flying supersonic. From the Santa Cruz Sentinel:
The mystery has spurred its share of conspiracy theories. On the Sentinel Web site, readers comments suggested the boom was E.T.'s return, an intercontinental missile that North Korea, or test runs of new, secret U.S. Navy jets.

"It was a chemtrail weather modification program jet making rain for you," a reader going by the handle "sameold" wrote.

"The easiest answer is probably right. I'm going with aliens," commenter "jarbee" wrote.
"Sonic boom remains a mystery"