The rocket is carrying into space a payload from the National Reconnaissance Office, according to the United Launch Alliance website. The Delta IV Heavy rocket has been launched five times before, but all previous launches occurred in Florida.
It's possible that the launch caused a few windows to rattle in the Lompoc area.
About 350 Pratt & Whitney Rocketdyne engineers and technicians spent nine years developing and building the rocket. Many of them may be seeing the rocket blast off for the first time because it is taking off so close to home, according to the Los Angeles Times.
Although areas around the base have been closed to discourage viewers from getting too close, authorities expect everyone in the area to be watching.
"Everyone will be in their front yards for this one," Lompoc Mayor John Linn told the Los Angeles Times. "Living here, you get used to launches. But this is different. This is the big kahuna."
What the massive rocket is carrying is classified information, but some analysts say it is probably a $1-billion spy satellite that would allow the U.S. to identify minute details like the model and make of a car from hundreds of miles away, the Los Angeles Times reported.