Then a local TV station phoned the scientist, who studies images from the Hubble Space Telescope, to ask him to explain what had happened.
Frantic eyewitnesses across the state called local news outlets to report what they saw.
The explosion shook Tony Kubrak's house, too, he told CNN affiliate KGUN, which received a flood of calls and hundreds of posts to its Facebook page.
Kubrak went outside to check it out.
"I see this tremendous, white, bright light in the western sky. And it was just ... it was absolutely enormous, I couldn't believe it."
Others took to social media.
"Did y'all see the meteor that flew above Tucson? Crazzzzy. That was toooo craaaazy!" Tucson resident Eric Gomez posted on Twitter.
People around the world can enjoy what bedazzled Arizonans until at least Monday, NASA said. The Geminid meteor shower this year will be "rich in fire balls."
They can be viewed best from 11 p.m. to 3 a.m. ET.
"Of all the debris streams Earth passes through every year, the Geminids are by far the most massive," said NASA astronomer Bill Cooke. "When we add up the amount of dust in the Geminid stream, it outweighs other streams by factors of 5 to 500."
NASA calls it the 900-pound gorilla of meteor showers.
Most meteor showers are caused by comets, but not Geminid, which contains the name of the constellation Gemini.
A large space rock named 3200 Pheathon flings the debris that makes the sparkling magic.