Various cameras caught the flash on Friday, including some of NASA's cameras.
While some people thought it was a lightning flash, there was no thunderstorm activity in the vicinity.
Some area astronomers thought it could've been a meteor.
"It was going so fast that it gets through the atmosphere, that makes the glow," said Houston Natural Science Museum's Carolyn Summers. "I happened to be walking and I looked up and saw a big greenish blue flash. Like a UFO taking pictures of the sky like a big flash."
The National Weather Service has weighed in, as well. They say it may have been debris from a Russian satellite as it reentered the atmosphere.