Friday night, Mexico experience a massive earthquake—the biggest they've experienced in 100 years. The 8.4 magnitude quake has killed a reported 35 people, according to ABC News.
As the ground rocked, something odd also appeared in the sky. Flashes of green and blue lights burst out in the night sky. See for yourselves.
As people ran outside to the avoid danger, they were greeted by another shocking sight. The lights, which lit up the sky throughout the earthquake, have no completely solid explanation. That doesn't mean science hasn't posited likely answers.
They've been happening for years, says The Telegraph—whenever the ground was shook violently enough. One expert says it's connected to energy being released from elements within the ground. Others say it's simply explosions from power stations or electricity cables.
Other people have wondered if the lights have a supernatural significance, but Friedemann Freud, author of a study about the lights, says there's a natural explanation.
"In the past, people often interpreted [earthquake lights] in religious terms, and in modern times they thought of UFOs, although there is a completely rational physical explanation that we are working on," he said.
That "rational" explanation is that the lights are released because of the electrical properties of the rocks in the ground. Energy from the tremors caused by the earthquake released electrical charges from he rock. Those flashes show as bright blue or green lights in the sky.
Other geological experts disagree. They say the lights are simply small explosions coming from generators and other power systems.
Either way, the lights are certainly a mystifying addition to the chaos and fear caused by a earthquake. How would you feel if you saw them in the sky? Let us know in the comments. Also, don't miss our latest story about the incredible tackle a homicide detective made after a high speed chase.