A strange red light in the sky inspired awe and speculation on Thursday night in Tamaulipas after appearing around 10:50 p.m. and becoming visible throughout the southern end of the state.

Many residents of the city of Tampico shared photos and videos on social media of the glowing pillar. Some thought it could be a meteorite or rocket, while others joked about alien invaders.

“Well, Tampico is going to be the first city colonized by aliens. Goodbye,” Twitter user Fer Castillo wrote, sharing an image of the light pillar.

After receiving reports from concerned citizens, regional Civil Protection officials released a statement assuring worried tamaulipecos that there was nothing amiss, and attributing the light to sprite clouds, a rare type of flickering red lightning.

Alexander Dadderio, a Tampico meteorologist, said that was incorrect. The stationary light column was, in fact, an example of the phenomenon known as a “light pillar,” which occurs when light reflects off tiny ice crystals in high-altitude clouds, he explained on his weather forecast page, MeteoAlert Tampico.

“There are a lot of conspiracy theories about a light that can be seen in the sky. The experts who aren’t experts at anything except making memes attribute it to sprite clouds or even earthquakes,” he wrote on Twitter, explaining that it was actually a light pillar reflecting from some light source on the ground.

That source could be the moon, a refinery, a Pemex gas flare, or many other things, he said.

“It’s very rare that it appears in the summer, but if there are very high cirrus clouds, it can be faintly seen on days like today,” Dadderio said.

Weather conditions in the U.S. state of Texas caused a similar pillar to appear in March, over a refinery near Houston, he noted.

The eerie phenomenon appeared just a day after an ominous shelf cloud swept over the city, caused by stormy weather at sea.

With reports from Milenio and Hoy Tamaulipas