LAS VEGAS (KLAS) — ‘Twas two nights before Christmas and up and down the Las Vegas Strip, people looked up and thought they saw a spaceship.

Spoiler alert: It was probably just a weather phenomenon, though a rare one for the Las Vegas valley.

Workers at the Sapphire Gentleman’s Club on Sammy Davis Jr. Drive posted the first videos of the phenomenon early on the morning of Friday, Dec. 23. From the parking lot, they filmed what appeared to be groups of red and white lights shining in the clouds.

“Honestly, this is really strange,” a voice can be heard remarking of the lights. “I mean, we’re here every night. I’ve never seen anything like this.”

The people recording the event speculated that it was a UFO hovering above the club, and they weren’t alone. Nexstar’s KLAS heard from a worker at a nearby marijuana-growing business who also saw the lights, claiming they stayed in place for more than an hour.

But the night was relatively cool with low clouds in the sky, leading to speculation it was just reflections from the lights along the Las Vegas Strip. This is probably correct, experts suggest, though it only happens during very specific weather events.

A meteorologist at the National Weather Service in Las Vegas told KLAS that since the lights in clouds did not appear to move, and the temperature in the clouds was cold enough, there’s a good chance what people saw this night was a phenomenon known as “light pillars.”

According to one National Weather Service, light pillars are described as the following:

Long pillars of multicolored light streaking the sky seem like the perfect backdrop for impending alien invasion, but in reality, light pillars are a common effect that can be found all over the world.

They do come from above — not extraterrestrials, but tiny crystals of ice hanging in the atmosphere. Ice is very thin, shaped like plates with hexagonal faces. When ice drifts down through the air, it falls close to horizontally. At the top and bottom are the faces with more area. Ice is very reflective, so when light hits those wider faces, it bounces around and reflects off more ice crystals.

That means we get these vertically stacked mirrors floating in the atmosphere. The light hitting it gets reflected up and up (or down and down, depending on the source), and becomes a radiant column in the sky.

Light can come from the sun, moon, cities, street lights — any strong light source.

National Weather Service

Other people online have even matched up the lights to some of the large hotel casinos along the strip. The red lights could be from Resorts world, and the other white lights from the Wynn, Encore, Strat, and Palace Station.