No LA, it's not aliens. It's a SpaceX rocket launch.

Look up. Is it a bird? A plane? Aliens?

It's definitely not aliens, but SpaceX CEO Elon Musk is trolling concerned Los Angeles residents and celebrities who noticed something eerie in the early evening sky Friday.

Many assumed the strange shape and smoke were from an alien spaceship or a UFO. 

But relax, it was a planned launch from the nearby Vandenberg Air Force Base. At 5:27 p.m., the Iridium-4 satellite was launched as part of a series to form the Iridium NEXT satellite constellation.

SpaceX is launching 75 of 81 new Iridium satellites that will be part of the low-Earth orbit network. The satellites are set to deploy about an hour after launch.

Even singer will.i.am and actor Don Cheadle freaked out about the mysterious object.

Pro-skateboarder Tony Hawk down in San Diego stopped to wonder what was flying above him.

Elon Musk took the opportunity to troll some people on Twitter. 

LA Mayor Eric Garcetti tried to calm people down ...

... but they kept freaking out anyway. 

LA, city of angels — and aliens.

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