Mysterious string of lights spotted in Bay Area sky

A mysterious string of lights appeared Thursday in the predawn sky over the greater Bay Area.

KRON reported that residents from Santa Clara to Pittsburg to Vallejo spotted the lights — lined up in a row and moving like a train — around 5:30 a.m.

"So did I just witness an alien squad or some random lights in the sky #BayArea," wrote one Twitter user.

Turns out the lights were not an alien spacecraft.

KRON's news anchor James Fletcher did some detective work and found Elon Musk was responsible for the spectacular show in the sky.

Musk's company SpaceX launched the Starlink satellites Feb. 15 from Cape Canaveral Space Force Station in Florida. The Falcon 9 booster lofted 60 Starlink satellites into the atmosphere.

These satellites are "60 times closer to Earth than traditional satellites," according to the company, and can provide communication service to remote, underserved areas.

Made from reflective material, the satellites can become visible when the sunlight strikes them in the hours just after sunset or before sunrise, according to the International Astronomical Union.

The union and the National Radio Astronomy Observatory have both expressed concern in the past over the satellites being too bright and causing problems for astronomers.

"The organisation, in general, embraces the principle of a dark and radio-quiet sky as not only essential to advancing our understanding of the Universe of which we are a part, but also as a resource for all humanity and for the protection of nocturnal wildlife," the union said in a statement posted online. "We do not yet understand the impact of thousands of these visible satellites scattered across the night sky and despite their good intentions, these satellite constellations may threaten both."

SFGATE reached out to SpaceX for this story and didn't hear back.