Why a Substation Fire Turned New York City's Sky Bright Blue

(Bloomberg) -- When an electrical substation catches fire, you might expect some white, yellow, maybe orange flames. But bright blue? That’s the color that lit up New York City’s sky when some faulty equipment at a Consolidated Edison Inc. substation caused a flash overnight.

It was so startling that Twitter ran wild with UFO conspiracy theories.

The more probable reason for the blue sky? Aluminum. That was in the equipment that was burning and likely cast a blue shade over the city, according to Allan Drury, a spokesman for ConEd. In fact, there are a lot of metals used in substations, especially in transformers, said Thomas Converse, president of the energy and engineering firm LIG Consultants in Canton, Massachusetts. They can give off a blue light when burning, especially when reflected off dust and other particles in the air, he said.

So feel free to take off the tin foil hats. No alien cover-up here, Drury said. “If it were a UFO,” he said, “I would’ve left town by now.”

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