First, the visual evidence.

At least three drivers captured the mysterious flash at night on Nov. 14. Their videos show a sudden yellowy-orange explosion that illuminates the night. Two of them show the flash seemingly originating from within the clouds.

People are kind of stumped.

A Russian scientist who is a member of the country’s awesome-sounding Committee on Meteorites told a Russian news outlet that it was probably the result of a falling piece of space rock. “It looks like a meteor fell,” he said. “Because of the low altitude clouds, it vanished above the clouds and lit up the sky.”

Phil Plait, who pens Slate‘s Bad Astronomy blog, initially thought it was a “bolide,” or a meteorite that enters Earth’s atmosphere and explodes in flames. But the color is weird, he writes:

The color is odd; the reddish glow, if accurately portrayed in these videos, isn’t something I generally see in bolide videos and photos (or from the few I have seen with my own eye). They tend to be green or blue, or just white. Not always, but just in general. Of course, the clouds may be affecting the color, too.

But a third video, also taken by dash cam, seems to show the explosion emanating from the ground.

The Russian military, meanwhile, dashed hopes that it was due to an experimental-weapons test gone awry, with a spokesperson telling Russian news source E1, “There were no accidents at this time in the area.”

And what if it was an exploding shell set off during some kind of ammunition disposal exercise, as emergency officials and local administrators reportedly said? The military denied that, too.

“No exercise and training were underway on that day, and no military units are based in the region, so we have nothing to do with it,” a military press representative told E1, according to a Russia Today translation.

Local residents reportedly said there used to be military activity in the area, but it’s long since left. Still, perhaps some explosives were left behind.

Long story short: Big boom and no one knows why.

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