'Stranger Things': Social media erupts as sky turns green during rare event

Dramatic images show the extremely rare moment the sky turned bright green in South Dakota in the US.

Triggered by storms moving across the country on Tuesday (local time), Sioux Falls residents rushed to take photographs and share them on social media.

Meteorologists confirmed the event occurred as a straight line of clouds, known as a derecho, roared through the sky at speeds of up to 160km/h.

There were reports of hailstones the size of baseballs as the front moved onto Iowa, Nebraska, Minnesota and Illinois.

Alarmed by the startling events, online detectives worked to find out what was causing it.

Others questioned whether some of the more dramatic images of the sky were real.

“I think they did turn on a filter that made it more green than it actually looked,” one person mused.

“It looks like a backdrop for the Green Goblin,” someone else added.

“Season five of Stranger Things is looking good!” another person joked.

What caused South Dakota's sky to turn green?

Scientists believe the green celestial phenomenon occurs when clouds carrying an abundance of water, scatter away all other colours but blue light, which it allows to shine through.

It then mixes with red light from the setting sun, creating an ominous green sky.

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Even hardened storm chasers were stunned by the event, with one posting to Twitter it was “the most eerie storm I’ve ever witnessed”.

Alarmed by the occurrence, another person wrote they would be checking to make sure relatives in the area were okay.

With Reuters

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