In the midst of a biblical thunderstorm, you could be forgiven for assuming the end was nigh when a large, red jellyfish appeared in the sky. The bizarre weather phenomenon is actually the result of red sprites, a type of electrical discharge that happens much higher up than conventional-looking lightning. That said, if I ever saw this in real life, I’m not sure the scientific explanation would do much to settle my fears that the evil overlord cnidarians had finally landed.

The picture above, taken by Stephen Hummel of the McDonald Observatory in Mount Locke, Texas, shows one such red sprite event. The ultra-fast bursts of electrical activity crackle their way up to 80 kilometers (50 miles) into the atmosphere, traveling far enough to be papped by the International Space Station. In these photos, they can be seen as red squiggles above the bright white light of a lightning storm.

They happen in response to lightning strikes, which release positive electric energy into the sky. The charge moves similarly to lightning, but as it’s much higher in the air it comes into contact with nitrogen floating in the Earth's atmosphere. When the nitrogen meets the electric charge, it emits a red glow, which are the wiggly tendrils we view like tentacles. They don’t always form in jellyfish formation as some appear simply as red columns in the sky that, while undoubtedly still very cool, carry less of a War of the Worlds apocalypse vibe. They were first discovered in 1989 and have since been seen over every continent except Antarctica. Dark skies free from excessive light pollution make it easier to see faint objects like sprites, and so views like this are increasingly harder to capture due to the increasing spread of light pollution.

The rare event lasts just a few tenths of a second and is often obscured from view by storm clouds. Luckily for Dark Skies Specialist Hummel of the McDonald Observatory, the electric performance kicked off in full view just as he was observing a storm from a ridge on Mount Locke.

"The reasons for the jellyfish-like shape, as opposed to more common column sprites or "carrot" sprites, are not fully understood," Hummel told IFLScience. "However, all of the heads of the sprite are at almost the same altitude, and are clustered around the large central head and tendrils. Some are slightly closer to our vantage point, and some are further away. So we are looking up at it, and it is looming over us!"

So, if you find yourself caught in a storm one day and spot a terror jelly in the sky, it’s probably not aliens. Unless…

[H/T: Business Insider]