Just a few days ago, on August 10, astronauts aboard the International Space Station witnessed a most bizarre phenomenon: an octopus-like red sprite that formed over southern Mexico as the country was battered by thunderstorms.

When the crew noticed the red sprite coming into being and photographed it, the International Space Station was hovering over Earth at an altitude of about 400 kilometers (250 miles).

As is always the case with such intriguing flashes, the red light tentacles vanished in the blink of an eye. Thus, scientists say odd phenomena of this kind usually last merely 3 to 10 milliseconds.

Needless to say, this explains why red sprites are almost never seen and why photos testifying to their occurrence high in the sky over one region or another are few and far between. It's all very frustrating if you think about it.

Red sprites usually occur at altitudes of about 65 to 75 kilometers (40 to 45 miles). As for the tendrils themselves, scientists say some stretch over as much as 90 kilometers (55 miles).

In a way, red sprites resemble lightning. After all, both phenomena come down to having flashes of light streak across the sky. However, researchers have yet to determine the exact environmental conditions that give rise to red sprites.

They suspect it might have something to do with irregularities in the ionosphere, i.e. a part of our atmosphere that is ionized by solar radiation, but further research is needed to confirm this hypothesis.