Strange phenomenon in the Tahitian sky

Sister Anne, don't you see anything coming?

But what happened in the sky over Tahiti on Wednesday, February 28th at sunset? Where could this strange blue beam that seemed to be sent to us by the sun have come from? Was it a divine sign, a message from the little blue men, yet another hole in the ozone layer, or perhaps Goldorak playing with his new laser?

Rays often observed in Polynesia 

Rest assured, none of that is the case, and ultimately, the explanation is quite simple. When the sun is at or just below the horizon, the presence of convective clouds, such as cumulus or cumulonimbus, prevents sunlight from illuminating the sky normally. This creates shadows, often blue, that appear to converge towards the sun. Seen from a great height, for example from the International Space Station, these rays are all parallel. But seen from the ground, due to the parallax effect, they appear to form a fan originating from the sun or the antisolar point diametrically opposite it. These are called twilight rays or anticrepuscular rays. The unusual aspect of Wednesday's phenomenon was that the shadow was caused by a single cumulus, a typical cauliflower-shaped cloud. Therefore, we only had one twilight ray visible in the sky.

Same old story this Thursday morning

They say that the early bird catches the worm. This adage was proven true again this Thursday morning, as around 5:50 a.m., rays, this time anti-twilight, stormed the sky, painting a fresco worthy of the greatest artists. The spectacle lasted only a few minutes. As the sun quickly gained altitude, its light naturally managed to pass over the clouds responsible for this brief and futile apparition. 

Fantastic celestial vault

Nature, and the sky in particular, often offers us fabulous spectacles that we rarely pay attention to. It's such a shame. So get into the habit of looking up and contemplating. These strange celestial phenomena are well worth a look. And maybe even a little stiff neck...

I thank Christophe SERPE and Alice CHAMPES for the photos.