The sky turned bright red across parts of England on Monday, October 16 triggering alarm on social media.
The phenomenon was spotted from as far south as Plymouth and as far north as Newcastle and was clearly visible in London.
One theory was that it was caused by Hurricane Ophelia sucking up dust from the Sahara and making the sky take on a scarlet sheen.
Forest fires in Portugal and Spain, which have killed 31 people, are also believed to be a contributing factor.
The dust makes blue light, which has a shorter wavelength, scatter and therefore appear red.
The Met Office said the "vast majority" of the dust was caused by forest fires in Iberia and smoke and fire debris had been dragged north by Hurricane Ophelia.
But many people on social media had more fanciful theories.
Some claimed it signalled the coming of Azor Ahai, a legendary warrior from Game Of Thrones.