sciencetech-blog

comments

The sight of three suns in the sky is enough to make most of us rub our eyes in disbelief, but centuries ago, the strange sight was seen as a bad omen. 

The unusual spectacle, called a parhelion, was captured on camera in Mongolia.

It is the result of a natural phenomenon in which sunlight passes though snow crystals in a particular way when they are suspended in the air.

Scroll down for video 

Seeing treble: This strange sight was captured in Mongolia and is the result of a rare natural phenomenon called a parhelion, which occurs when sunlight passes though snow crystals in the air

Stills of the event caught on an ITN video show the sun in the centre of the snowy scene, with two reflections either side, which can be described as sundogs or 'phantom suns'.

Sundogs are created when sunlight is refracted by large, hexagonal ice crystals, such as those in snowflakes. 

They typically appear as two coloured patches of light either side of the sun and though rare, can in theory be seen anywhere in the world in any season.

Photographs of the event show the sun in the centre, with two reflections either side, which can be described as sundogs or 'phantom suns'. They are always at the same level of the sun on the horizon, as seen here

Rare optical illusion creates THREE SUNS in the sky in Mongolia

They are created by the refraction of light passing through flat, hexagonal ice crystals in high, cold clouds.

The crystals act like prisms so that as light passes through them, it is bent by exactly 22 degrees before reaching viewers' eyes to make the illusion.

If the crystals are more randomly located in clouds, a complete ring around the sun is visible, called a halo.

But if the crystals sink through the air, they become arranged in vertical lines, so that the sunlight is refracted horizontally, to make sundogs, as seen in these images.

If the phenomenon is seen as the sun is rising, the sundogs gradually move further away from the sun, but always stay at the same elevation, so the three 'orbs' appear to be the same distance from the horizon.

They are reddest in colour when they are near to the sun and fade to yellow, orange and then blue as they move away. The colours of sun dogs merge into a white halo in some instances. 

THE HISTORY OF SUNDOGS 

The strange phenomenon is first known to have been recorded by Aristotle between 384 and 322 BC. 

The Greek philosopher wrote: 'two mock suns rose with the sun and followed it all through the day until sunset'. He noted that they were always to the sun's side and never rose above or below it.

The poet Aratus, who lived between 310 and 240 BC mentioned them in his catalogue of Weather Signs, saying that they indicate wind, rain or an approaching storm, while Artemidorus, a diviner in the second century, included the phantom suns in his list of celestial deities.

Sundogs were sometimes seen as an omen for bad times ahead, such as war, and observations of them feature in ancient texts by Aristotle, Seneca and Cicero, among others. This depiction of sundogs appeared in the Nuremberg Chronicle, an early printed book shwoing world history, published in 1493

Roman authors Cicero and Seneca mention them in their writings too. 

In later works it was feared that sundogs were omens for bad times ahead, such as war. 

An anthelion is said to have occurred before the Battle of Mortier's Cross in Herefordshire in 1461 - a major event in the War of the Roses.

Apparently the Yorkist commander, later Edward IV of England, convinced his frightened troops - who feared the worst - that the event represented the three sons of the Duke of York and they won a decisive victory, as described in William Shakespeare's King Henry VI.

A powerful anthelion in the summer of 1629 is believed to have influenced René Descartes to write his work of natural philosophy called The World. 

Sun dogs typically appear as two coloured patches of light either side of the sun and can be seen anywhere in the world in any season. This image shows a snowy landscape with the real sun on the left and a sundog on the right