Rising and setting 'Omega sun' melts into a 'lava-like blob' in trippy mirage photos

A rare phenomenon known as an "Omega sun" can be seen in this image of the setting sun taken July 11 on the island of Korčula in Croatia. (Image credit: Martin Gembec)

Photographers in the Mediterranean recently captured stunning images of the sun appearing to melt toward the horizon as it set one day and then rose again the next day, creating trippy "lava-like blobs" in the sky. 

On both occasions, an enormous sunspot was also clearly visible on the warped sun's surface.

On July 11, photographer Martin Gembec captured shots of the oozing sun from the island of Korčula in Croatia as the seemingly deformed star began to set behind the Adriatic Sea. Then on July 12, photographer David Marshall saw the same effect as the sun rose above the Adriatic Sea, but this time from the Italian coastline near San Benedetto del Tronto.

The rare phenomenon is known as the "Omega sun" — named after the Greek letter, which has a similar shape to the warped sun that stretches down and then out, according to Spaceweather.com. It is a type of "inferior mirage," which is caused by differences in air temperature above the water's surface. The effect is also dubbed the "Etruscan vase" due to the similarities between the shape of the warped sun and pottery made in what is now Italy between the 7th and 5th centuries B.C..

The images by Gembec (seen above) are only a partial Omega sun because the setting sun does not touch and spill out across the horizon. Marshall's photo (seen below) shows the phenomenon in its entirety as the sun rises from behind Earth's curvature. 

Related: Ethereal 'halo' and light arcs around the sun captured in photos of ultra-rare phenomena

A second image of an Omega sun taken during sunrise on July 12 from San Benedetto del Tronto in Italy. This example shows the effect in its truest form as the sun 'melts' into the horizon. (Image credit: David Marshall)

Inferior mirages are created when the ocean's surface, and the air just above it, is much warmer than the air further above the surface. The temperature difference causes light from an object (in this case the sun) to bend upward toward an observer, which counterintuitively creates a second inverted image of the object underneath, according to San Diego State University. So during an Omega sun, the bottom part of the sun is essentially being reflected by an invisible mirror. (The same mirage can also sometimes warp the moon in a similar way if it is near the horizon.)

As the sun sets, the last part of the sphere that dips below the horizon can also be warped into a triangle, making it look more like a pyramid (see below).

The Omega sun effect can cause the top part of the sun to look like a pyramid as it sets or rises. (Image credit: Martin Gembec)

The opposite of an inferior mirage, known as a superior mirage, is created by reverse conditions, where the temperature higher above the ocean is warmer than the air just above the water’s surface. This can cause objects, such as large boats, to appear as if they are levitating above the horizon.

The successive sightings of Omega suns in the Mediterranean may be linked to an extreme heatwave in Europe, which has caused temperatures to skyrocket to near-record levels for more than a week, according to the BBC. This excess heat could have been absorbed within the first few feet of the ocean's surface, which would cause the air around it to remain warm as temperatures cooled overnight.

In both images, a large sunspot, named AR3363, is clearly visible. On July 15, AR3363 spat out a cloud of fast-moving magnetized plasma, known as a coronal mass ejection (CME) that combined with another CME to form a "cannibal CME," which slammed into Earth on July 18.

Harry Baker
Senior Staff Writer

Harry is a U.K.-based senior staff writer at Live Science. He studied marine biology at the University of Exeter before training to become a journalist. He covers a wide range of topics including space exploration, planetary science, space weather, climate change, animal behavior, evolution and paleontology. His feature on the upcoming solar maximum was shortlisted in the "top scoop" category at the National Council for the Training of Journalists (NCTJ) Awards for Excellence in 2023.