An extremely rare cloud formation that creates an optical illusion and makes viewers think they are looking at an unidentified flying object (UFO) was recently spotted in the sky over the Turkish city of Bursa, the BBC reported on Friday.

This type of wavy cloud is known as a “lenticular cloud”.

Such an unusual cloud is a rare event, BBC journalists note.

The location of the city of Bursa at the foot of the mountains contributes to the emergence of this phenomenon.