Rare spectacle： the photographer photographed the moon ＂melting＂ on the sea.

　　An American amateur photographer recently captured a group of spectacular photos of the moon mirage in casco Bay, Maine. This rare astronomical phenomenon is called "Etruscan vases" by French science fiction writer jules verne. The reason for its formation is that layers of air at different temperatures bend the moonlight.

　　When light passes over the boundaries of different air layers, the moon in front of us will be deformed, creating the illusion that the second moon is tightly attached to the first moon. A few minutes later, the two moons separated, and the slightly lower "moon" slipped into the sea again.

　　After a full morning of sunshine, the sea surface began to heat up in the afternoon. Under this condition, an abnormal air layer with high temperature appeared and floated on the sea surface. On the day of this group of photos, the surface temperature of seawater reached 4 degrees Celsius, while the air temperature above the sea surface was only MINUS 8 degrees Celsius. When the light of the full moon hit the boundary between this cold and hot air layer, the path of the light would be deformed and refracted. So the illusion of a second moon appeared.

　　This phenomenon is similar to the illusion caused by puddles on the road in high temperature weather. Physicist Dr. Liz Cowley said: "The photo was taken in the evening. Under the irradiation of sunshine for a day, the sea water heats up, which makes the air temperature above the sea surface rise. Once the air in different layers has a temperature difference, the normal orbit of light passing through them will be deformed, which will produce this illusion. " He explained that the moon was blood red at that time, probably because the blue wavelength of light absorbed by the atmosphere was short, which allowed red light to pass through.

Editor: Li Xiuwei