"Moonbow" Observed in Ishigaijima Island
People would think rainbows are for the daytime alone and wonder if there are such things as nocturnal rainbows. The fact is there actually are rainbows at night called moonbows, and the islanders of Ishigakijima witnessed one last night, October 16.
The observatory in Ishigakijma, Okinawa, spotted and photographed a nocturnal rainbow cast over the island at around 20:30. It was a digital image but clear enough to show a mystic phenomenon at full moon - moonbeams refracted on water droplets in the air.
The photo shows a brilliant rainbow of red, yellow and green floating midair on a moonlight night. The Ishigakijima Observatory says a moonbow emerges only under a certain condition at full moon - dark sky, misty rains, etc. In most of the time, the moonlight is very faint and rainbows vague and whitish.
The observatory officials find the photograph taken this time exceptionally brilliant with all the seven colors conspicuous. Deputy director of the observatory, Mr. Hidekazu Hanayama, commented:
"The moonbow was observed for only ten minutes or so but clearly visible by the naked eyes. It was beautiful and very mystic."
A moonbow is in short produced by moonlight rather than sunlight and otherwise formed just as any other solar rainbows. The amount of light reflected from the surface of the moon is so faint that normally human eyes can't discern colors in a moonbow.
The image of the moonbow photographed in Ishigakijima is, therefore, very rare with all the rainbow colors clearly caught - unlike in long exposure photographs.
Maui Island in Hawaii is another location where moonbows are often observed. The Hawaiians believe moonbows bring luck to those who happen to see them.