It is an image worthy of a science fiction film: a rainbow, photographed in the middle of the night, glimmers in the foreground while behind it a brilliant star rises above the horizon. The effect is exotic and unworldly. Nevertheless, the picture is very much an earthly affair. It was taken by photographer Wally Pacholka while he was standing at the edge of Haleakala crater on the island of Maui in the Hawaii archipelago.

As Pachokla explains, that band of colours is, in reality, a moonbow. Like a rainbow, its daylight equivalent, a moonbow is produced when light is broken up into its constituent colours as it passes through water droplets. In both cases, the source of light is the same: the Sun. In the case of the rainbow, sunlight produces its effect directly. In the case of the moonbow, however, that sunlight is first reflected off the surface of the moon and then shines back down to Earth.

"A moonbow is just like a rainbow but is caused by the moon reflecting off rain mist at a certain angle," says Pacholka. "I was very fortunate to see this. But in a sense I created this fortune as I was always out there: I drove up the crater mountain that night but also about every night, even going twice the night before – early evening to shoot the evening sky then back again in early morning to shoot the morning sky."

As to that mysterious star rising above the horizon, it turns out to be the planet Mars which is currently making one of its closest approaches to Earth. The Red Planet is currently around a 100 million km distant from us and shines like a brilliant red beacon as it rises in the east on its journey across the night sky. Hence the impact of this photograph: a distinctive planetary display captured beside a rare moonbow.