Strange Green Light - UFO or Natural Phenomenon?

S.O.T.T: Harry Perton from Groningen, the Netherlands, likes to make pictures of nature. On Tuesday he set off in the Onlanden, the border between the provinces of Groningen and Drenthe.

Upon returning home, he looked up just and saw something weird. On one of his pictures of threatening skies is a green light phenomenon in the sky.

Perton "Suddenly saw something flashing," Harry wrote on his weblog. "I thought it was my device, but the flash was down.

There was not a drop on my lens. I decided it must have been the lightening of the sun. But at home I see something strange in one of the photos that I made at the end of the lane trees. "

Was it a UFO, a meteor or a special natural phenomenon?