A photographer has captured a shimmering green light in the night sky above Sweden. Peter Rosen said the light was coming from Venus and he captured it on January 8 (Monday). Explaining the phenomenon, spaceweather.com said that the cold atmosphere and an unusually sharp gradient in air temperatures over Stockholm acted like a prism, splitting the light from Venus to create the green colour. The phenomenon is called a green flash and is more familiar at sea when the Sun is low on a clear, calm horizon, the outlet further said.
"On Monday morning I woke up early to get a beautiful view of Venus and the Moon rising over Stockholm's skyline. Because of the extreme cold that still persists over southern Sweden, I also got an unexpected bonus in the form of a rare green flash on Venus," Mr Rosen told spaceweather.com.
This is not the first time that green flashes were observed on Venus, but Mr Rosen's video may be the best ever. "It was a magnificent sight," he said.
The bright flash lasted for about a second and the image has gone viral on social media.
The Sun too emits similar green flashes, especially when it rises above the horizon.
This happens due to refraction
In physics, refraction is the redirection of a wave as it passes from one medium to another. The bending causes the light to change its speed. So, when the sunlight enters Earth's atmosphere, the individual wavelengths gets partially refracted by gas molecules.
For example, the daytime sky appears blue because blue wavelengths scatter more than any other wavelength.
The speed of sound waves is greater in warm air than in cold. At night, air is cooled at the surface of a lake, and any sound that travels upward is refracted down by the higher layers of air that still remain warm. Thus, sounds, such as voices and music, can be heard much farther across water at night than in the daytime.
