A photographer has managed to capture a stunning example of the 'Green Flash' phenomenon that takes place just before the sun sets over the horizon.
Featured as NASA's picture of the day yesterday the format was a little different from the rest, and that's because it wasn't strictly a picture at all.
It was a timelapse that overlooked the Golden Gate Bridge in San Francisco. Now while that was a sight beautiful enough to watch anyway, Alex Rivest managed to capture something rather special at the end.
What he saw was the rare phenomenon known as the 'Green Flash'. Just before the sun completely sets over the horizon, a green flash can sometimes be seen.
It can appear in several different forms from a green ray shooting up into the sky to a glowing orb that cuts through the clouds, it can be big, small and lasts from milliseconds to seconds.
These utterly unpredictable events are caused by the sun's light being split through the atmosphere into its individual colours. It's impossible to predict and even harder to capture.