Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Others think it is true but its cause isn't known.
Adventurers pride themselves on having seen it.
It's a green flash from the Sun . The truth is the green flash does exist and its cause is well understood. Just as the setting Sun disappears completely from view, a last glimmer appears startlingly green. The effect is typically visible only from locations with a low, distant horizon, and lasts just a few seconds. A green flash is also visible for a rising Sun , but takes better timing to spot.