You are watching a beautiful sunset over
the ocean - the bottom edge of the sun kisses
the horizon and begins to disappear. At the
last moment before it vanishes, the upper
tip of the sun turns, for an instant, a brilliant
green. You have just seen the remarkable
The Green Flash is an astonishing sight.
Most people, including most astronomers have
never seen it.
The effect is real, though rare, because
conditions have to be exactly right for it
to occur. You must have an unobstructed view
to the horizon with no mountains, trees or
buildings to block the view. There must be
no cloud or haze or fog to swallow up the
sun before it touches the horizon. A view
west towards the ocean is ideal, but even
then the Green Flash can be obscured more
often than it is visible.
Unmistakable and unforgettable despite its
name, there is no flash of light. The flash
refers to its brevity. lt is over quick as
How to see the Green Flash
lf conditions are right, there is a trick
to looking for it. First, just before sunset,
check out the view. lf you can see the bottom
edge of the sun touch the sea, chances are
you will see the Green Flash. At that point
look away from the sun, so your eyes don't
succumb to the glare. Steal momentary glances
over your shoulder every few seconds to get
a sense of the sun's rate of descent.
When about ¾ to 7/8 of the sun has
set, look at the sun, as the last bit disappears,
you will see it glow green like an emerald.
Why does it happen?
lt is fairly complex phenomenon and is caused
by the fact that the different colours of
sunlight, the colours that form the rainbow's
spectrum, behave differently when travelling
through the air. Some of the colours are
absorbed, some are scattered. The thick atmosphere
in the direction of the horizon bends light
at different angles. At the moment the sun
sets, the green light is bent so it runs
parallel to the surface of the Earth and
straight into your eyes. The other colours
are either absorbed or bent at an angle so
they miss your line of sight. A ship at sea
is one of the best places in the world to
see the Green Flash. Seeing a Green Flash
is sure to bring a moment of pure happiness!