A moonbow is a rare and special phenomenon to behold, another of
the wonders of our incredible Mother Earth.
A moon bow is just as it seems: a rainbow but made from the light
of the moon rather than the sun. They are also called lunar rainbows.
Moon bows are rare because the moon shines very little light
compared to the light coming from our sun. Our Sun is roughly 400 times larger than the Moon. But the Sun also
happens to be 400 times further away than the Moon, and this has created an
amazing coincidence. This coincidence means that the sun and moon appear to be
the same size to us and this is why we experience the amazement of eclipses. In
actual terms the brightness we get from the sun is 400,000 times brighter than
that we receive from the moon, thus conditions have to be exactly right for us
to experience a moonbow or lunar rainbow.
In order for us to see a Lunar Rainbow the
moon must be almost full and be no more than 42 degrees away from the earth, or
ideally, closer. The lower the Moon is, the bigger
the moonbow. The tallest moonbows occur when the Moon is within an hour of
rising or setting
The Supermoons that we have experienced
this year would be a great time to observe a good moonbow as the Moon is larger
and closer to the earth when it is a supermoon.
The other conditions required for this
event are that the sky must be as dark as possible and there must be some sort of rain falling or other moisture
such as a big waterfall. The Moon must be
clearly visible in one part of the sky while rain or other moisture falls in
the opposite part. As the moon strikes the falling water
droplets, the primary rainbow is produced in exactly the same way as a rainbow
from the sun would be. The moonbow though is much less intense as there is a
lot less light and often looks dull grey or white to the naked eye. This is
because when we look at the moonbow, because of the low light we are using our
rod vision which is not colour sensitive.
Photographs of moonbows that show the
colours are possible because a long exposure with a camera can allow the
colours of the rainbow to filter through. Often photographs need to be exposed
400,000 times longer than would be normally used during the day to compensate
for the fact that the moon is 400,000 less bright! This means that often when
you look at photos of moonbows it appears like daylight but it isn’t it is just
the way the photograph has been exposed in order to see the moonbow.
The very best examples of a moon bow or Lunar Rainbow can be seen when water droplets are blown down-wind ahead of the main body of a
shower or convective cell. When this happens the Moonbow can be viewed against
a clear sky background filled with bright stars. The other great viewing
opportunities are near some of the world’s most spectacular waterfalls.
Yosemite National Park and Victoria Falls are particularly good places to spot
a moonbow. Other locations include Ireland and Hawaii.
I haven’t had the good fortune to
behold the wonder of a moon bow. I think that rainbows are such an impressive
site, so to see a moon bow would be amazing. I would love to hear from any of
you that have witnessed such a site.
“In this silver light he could hold
her gaze and as if he knew what she had in mind, he said, `I saw a moonbow
tonight.”
Will Davenport THE PAINTER
(2003)
Moon bow blessings, Alison
Wow, this is amazing! I would love to see this ;o)
ReplyDeleteYep me too, one day maybe.....xx
ReplyDelete