READ THE PASSAGE AND ANSWER THE QUESTIONS THAT FOLLOW.
Rainbows are meteorological phenomena
that you sometimes see when there is
both rain and sun at the same time. They
occur as a result of reflection, refraction
and dispersion of light in water droplets
that cause the spectrum of light to appear
in the sky. A rainbow has the form of a
multicoloured arc. When rainbows are
caused by sunlight, they always appear in
the sky directly opposite the sun. Sometimes
you might see a double rainbow in the sky.
Here, the primary rainbow, that which is
more vivid, will have red on the outer part
and violet on the inner, with all the colours
of the spectrum in between. The secondary
rainbow, which is normally less clear, will
have the reverse order of colours, with violet
on the outer and red in the inner sides of
the arc.
Rainbows are often thought to be very
beautiful and a relatively rare sight. As such,
they have inspired cultures and legends for
millennia. In Greek and Roman mythology,
the rainbow was thought to be a path
made by a messenger between the Earth
and Heaven. In Norse mythology, which
was once widely accepted by northern
Germanic and Scandinavian people, the
bridge connecting the realms of the gods
and humans, was a rainbow. In Chinese
mythology, the rainbow was thought to be
a cut, or slit, in the sky that was sealed by
the goddess Nüwa using stones that had
five different colours. In yoga, a popular
form of exercise and relaxation, it is taught
that there are seven centres, or chakras,
in the human body. These are thought to
reflect the colours of the rainbow and start
with red at the base of the spine and as
you move up the body, the colour changes
until you reach violet at the top of the head.
Today, rainbows are commonly thought of
as having seven colours, however some
of these are hard to distinguish from each
other and so it is possible to understand
why people may have thought that there are
only five. In actual fact, it is a continuum
of colour that gradually changes due to
differing wavelengths that the human eye
cannot see. Isaac Newton, discovered how
to reproduce the colours of the rainbow
using a glass prism and a slit of light. This
is a common experiment carried out by
schoolchildren all over the world who can
experience the phenomenon of splitting
white light into its constituent colours in
their classroom.
In Ireland, leprechauns are said to hide their
pots of gold at the end of a rainbow. The
idea is that, if you can find the end, you can
find the pot of gold. However, this place is
impossible to reach. A rainbow is an optical
effect, and can be considered an illusion,
that is dependent on the location of the
viewer. When you walk towards the end of
a rainbow, it will seemingly move further
away. Likewise, if two people observe a
rainbow simultaneously but from different
locations, they will disagree on the exact
positioning of the rainbow. Finding the end
of a rainbow will also be hindered by the fact
that they are in fact full circles, and have no
ends. So, it is impossible to find that ever
illusive pot of gold. We usually only see the
half of a rainbow due to our positioning with
respect to it. However, although even rarer
than seeing a half rainbow, it is sometimes
possible to see a full rainbow circle from
tall buildings or when flying in aeroplanes.
The rainbow is a natural and universal
symbol that works in any language and
in any culture. Whatever you associate
a rainbow with, it is undeniable that the
phenomenon is fascinating. In seeing the
colours of light separated out, we have
been able to make scientific advances in
optics and understand a lot about our world
and the universe beyond it. Our current
comprehension of how light works enables
us to stare at the night sky with specially
designed instruments so that we can see
distant stars and actually get a glimpse
of events that have happened in the past.
As the light from distant galaxies takes a
long time to travel to us, what we see with
our telescopes, is not happening now but
occurred many millennia ago.
Choose the best title or heading for the passage.
A Time travel using light
B How to find a pot of gold
C Somewhere over the rainbow
D Different ideas from around the world
