This natural phenomenon is called Aurora. An
aurora is a natural light display in the sky. phenomenon here , it appears
that the light is dancing in the sky. The bright dancing lights of the aurora are actually
collisions between electrically charged particles from the sun that enter the
earth's atmosphere. The lights are seen above the magnetic poles of the
northern and southern hemispheres. They are known as 'Aurora borealis' in the
north and 'Aurora australis' in the south..
Auroral
displays appear in many colours although pale green and pink are the most
common. Shades of red, yellow, green, blue, and violet have been reported. The
lights appear in many forms from patches or scattered clouds of light to
streamers, arcs, rippling curtains or shooting rays that light up the sky with
an eerie glow. Besides an Aurora, some people called the bright dancing lights
is The Northern Lights. Aurora are caused by
charged particles, mainly electrons and protons, entering the atmosphere from
above causing ionisation and excitation of atmospheric constituents, and
consequent optical emissions. Incident protons can also produce emissions as
hydrogen atoms after gaining an electron from the atmosphere. Aurora have many different color that
will amaze you because of it beautifulness. The most distinctive and brightest are the
curtain-like auroral arcs. They eventually fragment or ‘break-up’ into
separate, and rapidly changing, often rayed features which may fill the whole
sky. These are the ‘discrete’ auroras which are at times bright enough to read
a newspaper by at night.The ‘diffuse’ aurora, on the other hand, is a
relatively featureless glow sometimes close to the limit of visibility.It can
be distinguished from moonlit clouds by the fact that stars can be seen undiminished
through the glow. Diffuse auroras are often composed of patches whose
brightness exhibits regular or near-regular pulsations. The pulsation period
can be typically many seconds, so is not always obvious. Occasionally there is
a fast, sub-second, flickering. A typical auroral display consists of these
forms appearing in the above order throughout the night.
• Red: At the highest
altitudes, excited atomic oxygen emits at 630.0 nm (red); low
concentration of atoms and lower sensitivity of eyes at this wavelength make
this colour visible only under more intense solar activity. The low amount of
oxygen atoms and their gradually diminishing concentration is responsible for
the faint appearance of the top parts of the "curtains".
• Green: At lower altitudes the
more frequent collisions suppress this mode and the 557.7 nm emission
(green) dominates; fairly high concentration of atomic oxygen and higher eye
sensitivity in green make green auroras the most common. The excited molecular
nitrogen (atomic nitrogen being rare due to high stability of the N2
molecule) plays its role here as well, as it can transfer energy by collision
to an oxygen atom, which then radiates it away at the green wavelength. (Red
and green can also mix together to produce pink or yellow hues.) The rapid
decrease of concentration of atomic oxygen below about 100 km is
responsible for the abrupt-looking end of the lower edges of the curtains.
•
Blue: At yet lower altitudes atomic oxygen is, uncommon, and ionized
molecular nitrogen takes over in producing visible light emission; it radiates
at a large number of wavelengths in both red and blue parts of the spectrum,
with 428 nm (blue) being dominant. Blue and purple emissions, typically at
the lower edges of the "curtains", show up at the highest levels of
solar activity.
Maybe,
you’re curious about where is the best place to watch the northern lights
right? Well, Northern
Lights can be seen in the northern or southern hemisphere, in an irregularly
shaped oval centred over each magnetic pole. The lights are known as 'Aurora
borealis' in the north and 'Aurora australis' in the south. Scientists have
learned that in most instances northern and southern auroras are mirror-like
images that occur at the same time, with similar shapes and colors.
Because
the phenomena occurs near the magnetic poles, northern lights have been seen as
far south as New Orleans in the western hemisphere, while similar locations in
the east never experience the mysterious lights. However the best places to
watch the lights (in North America) are in the northwestern parts of Canada,
particularly the Yukon, Nunavut, Northwest Territories and Alaska. Auroral
displays can also be seen over the southern tip of Greenland and Iceland, the
northern coast of Norway and over the coastal waters north of Siberia. Southern
auroras are not often seen as they are concentrated in a ring around Antarctica
and the southern Indian Ocean. Areas that are not subject to 'light pollution'
are the best places to watch for the lights. Areas in the north, in smaller
communities, tend to be best. I know its not that possible for us to watch the
northern lights or aurora that easy, because the place that we lived is really
far away from the place that we can see the auroras. But, you know someone told
me, if you want it, then dream it, and make it come true. So, if you really
curious about this phenomenon maybe you can make it come true to see it directly.
