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NORTHERN LIGHTS
NORTHERN LIGHTS
Alias Aurora Borealis are natural light displays in the sky, particularly observed in a circle
around the North Pole. (Near the South Pole they are called Southern Lights or Aurora
Australis). Aurora Borealis is named after the Roman goddess of dawn, Aurora, and Boreas,
the ancient Greek personification of the north wind.
The solar wind is the ultimate source of the Northern Lights. During large explosions and
flares, huge quantities of solar particles are thrown out of the sun and into deep space. These
plasma clouds travel through space with speeds varying from 300 to 1000 kilometers per
second.
But even with such speeds (over a million kilometer per hour), it takes these plasma clouds
two to three days or more to reach our planet.
Earth’s magnetic field typically deflects the charged particles streaming out from the sun, but
some amount escapes into our atmosphere around the poles. That is where the Northern
Lights (or the Southern lights) can get created.
SUNSPOTS
A sunspot is an area on the Sun’s surface that is marked by intense magnetic activity,
which inhibits convection, forming areas of reduced surface temperature. They can be
visible from Earth without the aid of a
telescope, and appear as dark spots. Solar
winds often originate around the sunspots.
SOLAR WIND
A gas of electrons and ions - at supersonic
speed - is continuously emitted from the sun.
This stream of gas is called the solar wind.
The solar wind is filled with gusts and gales,
and when a strong eruption from the sun hits
earth, the stable situation - which may have
existed for several days - is strongly
disturbed. The most spectacular result of this
interaction is an intense Aurora significantly
closer to the equator than during normal
conditions.
THE AURORAL OVAL
The Auroral zones represent the places on
earth where Auroras occur most often and
with greatest intensity. The Auroral oval is
nearly twice as wide and twice as far from
the magnetic pole at midnight as at midday.
On the night side the oval is roughly 10
degrees (about 1100 kilometers) closer to the equator than at the day side. The Auroral
oval can be regarded as fixed in space with reference to the sun. As the earth revolves
underneath, the daily variations in the Aurora's position occur.
COLORS
The different colors depend on temperature and density of the local atmosphere. They
correspond to different quantum transitions in excited atoms of oxygen and
nitrogen.As the charged particles (electrons and protons) of the solar wind escape
through the magnetic field, they run into gas in Earth’s
upper atmosphere (above 80 km). Ionized nitrogen
atoms can regain an electron and oxygen and
nitrogen atoms can return from an excited state to
ground state.
Exitation energy is lost by the emission of a
photon of light or by collision with another atom
or molicule. The colors can range between green,
red and multiple shades of purple. Altitude also
affects Auroral color. Green or yellow is the most
frequently observed color.
The strong, green light originates at altitudes of 100
to 180 km. Red Northern Lights occur at even
higher altitudes, while blue and violet occur
mostly below 120 km. When the sun is
“stormy”, red colors occur at altitudes of 90
to 100 km. Entirely red Northern
Lights may sometimes be seen,
particularly at low latitudes. In
earlier times, people often
mistook this red light for fire
on the horizon. They are
something truly marvelous to
experience.
AURORAL INTENSITY
Compared to the light from the sun and the moon, the brightness of the Aurora is
rather weak.
With new optical instruments, we can now study weak Auroras with intensities well
below the threshold of our eyes.
Weak Northern Lights have a brightness comparable to that of the Milky Way, our
galaxy, which can be seen as a diffuse band of light across the sky on clear winter
nights.
Medium-strength Northern Lights are brighter than most stars. Thus, during a
medium-strength Aurora we cannot see stars that lie behind the Aurora in the line of
sight.
Strong Northern Lights are comparable to light from the moon. The Northern Lights
are then much stronger than starlight and 100 to 1000 times stronger than the weakest
observable light.
HOW TO OBSERVE AURORA
Chasing the Aurora is difficult, since the phenomenon seems to have a mind of its
own, hiding from observers who wait for weeks, only to reveal itself in a spectacular
display the day after they leave. We get a lot of questions regarding the best time to
visit Iceland to see the Aurora. There is no simple answer, because we simply do not
know for sure. No one does, not until a few hours before the actual display. But there
are some things you can do to improve your chances of observing a wonderful
Auroral display. A little bit like salmon fishing, sometimes you must wait for the
perfect conditions to “catch the big one” and get them at their finest. But, if you get
lucky, you will see why it is well worth the wait.
What complicates things for us observers is two things. One: the oval isn't fixed in
one place, because it rotates with the sun, and, two: it may grow and shrink in size
considerably in only a matter of hours. On (very) rare occasions the oval can cover
the entire hemisphere down to Mexico.
Normally the following areas offer the best conditions: Northern parts of the Nordic
countries, including all of Greenland and Svalbard. Iceland is therefore an excellent
location for viewing Northern lights Northern parts of Alaska, USA Northern and
middle parts of Canada.Northern parts of Russia.11-Year Solar Cycle - “The Age of
the Aurora”
The sun has a heartbeat. This is known as the solar cycle and is measured by the
number of sunspots visible on the sun. Solar activity goes through regular cycles of
increasing and decreasing magnetic activity periods. When solar activity is at t’s peak
we refer to it as solar maximum. The east active period we call a solar minimum.
Each cycle is approximately 11 years. Since we started observing there have been 23
whole such cycles. We are now in the middle of the 24th cycle and aiming for the next
solar maximum in May
2013. The probability
of seeing Northern
Lights is higher during
the years close to the
solar maximum
than
during a solar minimum.
Nevertheless we can
have periods of great
Northern Lights during
the dark hours of winter,
at any stage of the solar
cycle.
BEST MONTHS?
Aurora Borealis season in Iceland runs from August through the very first days of
May. These are the nights with darkness. From the 20th of May until the 20th of July,
the sun never goes lower than 6° below the horizon - making the skies basically bright
all night and eliminating any Auroral viewing. During these summer months it is just
too bright to see them at higher latitudes.
Auroras can still be spotted south of about 50° latitude during the summer. Once
every hundred years during solar storms the aurora can reach as far south as Cuba.
Statistically, the equinox months of September and March are best for Aurora activity.
The winter months of October-thru-February are of course also good (there is
definitely no shortage of darkness!). A mythbuster is that contrary to popular belief, it
does not have to be cold to see the Aurora, just dark and clear.... and clear skies
usually mean it’s cold, hence the association between Auroras and chilly nights.
WHAT TIME OF NIGHTS?
The peak hours are between 11pm and 2am, however, anytime it’s dark there is hope.
We have seen the northern lights at Hotel ION as early as 7 pm and as late as 9 am.
BASIC SETTINGS FOR PHOTOGRAPAHING THE NORTHERN LIGHTS:
To avoid blurry and unfocused pictures, use a tripod and if possible a remote to
prevent the camera from moving while attempting to catch the northern lights. If
possible lock the mirror to minimize the vibration of the camera. Take the stabilizer
setting off. Adjust the autofocus on a bright star and immediately adjust to the manual
setting. The light OP should be set to the most open option. The ISO and time setting
depends on the quality of the lens.