Aurora: The beauty maker of night-sky

Dhaka, Sunday   05 April 2020


Aurora: The beauty maker of night-sky

 Dhrubo Ekramul

 Published: 11:37 PM, 8 October 2019  

Photo: Collected

Photo: Collected

How do you consider the night beauty of the sky? A moonlit-night or a sky full of thousands of stars? But how you feel to see a sky full of different color lights. Yes, these types of lights really exist in the world. The lights are seen above the magnetic poles of the northern and southern hemispheres. They are known as 'Aurora Borealis' or ‘Northern Lights’ in the north and 'Aurora Australis' or ‘Southern Lights’ in the south. Sometimes it also known as Polar Lights. The lights offer an entrancing, dramatic, magical display that fascinates all who see it


What is Aurora?

The aurora is a natural light display in the sky which particularly seen in the arctic and Antarctic regions. The bright dancing lights of the aurora are actually collisions between electrically charged particles from the sun that enter the earth's atmosphere. Aurora that occurs in the Northern Hemisphere is called ‘Aurora Borealis’ or ‘Northern Lights.’ On the other hand, Aurora that occurs in the Southern Hemisphere is known as ‘Aurora Australis’ or ‘Southern Lights’. Both of them can be seen in the northern or southern hemisphere in an irregularly shaped oval centered over each magnetic pole.


What makes this happen?

Basically, Auroras are the result of collisions between gaseous particles (in the Earth’s atmosphere) with charged particles (released from the sun’s atmosphere).

Though Auroras are best seen at night, they are actually caused by the sun. The sun sends us more than heat and light. It sends lots of other energy and small particles our way. The protective magnetic field around Earth shields us from most of the energy and particles; even we don’t notice them. But the sun doesn’t send the same amount of energy all the time. There is a constant streaming solar wind and there are also solar storms.

During a solar storm called a coronal mass ejection, the sun burps out a huge bubble of electrified gas that can travel through space at high speeds. When the solar storm comes toward our planet, some of the energy and small particles can travel down the magnetic field lines at the north and south poles into Earth’s atmosphere. There, the particles interact with gases in our atmosphere resulting in beautiful displays of light in the sky.

 You can see the color variation in these magical lights.  Variations in color are seen due to the type of gas particles that are colliding. The most common aurora color which is green is produced by oxygen molecules located about 60 miles above the earth. The rarer red auroras are produced by high-altitude oxygen, at heights of up to 200 miles. Nitrogen produces blue or purple aurora.

The light of Auroras is changed with time. Over the night, they begin with glows and progress towards coronas, although they may not reach them. They tend to fade in the opposite order. At shorter time scales, auroras can change their appearances and intensity, sometimes so slowly as to be difficult to notice, and at other times rapidly down to the sub-second scale.


Aurora noise

The noise of lights? Yes, Aurora has the noise. it similar to a hissing, or crackling noise which begins about 70 m (230 ft) above the Earth's surface and is caused by charged particles in an inversion layer of the atmosphere formed during a cold night. The charged particles discharge when particles from the Sun hit the inversion layer, creating the noise.


When it is seen?

If you plan for an aurora-viewing trip, make sure not to schedule it in the middle of summer. You need darkness to see the lights, and places in the Auroral zone have precious little of it during the summer months.

You also need a clear sky. Winter and springtime are generally less cloudy than autumn in and around the northern auroral zone. January to March, probably the three most popular months for Aurora hunting because they bring long dark nights and plenty of snow to play in during the daylight hours while you wait for darkness to fall.

In the Arctic, January is a time of renewal as the sun reappears above the horizon but it can be very, very cold indeed. Nevertheless, it is sometimes said that the Aurora is more likely to appear on colder nights so perhaps we could recommend January to hardier souls. Generally speaking, February sees the weather slowly improving and in March, the temperatures begin to rise although it can still get pretty nippy especially at night. A thick, pristine layer of snow covers the ground and because most of the winter snow has fallen, it could be said that there are fewer snow clouds overhead to obscure the Aurora.

There is some speculation that the spring and autumn Equinoxes (around 20 March and 20 September) bring greater solar activity. Combine this with slightly warmer temperatures and improving weather (with the possibility of less cloud cover) and you may feel compelled to go Aurora hunting in late-March or very early April. The daylight hours will be stretching out by then so you’ll have to be prepared for some late nights but this can be a very rewarding time of year in The Auroral Zone. Ideally, time your trip to coincide with the new moon, and make sure to get away from city lights when it's time to look up.

Magical Places to View Auroras

There we have mentioned about some magical places where you can see the Aurora. But according to the places, there are variations in the proper time to visit.


Fairbanks, Alaska, US

Located just two degrees below the Arctic, near the airport and close to the impressive Denali National Park, Fairbanks is the best place in the U.S. to take in the northern lights. It even has its own forecast system and offers tours to take visitors far from city lights.


Tasmania and New Zealand

You hear about northern lights more often than southern lights (aurora australis) because there are fewer locations to see auroras from the Southern Hemisphere. Your best chance is on the southern tip of both Tasmania (Australia) and New Zealand, where a dark sky will help you see any active auroras over the southern horizon. These are the closest accessible places to the south magnetic pole, outside of Antarctica.


Northern Sweden

Sweden’s northernmost town of Kiruna is a gateway for nearby attractions. There are the ICEHOTEL, mountainous Abisko National Park, the local Sami culture, and plentiful reindeer. A short drive from the town takes you to a good spot for aurora viewing. The weather here is much more stable than the Norwegian coast, but it’s colder too.


Kakslauttanen, Finland

Gaze at the Northern Lights in style – from inside a glass-roofed igloo, and then duck into a traditional log cabin jazzed up with a sauna and open fire. This and much more at the Kakslauttanen Arctic Resort in Finnish Lapland. If the Lights stand you up, there is other stuff to keep you occupied – start with a reindeer safari or ski around the Urho National Park. You will also be about two hours by road from the Russian border so drive across or get all traditional on a dog sled and visit Santa at Koryatunturi.

Yellowknife, Canada

This Northwest Territories capital on the shores of Great Slave Lake boasts its own Aurora Village and special activities for northern lights tourism.

Canada is an aurora viewing paradise, thanks to its northern latitude and low light pollution; elsewhere in the country, Wood Buffalo and Jasper National Park are popular viewing spots.


Tromsø, Norway

The largest urban area in northern Norway is 217 miles north of the Arctic Circle, but thanks to the Gulf Stream the coastline has surprisingly moderate temperatures. It also has beautiful scenery, magnificent fjords, and the Lyngen Alps.

I have seen spectacular auroras from the village of Ersfjordbotn, 12 miles from Tromsø. Other popular locations in the country are the Lofoten Islands and the far northern towns of Alta, Nordkapp, and Kirkenes.


It’s possible to be too far north to see the northern lights—such is the case in northern Greenland. But head farther south for beautiful auroras and attractions like Qaleraliq Glacier, which has small floating icebergs even in summer.


Do other planets get auroras?

Obviously, Auroras are not just something that happens on Earth. If a planet has an atmosphere and magnetic field, they probably have auroras. We’ve seen amazing auroras on Jupiter and Saturn.

History of the auroral lights

For millennia, the lights have been the source of speculation, superstition, and awe. Cave paintings in France thought to date back 30,000 years have illustrations of the natural phenomenon.

In more superstitious times, the northern lights were thought to be a harbinger of war or destruction, before people really understood what causes them. Many classic philosophers, authors, and astronomers, including Aristotle, Descartes, Goethe, and Halley, refer to the northern lights in their work.

As early as 1616, the astronomer Galileo Galilei used the name aurora borealis to describe them, taking the name of the mythical Roman goddess of the dawn, Aurora, and the Greek name for the wind of the north, Boreas.

The aurora australis, or the southern lights, occur around the south polar region. But, since the South Pole is even more inhospitable than the North Pole, it is often trickier to view the southern lights.


Legends of the lights

So many myths and legends exist about the Aurora. ‘Aurora Borealis’, the lights of the northern hemisphere, means ‘Dawn of the North’. ‘Aurora australis’ means 'dawn of the south'. In Roman myths, Aurora was the goddess of the dawn. Many cultural groups have legends about the lights. In medieval times, the occurrences of auroral displays were seen as harbingers of war or famine. The Maori of New Zealand shared a belief with many northern people of Europe and North America that the lights were reflections from torches or campfires. Aboriginal people in southwest Queensland of Australia believe the auroras to be the fires of the Oola Pikka, ghostly spirits who spoke to the people through auroras. Sacred law forbade anyone except male elders from watching or interpreting the messages of ancestors they believed were transmitted through an aurora.

The Menominee Indians of Wisconsin believed that the lights indicated the location of manabai'wok (giants) who were the spirits of great hunters and fishermen. The Inuit of Alaska believed that the lights were the spirits of the animals they hunted: the seals, salmon, deer and beluga whales. Other aboriginal peoples believed that the lights were the spirits of their people.