Aurora Borealis & Science Behind It

All the natural phenomenon that takes place on this beautiful planet of ours are just worth watching, they are so mesmerizing that they truly make you feel content and you feel glad you had an opportunity to witness it. Now, obviously not all of them are beautiful & glorious to watch, something like volcanic eruption, tsunami or earthquake are couple things one wouldn’t like to be part of, which is reasonable those phenomena give us the feeling of fear & impulsive nature of our planet.

As a child everyone has wondered and asked why does the sky appears blue during day & orange at dusk & dawn. Answer to that will be Sunlight reaches Earth's atmosphere and is scattered in all directions by all the gases & particles in the air. Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue-sky during daytime. Whereas during dusk or dawn, as the Sun gets lower in the sky, sunlight is passing through more of the atmosphere to reach you. Even more of the blue light is scattered, allowing the reds & yellows to pass straight through to your eyes.

Now all of that happens under daylight, one of the similar effects happen during night sky. Aurora Borealis & Aurora Australis commonly known as Northern & Southern Lights respectively. The Northern Lights are featured on almost every traveler’s bucket lists, travelers from all over the world travel to countries in the 'Auroral Zone' in the hope to witness this unique spectacle. The Northern lights are one of Nature’s most jaw-dropping sights, & also are listed as one of the seven natural wonders of the world.

What Are Northern Lights?

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 & southern hemispheres. In the sky, an Aurora takes the shape of a curtain of light, or a sheet, scattered clouds of light to streamers, arcs, shooting rays that light up the sky with an eerie glow. Auroral displays appear in many colors although pale green and pink are the most common. Shades of red, yellow, green, blue, & violet have been reported. The most common aurora borealis color is green, which is produced by oxygen molecules located about 100 km above the earth.

Colors such as red, yellow, green, blue and violet are also seen occasionally. The rarer red auroras are produced by high-altitude oxygen, at heights of up to 300 km. Nitrogen produces blue or purple aurora. 

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 Ever Changing Color of The Sky, Reminds Us of Life's Uncertainty.

What Causes Aurora Borealis?

The Northern Lights are actually the result of collisions between gaseous particles in the Earth's atmosphere with charged particles released from the sun's atmosphere. Our sun is 148 million km away, but its effects extend far beyond its visible surface. The temperature above the surface of the sun is millions of degrees Celsius. At this temperature, collisions between gas molecules are frequent. Free electrons & protons are thrown from the sun's atmosphere by the rotation of the sun & escape through holes in the magnetic field. Blown towards the earth by the solar wind, the charged particles are largely deflected by the earth's magnetic field. However, the earth's magnetic field is weaker at either pole & therefore some particles enter the earth's atmosphere & collide with gas particles. When charged particles from the sun strike atoms in Earth’s atmosphere, they cause electrons in the atoms to move to a higher-energy orbit, further away from the nucleus. When the electrons drop back to a lower energy orbit, they release a photon: light, that we perceive as the dancing lights of the north (and the south).

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Interesting Note : Northern Lights are rarely seen from Southern Europe, but on the rare occasions that they appear, they are usually red, which can be terrifying for people unaware of its origin. A few weeks before the French Revolution the skies over England and Scotland turned red, so the lights were believed to be a bad omen.

Places To Watch The Auroral Display

The Northern Lights can be found in a band known as the “auroral zone” in the Northern hemisphere, which is a wider area around the magnetic pole. So, the best Aurora Borealis can be seen from Greenland, Iceland, Alaska, Northern Canada, Russia, Norway, Finland & Sweden. With less land in the south, the southern lights are perhaps less talked about as they mostly occur over water, but they can be seen from Antarctica, & over parts of New Zealand, Australia & Tasmania.

Astronauts on board of the International Space Station are at the same altitude as the auroras & see them from the side.

Northern Lights From International Space Station

The radiation bursts from the sun that occur during aurorae can harm astronauts in space. They can also alter the paths of orbiting satellites, increasing the likelihood of collisions between the thousands of objects orbiting Earth. A better understanding of when & where aurorae appear could help scientists better predict collision-free paths. 

Best Time To Experience It

Auroras occur throughout the year, however you need dark skies to see them. So, summer months render them invisible to the naked eye. Winter in the north is generally a good season to view lights. The long periods of darkness & the frequency of clear nights provide many good opportunities, period between December to March, are best as they bring long dark skies, but also pretty cold nights.

The Autumn can be more preferable time to watch the display if you are planning to avoid harsh cold nights. Another benefit of this season would be you can see the reflection of the lights over the lake or water if you are camping around one, creating the most beautiful sights of all times. The reflections over the water surface is something very unlikely during winter as the lakes are frozen. The best time apart from winters would be September & October.

However, since Aurora is a naturally occurring phenomenon, it is hard to predict in advance. Much is dependent on solar winds, so you might count on a bit of luck for that.

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Things You Need To Be Aware About

Observing the Auroral Show is a truly breathtaking experience, however, if you’re planning to go Aurora stalking, you should know that the lights might not appear bright green like in photographs. The naked eye sees the lights more greyish, unless they are very very bright.

You’ll need dark clear skies, but that is not the only key factor for them to be visible. Once they appear, the show can last for a few minutes or all night, depending on the magnitude of the arriving solar wind. So, when planning to see the Aurora, one of the most important things would be patience. All of that pays off once you witness it!

Aurora Borealis is influenced by activity of the sun which is roughly 11-Year Cycle, each solar cycle includes 3-4 years of solar maximum, accompanied by couple of years of transition & 3-4 years of solar minimum. So, obviously solar maximum would produce a lot of northern lights compared to solar minimum. Unfortunately the year 2021 lies under solar minimum which means there would be less dancing light.  

The colors in the aurora were also a source of mystery throughout human history. But science has an answer to most of the marvels. 

Myths About Polar Lights

• '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.

• 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 & beluga whales.

• Other aboriginal peoples believed that the lights were the spirits of their people.

• Some Inuit believed that the spirits of their ancestors could be seen dancing in the flickering aurora.

• In Norse mythology, the aurora was a fire bridge to the sky built by the gods.

• 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 & North America that the lights were reflections from torches or campfires.

Auroral Exhibition On Other Planets?

As said solar winds & atmosphere are big factor for the display, which means yes it can be seen on different planets. One more factor would be magnetic fields of a planet.

Mercury : Mercury also has a magnetosphere and so we might expect aurora there too. Unfortunately, Mercury is too small and too close to the sun for it to retain an atmosphere, meaning the planet doesn't have any molecules for the solar wind to excite and that means no auroras.

Venus : Venus does not have a magnetic field, so it would not have night-time aurora.

Mars : Today Mars has no visible aurora, but it does have ultraviolet aurora. These are known as proton aurora, and they occur with the solar wind strikes hydrogen atoms in the upper atmosphere of Mars. While these aurorae are invisible to the naked eye, they tell the story of how Mars became a dry world.

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Jupiter : The auroras are brilliant curtains of light in Jupiter's upper atmosphere. According to NASA, Jupiter has the most powerful auroras in the solar system. They are created when high-energy particles enter the planet's atmosphere near its magnetic poles and collide with atoms of gas.

Source : Northern Lights Captured On Hubble 

Saturn : Saturn's auroral displays are caused by an energetic wind from the Sun that sweeps over the planet, much like the Earth's aurora that is occasionally seen in the nighttime sky and similar to the phenomenon that causes fluorescent lamps to glow.

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Uranus : Uranus for along time was considered to not have magnetic fields so Auroral display is something that can’t happen. But two powerful bursts of solar wind traveling from the sun to Uranus fueled the most intense auroras ever detected on the planet. By watching the auroras over time, a team discovered that these powerful iridescent sections rotate with the planet. They also re-discovered Uranus’ long-lost magnetic poles, which were lost shortly after their discovery by Voyager 2 in 1986 due to uncertainties in measurements and the fact that the planet’s surface is practically featureless.

Neptune : The gas planet has a strong magnetic field, a dense atmosphere and, as a result, its own aurora. The exact nature of these auroras is slightly different from Earth’s, since the atmospheres and magnetosphere is different. The colors, for example, depend on the gases in the planet’s atmosphere. But the fundamental idea behind the auroras is the same.

People who might go mad for not including Pluto in that list, lets give you something to be hopeful of. Researchers think Pluto also may have an ionosphere and a weak magnetic field. However, it may have a magnetic field as well as an ionosphere — a place that is home to the auroras that dazzle the Earth's skies — the chances of seeing auroras in the skies of Pluto are very slim.