Why is the northern lights (Aurora Borealis) different from the southern lights (Aurora Australis)?
Faced with the spectacle of the polar aurora, some remain simply in admiration. Others, like these Norwegian researchers, are trying to unravel its mysteries. They now offer us an explanation for the asymmetries observed between the Aurora Borealis (northern lights) and the Aurora Australis (southern lights).
The polar aurora is a phenomenon which occurs in the upper atmosphere and which manifests itself during the night by the appearance in the sky of lights whose shape and intensity can change rapidly and whose color is generally between blue-green and yellow, more rarely towards red.
Name of polar lights, aurora polaris, northern lights, aurora borealis, or southern lights, aurora australis.
Aurora Borealis (northern lights)
Northern lights occur mainly in the polar regions, where the field lines penetrate the atmosphere. They occur both in northern latitudes (northern lights, also aurora borealis) and in the southern hemisphere (southern lights, also aurora australis).
These phenomena are also observed on other planets in the solar system . The prerequisite for this is that the planet has its own magnetic field and atmosphere. In 2015, astronomers were able to observe auroras outside the solar system for the first time. The activities observed on the low mass star LSR J1835 + 3259, 18 light-years away, were about 10,000 times more powerful than auroras on Jupiter.
What is the aurora borealis?
The aurora borealis comes from the Latin word “aurora borealis”. The word aurora means sunrise: it is also the name of the Roman goddess of the dawn, and borealis refers to the Greek name for the north wind.
Aurora Borealis is a member of the Northern Lights family. There are Northern Lights which are only visible in the Northern Hemisphere including in Iceland and Southern Lights which are only visible in the Southern Hemisphere. The polar aurora is marked by streaks of color that dance across the sky.
How do polar aurora occur?
According to scientists, this phenomenon is the result of the collision of energy-charged particles with atoms in the high-altitude atmosphere. This solar wind is then directed through the atmosphere by the Earth’s magnetic field.
Geomagnetic storms are an important part of the weather in outer space. It is caused by shock waves from the solar wind or magnetic field clouds. This is caused by transient magnetic disturbances in the interplanetary medium.
The aurora occur in a region of the atmosphere 100 km (60 mi) above the earth, while rays can extend from this level to 500 km (about 300 mi).
What color is the Northern Lights?
The Northern Lights and Southern Lights are typically fluorescent green, orange, and purple with undertones of red, pink, blue, and yellow. These colors are created by the gases present in the air: a fine mixture of oxygen and nitrogen.
When can we see the Northern Lights?
Seeing the Northern Lights and Southern Lights depends on weather conditions and several conditions must be met in order to see them. You can observe it on a dark night away from light with clear skies and a certain intensity of the Northern Lights.
In Iceland, they then occur year-round but are only really seen between September and April.
Where can we see the Northern Lights?
The Northern Lights are visible in the Nordic countries above latitude 60°N. In contrast, the aurora australis is seen below the latitude of 60°S.
The Northern Lights are easily visible from Alaska, Canada, Greenland, Iceland, Norway, Sweden, Finland, and northern Russia. During geomagnetic storms, the Northern Lights observation area is larger and more intense: they are then visible at lower latitudes (such as in the Baltic states) but the Northern Lights zone is more active between 10° and 20° from North Pole.
In the northern hemisphere, the Scandinavian countries have a front row seat. The Aurora Borealis has long been observed and even celebrated.
- In Norway: the city of Tromsø dedicates an open-air festival to it every year; the city of Alta acquired the first observatory in 1899; finally, Kirkenes which is a border town with Russia. Still further north, the Lofoten Islands and the wild Svalbard archipelago are also good places.
- Hunting for the Northern Lights in Finland is not very difficult, you have to head to the far north of Finnish Lapland, to the region of Kittilä, a town located 170 km above the Arctic Circle, or to the towns of Inari, Kaamanen or even towards the mountains of Kiilopää which are among the best spots.
- Sweden has an Aurora sky station specially dedicated to the Northern Lights and located in the middle of nowhere. It is reached by train and then by chairlift. These include the small Swedish village of Abisko, in the Kiruna region, and the village of Jukkasjärvi, where the first ice hotel was created.
- In Danish territory, let us quote the Faroe Islands. In a very good place, the island of Greenland and the town of Kangerlussuaq, due to its stable micro climate and it offers a spectacle in a most supernatural setting with its glaciers and these arctic landscapes. But of course northern lights in Greenland can also be seen in many other places, like Disko Bay, East Greenland and Nuuk.
- Less well known is the far north of Russia with wild observation points in the middle of the tundra and particularly difficult to access. The more adventurous will go to Murmansk or Salekhard.
- In Iceland, always head north: you have to get away from Reykjavík and the city lights, and go to the small village of Kálfafell or the very isolated village of Sandgerdi.
- Some pretty spots in Scotland are surprisingly located on the same latitude as some Norwegian or Canadian cities. The Hebrides and Shetlands are regions truly preserved from any light pollution, an important parameter for the observation of these celestial dances.
- In northern Canada, Alaska is distinguished by one of the lowest pollution rates. Jasper National Park, located in the Rocky Mountain Nature Reserve, offers good sky visibility. The cities of Fairbanks and Yellowknife are great places to see the Northern Lights.
Aurora Australis (southern lights)
Less known than the aurora borealis, which is the polar aurora of the northern hemisphere, the aurora australis arouses the same emotions in you with its breathtaking shows. It will reward you with an impressive phenomenon manifested by the appearance in the sky of dancing lights dominated by blue and green colors.
To be able to admire it, places close to the Antarctic Circle are to be privileged. If this adventure tempts you, here are the best times and the must-see destinations to see the Aurora australis up close.
The best times to see an aurora australis
To put the odds in your favor, it is best to plan your stay during the “polar night” period. This period corresponds to winter when darkness lasts 6 months in the Arctic. And since you are going to be in the southern hemisphere, it will therefore be the southern winter which extends from May to October even if the aurora australis can be observed over a long period, or even all along the year in some areas. And depending on where you choose, which can be Patagonia, southern Argentina or Chile, countries in southern Oceania, you will better observe an aurora australis when you have more climatic conditions. lenient. It is particularly spectacular when the sky is clear and the sun is more active.
You will then have the leisure to admire the aurora australis manifesting itself in many forms; they are sometimes presented in the form of a serpent of light which suddenly lights up the night, hence the legend of the dragon of light among some peoples. They can also take the form of dancing curtains of light, or even more spectacular in the form of a crown. Either way, have your cameras or camcorder ready to capture those intense moments and choose your destination.
The best places to see the Aurora australis in South America
Due to its proximity to the Antarctic Polar Circle, Patagonia is an exceptional observation point from which to admire the aurora australis. You will leave Ushuaia to discover Tierra del Fuego and take the same opportunity to admire the unique flora and fauna of this land at the end of the world. To give yourself a better chance of seeing an aurora australis, the month of September is particularly recommended. Although it is still cold, the sky is clearer, allowing you to admire this awe-inspiring spectacle. And to make the most of your stay, warm clothes are essential.
From the south of Chile, starting from Punta Arenas, you can make a trip to discover the region of Magallanes and the Chilean Antarctica which are favorable to the observation of the aurora australis. You will marvel at the beauty of these light shows dominated by green and blue but also by the furtive appearance of red and purple. As in the Argentine Patagonia, the observation period, which can extend throughout the year, is more favorable from May to October. The lights are particularly beautiful in September, with its clear skies and relatively mild temperatures. This will therefore be the opportune moment.
The best viewing places in Oceania
Although located at a higher latitude, South Oceania allows you to see an aurora australis as spectacular as an aurora borealis of the northern hemisphere. Here are the best viewing sites.
The island of Tasmania in Australia
The island of Tasmania is located in the south of Australia, and ironically, even though it is further north compared to Patagonia, this is where you are most likely to see a more breathtaking light show. and which can last several minutes. Favored by a less crowded atmosphere, the climate of Tasmania, especially in the south, is ideal. Heading to Mount Wellington in Hobart at 7 Mile Beach, you won’t tire of the view of the Southern Lights. Prefer the southern winter for better observation.
This stay will also be an opportunity to discover, during the day, the beaches and the beautiful waves that will delight surf enthusiasts. Also take advantage of your vacation to discover the flora and fauna that characterize the island of Tasmania. You will be amazed at the rate of endemicity of plant and animal species.
The South Island in New Zealand
Geographically closer to Antarctica, the South Island will provide you with a breathtaking light show. However, it will steer you away and forget about the artificial lights of big cities to give you every chance to make the most of it. Mount John, near Lake Tekapo, is a magnificent viewing point. Arrange to be there when the sky is clear. And as in the entire northern hemisphere, the most spectacular appearances occur during the southern winter.
Avoid making the trip just to observe an aurora australis. Make sure that your trip to New Zealand, also allows you to discover the awe-inspiring landscape of this country, namely the mountains crowned with eternal snow which fascinate with their beauty. You will also be able to meet the indigenous peoples who are distinguished by their culture where tattooing and respect for ancestral rites find their letter of nobility.
Observation sites on the Antarctic continent
This opportunity is not given to everyone. However, if you happen to embark on a cruise that crisscrosses this part of the world, take a break and scan the sky. You will be surprised by the quality of the light and the clarity of the sky which will give you a simply incomparable aurora australis.
If you have a predilection for the northern lights, opt for destinations favorable to their sightings. To get off the beaten track, cruises in Patagonia could be an enriching experience while in Oceania, it will be an opportunity to combine a stay of cultural discovery, a sporting holiday with the observation of these rare phenomena but which are worth being seen.
Why are the Aurora Borealis (northern lights) and the Aurora Australis (southern lights) different?
In the northern hemisphere, they are called the northern lights, and in the southern hemisphere, the southern lights. Besides a semantic difference, there is also a geophysical difference between the two types of aurora. What is the origin of this difference?
Ever since scientists realized that these two celestial phenomena are not the same, they have tried to figure out why. Geophysicists eventually discovered that this was due to asymmetry in the magnetic tail of the Earth’s magnetosphere.
“We initially thought that the asymmetry in the system emerged in the magnetosphere through a mechanism called tail reconnection. However, the data collected showed that this was in fact not the case, ”says Anders Ohma, a geophysicist at the University of Bergen in Norway.
1. Interactions between the solar wind and the terrestrial magnetospheric tail
It all comes down to the Earth’s magnetic tail (or magnetoceue), which is created by the interactions between our planet and the Sun. These interactions start with the Earth’s magnetic field, which comes from convection phenomena in the Earth’s core. Magnetic fields create invisible magnetic field lines forming an arc between the North and South Poles, which can govern the behavior of materials around them.
But the Earth’s magnetic field isn’t the only one that exists, the Sun has one as well, which affects the constant flow of highly charged plasma particles flowing in all directions. The magnetic field built into this flow, called the solar wind, interferes with the one the Earth generates, crushing it on the lighted side of the Earth facing the Sun and stretching it on the night side, opposite the Sun, into a shape of tail.
The magnetic field lines pass through the distorted field, and they are not fixed; they break and reform in chaotic events called reconnections. Geophysicists initially believed that this magnetic tail reconnection phenomenon was the source of the difference between the southern and northern lights.
2. The asymmetry between the magnetic field of the solar wind and the geomagnetic field
The researchers simultaneously collected far infrared observations of auroral phenomena and looked for similarities. Then they added data on reconnections in the Earth’s magnetic tail. But when they compared the two sets of measurements, they saw the exact opposite of what they expected to see: the magnetic reconnections did not cause asymmetry, on the contrary, they brought the auroras closer together.
Subsequent research showed that the magnetic field of the solar wind did not always align precisely with that of the Earth. When asymmetric, it introduces an asymmetry between the North and South Poles into the Earth’s magnetic field – and this mechanism, in turn, causes the physical differences between the southern and northern lights.