Aurora Borealis is an amazing phenomenon found in the northern and southern latitudes of the Earth. Therefore, it is more correct to call the northern lights - the polar lights. A similar phenomenon can be found on other planets of our system.
What is the northern lights?
Northern lights are beautiful overflows in the upper parts of the planet’s atmosphere. There is a magnetosphere, since it is often in contact with charged particles of solar winds. Represents millions of miniature lights that are clearly visible in the sky. They can be of different shapes, colors, sizes. In a matter of seconds, the skies are painted with a whole spectrum of shades and shine for many kilometers. At this time, it may feel like it's a day outside.
Aurora at all times amazed people with its grandeur. Some superstitious peoples are afraid of this phenomenon, and some simply admire its beauty.
Interesting fact: Archaeological excavations show that ancient people also observed auroras. The drawings in the caves are about 30 thousand years old.
Mikhail Lomonosov revealed the main cause of the aurora borealis - it consisted in the interaction of electric currents in the atmosphere. Charged particles of the Sun, falling into the atmosphere of the planet, interact with the air, after which magical overflows of lights appear.
A planet is a magnet for charged particles that forms magnetic fields thanks to a metal core. This attraction attracts all charged objects and directs them towards their magnetic poles. In the Northern and Southern Hemispheres, the solar wind collides with the Earth's atmosphere, creating a voltage that transforms into light, which is the northern lights.
Atoms begin to gradually calm down, a light photophone appears. When nitrogen is lost by electrons, the color of the radiance will be blue and purple. If nitrogen does not lose anything - reddish, and if oxygen interacts with the electron, then green and red hues appear.
Views of the Northern Lights
Northern lights are divided into two main types: diffuse, discrete.
Diffuse
Diffuse - in the form of a faceless glow in the atmosphere. Unlike the point, it can not even be seen with the naked eye, given the complete darkness.
Dot, discrete aurora borealis
Point, otherwise called discrete, can be of different brightness. You can see x only late at night, because during the day they are simply indistinguishable. In the north of Russia, the phenomenon was called the Northern Polar, and many tourists come there every year who want to watch this phenomenon.
How is the northern lights formed?
Aurora formation is associated with the release of particles of light in the upper atmosphere. The height of education is about 80 kilometers above the earth's surface. Radiance occurs due to the fact that the smallest particle of nitrogen and oxygen collide with each other, gradually acquiring an excited state.
When everything calms down, the electron is completely restored, forming light quanta. Interaction with different gas atoms leads to a change in glow to a different color.
The role of oxygen
Oxygen is the most unusual element, due to its return to its original state, which takes less than a second. The emission of green light lasts no more than two minutes, after which red appears.
Faced with other atoms, energy is absorbed and light ceases to be emitted. Such collisions do not happen so often, because in those parts of the atmosphere there is very little oxygen. More often, collisions occur as you move closer to the ground, so the red glow stops when you approach the ground, and the green completely disappears completely near the surface.
The role of the solar wind and magnetosphere
Constantly around the planet, solar winds pass around the planet; it represents discharged particles of red-hot plasma, which come from the Sun in all directions. The wind is due to the influence of millions of degrees of the crown of the sun.
The solar wind is approaching the planet at a speed of 400 km / s. Its density is approximately 5 ions per cubic centimeter. The magnetic field strength is measured in Tesla, for plasma it is from two to five. When magnetic storms occur on the Sun, the plasma moves faster. Interplanetary magnetic fields appear on the sun in places where sunspots occur, the solar wind quickly spreads by force lines to outer space.
Earth's magnetosphere
The formation of the Earth’s magnetosphere is closely related to the effect of solar winds on the planet’s magnetic field. The magnetosphere prevents solar winds from reaching the Earth, distracts them in good condition and strikes with magnetic waves. The width of the magnetosphere is approximately equal to 30 Earth radii, and on the dark side of the planet increases to 200 radii. The plasma flow in the magnetosphere becomes larger with increasing density, wind turbulence.
In addition to the perpendicular collision of the planet with the magnetosphere, plasma flows can move up and down. They completely lose energy in the areas of Aurora, which is why a glow appears.
How often does the northern lights occur?
It occurs in the territories of Russia, North America and Alaska. May not occur equally often, periodically their number varies greatly. The occurrence of the northern lights directly depends on solar activity at a given time. Once every 11.5 years, auroras appear extremely often, after which the activity fades somewhat.
Interesting fact: Aurora under normal conditions mainly spreads over up to three thousand kilometers, during times of solar storms this figure can increase very much and the Aurors will cover enormous territories.
Why does the northern lights come about?
Basically, you can observe the northern lights only at the Earth’s magnetic poles; the phenomenon looks like a green-red glow, which gradually dies away as you approach the surface. Dot lights show how the magnetic field looks at the given moment, as well as the yoke changes at certain intervals from a minute to several hours. Often the Aurors appear near the equinox.
Aurora borealis is extremely bright at those moments when the solar winds blow harder. Ions collide with each other, whole circles of light appear around the poles. Aurora is not only on Earth, but also on other planets. Appear due to the collision of oxygen ions, charged wind in the magnetosphere of the planet, color differences can be explained by the types of colliding gases.
The effect of solar activity
The connection between the activity of the Sun and the aurora was first suspected at the end of the 19th century; after 70 years, new studies were carried out, thanks to which the nature of the aurora became known to every inhabitant of the planet.
Due to the meeting of charged particles of various gases, a glow occurs. The solar surface has a temperature of about 6 thousand, but its crown warms up to millions of degrees Celsius. Ions collide extremely intensely, free positive and negative particles escape from the atmosphere of the Sun, flying free into the vast expanses of space.
The resulting wind enters the near-Earth space, where they are moved by the magnetic field towards the earth's poles. Our planet reliably protects us from solar winds.
Where is the most suitable place to observe the Northern Lights
At what pole of the planet can you see the northern lights?
Aurora borealis can be found at both poles of the planet.. It looks like an irregular ellipse with a center located directly above the Earth’s magnetic poles. Scientists have found that the auroras completely reflect each other at both poles of the Earth. Not only the shape is completely repeated, but also the size and color.
Where is it better to watch the northern lights?
Since the phenomena appear exclusively near the magnetic poles, Auroras should be observed in territories beyond the borders of the Arctic Circle. You can also meet them in the south of Greenland, Iceland, Norway and Siberia. Phenomena can be seen at both poles, in Antarctica and in the south of the Indian Ocean.
It is best to observe the phenomenon in dark areas (away from illuminated cities, highways), completely disabling all gadgets.
Most appropriate observation time
Aurora is a cyclical phenomenon, the peak of which is observed every 11 years, so it is during this period that solar activity reaches its peak. The previous peak was observed in 2013, and the next will be in 2024.
Winter at the North Pole of the planet is the best period for observation. At this time, the day lasts very little, but the nights are long and dark. The best time to watch is midnight.
Sounds generated by the Northern Lights
From time to time on special equipment you can fix the sounds made by the radiance. These are various noises like pops, cod and white noise, they are very short and hardly perceptible. Scientists for a long time could not detect the existence of sounds - they appeared so rarely that they could be attributed to equipment malfunctions.
The sound is hard to fix - the aurors are too far from the earth's surface. Researchers at the Finnish University have proven the existence of noise by recording them. The sound appeared at a distance of 70 meters above the surface due to the interaction of charged particles and gases. Sounds are extremely rare, so there are not so many lucky people who could hear them. The formation of noise is possible only in high solar activity in calm weather without other irritants.
In which countries can I see the northern lights?
The most beautiful are those auroras that are seen in the high latitudes of the planet, in the territories of Alaska, Canada, and the northern Scandinavian peoples. Also observed in southern Greenland. Most of the northern lights are observed during a period of high solar activity. The cheapest way to see the aurora is in Murmansk.
How to see the northern lights in Russia?
To see the northern lights, you need to be prepared for many situations. It should be understood that waiting for the appearance of aurora can take a long time. There will also be sleepless nights, since the chance to see the lights is more precisely at night. In cloudy weather it is better to go to bed - the northern lights will not be visible just like the stars in the sky.
Weather and lighting of settlements greatly spoil all plans - it is best to get out of town. Radiance is often weak, city lights only drown out its beauty.
Behind the Arctic Circle there are extremely cold nights, so clothes should be selected wisely - you should not take cold things. In the car there must be additional gasoline, you can take a thermos with hot tea. You can also take firewood and ignition fluid, build a fire and bask in it. You can also have a romantic dinner at the stake.
On the territory of Russia, the Northern Lights are well observed in the Arkhangelsk and Murmansk regions, the Komi Republic, the Taimyr Peninsula, and in the Khibiny Mountains.
Artificial "Northern Lights"
A glow similar to aurora appeared after experiments of the United States Department of Defense with nuclear explosions in the upper atmosphere in July 1957 - December 1958. The tests were conducted to study the aurora and radiation belt of the Earth.
A glow in the form of a raspberry arc with rays was noticed in early August 1958 in the Hawaiian Islands and in the region of Apia Island after explosions at an altitude of 70 and 40 km in the center of the Pacific Ocean over Johnson Atoll. Another similar phenomenon was observed in late August - September of the same year in the Atlantic Ocean after three explosions of Operation Argus, thundered hundreds of kilometers above the surface. A red glow was also noticed at the other end of the magnetic field - on the Azores.
Experiments have shown that nuclear explosions tens of kilometers above the ground not only led to the emission of gases, but also to serious disturbances in the magnetic field and ionized layers of the atmosphere.
Artificial auroras were caused by electrons formed at the time of a nuclear explosion after b-decay. These high-energy particles move tangentially to the Earth’s magnetic field and, when they collide with nitrogen and oxygen molecules, cause the emission of excited gases in the upper atmosphere. Such studies of images made it possible to understand the natural mechanism of the appearance of auroras and related natural phenomena.
In addition to charged particles, the luminescence of the upper atmosphere causes emissions of sodium and potassium from the engines of take-off rockets. The mechanism of this phenomenon is far from the aurora and closer to the usual glow of air, caused by natural causes.
There is another anthropogenic phenomenon of luminescence of high atmospheric layers, caused by the emission of sodium or potassium gas by rockets. This phenomenon can be called artificial glow, in contrast to artificial aurora, since its causes are close to those that cause the natural glow of air.
Northern lights and legends
Any natural phenomena amazed ancient people, since they were not studied. Aurora was also credited with a mystical origin. Some northern peoples assumed that the gods were so happy and that observers could expect happiness. Some, on the contrary, only expected trouble from the deity of fire. Different northern peoples had their own legends about the northern lights.
The inhabitants of Norway mentioned the rainbow bridge over which the gods descended to the earth. Some have suggested that the radiance comes from the lights in the hands of the Valkyries, reflecting off their armor and distorting into amazing patterns. Others suggested that the deceased girls dance like that.
The Finnish peoples believed that the radiance comes from the burning river Ruzhu, which separates the world of the living and the dead.
The Eskimos living in the territories of North America believed that the radiance can be caused by a whistle, and removed with a simple clap of hands.
The Eskimos living in Alaska feared aurora. They believed that it brings only misfortunes and misfortunes. Before going out into the street during the radiance, everyone took weapons with them. It was also believed that long observations of the lights lead to madness.
Perhaps even for dragon myths we should be grateful to the Aurora. The greatest battle of St. George and the dragon could also be associated with the northern lights.
