Occurrence of Aurora
In the ionosphere, the ions out of the solar wind collide with the oxygen atoms and also with the nitrogen from the Earth's atmosphere. Here the energy which is released during the collisions causes a colourful glowing type halo around the poles, this is known as an aurora. Studies say the most active auroras occur, at the time when the solar wind is the strongest.
Aurora is a light show that is caused when the electrically charged particles from the sun come in collision with the particles of gases such as oxygen and nitrogen that are present in the Earth's atmosphere. An aurora is usually caused by the streams of electrified particles (that is emitted by the sun) which is bounded in the magnetic field of the earth.
Aurora
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Aurora is a luminous phenomenon that occurs in the Earth’s atmosphere, this occurs mainly in the higher latitudes of both hemispheres. Auroras occurring in the Northern Hemisphere are known as the Aurora Borealis, Aurora Polaris, also they are commonly known as the northern lights. While, in the Southern Hemisphere it is known as aurora australis, also known as southern lights.
Auroras are generally caused by the interrelated action of the energetic particles which are mainly the electrons and the protons located in the solar wind with other atoms of the upper atmosphere. This interaction remains confined to the higher latitude regions. They are located in the oval-shaped zones which surround the Earth’s magnetic poles and also maintain an orientation that is according to the sun. During the time of low solar activity, this auroral zones shift towards the pole. While, during the periods of solar activity, these auroras occasionally extend towards the middle latitudes, like for example, the aurora borealis which has been seen as far as in the south which is 40° latitude in the US. The Auroral emissions generally occur at altitudes of about 100 km (approximately 60 miles). Though, they may occur anywhere which is between 80 and 250 km (that is about 50 to 155 miles) above the Earth’s surface.
Aurora Atmospheric Phenomenon
Aurora is at times referred to as the ‘polar light’ which is predominantly seen in the regions of higher altitudes like in the Arctic and the Antarctic regions. This aurora is caused by the gush of electrified particles, they are emitted by the sun.
Auroras are commonly seen in the latitudes which are around 70 degrees. They normally occur in a band which is known as the ‘auroral zone’. The auroral zone is about 3 to 6 degrees measured in terms of width in latitude. It lies between 10 to 20 degrees from the geomagnetic poles.
Aurora Borealis
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The northern lights, or the aurora borealis which offers an entrancing or dramatic, magical presentation that fascinates all those who see are a sight to cherish.
In the centre of this solar system, the sun is located which is a yellow star and this sustains life on our planet. The sun got many magnetic fields that distort and twist within itself as our parent star rotates around on its axis. While, when these fields become knotted together, they quite burst and create sunspots. They occur in pairs the largest sunspot can be quite almost several times the size of the planet Earth's diameter.
As the temperature at the centre rises and falls, the sun boils and turns into bubbles. These particles escape from the star and then escape from the sunspot, hurtling the particles of plasma, known as the solar wind, into space. It thus takes these winds which are around 40 hours to reach the Earth. After they reach the earth, they can cause dramatic displays which are known as the aurora borealis.
Aurora Polaris
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The northern lights are considered one of the several astronomical phenomena, they are called the polar lights (also known as the aurora Polaris), they act as shafts or as the curtains of the coloured light which is visible on an occasion in the night sky.
Polar lights (or the Aurora Polaris) are a natural phenomenon that is found in both the northern and southern hemispheres. This streak of light is truly awe-inspiring. These northern lights are also known by their scientific name, which is known as aurora borealis, and the southern lights are also called the aurora australis.
Fun Facts
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This is a picture of Aurora Australis. It is a display of the southern lights, which are quite manifesting by itself and as a glowing loop, this is an image of a part of Earth's Southern Hemisphere, which is taken from space by the astronauts.
FAQs on Aurora
1. What is an aurora and what are its common names?
An aurora is a spectacular natural light display that occurs in the sky, primarily visible in the high-latitude (polar) regions. This phenomenon is caused by the interaction of energetic charged particles from the sun, carried by the solar wind, with atoms in the Earth's upper atmosphere. When seen in the Northern Hemisphere, it is called the Aurora Borealis or Northern Lights. In the Southern Hemisphere, it is known as the Aurora Australis or Southern Lights.
2. What are the different forms or shapes an aurora can take?
Auroras are not static; they appear in various dynamic forms and shapes, which can change over minutes or hours. The most common forms include:
Arcs and Bands: These are smooth or rayed curves of light that stretch across the sky, often from one horizon to another.
Rays: Vertical shafts of light that can appear isolated or as part of a larger curtain-like structure, often looking like they are reaching upwards.
Curtains or Draperies: One of the most iconic forms, where the aurora appears as folded, moving sheets of light, resembling curtains waving in the wind.
Diffuse Glow: A faint, shapeless glow near the horizon that can sometimes be mistaken for city lights or twilight, but with stars visible through it.
3. Why do auroras have different colours like green, red, and purple?
The colour of an aurora is determined by two main factors: the type of gas particle being struck by solar particles and the altitude at which the collision occurs. The most common green colour is produced by excited oxygen atoms at altitudes of about 100 to 300 km. At higher altitudes (above 300 km), collisions with oxygen can produce rare, all-red auroras. Collisions with nitrogen molecules typically create blue, purple, or deep red colours at lower altitudes.
4. What is the scientific process that causes an aurora to occur?
The creation of an aurora is a multi-step process driven by the Sun. It begins when the Sun emits a stream of charged particles called the solar wind. This solar wind travels towards Earth and interacts with our planet's magnetic field (magnetosphere), which funnels these particles towards the magnetic poles. As these high-energy particles enter the Earth's upper atmosphere, they collide with gas atoms like oxygen and nitrogen, transferring their energy and causing the atoms to become 'excited'. To return to their normal state, these atoms release the excess energy in the form of photons, which we see as the beautiful, dancing lights of the aurora.
5. Why are auroras typically visible only near the Earth's North and South Poles?
Auroras are concentrated around the poles because the Earth's magnetic field lines act like a protective shield, deflecting most of the solar wind. However, the field lines curve downwards and converge at the North and South magnetic poles, creating a funnel-like area. These regions, known as the auroral ovals, are where the charged particles from the sun can most easily penetrate the atmosphere and cause the light-emitting collisions. This is why the phenomenon is also called 'polar lights'.
6. What is the difference between the Aurora Borealis and the Aurora Australis?
Scientifically, there is no difference in the phenomenon itself; both are created by the same process. The only distinction is their geographical location and name. The Aurora Borealis (Northern Lights) occurs in the Northern Hemisphere's auroral oval, visible from places like Alaska, Canada, and Scandinavia. The Aurora Australis (Southern Lights) occurs in the Southern Hemisphere's auroral oval, visible from Antarctica, parts of Australia, and New Zealand. They are essentially mirror images of each other, occurring simultaneously.
7. How is solar activity, like sunspots and solar flares, linked to the intensity of auroras?
Solar activity is the direct driver of aurora intensity. Sunspots are temporary, cooler areas on the Sun's surface with extremely strong magnetic fields. These fields can suddenly release energy, causing massive explosions like solar flares and Coronal Mass Ejections (CMEs). These events hurl vast quantities of charged particles into space. When a strong CME is aimed at Earth, it results in a 'geomagnetic storm', causing the auroral ovals to expand and the auroras to become much brighter, more dynamic, and visible at lower latitudes than usual.
8. Is it possible to see an aurora from India?
Seeing an aurora from India is extremely rare. Due to its location far from the North magnetic pole, India lies well outside the normal auroral oval. However, during exceptionally powerful geomagnetic storms, the auroral oval can expand significantly. On very rare occasions, this expansion has made it possible to witness a faint auroral glow from high-altitude, low-light-pollution areas in the northernmost parts of India, such as Ladakh. These sightings are not a regular occurrence and are considered a once-in-a-decade (or rarer) event.
