The disco lights of nature – Aurora!

The amazing dancing lights that take up the stage to offer a magical display is an awesome phenomenon due to the earth’s magnetic fields and the sun’s radiations. The aurora lights are also known as polar lights as they are predominantly seen in the higher latitudes. These magnificent displays have been captivating humans since thousands of years.

To get a glimpse of the magnificent lights watch the video:

What is aurora and where can we see it?

Auroras are the results of interactions between the sun storms and the earth’s magnetic fields. The one appearing near the North Pole are called aurora borealis and near the south poles are aurora Australis. Mostly it can be seen in pink, green, yellow, blue, violet and occasionally orange and white. The best places to see the northern lights are Alaska and northern Canada. Norway, Sweden and Finland also offer excellent vantage points. During periods of particularly active solar flares, the lights can be seen as far south as the top of Scotland and even northern England. Auroras are always present but best time to see is winter.

History

For about millennia auroras were a source of awe, speculation and superstitions. Cave paintings in France dating back to 30,000 years have been found illustrating the phenomenon. Many classic philosophers, astronomers, authors like Aristotle, Descartes, Halley have mentioned northern lights in their works. Galileo used the name aurora borealis to describe them, taking the name of Roman goddess of dawn – Aurora and Greek word for wind – boreas.

What causes auroras?

The journey of aurora starts right from the centre of the sun. Here the temperature is very high about millions of degrees. Here collisions between the H and He atoms takes place releasing charged particles and lot of energy. This charged hot gas creates a magnetic field inside the surface. At some places where the magnetic field is strong, the charged particles   push their way out of the surface and are blown towards the earth due to solar winds. This solar storm crosses Mercury, then Venus and finally reaches the Earth and disturbs the magnetosphere. Hereby the trajectories of the charged particles change and is bent towards the poles, loose energy and gets precipitated. The resulting ionization and activation of atmospheric elements emits lights of various colours. Usually when the particles collide with oxygen, yellow and green lights are produced whereas interactions with nitrogen create red, violet and occasionally blue (in case of atomic nitrogen).

Current works and the need to study aurora

Understanding the functioning and functioning of aurora, helps us to study more about the complex space around our earth. The radiations and energies in this space may have various effects on the satellites in orbits – disrupting their electronics, communication and navigation signals, etc. The space environment of our entire solar system can be predicted by the sun’s activity. Also with our increased dependence on GPS and expanding space explorations make his study more important. Though aurora lights have made us wonder since thousands of years, their nature that they are the electromagnetic interactions in response to the solar activity was realized in the last 50 years.

NASA’s THEMIS is a five-spacecraft mission dedicated to understanding the processes behind auroras, which erupt across the sky in response to changes in Earth’s magnetic environment, called the magnetosphere. The scientists found the aurora moved in harmony with the vibrating field line. Magnetic field lines oscillated in a roughly six-minute cycle, or period, and the aurora brightened and dimmed at the same pace. All thanks to the coordinated network of satellites, magnetic sensors and cameras have enabled the close study of auroras over few decades. Still auroras continue to amaze and mystify all, dancing far above the ground!

 

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