Aurora : Nature’s Double-Edged Sword
Recently, the internet has been abuzz with news of the aurora. It is again that time of the year when the stunning natural light show illuminates the polar skies. However this year the Indian mainland has been blessed with the arrival of the aurora! Scientists from India’s dark sky reserve happened to capture the breathtaking light show at Hanle, Ladakh. But is this a cosmic blessing or a forewarning of potential catastrophe? Let’s find out!
In the previous blog, I attempted to explain the basics of sun and the formation of sunspots. In short, the sun is a huge ball of plasma and the movement of the plasma gives rise to the solar magnetic field anywhere on the sun’s surface, literally making it a self-sustaining dynamo. The solar activity is primarily due to this very movement of plasma. So what are the consequences of a higher solar activity? Solar winds and coronal mass ejections (CME) which could cause geomagnetic storms strong enough to fry satellites!
The plasma rises from the outermost layer of the sun’s atmosphere — corona — and is thrown out towards the earth as solar winds. The winds carry charged particles which are capable of entering the earth’s atmosphere and disrupt life — thanks to the earth’s magnetic field. However, the magnetic fields that cut off at one end because of the wind re-emerge on the other side, leading the charged particles to enter the atmosphere via the poles. We are familiar from our geography classes that our atmosphere consists mainly of Oxygen and Nitrogen. Thus these charged particles interact with them, raising them to excited energy levels. When they fall back to their ground state, photons are emitted — thus giving rise to the phenomenal Northern and Southern lights! Here’s a short animation for enhanced visualization. The reddish and greenish ribbons of light are due to the presence of Oxygen while purple and blue colors are due to Nitrogen.
The intensity of solar activity varies over an approximately 11-year cycle. During the peak of this cycle, sunspot activity increases, leading to more frequent and intense solar storms. While Earth’s magnetic field provides some protection, it’s not entirely impenetrable.
Historical records reveal the devastating effects of severe geomagnetic storms. The Carrington event of 1859, which lit up the skies with aurorae for several days. Countries located near the equator like Cuba were able to witness it. Apart from the usual aurora, humanity had to face a devastating telecommunication disaster. The CME that set out during the early September of that year caused a geomagnetic storm so intense that it fried up the telegraph lines across the world; setting fire to the telegraph offices, disrupting communication and electric power lines. Carrington Event was named after Richard Carrington, a British astronomer who witnessed and documented a massive solar flare on September 1, 1859. His observations played a crucial role in linking the solar flare to the subsequent geomagnetic storm.
Another noteworthy geomagnetic storm was caused by an equally intense CME recorded in 1989, resulting in the blackout of a Canadian province, Quebec. This event was referred to as “the day the sun brought darkness”. The Hydro-Quebec power grid failed and as a result, the Quebecoids had to face a 9 hour blackout with no light or heat. There are many such incidents that have been recorded. Despite being less intense than the infamous Carrington effect, they did create havoc in the peaceful society.
Prof. Hisashi Hayakawa studied the old data of geomagnetic storms and claims that a Carrington-like event occurs every few decades.
The current solar cycle is at its peak this year and is quite evident from various factors — one of them being the occurrence of aurora in low-latitude regions like Ladakh and Brazil. Scientists from the Indian Institute of Astrophysics say that such events are an indication that we are on the right track in the prediction of solar activity, which will help us in great amounts predicting the space weather and hence prepare for potential disruptions. So even if we were destined to face the wrath of a telecommunication catastrophe, we are now well equipped with tools to mitigate the risks associated with solar storms.
Events like these make me realize technology is a boon to humanity, until I encounter random posts on the internet claiming the Earth is flat :P
