Science Reporter, JULY 2016 28

THE Sun is our default light option. But what happens when it does not shine?

In the year 1815, the repercussion of a very unusual event was felt worldwide for a fairly long period. The incident was a volcanic eruption in Mount Tambora. In Indonesia, there is an island Sumbawa in its peninsula. This is a part of the Sunda islands that forms a segment of Sunda Arc. This is recognised as a string of volcanic islands.

In Mount Tambora, there exists a stratovolcano. It contains lava, pumice, volcanic ash, other materials and different gases. In many cases, a volcano looks like a cone, as the hot liquid lava emerging from it cannot fl ow to long distances away from the vent or opening of the volcano, due to large viscosity. As soon as the lava cools, it solidifi es around the caldera of the volcano.

It may be mentioned that when two tectonic plates inside the earth are slowly approaching each other, one of them may go under the other. Then the boundary area between the two plates is known as a subduction zone, which is prone to volcanoes.

Before the volcanic eruption Mount Tambora was the highest peak in the region. However, as soon as the volcano took place on 10th April 1815, the height of the peak fell by more than 1.5 kilometre creating a large caldera (depression) on the throat of the volcano due to the forcible ejection of huge amounts of magma accumulated under the Earth’s crust.

The intensity of the volcano was rated as seven in V.E.L. (Volcanic Explosive Index). This indicates the severity of the eruption and classifi es the volcano as a rare case. In fact, the ejection of lava had a volume of 160 cubic kilometres – the highest recorded so far in known history.

The explosion was so loud that it could be heard up to 2000 kilometres. The Tambora eruption killed 11500 people with its hot molten rock pieces and ash. Besides, 71000 people lost their lives due to shortage of food, destruction of crops and paddy fi elds. The peak of the volcano suddenly appeared like a cauldron having a deep depression (collapse).

But the effect was not just limited to Indonesia. The destruction was spread far and wide. Even European countries could not be spared of its evil consequences. The atmosphere in the West was covered by the volcanic ash of Tambora, as a result of which the sun-rays could not reach the surface of the Earth. Due to reduction of solar warmth, heavy snowfall and fatal frost was found even during June to August, 1816. There was intense cold and the situation turned worse as famine-conditions developed in European and North American countries.

Many people from England started to rush to the lake side of Geneva, Switzerland for warm climatic conditions. Such a discouraging state of affair and unfair weather continued for more than one year. People named 1816 as the ‘Year Without Summer’ due to the continuous dimness of daylight; and this continued for almost three years in different degrees. Gillen D’Arcy Wood’s recent book, Tambora: The Eruption that Changed the World, has described the horrors of the volcano realistically.

People were highly despondent in these adverse circumstances. Artists painted fi ery sunsets. Novelists wrote about vampires. Under these trying conditions, four young British friends gathered in Geneva. Mary Shelly, her future husband P.B. Shelly, Lord Byron and Dr. Polidori discussed among themselves, in the fl ickering candle lights, about writing a horror-story. In fact there was a competition between them, who would write the best piece.

Dr. Polidori wrote The Vampire (1819), the fi rst of its kind in English literature. But the biggest contribution was that of the eighteen year-old Mary Shelly’s Frankenstein – the monster or the human vampire. (Ref: ‘How a volcanic eruption gave birth to vampire’, William J. Broad, New York News Service, 26.8.2015).

So, we can see how the blocking of sunlight to the earth can disrupt our life, the way of living and thinking, art, culture and above all peace and tranquillity of the society at large.

However in the Tambora volcano case, the reason behind

NIKHILANAND PANIGRAHY

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Mt. Tambora Volcano with its caldera after eruption

Science Reporter, JULY 201629

number of sunspots was remarkably small. But incidentally this is the period that covers the middle and coldest part of the above-mentioned Little Ice Age. Their proposition is named as Maunder Minimum by astronomers.

According to recent fi ndings of Professor Valentina Zharkova and her team as presented in the National Astronomy Meeting in Llandudno, there will be fewer sunspots in the solar cycle 26, which will happen from 2030 to 2040, similar to the Little Ice Age (1500-1850). Hence the earth is likely to suffer the next Mini Ice Age, coming in the next 15 years (Ref: Alice Harrold, The Independent, 12.7.2015). Of course such a claim needs more rigorous scrutiny and Valentina’s ‘Principal Component Analysis’ model, based on solar magnetic fi eld, may go wrong. But if at all this happens, the Sun, which makes our life comfortable, may be really a tormentor.

Whether this will be true or not is to be verifi ed in future. But another thing is certain. The Sun is estimated to be almost fi ve billion years old at present. It has already spent half of its life. After this period, the Sun will die. Every second it is converting about fi ve billion tonnes of matter to release energy equal to 3 x1026 watt, as per Einstein’s famous mass-energy equivalence principle. Because of the continuous use of hydrogen as fuel at its core the burning will be quite visible even in its outer surface at a later stage. As a result, it will look extremely bright and unfortunately dry the Earth’s oceans. Then the Earth will be lifeless and convert into a desert. Gradually the size of the Sun will increase and it will swallow nearby planets like Mercury and Venus.

This future sunshine defi nitely will not be enjoyable, as we know it now. It will annihilate all forms of life on our planet. Our saviour may turn the ultimate killer in the long distant future.

Dr. Nikhilanand Panigrahy is Director Retd., Text Book Bureau. Address: Badakhemundi Bunglow, Utkal Ashram Road, Berhampur–760001; Email: nikhilanand.panigrahy@gmail.com

this mini-collapse is squarely concerned with the earth and the structure and composition of the materials inside the earth. But there can also be a cause equally disturbing. It is not terrestrial and seems to be a cause of concern for the near future.

It has more to do with the Sun itself. The inside of the Sun is divided into different layers (of course, not with defi nite boundaries). Among them are the core, the innermost part of the center. Going outwards from the center, there is the radiative zone, followed by a convective zone, next to which is the visible surface of the sun, i.e., Photosphere. Immediately after it comes the chromosphere, the outermost part being the corona.

The light and heat we receive on Earth from the Sun is due to energy created by the core through nuclear reaction, under very high temperature (about 15 million Kelvin). If we concentrate our attention on the photosphere-layer, some spots are observed that appear dark, in contrast to the very bright surrounding photosphere. These sun-spots were fi rst observed by Galileo, Thomas Harriot, Johannes Fabricius and Christoph Scheiner independently. Here the use of the word ‘spot’ may be a misnomer, since the sun-spot in reality is so large that its size can be more than several earths combined together.

It is observed that the number of sun-spots at a given time may be small. But with the passage of time, the number

increases to reach a maximum and then again falls to zero. This waxing and waning is like a cycle, known as the solar cycle, which is about 11 years. This mystery was solved in the year 1843.

Going back to the past, Europe and North America experienced a Little-Ice Age between 1500 and 1850. The cold was so intense that the Thames River, in England, was frozen for seven weeks. A couple Annie Maunder (1868-1947) and E. Walter Maunder (1851-1928) later on investigated the cause behind it. They found there may be a close relation with the then sunspot activity and the climatic coldness during the little ice age.

During 1645 to 1715, the

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Sunspots (marked black)

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Mary Shelly’s Frankenstein

Anatomy of the Sun

A painting of the Little Ice-Age

Core

Corona

Chromosphere Photosphere

Convection Zone

Radiative zone