Total solar eclipses – being in tune with the universe
In today’s "so exciting" and "so important" daily life only a few occasions remind us of the source of this very life on planet Earth. Some of those rare incidents include the mood-changing effect of a sunny day after a week of rain, or a red sky-tinted sunset. In fact, it is very rarely acknowledged that not only our emotional life, our rhythm and our very existence on this planet depend on the sun. All this is intensively brought to attention when the moon moves in a position between the sun and earth. The moon’s shadow races over the planet’s surface, creating a stunning effect for the observer standing in the narrow shadow path. Not only is the experience of a solar eclipse a very amazing astronomical phenomenon, it also reminds us of our place in the big picture – it tunes us in with the universe.
As the moon has to be New and its orbit is 5 degrees inclined to the earth's, it passes only roughly every 17 months through the ecliptic plane. Only then do the paths of sun and moon intersect in the sky – which means that the sun, moon and earth are aligned. Most of these alignments are only approximate, so that only a narrow corridor of the moon's shadow grazes the earth's surface (which is mostly water and uninhabited land), giving a partial eclipse which hardly anyone notices. But there's another factor: the moon's orbit around the earth is elliptical, meaning that it can be a bit closer to or more distant from the earth when the alignment occurs. When the moon is more distant it is too small to cover the sun completely and a ring remains. The last annular eclipse could be seen in Portugal on the 3rd October last year. This annular eclipse was already a very magnificent preview of what one can experience at totality, when the moon is closer to the earth and covers the sun completely. The most noticeable effect is the strange colour disturbance, when only a very few of the sun’s rays reach the earth. An intense colour shift to blue light can be observed, very different from a normal red shift during sunset. Grass turns to silver, the landscape becomes platinum print-like, the sky becomes navy blue, skin becomes silver. Although already quite impressive, especially the sight of the perfect ring of fire on the sky, an annular eclipse is no match for a total solar eclipse. During an annular eclipse, it is still quite bright and one cannot see stars or the magnificent, otherwise invisible corona of the sun. At the moment of totality during a total solar eclipse this is very different, but there is also quite a spectacular time before and after. To observe a total solar eclipse one should not just focus on the moment of totality, but rather see the whole event from the beginning to the end. This is especially spectacular in summer, when an otherwise normal sunny morning with the warmth of the sun and busy insects and birds is suddenly turned into cold, dark night. Observing the eclipse from a spot with an attractive surrounding view and beautiful landscape makes this effect even more impressive. While moon and sun slowly overlap one should take time to contemplate on every detail of the landscape’s change in colour and appearance. Until more than half of the sun is covered things seem to be unaffected – it gets a bit cooler though. Then, as the totality nears, things accelerate with an immense speed: the colour change is rapid and not only the whole landscape takes on a metallic blue green tint, the sky and isolated clouds display an unseen change in colour, a sunset in time lapse. At totality it is very silent and this is the moment when without even forcing it, one realizes the meaning of the word universe when one sees the dark disc on the sky surrounded by an ever-changing display of silver rays stretching out in the black sky and appearing to reach for the observer. The sky in which stars can be seen at this point is pitch black. Moved by such a profound disintegration of self into the all-encompassing universe, standing at the focal axis of sun, moon and earth, an unparalleled rush of total gratefulness grips the observer and this is usually quite an intense emotional experience, being in tune with the universe makes one unable to hold back tears. The brightening horizon with its otherworldly bluish sunset light announces the edge of the shadow and soon after the first rays peek around the moon, making one aware how cold it had become. With increasing speed the sky brightens.
No wonder that such a display of natural forces made people think of eclipses as bad omens in ancient times and also in most religions. Eclipses have been associated with celestial creatures devouring the Sun - a dragon for the Indian, Indonesian and Chinese, a jaguar in Argentina or a vampire in Siberia, these celestial monsters are responsible for the disappearance of the Sun. An interesting Chinese legend reports that the total solar eclipse in China on 22 October 2134 BC took everybody by surprise as the astronomers failed to predict the event correctly. As a consequence, people were not prepared to scare the dragons away and chaos arose. The responsible astronomers were beheaded. Besides the use of eclipse predictions as a powerful political tool by emperors and priests, the well chronicled occurrences allow those reports to be dated as precisely as it is possible in order to calculate all eclipses in the past and future very exactly nowadays. An often cited example of the influence eclipses had on world order was the end of a five-year war between the Lydians and the Medes, two Middle Eastern dynasties which were locked in battle when a total solar eclipse occurred in May 28, 585 B.C. which was startling enough to cause both nations to stop fighting at once. In the medieval period, when understanding of eclipses was even poorer than in ancient times, historian Roger of Wendover reported on the total eclipse of May 14, 1230, which occurred early in the morning in Western Europe: "... and it became so dark that the labourers, who had commenced their morning's work, were obliged to leave it, and returned again to their beds to sleep". A more profound effect of an total solar eclipse on science was the proof of Albert Einstein's theory of General Relativity by the eclipse on 29th May 1919 where observation showed that gravity can bend light. The last eclipse of the 20th century on 11th August 1999, whose path of totality crossed central Europe, caused much speculation about our future in the next millennium, even though one would think that influence of total solar eclipses on world politics and fate were a relic of the past. Quite the contrary, their influence on people is now more potent than ever. With the scientific understanding of the basis of the phenomenon, one can much better absorb the nature of the event, and of course one can travel around the globe for the purpose too.
What should be the emotional and technical equipment to tune in with the universe? Eclipses are very powerful moments. One should allow plenty of time before and especially after the eclipse. Preparation should involve scouting for an ideal location, weather conditions should allow for a clear sky, elevation over the surrounding terrain is a plus, watching the shadow of totality approach through the landscape is part of the experience. Nature is a must, possibly a particularly beautiful landscape. To observe the stages of the eclipse specially produced filters are necessary – because the intensity of the sun, even when 99% of the disc is obscured by the moon, is enough to damage the retina permanently. Special sun observation glasses are available and inexpensive. If binoculars or a telescope are used it is absolutely essential that they be shielded with special filters too. And one should not forget a blanket to lie on: comfort adds to the joy of the experience. The next total solar eclipse will be on 1st August 2008 and will be visible in North America, Russia and parts of Asia. See you there.
sunearth.gsfc.nasa.gov/eclipse/eclipse.html