3 January 2019

WATCH THE SKIES

Jonathan Powell. Rare Astronomical Sights and Sounds. Springer Nature, 2018

“Our ancestors lived and died by observations and rituals created around annual events in the sky.” “To acknowledge the sky and its perceived power, many sacrifices were made, all of which were observed with great timing and accuracy.” Thus begins our journey from the past to the present and on into the future. 
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The journey is both interesting and informative, as the author discusses how our ancestors were continually challenged in the way they saw the skies and how they corrected and augmented their findings over thousands of years.

He uses philosophical phrases throughout, such as: “What distinguishes the passage of time to and from multiple zones in one’s life are certain key features that turn the ordinary to the extraordinary where the automation is temporarily eclipsed by a bright flash, or a sound that momentarily breaks the silence in a world that has so much noise”. This is what happens when studying the wonders of the Universe. He also makes other interesting points, for example that objective times can move at the same pace and it is merely the perception of time and its usage that makes the difference. Some of the greatest unanswered questions are linked to time.

Ancient Egyptian myths clearly relate to the riddles of the night sky. Sir Joseph Norman Lockyer (1836-1920) found that the majority of Egyptian temples had an east-west orientation and were also oriented to sunrise at midsummer towards the brightest star in our skies, Sirius, the Dog Star. Lockyer also estimated the approximate year of construction of Stonehenge from the evident orientation of the Heel-Stone to sunrise at midsummer.

There are many inclusions of myths and facts about American Indians and the Incas. Astronomy played a vital role to them due to the importance of agriculture. “Cuzco city was the political and spiritual focal point of the Incas. It was laid out in a radial plan that mimicked the night sky. This strong link is exemplified by the emergence of the Pleiades star cluster above the horizon. As the cluster rose, it marked the beginning of the Inca new year”. “The use of astronomy was chiefly dedicated to agriculture. The Incas carefully erected stone pillars on the foothills overlooking Cuzco to match specific orientations, and when the Sun rose or set between the pillars it was time to plant at specific altitudes. These pillars formed a massive timepiece, marking time as accurately as possible for the high altitudes right down to the floor of the valley. The Incas made sacrifices to the Sun in the hope that the Sun would rise in the proper place for this planting”.

Powell explains that the Phoenicians were the first civilisation known to have discovered glass-making around 5000BC while cooking over fire in the sandy desert. Around 3500BC the first known glass artefacts appeared in Egypt and Mesopotamia. 5000 years later glass was eventually shaped into accurate lenses to create the first telescope by the Dutch-German spectacle maker Hanns Lippershey (1570-1619), who was also one of the first to try to obtain a patent for the device, filed in 1608, “for seeing things far away as if they were near”. There is a tale that one day in his optics shop two children, while playing, combined together the lenses that made the image of a distant weather vane appear closer. Another story claims that Lippershey stole the design from a fellow eyeglass maker Zacharis Jansen (1585-1632).

Galileo Galilei (1564-1642) improved the magnification of the spy-glass from three up to a factor of nine times. Using his own device, he studied craters on the moon and made detailed tracking observations of the phases of Venus. He also famously discovered the four inner moons of Jupiter: Io, Europa, Ganymede and Callisto, which had a huge impact on the world of astronomy.

In 1615 it was heresy to go against the directive from the Church that celestial bodies orbited the Earth. Galileo revealed that the heliocentric Copernican system was correct. He was summoned to Rome and warned not to teach or write about his theory, but he stubbornly believed that if he could mathematically prove that his argument was correct it would be accepted by the Church. However, the Church remained intransigent. In 1632 he was again summoned to Rome and charged with heresy, spending the remaining years of his life under house arrest.

The author relates that “after learning to locate the simple wonders of the night sky, from the craters on the Moon to Saturn’s rings and beyond, the eagerness to observe rarities of astronomical nature may entice the observer to seek out a more specialised field. For some, comets become the obsession, while for others it is deep sky observations, with a proportion solely interested in asteroids and other small debris”.


It is clear that the author revelled in writing this book and he is filled with the wonder of collecting data on the celestial movements of this Universe. On the subject of Rare Transits he supplies a lot of detail on those of Mercury and Venus: “There are vast differences between the transits that occur in May and those that occur in November, with November transits only 10 arcseconds in diameter, as Mercury is near perihelion. An arcsecond is a unit of measurement that amounts to one sixtieth of an arcminute, equal to 1/3600 degrees of an arc” This kind of information may seem overly complex, but I would not let this deter the general reader from buying the book. There is a lot of good reading and a learning curve is always present in these pages.

There is more helpful information for the would-be astronomer in this book. Different organisations around the world recommend the best quality sites in which to view the night skies. The International Dark-sky Association] has five types of designations: International Dark Sky Communities, International Dark Sky Parks, International Dark Sky Reserves, International Dark Sky Sanctuaries and Dark Sky Developments of Distinction. They have instigated an order of merit ranging from Gold, Silver and Bronze, further broken down into nine classes to evaluate the darkness and usefulness of an observing site.

The Northern and Southern Lights phenomena in Iceland, Finland, Norway, Sweden and New Zealand is explained clearly. Many other countries have their own special astronomical observations that are particularly impressive. For example, in New Zealand the Aoraki Mackenzie International Dark Sky Reserve provides some of the best sights of the Southern Hemisphere, including Aurora Australis, the Southern Cross, and the Southern Star. The reserve is also the biggest designated by the IDA,  measuring 4,500kmSq.

Of course, the Sun at the heart of our Solar System, at a distance of 150 million km from Earth, receives special attention from the author. “This middle-aged yellow star shines its way through the depths of space to breathe life into our world. Its heat and light warm Earth’s surface, driving weather patterns, ocean currents, and the process of photosynthesis”. The Sun, approx. 4.5 billion years old, is 109 times larger in diameter than the Earth but is in fact actually quite small for a star in relative terms. For comparison, the red giant star Betelgeuse in the constellation of Orion is 1,000 times larger than the Sun, while the largest known star, VY Canis Majoris, measures 2,000 times larger than the Sun. At the core lies one of the most powerful processes in the Universe, that of nuclear fusion; hydrogen nuclei smash together forming helium and releasing substantial amounts of energy. The core temperature reaches 14 million degrees C and as long as this fuel burns the Sun and every other star will continue to generate light and heat until the source of the fuel is eventually exhausted.

The other Chapters contain more information about halos, sundogs, sun pillars and the Parhelic Circle (the circles generated vertical or nearly vertical by ice crystals of any shape reflecting sunlight or moonlight). We are also given The Belt of Venus, Moon Illusion, Earthshine, Blue Moon and Red Moon, Moonbow and many others. The Noisy Universe section mainly concerns Radio Astronomy and cosmic objects that produce signals such as Pulsars and Quasars. All in all, it is a comprehensive book on the sights and sounds of the night sky and all its mysteries. It is a never-ending quest of discovery and many more revelations are surely yet to come! -- Gerrard Russell


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