Eclipse Chasers

By Nick Lomb and Toner Stevenson

Witnessing a total solar eclipse is a wondrous and unforgettable event!

Eclipse Chasers is a guide to past and future Australian total solar eclipses, exploring historical and cultural knowledge, as well as featuring five upcoming eclipses that will be visible in Australia.

The science of eclipses is explained, as well as how to prepare for an eclipse and view it safely. For upcoming eclipses the best locations to view each one are revealed, alongside tips for taking photographs.

The book also reveals untold stories of how past Australian astronomers observed the total eclipses that have occurred since European settlement, and how these eclipses were celebrated in popular culture, poetry and art. It explores the great significance of solar eclipses for First Nations peoples, and their observations and cultural meanings.

Eclipse Chasers showcases the drama and beauty of total solar eclipses and is essential for anyone fascinated by these amazing events.

• Language: English
• Publisher: CSIRO PUBLISHING
• Release date: Mar 1, 2023
• ISBN: 9781486317097

Nick Lomb

Astronomy Professor Dr Nick Lomb has guided Australians in all things astronomical for decades. Nick was the Powerhouse Museum/Sydney Observatory Astronomy curator for 30 years, and is the author of the annual Australasian Sky Guide.

Book preview

1

Why observe eclipses?

Toner Stevenson

The effect of the rapidly diminishing sunlight on the surrounding landscape was weird and uncanny. The open trees and glorious blue sky gradually became neutral tinted and lifeless; then as the light faded yet more, an ashen hue covered everything … and then the light went out and we saw it in all its glory … (Chisholm MS, Tindal FJ (1924) Total Solar Eclipse of September 21st, 1922. As seen by Miriam S. Chisholm and F.J. Tindal, Memoirs British Astronomical Association 24, 94–100.)

Atotal solar eclipse is such a spectacular natural phenomenon that once seen, it will never be forgotten. It occurs when the Moon is between the Earth and the Sun and, for a very short period of time, never any longer than 7 minutes at any one location, the Moon’s shadow is cast onto the Earth and completely blocks out the Sun during daylight. This is a dramatic event and even more so with the sight of the aptly named Diamond Ring , a brief burst of light at the edge of the Sun. If you are not in the narrow path of totality you will not see this in the same way, seeing a partial solar eclipse is simply not the same as experiencing the sky go dark and the Moon completely cover the Sun during totality.

We live in an amazing solar system where certain phenomena, such as eclipses, can be predicted. In Australia, we are most fortunate to have five total solar eclipses coming up relatively close to each other over a period of less than 17 years: 20 April 2023,* 22 July 2028, 25 Nov 2030, 13 July 2037 and 26 December 2038. This is a remarkable sequence because there are one and sometimes two, total solar eclipses each year, but in any one location generally they can only be seen once every few hundred years.

Solar eclipses take place during the day and protecting your vision is one of the foremost concerns when viewing an eclipse. In the past, some people have missed out on experiencing the eclipse, because they were not prepared, or had inaccurate information about how it is possible to view an eclipse with the most rudimentary equipment. There are recommendations on where the five eclipses can be best experienced, how to prepare yourself and make some effective, yet simple and safe viewing instruments in this book.

Lunar eclipses, when the Moon moves into the shadow of the Earth, are far more frequent. When they occur they can be seen across a large area of the Earth and they occur at night. There is always a lunar eclipse two weeks before or two weeks after a solar eclipse. A lunar eclipse is interesting to observe but without the awe-inspiring impact of a total solar eclipse.

The totally eclipsed Sun as it is likely to look over the Sydney Opera House with the Harbour Bridge beyond, just after 2 pm on 22 July 2028. The planet Mercury will be below and to the left or west of the Sun. Lights on the Opera House and in the forecourt can be expected to switch on in the sudden darkness. Artwork: Geoffrey Wyatt.

A solar eclipse is not only a visual phenomenon, there are other senses which are stimulated. Because the Sun is covered during an eclipse, you can feel the temperature drop and air-movement change around you. A gusty wind before the eclipse can transform into complete stillness during totality. All living things, including humanity, are connected to the fundamentals of our planetary existence in our solar system. During an eclipse you can hear nature respond to the Sun and become quiet as the birds stop singing for the few minutes of totality. Other animals, such as nocturnal birds and animals, awaken and become active. There is much to observe.

As mentioned, total solar eclipses are rare because they rely on the perfect alignment of three celestial bodies and yet Australians have been fortunate to have had the opportunity to see a few in living memory, and to have a history of well-documented eclipse expeditions.

For First Nations peoples these events were no less spectacular and were the inspiration for storytelling and cultural interpretation. The stars, Moon, Sun and planets are still significant for Aboriginal Australians and rare events, such as total solar eclipses, have been passed on through oral traditions. Stories and cultural symbols such as dance provide evidence of Aboriginal Peoples’ interpretation of astronomical events. As related in Chapter 2, in Australia we are fortunate to have Elders who hold this continuity of knowledge and connection with the land, sea and sky.

So why eclipse chasers?

For every predicted eclipse, there is an adventure to be had in getting to, and often from, a location that is in the narrow path of totality, which can at its absolute maximum be 250 kilometres wide, but most often as little as 100 kilometres wide. If you are not on that path you may still see a partial eclipse, but as explained this is not the same experience. Those few minutes of totality pass quickly and everything has to be right. You don’t get a second chance.

While men were predictably the eclipse party leaders in the late 19th and early 20th centuries, there were often women behind the scenes. Some were expert, but unacknowledged scientists, others were passionate for adventure, and willing to lend a hand. On occasion, it was a woman who did the preparation for the long journey to the eclipse site and in more recent times women have led such expeditions. These eclipse adventures were more than scientific events; they were communal efforts, where local knowledge, courage and quick thinking often prevailed. You will read about the vital contributions by First Nations peoples in two eclipse expeditions in 1922 and how local knowledge was essential to success.

These stories of the past are unique in the challenges posed by the Australian landscape and weather conditions. As we will explore in Chapters 3 to 5, the journey to see a total solar eclipse could take months and involve several modes of travel, such as horse, donkey, camel, sailing ship, steamship and steam train. There were delays, rescues and near misses. Every expedition was an adventure and the spirit of discovery continues.

A word of warning. Once you have experienced your first total solar eclipse you may well be thinking about and planning for the next one, eclipse chasing can be addictive as it has been for the authors of this book.

An eclipse is still of scientific interest

For scientists of the past a total solar eclipse held enormous importance as they could observe the physicality of our solar system and the nature of space in ways not possible at other times. Eclipse expeditions were undertaken in the quest to be at the forefront of explaining the nature of our closest star, the physical relationships in our solar system and the laws of physics, which our universe demonstrates. To do this many different instruments were required, and new equipment was developed to capture the measurements and provide the evidence required to prove or disprove a scientific theory.

The first extant photograph of an eclipsed Sun was taken in 1851 at the Royal Observatory in Konigsberg in Prussia (now Kaliningrad in Russia), by Julius Berkowski, who was an expert in Daguerreotype photography. In this technique the image is on a sheet of copper, plated with silver and polished so that it was like a mirror. The surface was treated with light-sensitive fumes, which, when exposed in a camera, created an image. This was first processed with chemicals and then carefully sealed behind glass to protect its fragile nature. It was a very difficult method and, while repeated a few years later in North America, it was dangerous and unhealthy because the fumes contained the highly toxic metal, mercury. Also, the method was not consistent in its results.

Over the past 150 years much has been revealed about the nature of the Sun because of the advances in photography and other analytical tools. The 19th century saw continual improvements in the use of telescopes as giant cameras. As we will see in Chapter 5, by 1922 photography had advanced considerably, so that images of a total solar eclipse in Australia provided the opportunity to confirm unequivocally Einstein’s theory of general relativity. But there are still many unknowns and an eclipse can still help us to understand our physical universe.

There is a halo of light seen around the Sun during totality called the corona, which is still imperfectly understood by modern astrophysicists. We know the corona contains rarefied and extremely hot gases, but how the Sun, the visible disc of which has a temperature of 5500°C, can heat its atmosphere to millions of degrees is an active area of study. Until recently, total eclipses of the Sun provided the only opportunity to study the corona, but now there are telescopes in space dedicated to continually observing the Sun. Unlike space observations, however, total solar eclipses allow observing the corona right to the edge of the Sun.

As well as exploring fascinating stories about past eclipses, the purpose of this book is to explain the science of total solar eclipses and why eclipses occur, as fully discussed by Kirsten Banks in the final chapter.

The power of an eclipse

Since ancient times eclipses have been interpreted as strong, powerful forces, often symbolic of power or culturally significant. So much so that eclipse experiences have been passed down through many generations and thousands of years. In the next chapter, we will find out how Aboriginal Peoples in Australia observed and interpreted eclipses and some of the associated cultural manifestations. In most parts of the world, early civilisations gave eclipses significant meaning.

Over 2400 years ago the ancient Chinese could possibly predict eclipses, and when one occurred they made all sorts of noises to chase away the dragon, that was supposedly eating the Sun. At around that same time, the ancient Greeks and Romans held the knowledge to predict eclipses and their knowledge was often used as a symbol of power. The philosopher Thales of Miletus supposedly predicted the eclipse of 28 May 585 BCE, but it is difficult for us to imagine how such rare events could be predicted without technology. A few centuries later, the Greeks did have an astronomical calculator, called the Antikythera mechanism, which could be rotated by hand in cycles and helped to predict eclipses. This has been dated back to 67 BCE or even earlier.

The power of being able to predict an eclipse was manifest in many ways. Imperator Nerva Caesar Augustus was a Roman emperor in the years 96–98 CE. During this short reign he proved to be a great negotiator and when he unexpectedly died of a severe fever, the day of his funeral was held over until a predicted eclipse of the Sun. The Roman emperor called Hadrian, who is better known because of his long reign and colonisation of many countries including parts of Britain, was particularly enamoured with total solar eclipses. On 3 September 118, a little over a year after he came to power, a spectacular solar eclipse was seen from a large section of the Roman empire and it is thought that the design of a coin minted in that era reflects the significance of this event. The crescent is the Moon and the star could represent the Sun. There are many other numismatic examples where this symbolism has been used.

This use of the timing and the imagery of a total solar eclipse for political purposes is just one example of cultural appropriation. There are many other ways this phenomenon can impact society. For example, the total solar eclipse that swept across North America in 2017 caused the largest mass migration of people of all time in that country, as locals and foreigners headed to the path of totality. This created a significant boost in the economy of those country towns that had anticipated the public’s eagerness to experience the event and prepared well for the influx.

Silver Roman coin minted during Hadrian’s rule possibly to commemorate a total solar eclipse not long after his coming to power, © The Trustees of the British Museum. All rights reserved, 1860,0330.106.

A cultural phenomenon

As you will see in the next chapter understanding, predicting and interpreting eclipses are embedded within First Nations’ cultures in Australia. In later chapters, we are fortunate to have spectacular photographs of Australian eclipses dating back to 1871 that give us rare insights into how astronomers worked outside their observatories, away from their normal routine tasks. A fascinating aspect of these photographs is that many of the people are dressed in their finest for a total eclipse. They are at their instruments in top hats and bow ties or flowing dresses, even in comparatively harsh conditions. This seems unusual to us today but there was a real sense of occasion and rarity about an