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Overview
Product Details
| ISBN-13: | 9781877551062 |
|---|---|
| Publisher: | Awa Press |
| Publication date: | 11/01/2004 |
| Series: | The Ginger series |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 160 |
| File size: | 2 MB |
About the Author
Read an Excerpt
How to Gaze at the Southern Stars
By Richard Hall
Awa Press
Copyright © 2004 Richard HallAll rights reserved.
ISBN: 978-1-877551-06-2
CHAPTER 1
Why gaze at the stars?
THE HUMAN FASCINATION with outer space is reinforced in a song most New Zealanders learned as children:
Twinkle, twinkle, little star,
How I wonder what you are.
Up above the world so high,
Like a diamond in the sky.
Twinkle, twinkle, little star,
How I wonder what you are.
I started to wonder at a very young age and this book draws on my lifelong passion for all things astronomical. I hope to share some of my awe of the cosmos with those of you about to begin what has been for me a fascinating, exciting and unending journey. Astronomy is such a vast subject, with links to every other science, that no book, however large, can do it justice. However, I hope this book will stimulate you, the reader, to discover for yourself some of the amazing objects the universe contains.
My interest in the stars began when I was at junior school. I lived about an hour's train ride from London. My mother often took my sisters and me to the great museums in London. My favourite was the Natural History Museum, and the most inspiring place the fossil gallery. When I first walked into the enormous gallery and was confronted with the skeleton of a diplodocus, a 97foot long dinosaur that walked the Earth 120 million years ago, I was hooked. Once upon a time there really were dragons! I became fascinated with the Earth's past – the pageant of life and the ever-changing geography and environment of our world.
My mother also took us to the movies regularly and one evening she took us to see Invaders from Mars. In this film a young boy sees a flying saucer landing in a field during a thunderstorm. No one in his town believes him, and the Martians, hidden in their subterranean space ship, begin to control the inhabitants, including the boy's own father and mother.
Watching this was a terrifying experience, but it also set me thinking. That night when we came home the sky was clear and studded with stars. I can remember wondering if one of those twinkling points of light was Mars. Perhaps there were strange beings out there, across the depths of space? When I considered the marvels that had occurred on this world, I began to contemplate what might exist elsewhere. That wonderment remains with me to this day.
We live in a universe that is built on a scale beyond the comprehension of the human mind. There are more stars in the known universe than there are grains of sand on all the beaches of the world. Each star is a sun. In all likelihood, orbiting around each of those suns is a system of planets.
The number of worlds in the known universe must be almost countless. Just about anything we can imagine, and more, probably exists out there somewhere. It is this, the grand mystery of the universe, plus its exquisite beauty, that captivates me. For me astronomy is an adventure of the imagination into time and space.
A lot of people think the rest of the universe is somehow remote, and of no great importance to our daily lives. Nothing could be further from the truth. Our star – the sun – provides us with warmth and light without which life on Earth would be impossible. Its energy drives our weather systems; fluctuations in this energy can produce droughts, floods and ice ages. The moon, and to a lesser extent the sun, causes the tides to ebb and flow. Giant meteors occasionally strike the Earth, devastating the environment and changing the course of life. Cosmic radiation causes genetic changes in living things. We are intimately connected to the rest of the universe – and it's a lot closer than you think. As the famous English astronomer Fred Hoyle once remarked, 'Space isn't remote at all. It's only an hour's drive away if your car could go straight upwards.'
I have often been asked if the vastness of the universe makes me feel insignificant. It doesn't. Human beings are not something separate from the rest of the universe; we are part of it. The atoms and molecules that make up our bodies were manufactured in the interiors of stars millions of years before the Earth was born. When these stars died they hurled their substance out into space. This material was eventually swept up in the formation of new stars and planets, one of which was our world. Each of us is literally made of stardust. Raised to a level of consciousness, we are the universe looking at itself.
CHAPTER 2How to get started
WHAT DO YOU need to become an astronomer? For a lot of people astronomy, along with many other sciences, lives in the too-hard basket. On more than one occasion someone has told me he or she has always been interested in astronomy but doesn't know enough maths to become involved. But you don't need to be a mathematician to gain an understanding of astronomy, any more than you need a degree in botany to appreciate and learn about a native forest. All you need is enthusiasm.
Unless you intend to remain an armchair astronomer, you will first need to familiarise yourself with the night sky. You do not need a telescope to take up stargazing; all you need is your eyes. Use the charts in this book to find your way among the stars, planets and constellations. When I started all I had were simple star charts and a red torch to read them by. The latter can be an ordinary small torch covered with red cellophane.
Why do astronomers use red lights? If you go outside on a clear dark night from a brightly lit room you will find you can see little. At first you will see only the brighter stars. Then, slowly, fainter and fainter stars become visible. It takes at least ten minutes for your eyes to become fully adjusted to the dark. By this time the magnificent intricate structure of the Milky Way will be discernible. Should you now use a bright white light you will instantly lose your 'dark adaptation'. Red light affects the eyes' dark adaptation the least, so if you need to look at charts use a red light that is just bright enough to read by.
The only other must is warm clothing; even on a summer's night you can get cold if you are not moving around. The winter night sky in New Zealand is magnificent, but to enjoy it you will need thermal underwear, a woollen or polypropylene hat, woollen socks and gloves.
A telescope is not essential. Before you consider getting one I suggest you invest in a pair of binoculars. A good pair of binoculars will show you a lot more than a cheap telescope. They are a worthwhile investment because you will still use them even if you later acquire a telescope – and of course they are useful for purposes other than stargazing.
For astronomy, the most important characteristic of a telescope or binoculars is the aperture, the diameter of the objective lens or primary mirror. This is what gathers the light and determines how faint an object you can see. The naked eye is limited in what it can see by the aperture of its iris, which is at best about 5mm in diameter. A telescope with a 150mm aperture lens effectively gives you an eyeball the size of a cartwheel.
Two numbers, for example 6x40, designate the primary characteristics of a pair of binoculars. The '6x' is the magnification and the '40' the aperture in millimetres. Although magnification is not as important as the aperture, it must be borne in mind that the higher the magnification the smaller the field of view. Because the best views of star fields and the Milky Way are achieved with a large field of view, I recommend a low magnification for binoculars. In addition, if the magnification is much more than 8x you will have difficulty holding the binoculars steady without extra support. The bigger the aperture the better, but bigger aperture means a bigger price. I consider the best all-round binoculars for astronomy are 7x50. These are what the navy uses for night vision.
If you get hooked on astronomy, it probably won't be long before you want to acquire a telescope. A good astronomical telescope is expensive; if you are buying new, you are unlikely to get much change out of a thousand dollars for even a modest instrument. On the market there are a lot of cheap telescopes whose manufacturers exaggerate what they are capable of, and if you are not careful you will be investing in a junky toy. Further more, no single telescope design is suitable for all aspects of astronomy. Long focal-length telescopes are good for observing the planets, while short focal-length telescopes are best for extended objects such as galaxies (island universes of billions of stars held together by gravitational attraction) and nebulae (large interstellar clouds of gas and dust).
Some people are disappointed when, looking through their $250 telescope, they can't see what the Hubble Space Telescope can. But when you think about it, why would NASA spend over two billion dollars on the Hubble if all they had to do was buy a plastic fantastic from a department store? My suggestion is that you join a local astronomical society and try out different telescopes before you purchase your own. There you can often get good second-hand telescopes, plus good advice from experienced observers. The astronomical society to which I belong has available for use by members a range of large telescopes which would be beyond the financial reach of most people.
This is not a textbook on astronomy. It is an introduction to some of the magnificent wonders of our southern night sky, and the colourful myths and legends associated with the stars. It is a fireside book that can be taken outside to help you discover the stars for yourself. I hope it will encourage you to try.
First I discuss the origins of star lore, and why astronomy was a cornerstone of the rise of civilisation. Next I explain our Earth-bound view of the night sky, and 'how it all works'. Then we take a tour of the night sky, identifying bright stars, important southern constellations and some of the wonders of the universe. Bear in mind that any tour of the night sky can never be comprehensive, simply because of the sheer scale of the universe. I will introduce you to stars and constellations that are easy to identify, but be aware there is much, much more.
Throughout I discuss both the science and the myths associated with celestial objects. Science reveals the wonders of the universe, while the myths dramatically show how our ancestors attempted to gain an understanding of the universe around them.
CHAPTER 3Ancient campfires
HUMAN FASCINATION with the stars began long ago. Imagine if you will the red glow of sunset fading over the African savannah. As night falls a small family of our ancestors huddles around the campfire. Robbed of vision, they are vulnerable in the darkness. Throughout the night they hear the call of wild animals, the lion, leopard and hyena. The night is the time of the predator. The flames of the fire comfort them: as well as providing warmth and light, they help keep the predators at bay.
As they listen to the crackle of the fire and the sounds of the night they look upwards and watch the stars. What, they wonder, are these mysterious lights in the sky? Some of the stars flicker, just like their campfire. Perhaps they are the distant campfires of other wanderers? The bright stars, and the patterns they formed, would have been very familiar to these early stargazers. While their world was full of uncertainty, the stars had a permanence and predictability that must have offered some reassurance.
More than five thousand generations separate us from this small family gathering where, by the campfire, a journey began that would change the way of life of the human species. About 100,000 years ago our ancestors emerged from the cradle of Africa and migrated into Asia. About 60,000 years ago they reached what is now the continent of Australia. These migrants occupied tropical or subtropical regions where seasonal changes were minor and food supplies abundant. Although they used fire and built shelters, they manufactured only simple hand-held stone tools. Living in small family groups, their total numbers were small and they had little impact on the physical environment.
About 40,000 years ago – 60,000 years after the diaspora from Africa began – our species underwent its first population explosion. A race of people with a new and advanced technology emerged in Europe and Asia Minor. As well as rapidly overrunning territories occupied by the first migrants, they moved into temperate and arctic regions. By the end of the ice age eight to ten thousand years ago, they had inhabited most major land-masses. By a thousand years ago all habitable land masses on Earth had been reached, Aotearoa-New Zealand being the last.
What generated this great expansion? Why were these people so successful? Unlike their predecessors, the new people fashioned finely crafted tools and weapons. They used needles and thread to make garments and footwear, and hunted with bows and arrows and harpoons. They also created works of art, and traded goods over widely separated areas. They were still hunter-gatherers living in small nomadic groups, but there had been a huge leap in technology and culture.
The new culture originated in a temperate zone with marked seasonal changes. To survive, these people had to cope with extremes of climate, and a food supply that varied markedly with the seasons. This required extensive advancement in technology, which in turn demanded a large increase in the knowledge base of the group. Complex information needed to be passed from person to person, and from generation to generation. We know that the forebears of this new people, unlike those before them, hunted large and dangerous game, an activity requiring planning, teamwork and rapid communication. It seems highly probable that what made this all possible, and these people different from their predecessors, was the emergence and development of a complex language.
Many animals, particularly primates, which live in social groups use a simple language to communicate with each other – a number of different sounds or gestures which are equivalent to words. With the possible exception of dolphins, humans are unique in having the ability to string words together to convey complex information.
Language, the ability to both formulate complex ideas and articulate them to others, may have resulted from genetic changes within one particular isolated group of people. It is sobering to think that every society in the world, every culture and every language may have a common origin in a small band of men and women who lived 40,000 years ago – a group of people of whom we know nothing.
CHAPTER 4Following the stars
FOR THOSE PEOPLE who migrated beyond the African Eden, knowledge of the stars was essential. Like their more recent counterparts on the North American plains, they would have followed the seasonal migration routes of large game animals. The ability to navigate would have been vital, particularly for people who dwelt on vast open terrains and had to travel great distances, and they undoubtedly used the sun, moon and stars.
Most of the names of stars in common use today are Arabic in origin. Arabian people were great navigators, across oceans not of water but of sand. Imagine being confronted with a searing hot, featureless desert. Out there somewhere, beyond the horizon, is an oasis you will need to find if you are to survive. In the vast expanse of drifting sands there are no roads or landmarks. How do you find your way? Like the people who lived 40,000 years ago, you use the stars.
For a nomad living in the northern latitudes it was vital to be able to predict seasonal changes. Game animals, when they migrate, move much faster than people do on foot. You wake up one morning and the forest is silent – the animals and birds have moved on. If there are no berries or vegetables your food source has vanished overnight. Arrive at a place too early and there may be no food to gather; leave too late and rising rivers or falling snow could trap you. Knowing when to move on was often the difference between life and death. But how would you know?
Each season different stars are seen in the night sky. However the same stars appear at the same time each year. Our ancestors would soon have realised that the appearance of certain stars heralded coming seasonal changes. They started linking these stars together to form patterns they could easily recognise. Today we call such star patterns 'constellations'. The names given to important stars or constellations often reflected something that happened in that particular season. It could be the appearance of certain animals or birds such as the swan (Cygnus), the lion (Leo) or the bear (Ursa Major). Or it could be a seasonal change such as a shift in winds or coming of rains.
(Continues...)
Excerpted from How to Gaze at the Southern Stars by Richard Hall. Copyright © 2004 Richard Hall. Excerpted by permission of Awa Press.
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