Universe: The story of the Universe, from earliest times to our continuing discoveries. Peter Grego
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Ever since our ancestors were first struck by the majesty of the heavens and pondered its meaning, human beings have felt a profound curiosity about realms beyond the Earth. Unimaginably distant and seemingly untouchable, the wider cosmos – from our closest planetary neighbours to the stars beyond – has inspired humans in countless ways through the centuries.
Splendour of the heavens
Although science has provided incredible insights into the Universe, our feelings of awe at viewing a star-spangled sky are the same as those experienced by our prehistoric ancestors.
Inklings of the infinite
Throughout history, everyone with the slightest degree of curiosity about the world around them has looked up at the sky and asked questions about it – seeking answers by questioning others, formulating their own theories and by arriving at their own answers through observation.
Galaxies in their thousands – a deep view of the Universe, captured by the Hubble Space Telescope.
Eternal musings
How far away are the stars and what’s the furthest thing in the Universe that our eyes can see? Does it all go on forever? Are there other planets like the Earth, inhabited with beings intelligent enough to question who they are, and how they, their world and the Universe itself came into being? If the Universe is infinite, could there be another person like me wondering exactly the same things at that very same moment in time? Will they reach the same conclusions as me? These sorts of questions have been asked by people of all ages ever since our ancestors developed the mental capacity to lay aside their basic survival instincts for a moment or two and view the world around them – and the skies above them – with a genuine curiosity and a desire to know more about the cosmos.
Cosmic connection
The cosmos includes everything – the Earth included – and while science has amassed a great deal of knowledge about the physical nature of our home planet, the intricate processes at work on its living surface, and in its oceans and atmosphere, remain only partly understood. In modern times, living in a polluted big city where the Sun itself competes for attention amid the concrete canyons, it is easy for an individual to feel utterly detached from the Earth and the rest of the Universe – spiritually, mentally and physically. In the pre-industrial age, our ancestors were much more aware of the cycles of the heavens and the Earth. However, plant any 21st century urbanite beneath a dark, star-studded night sky, away from light pollution and the trappings of ‘civilisation’, and all those hardwired visceral feelings soon return.
Our physical bodies, our clothing and jewellery, the book you’re holding right now and the chair you’re sitting on – everything around you, including the planet beneath your feet – is all made from material produced inside long-dead stars. Knowing that we are made of ‘star-stuff’ allows us to feel more intimately connected with the Universe.
Viewing the awesome cosmos.
Sunshine and starlight
Without the stars, the night skies would lose much of their splendour; without the Sun, there would be nobody around to appreciate the stars. The Sun may not be the most important star in the cosmos, but it is critical to the existence of the Earth.
must know
Cosmic speed limit
Light travels at the staggering speed of around 300,000km per second. The Moon is 1.3 light seconds away and sunlight is around nine minutes old. Light from the nearest stars in our galaxy takes more than four years to reach us, and light from the most distant galaxies is billions of light years old. Nothing in the Universe can travel faster than light.
Stellar energy, cosmic distances
That blindingly brilliant object that illuminates the daytime sky – our nearest star, the Sun – appears to be the single most important object in the heavens. If it emitted less heat and light than it currently does, humans would struggle to survive; our species would face the bleakest of prospects as the Earth’s oceans froze and most plant and animal life on our planet became extinct. If its heat and light were switched off, human life could not survive at all. If the Sun were a solid lump of coal, it would burn itself to a cinder within a few thousand years. After millennia of speculation, the source of the Sun’s prodigious output of energy (and that of all the stars visible in the sky) was finally explained in 1926 by the British scientist Arthur Eddington. Something far more powerful than simple chemical combustion powers the Sun. We rely on the thermonuclear processes elegantly encapsulated within Einstein’s formula E=mc2 for our continued existence.
As the skies gradually darken after sunset, stars begin to appear. It may seem ironic that the starlight upon which such hopes and dreams for the future are made actually set out on its journey across the galaxy in the remote past – its light may be just over four years old or more than 3,000 years old. Rigil Kent, a star in the constellation of Centaurus, is 4.4 light years away, and the bright star Deneb in Cygnus