Wonders of the Solar System Text Only. Andrew Cohen

are slightly different. Venus experienced a runaway greenhouse effect that raised its surface temperature to over 400 degrees Celsius and atmospheric pressure to ninety times that of Earth. Because the laws of physics that control the evolution of planetary atmospheres are the same on Earth and Venus, our understanding of the Greenhouse Effect on Earth can be transferred to and tested on Venus. This provides valuable additional information that can be used to tune and improve those models. The discovery that this benign, blue planet which shimmers brightly and with such beauty in the twilight skies of Earth was transformed long ago into a hellish world of searing temperatures, acid rain and crushing pressure has had a genuine and profound psychological effect because it demonstrates in stark terms that runaway greenhouse effects can happen to planets not too dissimilar from our own.

      Similar salutary insights have accrued from our studies of Mars. In the early days of Mars exploration, observations of the evolution of dust storms on the red planet provided support for the nuclear winter hypothesis on Earth. Storms that began in small local areas were observed to throw large amounts of dust into the Martian atmosphere. Over a period of a few weeks, the dust encircled the entire planet, exactly matching the models of the evolution of the dust and smoke clouds that would be created by a large-scale nuclear exchange. When a planet is shrouded in dust, the warmth of the Sun is reflected back into space and temperatures quickly fall, leading to a so-called nuclear winter that could last many decades. On Earth, this could lead to the extinction of many species, including perhaps our own.

      The observation of a mini-nuclear winter periodically playing itself out on Mars was a major factor in the acceptance of the theory, and this in turn profoundly influenced the thinking of major players at the end of the cold war. As former Russian president Mikhail Gorbachev said in 2000, ‘Models made by Russian and American scientists showed that a nuclear war would result in a nuclear winter that would be extremely destructive to all life on Earth; the knowledge of that was a great stimulus to us, to people of honor and morality, to act in that situation’.

      Wonders is also a story of human ingenuity and engineering excellence. Russia’s First Cosmic Ship began its voyage beyond Earth just fifty-five years after the first powered flight by Orville and Wilbur Wright in December 1903. Wright Flyer 1 was constructed from spruce and muslin, and powered by a twelve-horsepower petrol engine assembled in a bicycle repair shop. By 1969, less than one human lifetime away, Armstrong and Aldrin set foot on another world, launched by a Saturn V rocket whose giant first-stage engines generated around 180 million horsepower between them. The most powerful and evocative flying machine ever built, the Moon rocket stood 111 metres (364 feet) high, just thirty centimetres (twelve inches) short of the dome of Wren’s magisterial St Paul’s Cathedral. Fully fuelled for a lunar voyage, it weighed 3,000 tonnes. Sixty-six years before Apollo 11’s half-a-million mile round trip to the Moon, Wright Flyer 1 reached an altitude of three metres (ten feet) on its maiden voyage. This rate of technological advancement, culminating with our first journeys into the deep Solar System, is surely unparalleled in human history, and the benefits are practically incalculable.

      Most importantly of all, Wonders is a celebration of the spirit of exploration. This is desperately relevant, an idea so important that celebration is perhaps too weak a word. It is a plea for the spirit of the navigators of the seas and the pioneers of aviation and spaceflight to be restored and cherished; a case made to the viewer and reader that reaching for worlds beyond our grasp is an essential driver of progress and necessary sustenance for the human spirit. Curiosity is the rocket fuel that powers our civilization. If we deny this innate and powerful urge, perhaps because earthly concerns seem more worthy or pressing, then the borders of our intellectual and physical domain will shrink with our ambitions. We are part of a much wider ecosystem, and our prosperity and even long-term survival are contingent on our understanding of it.

      ‘Many years ago the great British explorer George Mallory, who was to die on Mount Everest, was asked why did he want to climb it. He said, “Because it is there.” Well, space is there, and we’re going to climb it, and the Moon and the planets are there, and new hopes for knowledge and peace are there. And, therefore, as we set sail we ask God’s blessing on the most hazardous and dangerous and greatest adventure on which man has ever embarked.’

      — John F. Kennedy, Rice University 1962

      In 1962, John F. Kennedy made one of the great political speeches at Rice University in Houston, Texas. In the speech, he argued the case for America’s costly and wildly ambitious conquest of the Moon. Imagine the bravado, the sheer power and confidence of vision in committing to a journey across a quarter of a million miles of space, landing on another world and returning safely to Earth. It might have been perceived as hubris at the time, but it worked. America achieved this most audacious feat of human ingenuity within nine years of launching their first manned sub-orbital flight. Next time you glance up at our shimmering satellite, give a thought to the human beings just like you who decided to go there and plant their flag for all mankind.

      At the turn of the twenty-first century, the Solar System is our civilization’s frontier. Our first steps into the unexplored lands above our heads have been wildly successful, revealing a treasure chest of new worlds and giving us priceless insights into our planet’s unique beauty and fragility. As a species, we are constantly balanced on a knife-edge, prone to parochial disputes and unable to harness our powerful curiosity and boundless ingenuity. The exploration of the Solar System has brought out the best in us, and this is a precious gift. It rips away our worst instincts and forcibly thrusts us into a face-to-face encounter with the best. We are compelled to understand that we are one species amongst millions, living on one planet around one star amongst billions, inside one galaxy amongst trillions. The beauty of our planet is made manifest, enhanced immeasurably by the juxtaposition with other worlds. Ultimately, the value of young, curious and wonderful humanity as we take our first steps outwards from our home world is brought into such startling relief that all who share in the wonder must surely be filled with optimism and a powerful desire to continue this most valuable of journeys.

      CHAPTER 2

      AN ORDINARY STAR

      At the heart of our complex and fascinating Solar System sits its powerhouse. For us it is everything, and yet it is just one ordinary star amongst 200 billion stars within our galaxy. It is a large wonder that greets us every morning; a star that controls each and every world that it holds in its thrall – the Sun. The Sun reigns over a vast empire of worlds and without it we would be nothing; life on Earth would not exist. Although we live in the wonderous empire of the Sun, it is a place we can never hope to visit. However, thanks to the continual advances in technology and space exploration, and through observation from here on Earth, each spectacular detail we see leads us closer to understanding the enigma that is the Sun.

      In the north of India, on the banks of the river Ganges, lies the holy city of Varanasi. It is one of the oldest continuously inhabited cities in the world, and for Hindus it is one of the holiest sites in all of India.

      Varanasi, or Banares, to give the city its old name, is a city suffused with the colours, sounds and smells of a more ancient India. Mark Twain famously wrote: ‘Banares is older than history, older than tradition, older even than legend, and looks twice as old as all of them put together’.

      Each year a million pilgrims visit Varanasi to bathe in the holy river and pray in the hundreds of temples that cover the city. Part of what makes the city so special is the orientation of its sacred river as it flows past; it’s the only place where the Ganges turns around to the north, making it the one spot on the river where you can bathe while watching the Sun rise on the eastern shore. And sunrise over Varanasi is certainly one of Earth’s great sights. The humid, tropical air adds a soporific quality to the light, which in turn lends a fairy-tale quality to the brightly coloured buildings and palaces that line the holy river. It is a misty, pastel-shaded, dream-like experience, as though the city is materialising not from the dawn but from the past.

      But on 22 July 2009, at precisely 6.24am, a different type of pilgrim was to be found waiting beside the Ganges to witness one of the true wonders of the Solar System.

      At this time, across