Right here, about 4.6 billion years ago.
About 4.6 billion Earth years ago, an unimaginably large cloud of hydrogen gas, now known as the solar nebula, swirled in the vast velvet void of space. Had there been anyone around to see it, it would have been an impressive sight.
Nearby is a term that is relative. But, some light years away – nearby, in cosmic terms – a happening would set in train a series of events which would have a direct and fundamental influence on the eventual existence of the whole of humanity. A ten billion-year-old star went supernova: it exploded producing a colossal pulse of energy which spectacularly marked the end of its existence.
Stars like to go out with a bang.
Though this star seemed to be a long way from the solar nebula – just one light year is, after all, 9,460,730,472,580.8 kilometres – such is the energy released by a supernova, that it had a profound effect on the swirling cloud.
Most of the matter – 99.8% – was compressed together into a massive ball of gas which contracted under its own gravity and began to heat up. When the temperature rose to the right level – about 15,000,000° C – a process now known as nuclear fusion began at the core of the swirling ball. Hydrogen atoms were converted to helium atoms. The ball had become a star; and huge amounts of energy in the form of solar radiation were released: sunlight flooded the space where the solar nebula had been, and raced to infinity.
The remaining matter – that which had not collapsed to form the burning ball – gathered into a flattened disk around the new star, brought under the influence of its massive gravitational field.
That matter – now swirling round the star at varying distances – over thousands of millennia, began to cluster into distinct objects. Those clumps coalesced and formed larger ones – some boiling gases; others molten rock and ore. At a series of critical distances from the great gravitational centre of the solar system – the sun – the debris gathered. And so, a line-up of planets evolved.
Then things started to settle down.
The Earth, the third planet from the star that would become known, amongst other names, as aurinko, masoandro, jua, haul, Qorraxdu, le soleil and el sol, but, in the English-speaking world, as the Sun, span increasingly slowly and more regularly as it cooled. The element that would become known as iron – slick, liquid with heat – found its way to the centre of the forming globe and established a heavy stable core for the rest of the debris to cling to. For 70,000,000 years, it turned alone in the new solar system.
Then, just as the Earth was stabilising, a rogue late-developer, a partially formed planetoid, slammed into it. The impact tore a great chunk from the Earth, blasting billions of tonnes of debris into space. In imitation of the Earth’s coalescence, the hunks of rock gathered, over millions of years, into a single huge ball, caught in the Earth’s gravitational field: the Moon was formed.
Had the Moon not been formed by this chance impact, it is probable that the Earth would not have settled enough for life to have evolved. The Moon’s steadying influence controls the tides of the seas; it balances the planet, allowing the Earth’s climate to be more stable than it would otherwise have been. Travelling at 3,700 kilometres per hour, it describes an orbit of nearly 2.3 million kilometres in a little under twenty-eight days.
Then, for the next 4.53 billion years, the Moon span majestically round the Earth, occasionally suffering the indignity of a meteorite strike. The two globes were inextricably linked in a cosmic waltz, the Earth swinging its partner through the dance of time. And, like a dance partner, the Moon offers the same face to the Earth as it spins on its own axis.
4,599,999,900 years later...
Earth date: 21st July, 1969: Neil Armstrong sets the first human foot on the Moon.
100 years later...
Earth date: 5th July, 2069, 10.45 am: Lesson Two: Maths.