The novel begins simply: Sooner or later, it was bound to happen.
"It" being a meteorite collision early in the twentieth century, narrowly missing Moscow by four thousand kilometres. Then halfway through the century, "it" happened again - this time missing another Russian city, Vladivostok, by a mere four hundred kilometres. And there was nothing that humankind of that time could have done to protect itself against, as Clarke put it, "the last random shots in the cosmic bombardment that had once scarred the face of the Moon." Luckily, those two collisions occurred in uninhabited areas. But by the end of the 21st century, there was no area on Earth that humanity did not occupy.
Thus, in the summer of 2077, on the morning of September 11 (what an eerie coincidence that Clarke would choose a date so heavy with meaning in our time), we are told of a third meteorite collision of modern times. This one slams into northern Italy, obliterating the cities of Padua and Verona, and causing Venice to sink into the sea.
The sheer scale of this natural disaster causes humankind to unite in a way that it had never before: the human race pools its resources to ensure that Earth will never again be vulnerable to another meteor or other potentially deadly body from space. The elaborate planetary defense system that comes into existence is called Spaceguard.
Fifty years after its creation, Spaceguard indeed proves its worth when it detects a massive celestial object headed toward the Solar System. But this time it is not a meteor at all that has come visiting...
So, the line "sooner or later, it was bound to happen" could also be implied to mean Man's first contact with extra-terrestrial intelligence. After all, humans have a habit of bumping into superior alien powers in Clarke stories.
This is a very short introductory chapter - really more like a prologue. But what it describes is immediately compelling - nothing like woe and destruction to get your attention. Clarke wastes no time in providing a startling, cinematic opening - the kind of scene since used by a host of modern disaster movies, though Armageddon and Deep Impact come most readily to mind. It takes a tragedy of apocalyptic scale to motivate all of humankind to unified action, to distract it from its self-destructive ways. Perhaps it is naive of Clarke to suggest that human beings would suddenly cease hostilities toward each other - even for their own cosmic survival. There will certainly be jaded readers out there who may scoff at such a scenario, but to me it is credible enough within the context of this story. Besides, Clarke's idealism is one of the reasons why his work appeals to me.
Also, the scenario of big objects from space colliding with Earth is very relevant today, as witnessed by the close calls we've had in recent years.
I also want to say that this opening chapter establishes Clarke's outlook: that man is small and fragile against the impersonal and implacable cosmos, but that man also has the capacity to survive via his intelligence.
