Shoemaker-Levy 9 and Arthur C Clarke - 22 July 1994

I don't think there's any question what is the biggest thing that's happened to us in America, in Europe, in Africa, in Asia, Australasia to all of us six billion midgets who, seen from anywhere outside our orbit, inhabit a Christmas tree ornament hanging in the dark.

Talking about last week's big bang and the loudest and largest there's been we're told since the one that exterminated the dinosaurs and it's one that if it had been considerably closer than 400-odd million miles would have cooked our planet and sautéed all of us. I mean of course the bombardment of Jupiter by fragments of the dying comet Shoemaker-Levy.

I wonder if any of us has the imagination as far ranging as Shakespeare's, as prophetic as Einstein's, to take in the scope of the scene a fragment of a comet hurtling along at 130,000 miles an hour slamming into a planet – all that energy coming to a screaming halt and letting off a blast of heat millions of times the mega-tonnage of the most powerful hydrogen bomb ever detonated and, incidentally, producing a fireball and a churning tempest of gases as wide as our earth. It gives a new meaning to the word awesome, which recently has been confined to such other marvels as a hole in one or a World Cup player scoring two goals.

I think the whole thing is beyond us, we'd better return to earth and look at one or two achievements we take for granted that are, however, due to the exploration of space. For example, I don't know how it is with you but now on our nightly tube and the morning papers, the five-day weather forecast is routine. It has saved hundreds of thousands of lives that 20, 30 years ago would have been lost in hurricanes, floods, it's been a priceless boon to farmers and sailors and, if its not always accurate in timing, it's almost perfect in predicting the sequence of the coming systems. This is something that would have been considered magical when I was a boy and now the American weather service has added a new note to its nightly forecasts, it's a warning about a menacing faraway threat to human life, the sun.

I had the idea to talk about this after coming back from a stretch in sunny and hot London where an American girl, whoops woman, my generation is showing, an American woman said to me, "when the sun comes out, the British go ape, they tear off all their clothes and lie prostrate in any available patch of green, shut their eyes face the sun and say, go ahead give me cancer".

The new weather note is added to remind the American public about ultraviolet radiation, the risk of which has become ever present since we've had certain proof from out of space about the thinning of the ozone layer, for countless centuries lying somewhere between 50,000 and 135,000ft. This ozone layer has protected humans from the sun's ultraviolet rays, which cause skin cancer. This protective belt has been seriously thinned or punctured by as we used to say in the late 1950s, by the radioactive fallout from Soviet, British and American nuclear tests in the atmosphere. Then the scientists took a closer look and predicted that by the early 1970s, about a million tons of Freon would be released into the atmosphere.

Freon is a gas, one of a series of gases that had derived from methane and are used as refrigerants, but known best to most of us as the gas that does the propelling in aerosol products. The proof about Freon was damaging enough to cause the United States Congress in 1977 to ban nearly all aerosol products.

During the congressional hearings on this bill, the scientists called as witnesses were unanimous in predicting that the ozone layer was being depleted so fast that we could expect a marked increase in human skin cancers in the next 50 years, they were it turned out much too cheerful.

The skin doctors of America are bringing together this spring a host of studies proclaimed the month of May as melanoma skin cancer prevention month and they've put out a barrel of statistics. In the past 50 years, the rate of deadly skin cancer in humans has gone up by 15 times. In this country alone, there are 32,000 new cases every year. The most interesting conclusion that comes out of all this dire information is that in white people, 90% of the visible ageing of the skin is due to sun damage not to time, the most susceptible people are Europeans especially north Europeans in middle-age who've spent a fair amount of time in the sun.

If you want to check the incredible 90% figure says one skin expert, examine your own bottom, the skin there is as healthy as that of a 10-year-old. This astonishing figure 90% sun, 10% for the time was confirmed in a check by three other eminent dermatologists consulted here in San Francisco, one is the chairman of a recent photo biology task force just about right he said about the 90% and sun tanning today is of course a pretty certain recipe for melanomas in later life. The sun certainly is what makes middle-aged, sun-tanners look first like angry lobsters and then like burnt shoe leather. And one Dr Epstein approves of publicising the 90% figure very good he says, "you can't scare young people with cancer, you can scare them more easily with fear of getting and looking older than they are".

Well, the thought of the poor shrinking ozone layer in outer space brings to me a twinge of guilt about something I said at the beginning that when we, our planet is looked at, well for instance, by those men on their way to the moon, we looked like a Christmas ornament dangling in the dark. That brilliant image, I'm sorry to say is not mine, it came from the great Arthur C Clarke in a piece he wrote this week to celebrate the 25th anniversary of the moon landing, a splendid piece which began by recalling the shouts of joy and the cries of doom let out by famous men on contemplating that first landing, thus Reinhold Niebuhr, "this tremendous technical achievement portrays our moral weakness" … Lewis Mumford, "it is a symbolic act of war" … Colonel Charles Lindbergh on the contrary wrote "this development of space is really a flowering of civilisation towards the stars". Various other pundits and public figures affected to be unimpressed. A lot of quite intelligent people picked up the contemptuous remark of a very early and disillusioned astronaut the only good thing to come out of space flights is the non sticking frying pan.

Well on that score alone, the spin-offs for you and me, Arthur C Clarke pointed out that, if it had not been for the Apollo programme, we could have waited decades for the things it precipitated: satellite news and entertainment, the global weather maps on television, video cassette recorders, the whole field of personal computers. Beyond that, Arthur C goes into the importance of human exploration as distinct from exploration by robots. Our own planet has been explored to the limit, indeed he says, "environmentalists", quote, "armed with data that can be obtained only from satellites might plausibly argue that the contraction of our planet has begun". So Clarke feels that the leap into worlds beyond us was one that we had to take.

On a more practical though terrifying level, he reminds us of the slamming of Shoemaker-Levy into Jupiter and believes it is not too early to begin to advance protective astronautical technology. Let us hope he says in a scary benediction, it is ready in time to protect our fragile home or in the worst case to ensure that some humans survive elsewhere. These scenarios are not science fiction, but future certainties.

Now that's not HG Wells talking from the grave, but the man who when most of you weren't born and I was a stripling wrote a short science paper on something so wildly fictional, so barmy that nobody in authority in government or science took any notice of it. He wrote about the day sure to come soon when men would fly through space, he drew accurate pictures of something he called satellites to explore space to bounce pictures and information off. Just think it's been 44 years since he wrote interplanetary flight, followed the same year by the exploration of space. Since then, he's written about 45 scientific books on space, other planets and about 30 works of fiction on the same theme and he's been honoured I suppose more than any living scientist by every sort of academy and nation. One line in his Who's Who entry is riveting, it simply says "1945 originated communications satellites", wow that's nearly 50 years ago.

I've gone into his awesome career because I always get the feeling when I'm in England that England knows too little of one of its giants, he's never had the Nobel Prize, I don't even know if he's ever had a knighthood. I was reminded of this again by the footnote to his piece, which was printed also in an English, a rather distinguished, English newspaper it said "Arthur C Clarke is the author of 2001: A Space Odyssey, which is rather like ending another great man's article with "Leonardo De Vinci is an Italian who draws model airplanes".

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