The most important advances, the qualitative leaps, are the least predictable. Not even the best scientists predicted the impact of nuclear physics, and everyday consumer items such as the iPhone would have seemed magic back in the 1950s.

There is an ever-widening gap between what science allows and what we should actually do. There are many doors science can open that should be kept closed, on prudential or ethical grounds.

The stupendous time spans of the evolutionary past are now part of common culture (though maybe not in the United States Bible Belt, nor in parts of the Islamic world). Most people are at ease with the idea that our present biosphere is the outcome of four billion years of Darwinian evolution.

We are 'nuclear waste' from the fuel that makes stars shine; indeed, each of us contains atoms whose provenance can be traced back to thousands of different stars spread through our Milky Way.

Some global hazards are insidious. They stem from pressure on energy supplies, food, water and other natural resources. And they will be aggravated as the population rises to a projected nine billion by mid-century, and by the effects of climate change. An 'ecological shock' could irreversibly degrade our environment.

Maybe the search for life shouldn't restrict attention to planets like Earth. Science fiction writers have other ideas: balloon-like creatures floating in the dense atmospheres of planets such as Jupiter, swarms of intelligent insects, nano-scale robots and more.

If you take 10,000 people at random, 9,999 have something in common: their interests in business lie on or near the Earth's surface. The odd one out is an astronomer, and I am one of that strange breed.

During the 20th century, we came to understand that the essence of all substances - their colour, texture, hardness and so forth - is set by their structure, on scales far smaller even than a microscope can see. Everything on Earth is made of atoms, which are, especially in living things, combined together in intricate molecular assemblages.

To most people in the U.K., indeed throughout Western Europe, space exploration is primarily perceived as 'what NASA does'. This perception is - in many respects - a valid one. Superpower rivalry during the Cold War ramped up U.S. and Soviet space efforts to a scale that Western Europe had no motive to match.