Nasa has been known to make schoolboy errors from time to time. In 1999, for instance, its Mars Climate Orbiter crashed because scientists forgot to convert between imperial and metric units. Last week a German schoolboy suggested it had goofed again. An asteroid called Apophis caused a brief stir in 2004 when calculations indicated it had a 3 per cent risk of a collision with Earth in 2029. It was accordingly named after the Egyptian god of destruction.

As usually happens, further observations revealed a false alarm. Apophis will miss us - only by a smidgen in astronomical terms, but by more than enough for life to go on. The chances of disaster are just one in 45,000.

According to Nico Marquardt, however, Nasa's sums are wrong. Apophis, the 13-year-old calculated, will fly close enough to strike a satellite, which could throw it into a more dangerous orbit.

“Boy humbles Nasa” is a fantastic headline, but sadly it isn't true. While Apophis will pass within the distance at which geostationary satellites orbit, it won't affect the belt where they fly. We should be safe - this time.

The threat to civilisation from asteroids and comets is a stable of silly season stories and Bruce Willis movies.

But if most reports of Earth-bound objects are exaggerated, the broader threat is not. An asteroid probably did for the dinosaurs 65 million years ago. A recent paper suggested that a comet might explain the Biblical destruction of Sodom and Gomorrah, and objects large enough to wipe out London strike every thousand years.

The actual chances of a devastating impact may be even greater than that. Nico might have been wrong about Apophis, but he was right that satellites increase the size of the target our planet presents to space.

New research by Mark Boslough, of the US Sandia National Laboratories, has also indicated that the asteroid that obliterated more than 800 square miles of Siberian forest in 1908 may have been much smaller than previously assumed. That would mean similar events could be common.

There is still no need for us to fear Apophis, but we are sitting in harm's way. Money spent on tracking asteroids, and on investigating how they might be deflected, is certainly not money wasted.

The same cannot be said for vitamin supplements. This lucrative business has always had shaky foundations, as a balanced diet provides more than enough nutrients. The industry's response to the Cochrane review's finding that excessive intake can raise mortality has now proved that it doesn't do science. The Health Food Manufacturers' Association said that, as the study incorporated only 9 per cent of available trials, its results were misleading. Yet the excluded research was left out deliberately as it was methodologically flawed. There isn't just evidence that overdoing vitamins can be harmful. It is the best evidence going.

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