The following correction was printed in the Observer's For the record column, Sunday March 12 2006

In the article below, Dr Milton Wainwright was quoted as saying that red rain lacked DNA. Dr Wainwright has asked us to make clear that currently he has no view on whether red rain contains DNA and that it is physicist Godfrey Louis who is of that view.





There is a small bottle containing a red fluid on a shelf in Sheffield University's microbiology laboratory. The liquid looks cloudy and uninteresting. Yet, if one group of scientists is correct, the phial contains the first samples of extraterrestrial life isolated by researchers.

Inside the bottle are samples left over from one of the strangest incidents in recent meteorological history. On 25 July, 2001, blood-red rain fell over the Kerala district of western India. And these rain bursts continued for the next two months. All along the coast it rained crimson, turning local people's clothes pink, burning leaves on trees and falling as scarlet sheets at some points.

Investigations suggested the rain was red because winds had swept up dust from Arabia and dumped it on Kerala. But Godfrey Louis, a physicist at Mahatma Gandhi University in Kottayam, after gathering samples left over from the rains, concluded this was nonsense. 'If you look at these particles under a microscope, you can see they are not dust, they have a clear biological appearance.' Instead Louis decided that the rain was made up of bacteria-like material that had been swept to Earth from a passing comet. In short, it rained aliens over India during the summer of 2001.

Not everyone is convinced by the idea, of course. Indeed most researchers think it is highly dubious. One scientist who posted a message on Louis's website described it as 'bullshit'.

But a few researchers believe Louis may be on to something and are following up his work. Milton Wainwright, a microbiologist at Sheffield, is now testing samples of Kerala's red rain. 'It is too early to say what's in the phial,' he said. 'But it is certainly not dust. Nor is there any DNA there, but then alien bacteria would not necessarily contain DNA.'

Critical to Louis's theory is the length of time the red rain fell on Kerala. Two months is too long for it to have been wind-borne dust, he says. In addition, one analysis showed the particles were 50 per cent carbon, 45 per cent oxygen with traces of sodium and iron: consistent with biological material. Louis also discovered that, hours before the first red rain fell, there was a loud sonic boom that shook houses in Kerala. Only an incoming meteorite could have triggered such a blast, he claims. This had broken from a passing comet and shot towards the coast, shedding microbes as it travelled. These then mixed with clouds and fell with the rain. Many scientists accept that comets may be rich in organic chemicals and a few, such as the late Fred Hoyle, the UK theorist, argued that life on Earth evolved from microbes that had been brought here on comets. But most researchers say that Louis is making too great a leap in connecting his rain with microbes from a comet.

For his part, Louis is unrepentant. 'If anybody hears a theory like this, that it is from a comet, they dismiss it as an unbelievable kind of conclusion. Unless people understand our arguments - people will just rule it out as an impossible thing, that extra-terrestrial biology is responsible for this red rain.'