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Remember that rain of ‘blood’ in India about a decade ago? Earlier this week, a rather fascinating paper was posted at arXiv.org regarding the ‘red rain of Kerala’: “Growth and replication of red rain cells at 121°C and their red fluorescence“. One of the authors is Chandra Wickramasinghe, well known for his work with Sir Fred Hoyle in developing the theory of panspermia (which asserts that life exists throughout the Universe, and spreads between planetary bodies – see this documentary for a detailed look at it).

The first interesting thing noted by the paper is that examination of biological material found in the red rain gave a surprising result: the cells not only survived, but grew, at a temperature of 121°C. As the researchers note, most forms of life on Earth “are adapted to growth within the temperature range, 10-45°C, with only ‘extremophiles’ – such as bacteria found near hydrothermal vents – being able to survive temperatures above 100°C:

We have shown that the red cells found in the Red Rain (which fell on Kerala, India, in 2001) survive and grow after incubation for periods of up to two hours at 121°C . Under these conditions daughter cells appear within the original mother cells and the number of cells in the samples increases with length of exposure to 121°C. No such increase in cells occurs at room temperature, suggesting that the increase in daughter cells is brought about by exposure of the Red Rain cells to high temperatures. This is an independent confirmation of results reported earlier by two of the present authors, claiming that the cells can replicate under high pressure at temperatures up to 300°C.

Considering the possibility that such extremophiles may have originated in space, the paper goes on to note a second interesting point which could suggest an extraterrestrial origin:

The fluorescence behaviour of the red cells is shown to be in remarkable correspondence with the extended red emission observed in the Red Rectangle planetary nebula and other galactic and extragalactic dust clouds, suggesting, though not proving an extraterrestrial origin.

It’s heady stuff, but is it likely to be correct? My skepticism is based on the fact that similar falls of coloured rain have been reported in the area previously – if it’s a localised phenomenon, it seems likely its origin would be too (though not necessarily so). Candidates include spores from algae, dust blown across from the deserts of Arabia, and volcanic ejections (which could sit well with the extremophile findings). However, researchers claim that all of the possible explanations suggested thus far have faults (such as volcanic and dust particles not being found in the red rain), so at this point the case continues to remain unsolved.

It certainly offers some great storylines for SF-horror writers though!