Colored rains, most often in red hues, have been sporadically observed in India since the 19th Century, with the most recent occurrence in 2012.
The picturesque precipitation usually falls on areas of just a few square miles, with some extremely localized cases that were spread over mere meters. During their investigations of the phenomenon, scientists have discovered that a brownish-red solid they separated from the rain contained 90 percent round red particles and the rest debris.
One hypothesis, long of conjecture and light on facts, speculates that the debris might be an extraterrestrial life form that rode in on a comet. The proponents this interstellar idea, Godfrey Louis and Santhosh Kumar, were employed as physicists at Mahatma Gandhi University in 2001 when such rains occurred. When the pair examined the red particles under a microscope, the particles appeared to living cells.
Pairing this with a loud bang heard early in the morning of the first red rainfall that year, Louis and Kumar concluded this was the sonic boom of a comet. They further speculated that its contents were spewed throughout the sky and into rain clouds.
But this idea failed to explain how debris from a meteor could have continued to fall on the same area over a period of two months, despite the changes in climatic conditions and wind pattern spanning over two months. Or why it would have been limited to such a small geographic area.
Besides, a joint report issued by the Indian government and private science organizations concluded that there was no meteoric, volcanic, or desert dust origin present in the rainwater. Moreover, its color was not found to be caused by dissolved gases or pollutants.
And the joint report concluded, “The color was due to the presence of a large amount of spores of a lichen-forming alga belonging to the genus Trentepohlia.” The red rain has even happened several times since 2001 and each time botanists have found Trentepohlia spores to be the cause.