A red rain phenomenon occurred in Kerala, India starting from July 25th, 2001, in which the rainwater appeared colored in various localized places that are spread over a few hundred kilometers in Kerala. Maximum cases were reported during the ﬁrst 10 days and isolated cases were found to occur for about 2 months. The striking red coloration of the rainwater was found to be due to the suspension of microscopic red particles having the appearance of biological cells. These particles have no similarity with usual desert dust. An estimated minimum quantity of 50,000 kg of red particles has fallen from the sky through red rain. An analysis of this strange phenomenon further shows that the conventional atmospheric transport processes like dust storms etc. cannot explain this phenomenon. The electron microscopic study of the red particles shows ﬁne cell structure indicating their biological cell like nature. EDAX analysis shows that the major elements present in these cell like particles are carbon and oxygen. Strangely, a test for DNA using Ethidium Bromide dye ﬂuorescence technique indicates absence of DNA in these cells. In the context of a suspected link between a meteor airburst event and the red rain, the possibility for the extraterrestrial origin of these particles from cometary fragments is discussed.
Keywords: red rain; red rain cells; meteor airburst; astrobiology; exobiology; cometary, panspermia.
The mysterious red rain phenomena occurred over different parts of Kerala, a State in India, starting from July 25th, 2001. The news reports of this phenomenon appeared in various newspapers and other media (Nature, 2001)and are currently carried by several websites (Ramakrishnan, 2001; Radhakrishnan, 2001; Surendran, 2001; Solomon, 2001; Nair, 2001). In an unpublished report, Sampath et al. (2001) claimed that the red rain particles were possibly fungal spores from trees. But they also raised several The original publication will be available at www.springerlink.com after the date of publication.2 Red rain phenomenon of Kerala.unexplained questions regarding the origin of huge quantity of red particles amounting to several tons and the unexplainable mechanism by which the red particles can reach the rain clouds etc. From the observation of a dust layer in the atmosphere using multi-wavelength LIDAR data of July 24th and 30th, 2001 above Thiruvananthapuram (8.33 deg. N, 77 deg. E), Satyanarayana et al. (2004) and Veerabuthiran & Satyanarayana (2003) claimed that the dust generated from desert areas of the west Asian countries was a possible cause of the observed colored rain. However their study did not address the cause of red rain that continued to occur in Kerala for an extended period of time.
Further, the nature of the red particles, which colored the red rain, was not examined in their study. In this paper we give a detailed account of the geographical and time distribution patterns of the red rain phenomenon of Kerala and also provide the photomicrograph study of the red particles. The possible biological nature of the red rain particles is also investigated through electron microscopy and elemental analysis. The result of the test for DNA using Ethidium Bromide dye ﬂuorescence technique is also reported in this paper. It is also discussed how this phenomenon cannot be explained using ideas like desert dust storm activity. Considering the suspected connection of the red rain phenomenon with a meteor air burst event, it is further discussed, how the red rain phenomenon can be explained as due to the fall of fragments from a fragile cometary meteor that presumably contain a dense collection of red cells.
Accepted for publication in Astrophysics and Space Science