From July 25 to September 23, 2001, red
rainRain is liquid precipitation, as opposed to other kinds of precipitation such as snow, hail and sleet. On Earth, it is the condensation of atmospheric water vapor into drops heavy enough to fall, often making it to the surface...
sporadically fell on the southern
IndiaIndia, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal...
n state of
KeralaKerala , is a state located in southwestern India. The state was created in 1956 on linguistc basis, bringing together those places where Malayalam formed the principal language...
. Heavy downpours occurred in which the rain was colored red, staining clothes pink. Yellow, green, and black rain was also reported. Colored rain had been reported in Kerala in as early as 1896 and several times since then.
It was initially thought that the rains were colored by fallout from a hypothetical
meteorMETEOR is a metric for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision...
burst, but a study commissioned by the
Government of IndiaThe Government of India, also known as the Union Government or the Central Government, was established by the Constitution of India, and is the governing authority of a union of 28 states and seven union territories, collectively called the Republic of India...
found that the rains had been colored by airborne
sporeIn biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions...
s from locally prolific terrestrial
algaeAlgae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in...
.
It was not until early 2006 that the colored rains of Kerala gained widespread attention when the popular media reported that
Godfrey LouisGodfrey Louis is a solid-state physicist, who, while at Mahatma Gandhi University in Kerala, achieved notoriety for his hypotheses about the red rain in Kerala. In April 2006, he published a paper...
and Santhosh Kumar of the
Mahatma Gandhi UniversityMahatma Gandhi University, also known as M G University, was established on 2 October 1983 in Kottayam. The Mahatma Gandhi University , has been accredited by the National Assessment and Accreditation Council,India...
in
KottayamKottayam is a city in the Indian state of Kerala. It is located in central Kerala and is also the administrative capital of Kottayam district. Kottayam has an estimated population of 60,725, according to the 2001 census. The town is an important trading center of spices and commercial crops,...
proposed a controversial hypothesis that the colored particles were
extraterrestrialExtraterrestrial life is defined as life which does not originate from planet Earth. The existence of life outside the planet is theoretical and all assertions of such life remain disputed....
cells.
Occurrence
The colored rain of Kerala began falling on July 25, 2001, in the districts of Kottayam and Idukki in the southern part of the state. Yellow, green, and black rain was also reported. Many more occurrences of the red rain were reported over the following ten days, and then with diminishing frequency until late September. According to locals, the first colored rain was preceded by a loud
thunderThunder is the sound made by lightning. Depending on the nature of the lightning and distance of the listener, it can range from a sharp, loud crack to a long, low rumble . The sudden increase in pressure and temperature from lightning produces rapid expansion of the air surrounding and within a...
clap and flash of light, and followed by groves of trees shedding shriveled grey "burnt" leaves. Shriveled leaves and the disappearance and sudden formation of
wellA water well is an excavation or structure created in the ground by digging, driving, boring or drilling to access groundwater in underground aquifers. The well water is drawn by an electric submersible pump, a vertical turbine pump, a handpump or a mechanical pump...
s were also reported around the same time in the area. It typically fell over small areas, no more than a few square kilometers in size, and was sometimes so localized that normal rain could be falling just a few meters away from the red rain. Red rainfalls typically lasted less than 20 minutes. Each milliliter of rain water contained about 9 million
redRed is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths than this are called infrared , and cannot be seen by the naked human eye...
particles, and each
liter
of rainwater was contained approximately 100 milligrams of solids. Extrapolating these figures to the total amount of red rain estimated to have fallen, it was estimated 50,000 kilograms of red particles had fallen on Kerala.
Description of the particles
The brownish-red solid separated from the red rain consisted of about 90% round red particles and the balance consisted of debris. The particles in
suspensionIn chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometre. The internal phase is dispersed throughout the external phase through mechanical agitation, with the use of certain...
in the rain water were responsible for the color of the rain, which at times was as strongly colored red. A small percentage of particles were white or had light yellow, bluish gray and green tints. The particles were typically 4 to 10
µmA micrometer , sometimes known as a micrometer screw gauge, is a device used widely in mechanical engineering and machining for precision measurement, along with other metrological instruments such as dial calipers and vernier calipers...
across and spherical or oval. Electron microscope images showed the particles as having a depressed center, suggestive of biological cells. At still higher magnification some particles showed internal structures.
Chemical composition
Several groups of researchers analyzed the chemical elements in the solid particles and different techniques gave similar results. The particles were composed mostly of
carbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
and
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
with lesser amounts of
hydrogenHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
,
nitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
,
siliconSilicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. A tetravalent metalloid, silicon is less reactive than its chemical analog carbon...
,
chlorineChlorine Chlorine Chlorine ( , from the Greek word 'χλωρóς' (khlôros, meaning 'pale green'), is the chemical element with atomic number 17 and symbol Cl. It is a halogen, found in the periodic table in group 17 (formerly VII, VIIa, or VIIb). As the chloride ion, which is part of common salt and...
and
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
s.
The samples of water were brought to the Center for Earth Science Studies (CESS) in India, where they separated the suspended particles by filtration. The
pHpH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations...
(acidity) of the water was found to be around 7 (neutral), which is the pH for normal rain water. The
electrical conductivityElectrical conductivity or specific conductance is a measure of a material's ability to conduct an electric current. When an electrical potential difference is placed across a conductor, its movable charges flow, giving rise to an electric current...
of the rainwater showed the absence of any dissolved salts. Sediment (red particles plus debris) was collected and analyzed by the CESS using a combination of ion-coupled plasma mass spectrometry, atomic absorption spectrometry and wet chemical methods. The major elements found are listed below. The CESS analysis also showed significant amounts of
heavy metalsA heavy metal is a member of an ill-defined subset of elements that exhibit metallic properties, which would mainly include the transition metals, some metalloids, lanthanoids, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic...
in the raindust, including
nickelNickel is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. It is one of the four ferromagnetic elements at about room temperature, other three being iron, cobalt and gadolinium...
(43
ppmParts-per notation is used, especially in science and engineering, to denote relative proportions in measured quantities; particularly in low-value proportions at the parts-per-million , parts-per-billion , and parts-per-trillion level...
),
manganeseManganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
(59 ppm),
titaniumTitanium is a chemical element with the symbol Ti and atomic number 22. Sometimes called the “space age metal”, it has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color.Titanium can be alloyed with iron, aluminium, vanadium, molybdenum, among other...
(321 ppm),
chromiumChromium is a chemical element which has the symbol Cr and atomic number 24, first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odourless, tasteless, and malleable...
(67ppm) and
copperCopper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity. Pure copper is rather soft and malleable and a freshly-exposed surface has a pinkish or peachy color...
(55 ppm).
CESS analysis: Major elements present in the dried sediment
| Element |
|
|
|
|
|
|
|
|
|
| Weight % |
1.00 |
0.26 |
1.48 |
2.52 |
0.49 |
0.61 |
7.50 |
51.00 |
0.08 |
Louis and Kumar used energy dispersive X-ray spectroscopy analysis of the red solid and showed that the particles were composed of mostly carbon and oxygen, with trace amounts of silicon and iron (see table below).
Elemental composition of red cells by EDXRF analysis
| Element | Weight % | Atomic % | Standards |
|---|
|
49.53 |
57.83 |
CaCO3 |
|
45.42 |
39.82 |
QuartzQuartz is the second most abundant mineral in the Earth's continental crust . It is made up of a continuous framework of SiO 4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO 2.There are many different varieties of...
|
|
0.69 |
0.42 |
AlbiteAlbite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. As such it represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula NaAlSi 3O 8. It is a tectosilicate...
|
|
0.41 |
0.21 |
Al2O3 |
|
2.85 |
1.42 |
Quartz |
|
0.12 |
0.05 |
KCl The chemical compound potassium chloride is a metal halide salt composed of potassium and chlorine. In its pure state it is odorless. It has a white or colorless vitreous crystal, with a crystal structure that cleaves easily in three directions. Potassium chloride crystals are face-centered cubic...
|
|
0.97 |
0.24 |
Fe |
A
CHN analyzerA CHN Analyzer is a scientific instrument which can determine the elemental composition of a sample. The name derives from the three primary elements measured by the device: carbon , hydrogen and nitrogen...
showed content of 43.03% carbon, 4.43% hydrogen, and 1.84% nitrogen.
J. Thomas Brenna in the Division of Nutritional Sciences at
Cornell UniversityCornell University is a private university located in Ithaca, New York, USA, that is a member of the Ivy League.Cornell counts more than 255,000 living alumni, 28 Rhodes Scholars and 41 Nobel laureates affiliated with the university as faculty or students...
conducted carbon and nitrogen isotope analyses using a scanning electron microscope with X-ray microanalysis, an elemental analyzer, and an isotope ratio (IR) mass spectrometer. The red particles collapsed
when dried, which suggested that they were filled with fluid. The amino acids in the particles were analyzed and seven were identified (in order of concentration):
phenylalaninePhenylalanine is an α-amino acid with the formula HO
2CCHCH
2C
6H
5. This essential amino acid is classified as nonpolar because of the hydrophobic nature of the benzyl side chain. The codons for
L-phenylalanine are UUU and UUC...
,
glutamic acidGlutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid...
/
glutamineGlutamine is one of the 20 amino acids encoded by the standard genetic code. Its side chain is an amide formed by replacing the side-chain hydroxyl of glutamic acid with an amine functional group. It can therefore be considered the amide of glutamic acid. Its codons are CAA and CAG. Glutamine is...
,
serineSerine is an organic compound with the formula HO
2CCHCH
2OH.-Occurrence:...
,
aspartic acidAspartic acid is an α-amino acid with the chemical formula HO2CCHCH2CO2H. The carboxylate anion of aspartic acid is known as aspartate...
,
threonineThreonine is an α-amino acid with the chemical formula HO
2CCHCHCH
3. Its codons are ACU, ACA, ACC, and ACG. This essential amino acid is classified as polar...
, and
arginineArginine is an α-amino acid. The
L-form is one of the 20 most common natural amino acids. Its codons are CGU, CGC, CGA, CGG, AGA, and AGG. In mammals, arginine is classified as a semiessential or conditionally essential amino acid, depending on the developmental stage and health...
. He concluded that the results were consistent with a marine origin or a terrestrial plant that uses a
C4C
4 carbon fixation is one of three biochemical mechanisms, along with C
3 and CAM photosynthesis, functioning in land plants to "fix" carbon dioxide for sugar production through photosynthesis...
photosynthetic pathway.
Official report
Initially, the
Centre for Earth Science StudiesCentre for Earth Science Studies is an autonomous research centre to promote and establish scientific and technological research and development studies in the earth sciences. CESS pursues multidisciplinary approach in problems related to land, sea and atmosphere...
(CESS) stated that the likely cause of the red rain was an exploding meteor, which had dispersed about 1,000 kg (around one ton) of material. A few days later, following a basic
light microscopyThe optical microscope, often referred to as the "light microscope", is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest and simplest of the microscopes...
evaluation, the CESS retracted this as they noticed the particles resembled spores, and because debris from a meteor would not have continued to fall from the stratosphere onto the same area while unaffected by wind. A sample was, therefore, handed over to the Tropical Botanic Garden and Research Institute (TBGRI) for
microbiologicalMicrobiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. This includes eukaryotes such as fungi and protists, and prokaryotes. Viruses, though not strictly classed as living organisms, are also studied...
studies, where the spores were allowed to grow in a medium suitable for growth of algae and fungi. The inoculated petri dishes and conical flasks were incubated for three to seven days and the culture was observed under a microscope.
In November 2001, commissioned by the
Government of IndiaThe Government of India, also known as the Union Government or the Central Government, was established by the Constitution of India, and is the governing authority of a union of 28 states and seven union territories, collectively called the Republic of India...
's Department of Science & Technology, the Center for Earth Science Studies (CESS) and the Tropical Botanical Garden and Research Institute (TBGRI) issued a joint report which concluded that:
The color was found to be due to the presence of a large amount of spores of a lichenLichens are composite organisms consisting of a symbiotic association of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
-forming algaAlgae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in...
belonging to the genus TrentepohliaIn botany, Trentepohlia is a genus of filamentous green chlorophyte algae, specifically of the family Trentepohliaceae, living on terrestrial supports such as tree trunks and wet rocks....
. Field verification showed that the region had plenty of such lichens. Samples of lichen taken from Changanacherry, when cultured in an algal medium, also showed the presence of the same species of algae. Both samples (from rainwater and from trees) produced the same kind of algae, indicating that the spores seen in the rainwater most probably came from local sources.
The site was again visited on August 16, 2001 and it was found that almost all the trees, rocks and
even lamp posts in the region were full of
Trentepohlia lichen, and estimated that the extent of lichen in the region is sufficient to generate the quantity of spores seen in the rainwater. Although red or orange,
Trentepohlia is a
ChlorophyteChlorophyta, a division of green algae, includes about 7,000 species of mostly aquatic photosynthetic eukaryotic organisms. Like the land plants , green algae contain chlorophylls a and b, and store food as starch in their plastids...
green alga which can grow abundantly on tree bark or damp soil and rocks, but is also the photosynthetic
symbiontThe term symbosis commonly describes close and often long-term interactions between different biological species...
or photobiont of many lichens, including some of those abundant on the trees in Changanacherry area. The strong orange colour of the algae, which masks the green of the
chlorophyllChlorophyll is a green pigment found in most plants, algae, and cyanobacteria. Its name is derived from the Greek χλωρός and φύλλον...
, is caused by the presence of large quantities of orange
carotenoidCarotenoids are organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some types of fungus and some bacteria....
pigments.
A lichen is not a single organism, but the result of a partnership (
symbiosisThe term symbosis commonly describes close and often long-term interactions between different biological species...
) between a fungus and an alga or cyanobacteria.
The report also stated that there was no meteoric, volcanic or desert dust origin present in the rainwater and that its color was not due to any dissolved gases or pollutants. The report concluded that heavy rains in Kerala -in the weeks preceding the red rains- could have caused the widespread growth of lichens, which had given rise to a large quantity of spores into the atmosphere. However, for these lichen to release their spores simultaneously, it is necessary for them to enter their reproductive phase at about the same time. The CESS report noted that while this may be a possibility, it is quite improbable. Also, they could find no satisfactory explanation for the apparently extraordinary dispersal, nor for the apparent uptake of the spores into clouds. CESS scientists noted that "While the cause of the color in the rainfall has been identified, finding the answers to these questions is a challenge."
Parts of the CESS/TBGRI report were supported by Milton Wainwright at Sheffield University, who, together with
Chandra WickramasingheVidya Jothi Nalin Chandra Wickramasinghe, FIMA, FRAS, FRSA is Professor of Applied Mathematics and Astronomy at Cardiff University. He is the Director of the Cardiff Centre for Astrobiology. Born and educated in Sri Lanka, he currently lives in Cardiff, Wales, UK.He was a student and collaborator...
, has studied
stratosphericThe stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler...
sporeIn biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions...
s. In March 2006 he said the particles were similar in appearance to spores of a
rust fungusRusts are fungi of the order Uredinales. Many of these species are plant parasites. Some are superficially similar to the smuts, although their relation to each other is not clear. The taxonomy of Urediniomycota, as a whole, is in a state of flux....
, later saying that he had confirmed their similarity to spores or algae, and found no evidence to suggest that the rain contained dust, sand, fat globules, or blood.
Alternative hypotheses
History records many instances of unusual objects falling with the rain — in 2000, in an example of
raining animalsRaining animals is a rare meteorological phenomenon, although occurrences have been reported from many countries throughout history. One hypothesis that has been offered to explain this phenomenon is that strong winds travelling over water sometimes pick up creatures such as fish or frogs, and...
, a small
waterspoutA waterspout is an intense columnar vortex that occurs over a body of water and is connected to a cumuliform cloud. In the common form, it is a non-supercell tornado over water. While it is often weaker than most of its land counterparts, stronger versions spawned by mesocyclones do occur...
in the
North SeaThe North Sea is a marginal, epeiric sea on the European continental shelf. The Dover Strait and the English Channel in the south and the Norwegian Sea in the north connect it to the Atlantic Ocean. It is more than long and wide, with an area of around...
sucked up a school of
fishA fish is any aquatic vertebrate animal that is typically ectothermic , covered with scales, and equipped with two sets of paired fins and several unpaired fins...
a mile off shore, depositing them shortly afterwards on
Great YarmouthGreat Yarmouth, often known to locals as Yarmouth, is a coastal town in Norfolk, England. It is at the mouth of the River Yare, 20 miles east of Norwich....
in the
United KingdomThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
. Colored rain is by no means rare, and can often be explained by the airborne transport of
dustDust is a general name for minute solid particles with diameters less than 20 thou . Particles in the atmosphere arise from various sources such as soil dust lifted up by wind, volcanic eruptions, and pollution...
from
desertA desert is a landscape or region that receives almost no precipitation. Deserts are defined as areas with an average annual precipitation of less than per year, or as areas where more water is lost by evapotranspiration than falls as precipitation. In the Köppen climate classification system,...
or other dry regions which is washed down by rain. "Red Rains" have been frequently described in southern Europe, with increasing reports in recent years.
One such case occurred in
EnglandEngland is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west and the North Sea to the east, with the English Channel to the south separating it from continental...
in 1903, when dust was carried from the
SaharaThe Sahara , , "The Greatest Desert") is the world's largest hot desert. At over 9,000,000 square kilometres , it covers most of Northern Africa, making it almost as large as the United States or the continent of Europe. The desert stretches from the Red Sea, including parts of the Mediterranean...
and fell with rain in February of that year.
At first, the red rain in Kerala was attributed to the same effect, with dust from the deserts of
ArabiaThe Arabian Peninsula , Arabia, Arabistan, and the Arabian subcontinent is a peninsula in Southwest Asia at the junction of Africa and Asia...
initially the suspect.
LIDARLIDAR is an optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target. The prevalent method to determine distance to an object or surface is to use laser pulses...
observations had detected a cloud of dust in the atmosphere near Kerala in the days preceding the outbreak of the red rain. However, laboratory tests from all involved teams ruled out the particles were desert sand.
K.K. Sasidharan Pillai, a senior scientific assistant in the Indian Meteorological Department, proposed dust and acidic material from an eruption of
Mayon VolcanoMayon Volcano, also known as Mount Mayon, is an active stratovolcano in the province of Albay, in the Bicol Region, on the island of Luzon, in the Philippines....
in the
PhilippinesThe Philippines officially known as the Republic of the Philippines, is a country in Southeast Asia with Manila as its capital city. It comprises 7,107 islands in the western Pacific Ocean....
as an explanation for the colored rain and the "burnt" leaves. The volcano was erupting in June and July 2001 and Pillai calculated that the Eastern or Equatorial
jet streamJet streams are fast flowing, narrow air currents found in the atmosphere of planets at the tropopause, the transition between the troposphere and the stratosphere . The major jet streams on earth are westerly winds...
could have transported volcanic material to Kerala in 25–36 hours. The Equatorial jet stream is unusual in that it flows from east to west at about 10° N, approximately the same latitude as Kerala (8° N) and Mayon Volcano (13° N). This hypothesis was also ruled out as the particles were neither acidic nor of volcanic origin, but were spores.
A study has been published showing a correlation between historic reports of colored rains and of meteors; the author of the paper, Patrick McCafferty, stated that sixty of these events (colored rain), or 36 %, were linked to meteoritic or cometary activity. But not always strongly. Sometimes the fall of red rain seems to have occurred after an airburst, as from a meteor exploding in air; other times the odd rainfall is merely recorded in the same year as the appearance of a comet.
Extraterrestrial hypothesis
In 2003
Godfrey LouisGodfrey Louis is a solid-state physicist, who, while at Mahatma Gandhi University in Kerala, achieved notoriety for his hypotheses about the red rain in Kerala. In April 2006, he published a paper...
and Santhosh Kumar, physicists at the
Mahatma Gandhi UniversityMahatma Gandhi University, also known as M G University, was established on 2 October 1983 in Kottayam. The Mahatma Gandhi University , has been accredited by the National Assessment and Accreditation Council,India...
in
KottayamKottayam is a city in the Indian state of Kerala. It is located in central Kerala and is also the administrative capital of Kottayam district. Kottayam has an estimated population of 60,725, according to the 2001 census. The town is an important trading center of spices and commercial crops,...
, Kerala, posted an article entitled “Cometary panspermia explains the red rain of Kerala” in the on-line, non-
peer reviewPeer review is the process of subjecting an author's scholarly work, research, or ideas to the scrutiny of others who are experts in the same field. Peer review requires a community of experts in a given field, who are qualified and able to perform impartial review...
ed
arXivThe arXiv is an archive for electronic preprints of scientific papers in the fields of mathematics, physics, computer science, quantitative biology and statistics which can be accessed via the world wide web. In many fields of mathematics and physics, almost all scientific papers are placed on...
web site. While the CESS report said there was no apparent relationship between the loud sound (possibly a
sonic boomThe term sonic boom is commonly used to refer to the shocks caused by the supersonic flight of an aircraft. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion...
) and flash of light which preceded the red rain, to Louis and Kumar it was a key piece of evidence. They proposed that a meteor (from a comet containing the red particles) caused the sound and flash and when it disintegrated over Kerala it released the red particles which slowly fell to the ground. However, they omitted an explanation on how debris from a meteor continued to fall in the same area over a period of two months while unafected from winds.
Their work indicated that the particles were of biological origin (consistent with the CESS report), however, they invoked the
panspermiaPanspermia is the hypothesis that "seeds" of life exist already all over the Universe, that life on Earth may have originated through these "seeds", and that they may deliver or have delivered life to other habitable bodies....
hypothesisA hypothesis is a proposed explanation for an observable phenomenon. The term derives from the Greek, ὑποτιθέναι - hypotithenai meaning "to put under" or "to suppose." For a hypothesis to be put forward as a scientific hypothesis, the scientific method requires that one can test it...
to explain the presence of
cellThe cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos...
s in a supposed fall of meteoric material. Additionally, using
ethidium bromideEthidium bromide is an intercalating agent commonly used as a fluorescent tag in molecular biology laboratories for techniques such as agarose gel electrophoresis. It is commonly abbreviated as "EtBr", which is also an abbreviation for bromoethane...
they were unable to detect
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
or
RNARibonucleic acid is a biologically important type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate...
in the particles. Two months later they posted another paper on the same web site entitled "New biology of red rain extremophiles prove cometary panspermia" in which they reported that
"The microorganism isolated from the red rain of Kerala shows very extraordinary characteristics, like the ability to grow optimally at 300°C (572°F) and the capacity to metabolize a wide range of organic and inorganic materials."
These claims and data have yet to be verified and reported in any peer reviewed publication. In 2006 Louis and Kumar published a paper in
Astrophysics and Space ScienceAstrophysics and Space Science is a peer reviewed academic journal in the field of astrophysics and space science. It publishes original contributions, invited reviews and conference proceedings over the entire range of astronomy, astrophysics and space science...
entitled "The red rain phenomenon of Kerala and its possible extraterrestrial origin" which reiterated their hypothesis that the red rain was biological matter from an extraterrestrial source but made no mention of their previous claims to having induced the cells to grow. One of their conclusions was that if the red rain particles are biological cells and are of cometary origin, then this phenomena can be a case of cometary
panspermiaPanspermia is the hypothesis that "seeds" of life exist already all over the Universe, that life on Earth may have originated through these "seeds", and that they may deliver or have delivered life to other habitable bodies....
.
On August 2008 Louis and Kumar again presented their case in an astrobiology conference. The abstract for paper states that
"The red cells found in the red rain in Kerala, India are now considered as a possible case of extraterrestrial life form. These cells can undergo rapid replication even at an extreme high temperature of 300 deg C. They can also be cultured in diverse unconventional chemical substrates. The molecular composition of these cells is yet to be identified".
Criticism
A quotation attributed to
Carl SaganCarl Edward Sagan was an American astronomer, astrochemist, author, and highly successful popularizer of astronomy, astrophysics and other natural sciences...
that
"Extraordinary claims require extraordinary evidence" is often used regarding the claims of alien life. Debris from a meteor would not have continued to fall in the same area over a period of two months, as it would have been dispersed by winds.
Samples of the red particles were also sent for analysis to Milton Wainwright at Sheffield University and
Chandra WickramasingheVidya Jothi Nalin Chandra Wickramasinghe, FIMA, FRAS, FRSA is Professor of Applied Mathematics and Astronomy at Cardiff University. He is the Director of the Cardiff Centre for Astrobiology. Born and educated in Sri Lanka, he currently lives in Cardiff, Wales, UK.He was a student and collaborator...
at
Cardiff UniversityCardiff University is a leading university located in the Cathays Park area of Cardiff, Wales, United Kingdom. It received its Royal charter in 1883 and is a member of the Russell Group of Universities. The university is consistently recognised as providing the best university education in Wales...
. Wickramasinghe reported in December 2006 that "work in progress has yielded positive for DNA, however, this identification is not yet fully confirmed, and might be considered equivocal", The absence of DNA is key to Louis and Kumar's hypothesis that the cells were of extraterrestrial origins.
Wainwright is quoted as saying:
“There appears to be an increasing tendency among scientists to come up with wild explanations when asked by the press to comment on unusual, novel phenomena. A good example is provided by comments about the recent Indian red rain phenomenon."
A correction was printed in
The Observer regarding Dr. Wainwright's comment that the red rain lacked DNA. Dr. Wainwright asked in the correction to make clear that he currently had no view on whether the samples contained genetic material or not, and that it was physicist Godfrey Louis who held that view.
The primary function of most spores's wall and impermeability is to ensure its own survival through periods of environmental stress. They are therefore resistant to ultraviolet and gamma radiation,
desiccationDesiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately-well sealed container.-Science:-Desiccator:...
,
lysozymeLysozyme, also known as muramidase or N-acetylmuramide glycanhydrolase, are a family of enzymes which damage bacterial cell walls by catalyzing hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between N-acetyl-D-glucosamine...
,
temperatureIn physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics...
,
starvationStarvation is a severe reduction in vitamin, nutrient, and energy intake. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage, and eventually death...
and chemical disinfectants. Visualising spores under a light microscope can be difficult due to the impermeability of the ungerminated spore wall to dyes and stains used in cell biology methods.
The controversial conclusion of Louis et al. is the only hypothesis suggesting that these organisms are of extraterrestrial origin. Louis has not reported the use of any standard microbiology
growth mediumA growth medium or culture medium is a liquid or gel designed to support the growth of microorganisms or cells , or small plants like the moss Physcomitrella patens .There are different types of media for growing different types of cells....
to culture and induce
germinationGermination is the process in which a seed or spore emerges from a period of dormancy. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However, the growth of a sporeling from a spore, for example the growth of hyphae from fungal...
and growth of the spores, basing his claim of "biological" growth on absorbance measurements following precipitation by supercritical fluids.
Regarding the "absence" of DNA, Louis' only attempt to stain the spore's DNA was by the use of malachite green, which is generally used to stain bacterial endospores, not algal spores. Visualising algal spore DNA under a light microscope can be difficult due to the impermeability of the highly resistant spore wall to dyes and stains used in normal staining procedures. In order to stain the spores' DNA, which is tightly packed, encapsulated and desiccated, spores must first be cutured in suitable
growth mediumA growth medium or culture medium is a liquid or gel designed to support the growth of microorganisms or cells , or small plants like the moss Physcomitrella patens .There are different types of media for growing different types of cells....
and temperature in order to induce
germinationGermination is the process in which a seed or spore emerges from a period of dormancy. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However, the growth of a sporeling from a spore, for example the growth of hyphae from fungal...
.
Further occurrences
Reports indicated that on August 21, 2007 red colored rainfall occurred in a few places in the northern part of
Kozhikode districtKozhikode District is a district of Kerala state, situated on the southwest coast of India. The city of Kozhikode, also known as Calicut, is the district headquarters. The district is 38.25% urbanised....
. Places around Vadakara, a
municipalityA municipality is an administrative entity composed of a clearly defined territory and its population and commonly denotes a city, town, or village, or a small grouping of them. A municipality is typically governed by a mayor and a city council or municipal council.The notion of municipality...
in Kozhikode district, which is 50 kilometers (31 miles) northward of Kozhikode town witnessed this phenomenon. The Center for Water Resources Development and Management (CWRDM) an Indian government agency, was reported to be awaiting samples for examination.
A possibly related incident occurred in February 2008 when small
fishA fish is any aquatic vertebrate animal that is typically ectothermic , covered with scales, and equipped with two sets of paired fins and several unpaired fins...
started raining down during heavy rain in a village in
KeralaKerala , is a state located in southwestern India. The state was created in 1956 on linguistc basis, bringing together those places where Malayalam formed the principal language...
.
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