Red rain in Kerala - AbsoluteAstronomy.com

The Kerala red rain phenomenon was a blood rain
Blood rain
Blood rain or red rain is a phenomenon in which blood is perceived to fall from the sky in the form of rain. Cases have been recorded since Homer's Iliad, composed ca eighth century BC, and are widespread. Before the 17th century it was generally believed that the rain was actually blood...

(red rain) event that occurred from July 25 to September 23, 2001, when red-coloured

Red

Red 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 eye...

rain

Rain

Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...

sporadically fell on the southern India

India

India , 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 with over 1.2 billion people, and the most populous democracy in the world...

n state of Kerala

Kerala

or Keralam is an Indian state located on the Malabar coast of south-west India. It was created on 1 November 1956 by the States Reorganisation Act by combining various Malayalam speaking regions....

. 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 as early as 1896 and several times since then.

It was initially thought that the rains were colored by fallout from a hypothetical meteor

METEOR

METEOR 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 India

Government of India

The Government of India, officially known as the Union Government, and also known as the Central Government, was established by the Constitution of India, and is the governing authority of the union of 28 states and seven union territories, collectively called the Republic of India...

concluded that the rains had been colored by airborne spore

Spore

In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

s from locally prolific terrestrial algae

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

.

It was not until early 2006 that the colored rains of Kerala gained widespread attention when the popular media reported that Godfrey Louis

Godfrey Louis

Godfrey Louis is a controversial solid-state physicist, who, while at Mahatma Gandhi University in Kerala, achieved notoriety for his hypotheses about the red rain in Kerala...

and Santhosh Kumar of the Mahatma Gandhi University

Mahatma Gandhi University

Mahatma Gandhi University, also known as M G University, was established on 2 October 1983 in Kottayam. The University Grants Commission of India does not believe that the names of Indian universities should be unique, so another UGC-recognized government-run Mahatma Gandhi University was...

in Kottayam

Kottayam

Kottayam is a city in the Indian state of Kerala, spread over an area of 55.40 km2. It is the administrative capital of the Kottayam district. Kottayam Kottayam (Malayalam: കോട്ടയം) is a city in the Indian state of Kerala, spread over an area of 55.40 km2. It is the administrative...

proposed a controversial hypothesis that the colored particles were extraterrestrial

Extraterrestrial life

Extraterrestrial life is defined as life that does not originate from Earth...

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 thunder

Thunder

Thunder is the sound made by lightning. Depending on the nature of the lightning and distance of the listener, thunder 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...

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 well

Water well

A 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 trash 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 red

Red

particles, and each liter

Litér

- External links :*...

of rainwater 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 suspension

Suspension (chemistry)

In chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometer. 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 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 µm

Micrometer

A micrometer , sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw used widely for precise measurement of small distances in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, vernier,...

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 carbon

Carbon

Carbon 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 oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

with lesser amounts of hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

, silicon

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

, chlorine

Chlorine

Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

and metal

Metal

A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

s.

The samples of water were brought to the Centre for Earth Science Studies

Centre for Earth Science Studies

Centre 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. It was instituted by the...

(CESS) in India, where they separated the suspended particles by filtration. The pH

In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

(acidity) of the water was found to be around 7 (neutral), which is the pH for normal rain water. The electrical conductivity 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

Mass spectrometry

Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...

, atomic absorption spectrometry and wet chemical methods. The major elements found are listed below. The CESS analysis also showed significant amounts of heavy metals

Heavy metals

A heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic weight,...

in the raindust, including nickel

Nickel

Nickel 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. Nickel belongs to the transition metals and is hard and ductile...

(43 ppm

Parts-per notation

In science and engineering, the parts-per notation is a set of pseudo units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement...

), manganese

Manganese

Manganese 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), titanium

Titanium

Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

(321 ppm), chromium

Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the 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 odorless, tasteless, and malleable...

(67ppm) and copper

Copper

Copper 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 soft and malleable; an exposed surface has a reddish-orange tarnish...

(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 particles by EDXRF analysis**
Weight %	Atomic %	Standards
49.53	57.83	CaCO₃
45.42	39.82	Quartz Quartz Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
0.69	0.42	Albite Albite Albite 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 NaAlSi3O8. It is a tectosilicate. Its color is usually pure white, hence...
0.41	0.21	Al₂O₃
2.85	1.42	Quartz
0.12	0.05	KCl Potassium chloride The chemical compound potassium chloride is a metal halide salt composed of potassium and chlorine. In its pure state, it is odorless and has a white or colorless vitreous crystal appearance, with a crystal structure that cleaves easily in three directions. Potassium chloride crystals are...
0.97	0.24	Fe

A CHN analyzer

CHN analyzer

A 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 University

Cornell University

Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

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): phenylalanine

Phenylalanine

Phenylalanine is an α-amino acid with the formula C6H5CH2CHCOOH. This essential amino acid is classified as nonpolar because of the hydrophobic nature of the benzyl side chain. L-Phenylalanine is an electrically neutral amino acid, one of the twenty common amino acids used to biochemically form...

, glutamic acid

Glutamic acid

Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...

/glutamine

Glutamine

Glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders...

, serine

Serine

Serine is an amino acid with the formula HO2CCHCH2OH. It is one of the proteinogenic amino acids. By virtue of the hydroxyl group, serine is classified as a polar amino acid.-Occurrence and biosynthesis:...

, aspartic acid

Aspartic acid

Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...

, threonine

Threonine

Threonine is an α-amino acid with the chemical formula HO2CCHCHCH3. Its codons are ACU, ACA, ACC, and ACG. This essential amino acid is classified as polar...

, and arginine

Arginine

Arginine is an α-amino acid. The L-form is one of the 20 most common natural amino acids. At the level of molecular genetics, in the structure of the messenger ribonucleic acid mRNA, CGU, CGC, CGA, CGG, AGA, and AGG, are the triplets of nucleotide bases or codons that codify for arginine during...

. He concluded that the results were consistent with a marine origin or a terrestrial plant that uses a C4

C4 carbon fixation

C4 carbon fixation is one of three biochemical mechanisms, along with and CAM photosynthesis, used in carbon fixation. It is named for the 4-carbon molecule present in the first product of carbon fixation in these plants, in contrast to the 3-carbon molecule products in plants. fixation is an...

photosynthetic pathway.

Official report

Initially, the Centre for Earth Science Studies

Centre for Earth Science Studies

(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 microscopy

Optical microscope

The 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 design of microscope and were possibly designed in their present compound form in the...

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 Botanical Garden and Research Institute

Tropical Botanical Garden and Research Institute

Tropical Botanical Garden and Research Institute is an autonomous Institute established by the Government of Kerala on 17 November 1979 at Trivandrum, the capital city of Kerala. It functions under the umbrella of the Science, Technology and Environment Department, Government of Kerala...

(TBGRI) for microbiological

Microbiology

Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...

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 India

Government 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 lichen
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...

-forming alga
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

belonging to the genus Trentepohlia. 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 covered with 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 Chlorophyte

Chlorophyta

Chlorophyta is a division of green algae, informally called chlorophytes. The name is used in two very different senses so that care is needed to determine the use by a particular author...

green alga which can grow abundantly on tree bark or damp soil and rocks, but is also the photosynthetic symbiont

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

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 chlorophyll

Chlorophyll

Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...

, is caused by the presence of large quantities of orange carotenoid

Carotenoid

Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...

pigments.
A lichen is not a single organism, but the result of a partnership (symbiosis

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

) between a fungus and an alga or cyanobacterium.

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 Wickramasinghe

Chandra Wickramasinghe

Vidya Jothi Nalin Chandra Wickramasinghe , FIMA, FRAS, FRSA is Professor at Cardiff University and Honorary Professor at the University of Buckingham. He is the Director of the Buckingham Centre for Astrobiology...

, has studied stratospheric

Stratosphere

The 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...

spore

Spore

s. In March 2006 he said the particles were similar in appearance to spores of a rust fungus

Rust (fungus)

Rusts are plant diseases caused by pathogenic fungi of the order Pucciniales. About 7800 species are known. Rusts can affect a variety of plants; leaves, stems, fruits and seeds. Rust is most commonly seen as coloured powder, composed off tiny aeciospores which land on vegetation producing...

, 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 animals

Raining animals

Raining animals is a rare meteorological phenomenon in which flightless animals "rain" from the sky. Such occurrences have been reported from many countries throughout history. One hypothesis offered to explain this phenomenon is that strong winds traveling over water sometimes pick up creatures...

, a small waterspout

Waterspout

A 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 Sea

North Sea

In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

sucked up a school of fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

a mile off shore, depositing them shortly afterwards on Great Yarmouth

Great Yarmouth

Great Yarmouth, often known to locals as Yarmouth, is a coastal town in Norfolk, England. It is at the mouth of the River Yare, east of Norwich.It has been a seaside resort since 1760, and is the gateway from the Norfolk Broads to the sea...

in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

. Colored rain is by no means rare, and can often be explained by the airborne transport of dust

Dust

Dust consists of particles in the atmosphere that arise from various sources such as soil dust lifted up by wind , volcanic eruptions, and pollution...

from desert

Desert

A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...

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 England

England

England 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, with the North Sea to the east and the English Channel to the south separating it from continental...

in 1903, when dust was carried from the Sahara

Sahara

The Sahara is the world's second largest desert, after Antarctica. At over , it covers most of Northern Africa, making it almost as large as Europe or the United States. The Sahara stretches from the Red Sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic Ocean...

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 Arabia

Arabian Peninsula

The Arabian Peninsula is a land mass situated north-east of Africa. Also known as Arabia or the Arabian subcontinent, it is the world's largest peninsula and covers 3,237,500 km2...

initially the suspect. LIDAR

LIDAR

LIDAR is an optical remote sensing technology that can measure the distance to, or other properties of a target by illuminating the target with light, often using pulses from a laser...

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 Volcano

Mayon Volcano

Mayon Volcano, also known as Mount Mayon, is an active volcano in the province of Albay, on the island of Luzon in the Philippines. Renowned as the "perfect cone" because of its almost symmetric conical shape, Mayon forms the northern boundary of Legazpi City, the largest city in terms of...

in the Philippines

Philippines

The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

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 stream

Jet stream

Jet streams are fast flowing, narrow air currents found in the atmospheres of some planets, including Earth. The main jet streams are located near 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 Louis

Godfrey Louis

Godfrey Louis is a controversial solid-state physicist, who, while at Mahatma Gandhi University in Kerala, achieved notoriety for his hypotheses about the red rain in Kerala...

and Santhosh Kumar, physicists at the Mahatma Gandhi University

Mahatma Gandhi University

in Kottayam

Kottayam

, Kerala, posted an article entitled "Cometary panspermia explains the red rain of Kerala" in the on-line, non-peer review

Peer review

Peer review is a process of self-regulation by a profession or a process of evaluation involving qualified individuals within the relevant field. Peer review methods are employed to maintain standards, improve performance and provide credibility...

ed arXiv

ArXiv

The arXiv |Chi]], χ) is an archive for electronic preprints of scientific papers in the fields of mathematics, physics, astronomy, computer science, quantitative biology, statistics, and quantitative finance which can be accessed online. In many fields of mathematics and physics, almost all...

web site. While the CESS report said there was no apparent relationship between the loud sound (possibly a sonic boom

Sonic boom

A sonic boom is the sound associated with the shock waves created by an object traveling through the air faster than the speed of sound. 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 unaffected from winds.

Their work indicated that the particles were of biological origin (consistent with the CESS report), however, they invoked the panspermia hypothesis

Hypothesis

A hypothesis is a proposed explanation for a 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 cell

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, 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 bromide

Ethidium bromide

Ethidium 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 DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

or RNA

RNA

Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

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 Science
Astrophysics and Space Science
Astrophysics and Space Science is a peer reviewed, scientific journal published by Springer. It was first published in 1968. Each volume is published every two months. The Editor in Chief is Michael A. Dopita.-Aims and scope:...

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 phenomenon can be a case of cometary panspermia.

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 °C. They can also be cultured in diverse unconventional chemical substrates. The molecular composition of these cells is yet to be identified".

On September 2010 he presented a similar paper at a conference in California, U.S.A.

Criticism

Hypothesis' authors – G. Louis and A. Santosh – admitted no explanation on how debris from a meteor could have continued to fall in the same area over a period of two months, despite the changes in climatic conditions and wind pattern spanning over two months.
Samples of the red particles were also sent for analysis to Milton Wainwright at Sheffield University and Chandra Wickramasinghe

Chandra Wickramasinghe

at Cardiff University

Cardiff University

Cardiff University is a leading research 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 high quality research-based...

. 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. The team then reported in 29 August 2010 in the non-peer reviewed physics archive "arxiv.org" that they were able to have these cells "reproduce" when incubated at high pressure saturated steam at 121 °C (autoclave

Autoclave

An autoclave is an instrument used to sterilize equipment and supplies by subjecting them to high pressure saturated steam at 121 °C for around 15–20 minutes depending on the size of the load and the contents. It was invented by Charles Chamberland in 1879, although a precursor known as the...

d) for up to two hours. So their conclusion is that these cells reproduced, without DNA, at temperatures higher than any known life form on earth is able to. The cells, however, were unable to reproduce at temperatures that earthly cells do. The team also observed the cells using phase contrast fluorescence microscopy, and they concluded that: "The flourescence behaviour of the red cells is shown to be in remarkable correspondence with the extended red emission observed in the Red Rectangle Nebula

Red Rectangle nebula

The Red Rectangle Nebula, so called because of its red color and unique rectangular shape, is a protoplanetary nebula in the Monoceros constellation. Also known as HD 44179, the nebula was discovered in 1973 during a rocket flight associated with the AFCRL Infrared Sky Survey called Hi Star...

and other galactic and extragalactic dust clouds

Cosmic dust

Cosmic dust is a type of dust composed of particles in space which are a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location; for example: intergalactic dust, interstellar dust, interplanetary dust and circumplanetary dust .In our own Solar...

, suggesting, though not proving an extraterrestrial origin." The controversial conclusion of Louis et al. is the only hypothesis suggesting that these organisms are of extraterrestrial origin.

Regarding the "absence" of DNA, Louis has not reported the use of any standard microbiology growth medium

Growth medium

A 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 germination

Germination

Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. 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...

and growth of the spores, basing his claim of "biological" growth on light absorbance measurements following precipitation by supercritical fluids. Louis' only attempt to stain the spore's DNA was by the use of malachite green

Malachite green

Malachite green is an organic compound that is used as a dyestuff and has emerged as a controversial agent in aquaculture. Malachite green is traditionally used as a dye for materials such as silk, leather, and paper...

, which is generally used to stain bacterial endospores, not algal spores, whose primary function of their cell wall and their impermeability is to ensure its own survival through periods of environmental stress. They are therefore resistant to ultraviolet and gamma radiation, desiccation

Desiccation

Desiccation 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 sealed container.-Science:...

, lysozyme

Lysozyme

Lysozyme, also known as muramidase or N-acetylmuramide glycanhydrolase, are glycoside hydrolases, enzymes that 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...

, temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

, starvation

Starvation

Starvation is a severe deficiency in caloric energy, nutrient and vitamin 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 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 cultured in suitable growth medium

Growth medium

and temperature in order to induce germination

Germination

Creationism

Researchers Wickramasinghe and Hoyle have also used their data to argue in favor of creationism

Creationism

Creationism is the religious beliefthat humanity, life, the Earth, and the universe are the creation of a supernatural being, most often referring to the Abrahamic god. As science developed from the 18th century onwards, various views developed which aimed to reconcile science with the Genesis...

, the religious belief that humanity, life, Earth, and the universe are the creation of a supernatural being. In their latest paper they suggest that these organisms are of extraterrestrial origin and conclude:

Further occurrences

Reports indicated that on August 21, 2007 red colored rainfall occurred in a few places in the northern part of Kozhikode district

Kozhikode district

Kozhikode District , formerly Calicut, 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 municipality

Municipality

A municipality is essentially an urban administrative division having corporate status and usually powers of self-government. It can also be used to mean the governing body of a municipality. A municipality is a general-purpose administrative subdivision, as opposed to a special-purpose district...

in Kozhikode district, which is 50 kilometres (31.1 mi) 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 fish

Fish

started raining down during heavy rain in a village in Kerala.

External links

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