What is Blood Rain?
- bioworld090
- Jul 21, 2022
- 3 min read
Image Credit: Amar Ujala
Blood rain, also called red rain, is the common name for a phenomenon in which red-coloured rain occurs. Although it is called red rain, it is actually brown or sandy in colour. The rain often leaves a thin layer of dust behind when sand causes it. This sand that is left behind is capable of coating houses, vehicles, garden furniture, etc.
HOW COMMON IS THE BLOOD RAIN?
Blood rain is actually not too common but it occurs a few times a year in the UK, Spain and France. It has also been reported in India, Sri Lanka and Siberia.
Now the question is
WHAT CAUSES BLOOD RAIN?
In ancient times, blood rain was seen as a bad omen but now with the help of science, there is some explanation for its cause. However, it seems like there is not just a single explanation for what causes the blood rain. There are different explanations for the cause which are as follows:
1. Sand and Dust
This is the most common explanation for the phenomenon. According to this explanation, the sand from the Sahara Desert gets carried up in a storm and mixes with the clouds and then the clouds get carried over to Europe by winds and this results in blood rain in the UK, Spain and France.
2. Haematococcus pluvialis - a freshwater green microalgae
Image Source: Sciencealert
The blood rain of Zamora, Spain in 2014 is said to have been caused by the freshwater green microalgae, Haematococcus pluvialis. Scientists explain that H. pluvialis produce a red pigment called astaxanthin when they are under stress, The stress can be a result of a change in salinity, bright light and low availability of nutrients.
Image Credit: http://www.mikro-foto.de/
H. pluvialis usually move using flagella but when conditions become unfavourable they form a cyst around them and under sunlight, their red colour is more visible against light backgrounds.
Although H. pluvialis is found to be the reason for the blood rain in Zamora, one thing that is still not clear is where did they come from. This microalga is not found in the area so, they must have come from somewhere else.
3. Panspermia Hypothesis - Extraterrestrial link of blood rain
The blood rain case of 2001 that occurred in Kerala, India was first studied by Godfrey Louis and A. Santhosh Kumar. They related their findings to the panspermia hypothesis.
What does the panspermia hypothesis state?
The panspermia hypothesis states that life exists throughout the Universe and is distributed by space dust, meteoroids, asteroids, comets, etc.
What did Louis and Kumar find that led them to this conclusion?
Louis and Kumar studied the samples of water from the blood rain and found cells similar to algal cells. The shape of these cells ranged from spherical to ellipsoidal and slightly elongated. These cells had thick cell envelopes. The cells were also able to withstand some extreme conditions.
However, the thing that surprised these two physicians is the absence of DNA because if they were algal cells, they should have contained the DNA or genetic material. The other thing that supported their theory was a "sound". A sound very different from a thunderstorm. A sound that was similar to a sonic boom and was heard by the locals just a few hours before the first case of blood rain in Kerala in 2001. This sound was said to have come from a meteor airburst.
Louis and Kumar concluded that the cells came along with the meteorite and upon its explosion and disintegration, they mixed with the clouds.
Criticisms of Louis and Kumar's explanations
The idea of Louis and Kumar about the extraterrestrial cause of blood rain in Kerala was criticized. This was due to the findings of The Center for Earth Science Studies(CESS) and Tropical Botanic Garden & Research Centre(TBGRI). CESS and TBGRI found out that these were spores of the algae Trentepohlia.
Image Credit: Jason Hollinger
Why Louis and Kumar did not find DNA in the cells?
It is because of their use of improper techniques. Louis and Kumar are physicists and not biologists. Therefore, it was out of their expertise.
The cells found were spores of Trentepohlia and spores are one of the most resistant cells that can survive extreme temperatures, physical abuse, desiccation(being dried up), chemical disinfectants and even radiation. Louis and Kumar tried dying the spores without growing them and providing favourable conditions to them. Due to this, the cell membranes remained intact and they saw no genetic material. On the other hand, botanists at TBGRI first provided them with favourable conditions and grew them in a culture medium and then examined them which led them to see the DNA in the cells.
REFERENCES:
* Dunning, B. "Alien Downpour: The Red Rain of India." Skeptoid Podcast. Skeptoid Media, 21 Sep 2010. Web. 7 May 2022. <https://skeptoid.com/episodes/4224>
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