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Saturday, October 28, 2023

Aippaisi Pournami 2023 - Lunar Eclipse !!

Bright shining beautiful moon is visible now as today is Pournami – in a few hours there is to be Lunar Eclipse .. .. there could well be  a few people who jump to comment on all beliefs as ‘superstitious nonsense’ – but when the Western World reports, most of them would readily  accept all such theories !! 

நிலா அது வானத்தின் மேலே என்று அழகாக தெரிவது சந்திரன்.  நிலா,  நிலவு, அம்புலி, திங்கள், மதி, சந்திரன்- என பல பெயர்களில் அழைக்கப்படுவது  புவியின் ஒரேயொரு நிரந்தரமான இயற்கைத் துணைக்கோள். "நிலா' என்பதற்கான பொருள் "ஒளி' என்பதாகும் (நிலா-ஒளி) என்று உ.வே.சாமிநாதையர் தெளிவுபடக் குறிப்பிட்டுள்ளார். சிலப்பதிகாரம் காதையில் , "அங்கண் வானத்து அணிநிலா விரிக்கும்; திங்களஞ் செல்வன்' என்று கூறப்பட்டுள்ளது.  இடமகன்ற அழகிய வானில் குளிர்ச்சி பொருந்திய நிலவை (ஒளியை) பரவச் செய்யும் திங்களாகிய (சந்திரன்) செல்வன் என்பது இதன் பொருள்; சந்திரனால் பரவச் செய்யப்படும் ஒளியே "நிலா'.  இன்று பௌர்ணமி - சந்திர க்ரஹணமும் கூட. 

A century ago, in Feb 1919 -  two teams of astronomers from the Greenwich and Cambridge observatories set out for Sobral, Brazil, and Príncipe (an island off the coast of Africa), respectively, with sophisticated equipment that would allow them to photograph – a celestial phenomenon. !!  - Imagine what ? 

Chandran, Nilavu, Ambuli, Moon has enamoured mankind for ages.  The Moon (or Luna) is the Earth’s only natural satellite – considered to have been  formed 4.6 billion years ago around some 30–50 million years after the formation of the solar system. The Moon is in synchronous rotation with Earth meaning the same side is always facing the Earth.  In reality both sides of the Moon see the same amount of sunlight however only one face of the Moon is ever seen from Earth. This is because the Moon rotates around on its own axis in exactly the same time it takes to orbit the Earth, meaning the same side is always facing the Earth. 

Celestial phenomenons have found mentioned in our Ithihasa puranas ~ during Mahabaratha war there were two of them .. ..  perhaps the interim period when we could not have darshan of Emperuman are to be seen as eclipse or occultations.   The fourteenth day of the Mahabharata war was a crucial one for both sides. On the evening of the thirteenth day, Arjuna, devastated by the death of his young son, Abhimanyu, had vowed that he would kill Jayadratha  - by divine interference, Bhagwan Sree Krishna briefly shadows the Sun enabling Arjuna to complete his vow.    

The Sun always illuminates half of the Moon while the other half remains dark, Anywhere from four to seven times a year, our Earth, Moon and Sun line up just right to create the cosmic-scale shadow show known as an eclipse. The Moon's orbit around Earth is tilted relative to Earth's orbit around the Sun. This tilt is the reason why we have occasional eclipses instead of eclipses every month. There are two types of eclipses: lunar and solar. During a lunar eclipse, Earth’s shadow obscures the Moon. During a solar eclipse, the Moon blocks the Sun from view. 

                  The orbit of the Moon around Earth is inclined about 5.1° to Earth's orbit around the Sun. As a consequence, the Moon's orbit crosses the ecliptic at two points or nodes. If Full Moon takes place within about 17° of a node, then a lunar eclipse will be visible from a portion of Earth.  The Sun makes one complete circuit of the ecliptic in 365.24 days, so its average angular velocity is 0.99° per day. At this rate, it takes 345 days for the Sun - and at the opposite node, Earth's umbral and penumbral shadows - to cross the 34° wide eclipse zone centered on each node. 

A lunar eclipse so happening  is a celestial event which happens when Earth lines up directly between the sun and the moon. When this happens, Earth blocks the light from the sun to the moon. Earth's shadow then falls on the moon.    At least two lunar eclipses happen every year, though all of them may not be visible at some places of the earth. 

Tonight, a  Lunar eclipse is set to occur, just two weeks after a solar eclipse, and this Partial Lunar eclipse will be visible from all locations in India, beginning at 11:31 pm on October 28th." The duration of the eclipse is estimated to be 1 hour and 19 minutes, with the umbral phase starting at 01:05 am IST and concluding at 02:24 am IST on October 29th. Tonight's lunar eclipse will be visible in all Indian cities. It will also be visible in other Asian countries, Europe, Africa, and North America. We can see it in Chennai too. 

Today being Aippaisi Pournami, there was siriya mada veethi purappadu of Sri Parthasarathi Emperuman and here are some photos of today’s purappadu. 

If you remember that 3rd para of this post about astronomers traveling to Sobral in Feb 1919  - it was to photograph a solar eclipse as it cut across South America, the Atlantic Ocean, and Africa.  The purpose of the expeditions, arranged by Frank Dyson of the Royal Greenwich Observatory and Arthur Eddington of Cambridge University, was to test Albert Einstein’s theory of general relativity, which had been published in 1915 and was regarded with skepticism by many scientists at that time.  

In 1916, Albert Einstein published his general theory of relativity in full mathematical detail. That opened the window on a radically new framework for physics, abolishing established notions of space and time and replacing Newton’s formulation of the laws of gravity. Einstein’s revolution was to change the course of science; but in the years immediately after publication, there was no definitive observational evidence that his theory was correct. Enter Arthur Stanley Eddington took on the task of proving it. By harnessing a total solar eclipse, he argued that the deflection, or bending, of light by the Sun’s gravity could be measured. This was a critical test, because Einstein’s theory predicted a deflection precisely twice the value obtained using Isaac Newton’s law of universal gravitation. The needed eclipse came 100 years ago, in 1919. Eddington is now forever associated with two expeditions to view it: from Sobral in northern Brazil, and the island of Príncipe off the coast of West Africa.  Einstein’s theory, eight years in the making, sprang from insights he had developed after he published his theory of special relativity in 1905. 

Interesting ! 

adiyen Srinivasa dhasan
Mamandur Veeravalli Srinivasan Sampathkumar

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