Astronomically, the year 2013 is an important year. In total , FIVE eclipses ( 3 solar and 2 Lunar ) occur this year.
Solar eclipse will occur only on new moon days ( Amavasya ).
Lunar eclipse will occur only on full moon days ( Purnima ) .
How many eclipses in a year will occur ?.
It is a common question asked by many.
Many people think that every year there will be one solar eclipse and one lunar eclipse.
The fact is that the maximum eclipses in a year is seven and minimum is two .
An Ireland record reveals about a solar eclipse that occurred on November 30, 3340 BC.
A Chinese record reveals the eclipses of hundreds of years starting from Oct. 22, 2134 BC
A Syrian tablet reveals about a solar eclipse that occurred on May 5th, 1223 BC.
The ancient Babylonian astronomers called Chaldeans ( perhaps early 6th century BC ) by studying the records maintained on eclipses came to a great conclusion. They developed 'Saros cycle' which reveals that the eclipses repeat once in 18 years, 11 months and 8 hours ( 6585.3213 days ). Remember in BC the Babylonian astronomers found out that the eclipses occur in a fixed cycle. It was a great discovery done on mere studying of the records of the previous eclipses.
According to Saros cycle , the solar eclipse occured on 10th May 2013, again after 18 yrs, 11 days and 8 hours will reoccur but it will be visible in different part of the globe. In simple terms roughly once in 18 years a particular eclipse will repeat.( periodicity and reccurence of eclipses are purely based on Saros cycle ). Now I recall the sayings ( 1958 ) of my Astronomy Professor Shree Sathu Rao, " the discovery of this Saros cycle is enough to remember Babylonian astronomers for ever." Yes in astronomy, this discovery done in the sixth century BC by Babylonian astronomers is a great land mark.
Saros cycle is applicable for ever (perpetual), let me give a simple example of the cycle of a particular lunar eclipse.
One lunar eclipse had occurred on
Oct 27, 2004 at 10:04 pm EST it will repeat as follows.
Nov.8, 2022 at 5:59 am EST
Nov 18, 2040 at 2:03 pm EST
Nov 30, 2058 at 10:14 pm EST
EST = Eastern Standard Time
By observing the above list, one can easily understand that the eclipses are repeated roughly once in 18 years.
Seven eclipses in a year is a rare phenomena, out of seven , 5 Solar +2 Lunar ( or) 4 Solar+3 Lunar will occur.
The years of 7 eclipses : 1908, 1917, 1935, 1973, 1982, 2094....
The minimum number of eclipses in a year is two, both will be Solar, which means, there can be a year without a single lunar eclipse.
The solar eclipse of May 1919 made Einstein, the world famous.
( Just a little physics for you in simple terms , do not stop, please continue reading )
To total Solar eclipse that occurred on May 29, 1919 was unforgettable for the Physicist community of the world. It was a great day for them. The observations made during this Solar eclipse under the leadership of British Astronomer Sir Arthur Eddington confirmed the findings of Albert Einstein and by over night made him a celebrity.
In 1915 in the General Theory of Relativity , Einstein had said, the light rays that pass near the massive objects like the sun will bend.
Scientists know that the light rays reflect or refract but do not bend .( please know the difference between the reflection of light and bending of light , in reflection of light, light goes in a straight line, falls on an object ( mirror ) and bounces ( reflects ) . Bending of light is a slight deflection of the light rays like a curve.
Before Einstein , it was believed that the light rays would never bend. Therefore scientists rejected the sayings of Einstein, they believed firmly that the light rays would never bend like a curve. (Please do not get confused, bending of light is totally different from the reflection and refraction )
REFLECTION OF LIGHT is THE BOUNCING OF LIGHT.
We are able to see the moon because,
the rays of light from the sun fall on the moon and reflect.
REFRACTION OF LIGHT is THE CHANGE IN THE PATH OF THE LIGHT WHEN MEDIUM CHANGES.
When a light ray travels from air medium ( rarer ) to water medium ( denser) ,
the path of the ray deviates.
BENDING OF LIGHT is THE CHANGE IN THE PATH OF LIGHT LIKE A CURVE IN THE SAME MEDIUM.
See below diagram, the incoming ray is from a far away star,
when it passes by the side of the sun it bends like a curve.
See,when a ray of light passes near the massive Sun, it bends like a curve. Before Einstein, it was an established theory that the light rays would never bend. 1919 Solar eclipse proved Einstein's theory and confirmed the bending of light rays and made Einstein a great scientist of the world.
During the eclipse of 1919, it was found out by the astronomers ( headed by Arthur Eddington ) that the light rays which were coming from a far away star, when came near the massive sun, bent towards the sun.( bending of light rays is called Gravitational lensing ).
Next day THE TIMES magazine of London declared that Einstein was right. This made Einstein world famous, which made physicist proud.
The intellectuals of the world recognised the extremely high calibre of Einstein.
Now the common question is why the light rays bend like a curve when pass near the massive objects like the sun ( star ). The answer given in the General Theory of Relativity is that around every massive object , there is dip called SPACE TIME CURVATURE, when the rays of light pass through the dip, they bend. In astronomical language, the space around a massive body is WARPED.
Around the Sun there is a dip called Space-Time Curvature
When the light rays pass in the dip , they bend.
Let me remind,
1) Solar eclipse will occur only on new moon days. ( Amavasya )
2) Lunar eclipse will occur only on full moon days. ( Poorinima )
3) The eclipses will repeat once in 18 years , 11 days, 8 hours.( Saros cycle )
4) The maximum eclipses in a year is seven and minimum is two.
5) In case of minimum two eclipses, both will be solar, no lunar .
6) This year 2013 , five eclipses are occurring.
7) In the year 2094 , seven eclipses will occur.
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Certain information are repeated to enable the high school students to understand.
