Total SOLAR ECLIPSE on 22nd July 2009 – some Facts……….

Circulated to my group on 21^st July 2009 –

on the eve of Total Solar Eclipse in India.

Dear (s) 

The most spectacular celestial event is on the cards tomorrow – A TOTAL SOLAR ECLIPSE.  Here are some facts collated :

Solar Eclipse occurs when the new Moon gets between Earth and Sun and covers the solar disc completely. We all know that the   Earth and the Moon are not fixed objects. The moon is busy orbiting the earth. The earth is busy orbiting the sun and additionally rotating on its axis. This means that the spot on the earth where the umbra falls is always in motion and actually traces out a path.  At the time of eclipse, the Sun and Moon are in conjunction as seen from the earth.    The Umbra, Peunmbra and antumbra are names of distinct parts of shadow created by any light source.  The umbra is the darkest part of the shadow where the source of light is completely concealed by the occulting body.  Penumbra is the region in which only a portion of the occulting body is obscuring the light source or it is the region where some or all of the light source is obscured.

There would be Total, Annular, Hybrid and partial eclipses.  Total solar eclipse is the most spectacular celestial event when an eerie darkness would descend in its totality, birds fall silent and stars peer out in day time. Tomorrow provides opportunity to  Scientists and Sky gazers  a life time opportunity to view the Century’s longest solar eclipse.  This is expected to last 6 minutes and 44 seconds, making it the longest eclipse till 2132.   Here is a thematic depiction of eclipse :

When you gaze the sky, you may not exactly make out the size of Sun and Moon and they might look similar in size.  The Sun’s dia is approx. 1,391,980 km whilst that of the moon is about 1740 km and when you gaze from a limited zone, it is the distance factor which makes the illusion.  When total eclipse occurs, the match is so good that there is path of totality.  The total eclipse would be  visible from a narrow corridor through northern India, eastern Nepal, northern Bangladesh, Bhutan, the northern tip of Myanmar, central China and the Pacific Ocean, including the Ryukyu Islands, Marshall Islands and Kiribati.  In India, people can view this from cities of Surat, Vadodara, Bhopal, Varanasi, Patna.  According to some experts, Taregana 25 kms off Patna  in Bihar is the "best" place to view the event.

Taregna (means stars in local language) and nearby Khagual (derived from khagshastra means astronomy) are the places where sixth-century astronomer-mathematician Aryabhatta camped for his studies.   Interestingly,  Aryabhatta, born on April 13 (476 AD) in Kusumpura that later became Patliputra, wrote Aryabhatiyam at the young age of 23.  He discovered the notion of zero and also proposed that the earth rotates on its axis. Aryabhatta had traced out this location centuries back and made his observatory at the Sun Temple in Taregna.

Historically,  the longest seen in India earlier was on Aug 18, 1868. The next big total eclipse in the country takes place on June 3, 2114. Between then and now, there's only 1 total eclipse, on March 20, 2034, and it would just be visible in J&K.   The line of totality traverses a distance of over 3,000km. So, more Indians will be in the path of totality than ever in history!

But Exercise Caution :    Never view the sun with the naked eye or with any optical device, such as binoculars or a telescope!   Legend has it that Galileo went blind watching an eclipse.  It is also stated that he became blind at 72 from cataract and glaucoma.   But watching a partial eclipse with naked eye is dangerous.  Looking directly at the photosphere of the  Sun (the bright disk of the Sun itself), even for just a few seconds, can cause permanent damage to the retina of the eye, because of the intense visible and invisible radiation that the photosphere emits. This damage can result in permanent impairment of vision, up to and including blindness. However, during an eclipse, with so much of the Sun covered, it is easier and more tempting to stare at it. Unfortunately, looking at the Sun during an eclipse is just as dangerous as looking at it outside an eclipse, except during the brief period of totality, when the Sun's disk is completely covered.  Do it making absolutely sure that you have the correct filter. Just because a filter makes the sun seem dim does not mean that it's blocking invisible infrared or ultraviolet radiation that will certainly cause eye damage in short order. Do not use sunglasses, polaroid filters, smoked glass, exposed color film, x-ray film, or photographic neutral density filters.

The greatest epic Mahabharata features a total solar eclipse at an important juncture of the war.  Do you know the story of Jayadrata ?

With regards - S Sampathkumar.