Annular Experience

I had been to the Dhanushkodi on 15 January 2010 for observing annular solar eclipse. Dhanushkodi is small village of fishermen nearly 17 kilometer away from Rameshwaram in Tanil Nadu. Dhanushkodi was only place in India, which lies in the central line of eclipse where the Moon passed directly in front the Sun, leaving a ring of fire hanging in the afternoon sky for 10 minutes and 11 seconds. It was an awesome experience seeing such eclipse. Last annular eclipse was seen from Srinagar, Siliguri and Agartala on 23 November 1965 and will not be seen again from India until 2019.

An eclipse of the Sun is caused when the Moon comes in between the Earth and the Sun so that the shadow of the Moon sweeps across the surface of the Earth. This shadow consist of two parts, the umbra or total shadow, a cone in which no direct sunlight penetrates and the penumbra, or half shadow, which is reached by the light from some parts of the Sun's luminous disk. To an observer within the penumbra; the Sun's disk will appear to be partially covered.
From the above, it will be understood that a solar eclipse can occur only at new moon when the Moon is conjuction with the Sun. Had the plane of the Moon,s orbit around the Earth coincided with ecliptic ( that is the plane of the Earth's orbit around the Sun ), an eclipse of the Sun would have taken place at every new moon's orbit is inclined by about five degrees to the ecliptic and it is only at those times when the Moon happens to be at or near one of the Moon and the Earth are nearly in the same line and a solar eclipse can occur at other times the shadow of the Moon just disappears into space.

The kind of eclipse that will result, total or anular, is governed by the fact that orbit of the Moon around the Earth is not perfectly circular but is elliptical, with the result that the Moon is sometimes nearer to the Earth than at other times. When the Moon in is orbit is nearest to the Earth, this phenomenon is known as perigee, and when it is farthest from the Earth, it is known as apogee. The distance of the Moon from earth at perigee is 3,63,300 km and at apogee is 4,05,500 km. As the distance from the Earth to the Moon varies, so does the apparent size of the Moon in our skies. When it is closest, it appears larger in the sky than the Sun and can completely obscure the solar disk, but when it is at its farthest point, it smallest is not enough to cover the disk of the Sun.

In an annular solar eclipse the umbra of shadow cannot reach the EArth, instead a third type of shadow is born; the antumbral, or negative shadow. An annular solar eclipse is visible where the antumbral sweeps across the Earth's surface; this is known as the path of annularity. From within this region, the Moon's dark is centered on the Sun but unable to obscured all its light, leaving a brilliant ring of fire, or "annulus" of light, around the edge of the Moon in the sky. Unfortunately, the Sun's chromosphere and corona, which are visible during a total solar eclipse, are lost in the glare of of an annular eclipse and as such no scientific investigational work, as is carried out during a total solar eclipse is possible during an annular eclipse. But, of course this type of eclipse has its own beauty. I missed first contact of moon and sun, but observed annular phase and able to take some photographs.

There are so many misconceptions about solar eclipse, that we should not eat anything, should not stay outside during eclipse and not to see eclipse. Many people think it is bad omen. But I tell you one thing that solar eclipse is not visible from most planets in the solar system. We are so lucky in that case because nature already has made special arrangement for us, so that we could enjoy this shadow play. It is so happens that disk of the Sun is 400 times larger than that of the Moon and that coincidently the distance of the Sun from the Earth is about 400 times the distance of the Moon from the Earth, so that Sun and Moon have nearly equal angulur diameter of 0.5 degree. Thus, our Moon is just the right size to cover the bright disk of the Sun and cause a solar eclipse.

First, I thought that may be I was the only person from my group who was observing his first annular solar eclipse but, then I came to know that every one from my group were seeing the annular eclipse for first time. That's why we distributed chocolates among us to celebrate our first annular eclipse.