Solar eclipses have fascinated and terrified humanity since time immemorial. We in Gurgaon, are going to witness an annular solar eclipse of the Sun on Sunday the 21st.
Solar Eclipse occurs when the moon comes between the Earth and the Sun. It is a coincidence that the moon is 400 times closer and about 400 times smaller than the Sun, so their apparent diameters depending on the varying distanceare nearly equal. That’s when we get a total eclipse.
Annular eclipse
One would think that a total eclipse should occur once a month, but since the orbital plane of the moon is somewhat at an angle to that of the Earth, a total eclipse occurs for a short duration and in a narrow band of Earth’s surface. What we see more often are partial eclipses. Total eclipses are very rare.
Sometimes the apparent size of the disc of the moon is slightly smaller than that of the Sun. That is the time we get an annular eclipse, and the sight is of a dark circular blob with a ring of sum shining around it. That’s what will be visible on June 21, Sunday. We will be lucky to see it, weather permitting.
Direct into the eyes of the Sun, dare not!
However, it is dangerous to look directly at the Sun during an eclipse and doing so may result in permanent total blindness. Even sunglasses are not enough. The best way to “see” the eclipse is to project its image from a binocular or small telescope on to a white surface, but all precautions need to be taken before you decide to gaze up there.
As the daylight dims, one may get tempted to look at the Sun. DON’T! Only the visible spectrum disappears, but the remaining rays of the substantial electromagnetic spectrum are harmful, may cause irreparable damage the eye as the pupil expands to accommodate more light in the eye.
Earlier, people who somewhat understood the occurrence beguiled those who fearfully sought explanations for what appeared to portend the world’s end. Yet this understanding played a role in the development of astronomy. Anthropologists think all scientific study evolved from astronomy. Fortunately, the ability to beguile people ever reducing.
From the pages of history
Mentions in India of a solar eclipse are somewhat vague and non-specific. Volume 1 Part 1 of The History Of Science, Philosophy and Culture in Indian Civilization up to 600BC edited by GC Pande merely mention that “Calculation of dates of eclipses was a matter of national importance and it was the responsibility of the astronomer to foretell the time and duration of their occurrence.” The book also makes just a passing reference to “eclipse hymns” and the “notion of Rahu seizing the heavenly body”.
Records of eclipses found can be traced back in the 8th Century BC. The occurrence of the eclipse dates some historical battles. Predicting of eclipses could be fatal too as a tale from China talks of an emperor beheading two astronomers for getting the prediction wrong around 4000 years ago. However, now the science of determining the dates of future and past eclipses is well advance.
Happy & safe viewing!
About the author: Col Anil Chawla, 71, has a small telescope and looks at the sky frequently. He has other post-retirement interests in Military History, Social Issues and the Political Economy.
