The Hindu : Tamil Nadu / Chennai News : A spectacle that thrilled Chennaiites

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Monday, Mar 05, 2007
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Tamil Nadu - Chennai

A spectacle that thrilled Chennaiites

Lalithasai

Lunar eclipse was clearly visible in the city

CHENNAI: The moon slipped elegantly into the shadow of the Earth during the early hours on March 4.

Thanks to the crisp weather, the scene was clearly visible, thrilling stargazers and amateur astronomers who had gathered at the B. M. Birla Planetarium, Gandhi Mandapam Road, Chennai to watch the spectacle.

The event began at 3 a.m. when the southeast limb of the moon darkened. It reddened, and turned shades of grey and orange as the clouds glided over it. The Earth's shadow crawled across the moon and engulfed it completely by 4.14 a.m.

"It happened as we had estimated," said Iyamperumal, Executive Director, Birla Planetarium. The moon remained in the dark shadow of the Earth until 5. 28 a.m., after which the southeast limb started getting light from the Sun slowly.

According to the Executive Director, the dramatic colour changes on the moon occurred because it received only the scattered sunlight from the Earth's atmosphere. Blue wavelengths are scattered away by our atmosphere and do not reach the moon, but the longer reddish wavelengths do. This causes the moon to be lit up by a reddish orange light, giving it a coppery glow during the total eclipse.

"Another reason for the reddish hue is that the Earth's atmosphere contains varying amounts of water (clouds and precipitation) and solid particles (dusts). This material filters and attenuates the sunlight before being refracted" For an observer from the moon the Earth would have been in darkness but for a rim of reddish atmospheric glow around it. Mr. Iyamperumal says, "There is no scientific importance behind this event. If the moon is totally dark during the eclipse then the atmosphere of the Earth is supposed to be polluted heavily. But on Sunday the moon was visible with diminished brilliance." The event perhaps provided a scale to check the accuracy of astronomical computations.

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