Thursday, January 14, 2010

Star-gazers gear up for annular solar eclipse

Scientists and star-gazers are gearing up to witness a rare celestial event on Friday - the longest 'annular' solar eclipse of this millennium.
An annular eclipse occurs when the moon covers the centre of the sun, but not its edges as in a solar eclipse. The partially covered sun leaves a shining annulus (ring), visible around the dark moon.
The maximum hiding of the sun will happen around 1.15 pm.
The eclipse, that will last for 11 minutes and eight seconds, will give the scientists a unique opportunity to study the sun's atmosphere.
Although the Indian mainland will miss the centre line of the 323-km path of the eclipse, scientists consider it a chance to watch the equatorial atmosphere at noon. There will be a large reduction in ionisation and temperature.
The ionosphere, the part of the atmosphere that reflects radio waves for long-distance transmission around the world, becomes turbulent on certain days soon after the sunset.
These turbulences or eddies, pose a major threat to navigation systems based on GPS. The Indian Space Research Organisation will be firing a set of rockets to study atmospheric characteristics and disturbances that affect satelliteaided navigation.
Century's longest annular solar eclipse
Astronomy lovers are in for a rare celestial treat as they will be able to witness the century's longest annular solar eclipse on Friday.
"The solar eclipse on January 15 is the longest annular solar eclipse that will occur in the 21st century," Science Popularisation Association of Communicators and Educators (SPACE) C.B. Devgun said.
A solar eclipse occurs when the Moon passes between the Earth and the Sun, thereby totally or partially obscuring the Earth's view of the Sun, while an annular eclipse occurs when the Moon is farther from the Earth than normal, and hence its apparent size is not quite sufficient to cover the Sun completely, he said.
In annular solar eclipse, the Sun appears as a very bright annulus, which in Latin means 'ring', surrounding the outline of the Moon, giving the appearance of a 'Ring of Fire', Devgun said.
The photosphere of the sun shall be covered by the moon thereby forming a ring of fire in the sky for more than 10 minutes in some parts of India. The path of the annularity in India will pass over the states of Kerala, Tamil Nadu and Mizoram while the partial phase of eclipse will be visible all over the country, he said.

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