A celestial spectacle awaits sky watchers this Republic Day when the Moon [Images] covers a portion of the Sun resulting in a partial solar eclipse.
    
While star gazers in north-eastern, eastern and southern parts of the country will witness a partial eclipse of the sun, those in southern parts of Africa, Antarctica, South East Asia and Australia [Images] will be treated to a rare annular solar eclipse.
    
An annular solar eclipse occurs when the Moon is farther from the Earth than normal in its elliptical orbit, and hence
its apparent size is not quite sufficient to cover the Sun completely, Science Popularisation Association of Communicators and Educators president C B Devgun told PTI.
    
Even though the Sun-Moon-Earth alignment is perfect, the Moon in its farther point will appear slightly smaller in
diameter than the Sun and a thin ring of sunlight will remain visible around the dark silhouette of the Moon, he said.
    
The name annular eclipse comes from the Latin annulus, meaning ring. The best time to watch the eclipse in India will be between 1500  and 1530 hrs.
    
The eclipse will be visible to the other countries from 1000 hrs, it will be greatest at 1326 hrs and end at 1630, Devgun said. Devgun cautioned that the eclipse should not be watched with naked eyes.
    
Viewing the Sun during partial, annular eclipses and during total eclipses requires special eye protection, or indirect viewing methods, he said.
    
The Sun's disk can be viewed using appropriate filtration to block the harmful part of the Sun's radiation.
    
Sunglasses are not safe, since they do not block the harmful and invisible infrared radiation which causes retinal
damage, he said, adding that only properly designed and certified solar filters should be used for direct viewing of
the Sun's disk.
    
He also cautioned that self-made filters using common objects like a floppy disk removed from its case, a Compact
Disc, a black colour slide film must be avoided at all costs. The last partial solar eclipse occurred on August 1, 2008.