Wednesday, October 31, 2007

After 'UFO', a comet on city horizon

After much hoopla over an unidentified object in the Kolkata sky, another celestial phenomenon has caught the imagination of stargazers in Kolkata. The people of the city now have the opportunity to sight the exceptionally bright comet, Holmes.

Named after its discoverer Edwin Holmes, the comet was first spotted in 1892. It has been observed several times since with the comet revolving once every six years and nine months.

On October 24, it suddenly became about a million times brighter than its usual appearance. Since then, it has got brighter and is currently the third-brightest object in the Perseus constellation.

Scientists believe that the sudden increase in brightness may have been caused by an eruption or break-up of the comet nucleus measuring 3.4 km, thereby producing a huge amount of dust. The dust surrounding the nucleus that reflects sun light, has created a yellow halo. The size of its coma or inner-core consisting of mostly ionized hydrogen, has increased considerably over the last few days and it is now emitting blue light.

At present, Holmes has a circular image minus the tail. Kolkata residents can watch the Perseus constellation from little after sunset. The constellation rises on the north-eastern horizon around 5.45 pm and steadily moves westwards.

"The coma is around 12 arc minutes wide, which means that the coma is now bigger than a million kilometre, expanding at the rate of 575 kilometre per second from the nucleus. Weather permitting, this will be a true celestial treat," said M P Birla Planetarium director (research and academics) Debiprosad Duari.

No comments: