POLITICIANS of all hues have been searching the night sky for the latest portent of a forthcoming election, a visiting comet. For those who can read the signs, the appearance overhead of the HaleBopp comet is the clincher after the recent generous Budget and the elimination of water charges.
Leaving aside the soothsayer aspects, the arrival of a comet is noteworthy if only because they are a rarity and are often not visible to the naked eye.
Hale Bopp, now appearing in the sky near you, is an infrequent visitor - it won't be back in these parts for another 4,200 years - so if you don't have a look during the next few weeks, don't expect a second chance.
For those with a constitution that allows them to rise at 4.30 a.m. Hale Bopp can be seen before dawn low in the north eastern sky throughout this month. Those with more sense will attempt to spot the comet low on the north western horizon about 7.15-7.30 pm. each evening during this month and into April.
You must have a clear view of the horizon and be away from bright lights. A pair of binoculars would improve the view, according to Mr William Dumpleton of Dunsink Observatory.
Hale Bopp, like all comets, is an accumulation of ice, frozen gases and space dust - attributes which have caused them to be nicknamed "dirty snowballs" by the astronomy fraternity. It hurtles through space at 27 miles per second and measures between 10 and 40 kilometres across, so it is just as well that it is a comfortable 123 million miles away during its closest pass to Earth on March 22nd.
Astronomers believe that comets originate in a region of space known as the Oort Cloud, perhaps 4,650,000 million miles away. They orbit the sun and make infrequent visits because of the great distances they travel.
A comet's appearance is due entirely to the sun. As a comet approaches the sun it warms up, allowing frozen gases and dust to escape from its surface. This material causes a halo, called the coma, to form around the comparatively small core. The coma can be a million miles across, making the comet highly visible when sunlight reflects off it.
The characteristic tail can be 100 million miles long and is formed when the dust and gases trail away behind the comet, driven into space by the radiation flowing from the sun.
The Hale Bopp comet apparently has a longitudinally challenged tail - no laughing matter if you are a comet - but this, Mr Dumpleton says, is an illusion. "The reason why the tail is apparently not so huge is because of our viewing position on Earth, which for shortens it."
Not all comets are as benign as Hale Bopp comet Hyakutake, which appeared in our skies during March 1996. The Shoemaker Levy comet made quite an impact when it was captured in Jupiter's gravitational pull, broke up and crashed into the Jovian surface in July 1994. If it had struck Earth there would have been precious few of us left to admire Hale Bopp.
Such collisions with Earth do occur over geological time. The extinction of the dinosaurs was most likely brought about by a comet or asteroid which landed in Mexico 65 million years ago.
