This makes it even more exciting to consider that we may get some excellent shots from the European probe Giotto, which plans to have a really ‘close encounter’ (some 300 kms) with the nucleus. Dust and other mineral debris in a frozen mass of water, ammonia and few other elements forms the nucleus, which is so small (around 5 kms in diameter in the case of Halley’s) that no Earth telescope could hope to see it. However, broadly speaking, the famous description of comets as ‘dirty snowballs’ is very likely to be correct. There is a small armada of space vehicles from many nations ready to observe, measure and photograph various aspects of the comet, so we should be ready for possible surprises in our understanding of what comets are. If we knew all the details, we probably wouldn’t have launched millions of dollars of hardware into space in an effort to find out.
Like a waterskier being ‘whipped’ around a corner, it has been picking up speed ever since, until in March 1986 it will be hurtling through space at around 5 million kilometres per day. Halley’s comet began its current journey back toward Earth in 1948 when it was at the outermost part of its orbit more than 5,200 million kilometres from the sun, travelling at around 80,000 kilometres per day. Those in the Southern Hemisphere will have a better view than Northerners on this occasion, and the Central Australian town of Alice Springs, with its clear skies, is expecting up to 50,000 visitors, just to see the comet.Īt the time of writing it has already been sighted as a hazy speck by the naked eye (powerful astronomical telescopes first spotted it about three years earlier), but it will fade again and then reappear from behind the sun to be at its best in March and April 1986.
Unfortunately, it appears Halley’s will be further away from us than usual and so will probably not be as impressive this time as on many other occasions when its blazing tail stretched spectacularly across the night sky, evoking descriptions such as a ‘gorgeous fish’, or ‘giant crescent sword’ and the like. Both proved to be right! The flaming comet is featured on the famous Bayeux tapestry portraying the battle. Perhaps the best known example of this is the 1066 overthrow of the Saxon king Harold of England by William the Conqueror one saw the comet as a bad omen, the other as a favourable sign. The first recorded appearance of Halley’s comet was probably 240 B.C., and throughout human history it has often been regarded superstitiously as an omen. An astronomer had reported that the comet’s tail contained poisonous gases, and it soon became a common belief that millions would be gassed as the Earth passed through it’s tail. I well remember my grandmother telling how she bicycled home from boarding school in 1910 (the year of the comet’s last visit) so she could be with her parents when the end came. Especially, since most who see this event will never do so again in their lifetime. And although I won’t be rushing off to get the latest Halley’s T-shirt, it’s hard not to get excited about the coming reappearance of this regular visitor from the far reaches of the solar system. ‘Comet fever’! Tens of millions spent on everything from binoculars to bumper stickers, from celestial comet-maps to comet-shaped junk jewellery.
0 kommentar(er)
