Sting in the tail? Comet Hale-Bopp arrives. Dramatic picturesof Hale Bopp.

A SOON Online Magazine feature

	STING IN THE TAIL? Latest comet - Hale-Bopp, was one of the brightest and best comets of the 20th century. It will be one of the comets classed as 'Great Comets' - the 8th, and probably last in this century. It is much brighter than last year's Comet Hyakutake. Structure The central core of the comet is estimated at 40 kilometres across and is made of ice, rock, and dust.
		(Astronomer Fred Whipple first suggested in 1949 that the centre of a comet was a 'dirty snowball'.) This makes it one of the largest comets ever. It is the tail which makes the comet appear so large, although it has a very low weight. Heat from the sun turns the dust and ice in the core of the comet into a cloud of dust and vapour. The solar wind - radiation from the sun - then pushes this cloud away from the comet core, and away from the sun, in a huge tail millions of kilometres long. The tail always points away from the sun, but reflects the sun's light.
NASA, the American Space Agency, are launching sounding rockets just above the atmosphere of the earth, to find out detailed information on the tail.
Comet Hale-Bopp was nearest to earth on March 22nd and 23rd - about 200,000 kilometres away. It is interesting that also on March 23rd, there was a 'total eclipse' of the sun visible from parts of the earth, when the moon passed in front of the sun and blocked out its light.
Orbit
		Comets have orbits (revolve) around the sun, but unlike the earth and other planets, they revolve elliptically - that is, they approach the sun very closely at one end of their orbit, but the other side of their orbit is beyond the furthest planet, Pluto. The huge distance that they travel explains why comets may not return for periods varying between 33 years and the estimated 10,000 years before Comet Hyakutake returns. (Some may never return, because their orbit has been altered by pull of other planets.) This is also the reason why new unknown comets may arrive at any time.
Do they crash?
Not often! There is no definite historical record of a comet hitting the earth. But a comet the size of Hale-Bopp would cause huge damage - as much as several nuclear bombs, and probably create earthquakes and tidal waves around the earth. But recent research in Oman has confirmed that the Middle Eastern city of Ubar in Oman, may have been hit 1500 years ago by a meteor (rock from space) or a comet. There was an old story in Oman that the city had been wiped off the face of the earth by fire from the sky, as God's punishment for its evil ways. Gerrit Vershuur, a radio-astronomer, and Dr Mike Saba believe that huge crater holes near the site of the old city were caused by hits from space. Dr Eugene Shoemaker (co-discoverer of the Shoemaker-Levy comet) dated the craters to AD500, about the time that the city of Ubar was destroyed. Dr Vershuur says, "The evidence that Ubar was wiped out.... is very strong." It is certainly possible that a comet could strike the earth. Comet Shoemaker-Levy crashed into Jupiter in July 94, causing huge explosions and fireballs larger than the earth!
What does it mean?
Comets and other signs in the sky have for thousands of years been seen as messages or warnings for the people on earth. Many different cultures and religions have believed comets to be sent by God, telling of important or terrible events on earth. The arrival of Halley's Comet for instance, in 1910, was just before a European war of the most terrible slaughter, such as had never been seen before. Certainly 1997 has been a year of tragedy, but then, so have many other years. Eclipses of the sun, and other signs have always been believed to have meaning, and to be a sign of some important message, for good or bad. Already, people are getting excited about a total eclipse of the sun, which will be visible in the very West of England, and across part of Europe next year, the last such eclipse in this Millennium. No doubt many people will suggest this has a message for us. Remember, an unusual star or sign was seen before the birth of Jesus Christ - a sign which 'wise men from the East' knew was telling of the birth of a great king.
Signs in the sky
The Christian Bible, for instance, in many places, claims that unusual signs in the sky show the approaching of the end of the world, and God's judgement. Both the Koran and the Bible claim that Jesus will return to earth at the end of the age. Neither book claims to say exactly when this will happen. Many strange groups have believed they knew when the end of the world was coming, and have waited on top of mountains, only to be disappointed! Though they were wrong, we must consider the trends of this century. The Bible speaks of many signs which show that the end is coming near: earthquakes, plagues of illness, war, rapid increase of human knowledge, signs in the sky, the sun being darkened, and moon turning red. Certainly these are unusual days, and many things are happening which have never happened before.
The big questions?
Are we ready, if the world ends soon, or gets hit by a meteor? Or indeed, if we fall under a car tomorrow? Should our priorities change? Should we be searching for God? Why are we here? What is the purpose of life? Does the world deserve God's judgement? Can we escape? These are just about the biggest questions to face in life. Think big! Don't limit your questions to what to wear for tomorrow's party! Perhaps now is the time to start looking for some answers?