Probing the Giant, Galileo reaches Jupiter

It comes from the far reaches of our solar system, a frozen ball of gas and ice, leftover debris from the formation of sun and planets, known as a comet. This recently discovered comet seems to have enough potential to be the "star" of the century, and though it won’t be at its best until March 1997, it warrants talking about now.

In July of this year, two amateur astronomers named Alan Hale and Thomas Bopp separately discovered the comet while they were gazing at the night skies with their telescopes. What they found was an intruder, something that was not supposed to be there according to all the star maps. And to their thrill, it turned out to be a comet. And, as is customary, the comet is called Hale-Bopp, after its discoverers.

Comet Hale-Bopp is still far away, seven times the distance from the Earth to the Sun and is still too faint to be seen without at least a 10 inch telescope. But it is showing great promise. Astronomers speculate that this comet may be the brightest comet most of us have ever seen or will ever see.

Speculating is really all astronomers dare, and that only with trepidation. After all, a lot of people expected great things from Comet Kohoutek in 1974, the astronomers speculated big, and the public exaggerated that. What happened? Kohoutek fizzled out and was hard to find without a telescope.

Then it was the return of Comet Halley in 1986 that had everyone shouting in anticipation, everyone except the astronomers that is. They knew that Halley would not be a sight to see because when it reached its brightest, the Earth would be on the opposite side of the Sun. Still the tabloids reported great expectations of comet Halley and the public, expecting big things, was sadly disappointed.

The problem is that comets can be unpredictable. A good example was Comet Austin in 1989. Austin was expected to be bright. It appeared to be bright when it was farther away, but then it just dimmed; when it should have reached its peak, it was barely visible. Astronomers decided that Austin had undergone a nuclear outburst. The comet showed a temporary brightening due to the exposure of material in the comet’s nucleus to the sun’s radiation. This caused gases to be released which made the comet look brighter even though it was a great distance away. But once these volatile gasses dissipated, the comet dimmed.

If Hale-Bopp is undergoing a nuclear outburst, then it may dim considerably, and be so faint it cannot be seen except with a telescope when it gets here. But most astronomers think otherwise. Though it’s nucleus is fluctuating, the comet’s brightness did not change much in August. They believe Comet Hale-Bopp is bright because it’s big.

So how much of a show will Hale-Bopp put on? It’s still hard to say for sure. If it’s as big as most astronomers think it is, it should be at least as bright as Siruis, the brightest star in our sky. If the comet stays bright, observers with small telescopes will be able to pick it up in the pre-dawn skies of February 1996. By autumn of 1996, experienced observers with dark skies may well see it with the naked eye. The height of the show will be in March of 1997.

You may wonder why we are talking about Comet Hale-Bopp so soon. For one thing, it is a fascinating discovery, one that is worth following as it unfolds. But on another point, some tabloids have suggested that the comet could collide with the Earth! This is utter nonsense, fiction made to compete with the "trial of the century."

Astronomers have already plotted the orbit of Comet Hale- Bopp. It will, unlike comet Shoemaker-Levy 9 that ended up on a collision course with Jupiter, miss all of the planets and the moon and Sun. Hale-Bopp will pass no closer to us than 123 million miles, well over the distance from the Earth to the Sun. Stay tuned for more updates on Hale-Bopp!