Hale-Bopp is believed to be the largest of the comets. Hale-Bopp can only be seen every 4,000 years and gets no closer to earth than120 miles. Its rock nucleus is believed to be 25 miles across. In the next three paragraphs I will talk about what a comet is, the history of comets, and Hale-Bopp last visit.
A comet is a small celestial body consisting mostly of dust and gasses that move in an elongated elliptical, or nearly parabolic orbit around the sun. Comets can be seen for a few days or a few months. There have been many occurences of comets, but it wasn't until 1577, that Tycho Brache suggested that they travelled in elongated rather than circular orbits.
A comet far from the sun consists of a dense solid body, or conglomerate of bodies a few miles in diameter called the nucleus. As a comet reaches the sun, the solar winds drive particles and gases from the nucleus and come to form a tail which extends as much as 100 million
miles in length. Thus the tail always streams out in the direction opposite the sun. The origin of comets is still uncertain. According to scientists today comets were made when the solar system was built and are permanent members of it.
The history of comets started in 1705, when Edmond Halley concluded that the comet observed in 1682, was the same one that had been seen in 1531 and 1607. He predicted it would return in1758, or early 1759. The comet was seen during Christmas in 1758, and it returned again in 1885,1910, and 1986. While some comets appear to have parabolic orbits, others return to the inner solar system in highly elongated orbits with periods ranging from a hundred to thousands of years. Still others return at shorter intervels of less than ten years and reach aphlion near the planet, Jupiter. These have been captured into their smallest orbits by Jupiter's gravitational attraction.
The Hale-Bopp comet can be seen by the naked eye, binoculars, or a telescope. Each method reveals its different aspects. Binoculars do not reveal much detail around Hale-Bopp's bright nucleus. It is hidden by a halo of gas and dust. They do provide a better view of the tail, or more
precisely two tails. By studying Hale-Bopp through large infrared telescopes, Gehrz and several of his associates hope to learn what comets are made of and how they react to the sun
Hale-Bopp as you can tell, and the other comets have been around for a long time and scientist are still trying to figure them out. They are still some of the earth's greatest marvels.
Nicholas Cheney
