Comets are known since the antiquity. They were at that time and until
late into modern times taken to be disasterous celestial bodies.
They have a core out of iron, du´st and frozen gases. The core is surrounded by the so-called coma that forms when the comet comes the sun on its path so close that the frozen core melts away. Through the replulsion force of the sun (solar wind and pressure of radiation) gas particles of the coma are blown away. This is how the tail of the comet that is most often averted from the sun forms. Not all comets have a tail though.
But nevertheless it can be concluded that comets are disintegrating
continuously and that every comet is used up one time.
Aristoteles (384 - 322 B.C.) and Claudius Ptolemäus (ca.l 87 - 170 A.C.) took them to be vapouriasations in the athmosphere of the earth. Seneca was the first one to declare them to be real celestial bodies. Ticho Brahe (1548 - 1600) calulated for the first time the distances between some comets. He found out that the comets have to be moving far away from the gravitational field of the earth. But still it took several decades until this knowledge was somewhat accepted. Even Galileo Galiei (1564 - 1642) spoke against Brahe’s theory. It was not until 1682 when Edmund Halley (1656 - 1742) was able to identify a permanently returning comet - the Halley Comet and litte later he also calculated its orbiting time.
After the invention of the telescope the number of discovered planets increased rapidly.
Until 1948 there were altogether1738 comets dicovered of which
only 132 are not jet fully classified.
The comets were most often called after the last names of their discoverers.
There are also so-called Comet Families. That are comets that were distracted by a planet. These objects have, as a consequence, changed their path so that they are always returning to the planet after a certain period of time.
The planet Jupiter has a family of at least 68 objects, Saturn has five or six, Uranus 3, Neptun 9 and Pluto probably has a family of comets as well.
Nevertheless does every comet of these families have its own path/orbit.
Furthermore there are comet groups. That are several comets that have
the same path. Some of them might have been created through the disintegration
of one comet