Why was the appearance of a comet conceived to be a bad omen in ancient times?
Ancient people thought that comets caused calamities on Earth. Even in recent times people have been scared that gases from a comet’s tail would poison life on Earth.
Is it possible to see details of comets with the naked eye?
Comets can sometimes be seen with the naked eye. One can even identify their tail and the head. Once in a few thousand years, comets have appeared when even the luminous gas jets have been visible to the naked eye. The ‘swastika’ symbol is believed to be a representation of a comet with multiple gas jets and has been considered an auspicious symbol in many countries from the period of yore. Also the “Menorah” used in Jewish ceremonies is believed to be a representation of a comet with multiple tails.
How does a comet group come into being?
When a comet comes very close to the Sun the nucleus is subjected to various forces due to gravity, heat, pressure within and the force of its jets. Sometimes, these may cause the nucleus to crack up into fragments. If such fragments continue in orbit close together, they are called a comet group. In 1846, the comet Biela was observed to split into two fragments which moved together with each part showing all the characteristics of a comet including head and tail.