The arrival of a comet within sight of planet is an event of international significance. See the huge media attention that the Haley or Hale-Bopp have had when they have come within sight. The sight of these fantastic space objects is simultaneously frightening as well as awe-inspiring.

Most of all, it is throughout these comet viewings that the astronomer appears in all people. However, what is a comet? Where did it come from? And also exactly how does it get that amazing tail?