Page "Comet" Paragraph 1

Comets visible to the naked eye are fairly infrequent, but comets that put on fine displays in amateur class telescopes ( 50 mm to 100 cm ) occur fairly often — as often as several times a year, occasionally with more than one in the sky at the same time.

Commonly available astronomical software can plot the orbits of these known comets.

They are fast compared to other objects in the sky, but their movement is usually subtle in the eyepiece of a telescope.

However, from night to night, they can move several degrees, which is why observers find it useful to have a sky chart such as the one in the adjoining illustration.