The nucleus is the solid, central part of a comet, formerly termed a dirty snowball or an icy dirtball. A cometary nucleus is composed of rock, dust, and
radiation and the outstreaming solar wind plasma acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers
Comet81P/Wild, also known as Wild 2 (pronounced "vilt two") (/ˈvɪlt/ VILT), is a comet with a period of 6.4 years named after Swiss astronomer Paul Wild