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comet ![click to hear : comet click to hear : comet](../../images/speaker-vert.gif)
Small icy body that partially evaporates as it approaches the Sun; made up of a head with a solid core and tails composed of gas and dust.
coma ![click to hear : coma click to hear : coma](../../images/speaker-vert.gif)
Cloud of gas and dust particles emitted by the expulsion of gas from the nucleus when a comet approaches the Sun.
nucleus ![click to hear : nucleus click to hear : nucleus](../../images/speaker-vert.gif)
Central part of the comet; composed mainly of ice and rocky matter.
head ![click to hear : head click to hear : head](../../images/speaker-vert.gif)
Part made up of the nucleus and the coma.
dust tail ![click to hear : dust tail click to hear : dust tail](../../images/speaker-vert.gif)
Visible tail formed by dust particles pushed out of the coma by pressure from the Sun’s rays; can reach over 10 million kilometers in length.
ion tail ![click to hear : ion tail click to hear : ion tail](../../images/speaker-vert.gif)
Almost invisible tail formed by the gas of the coma pushed back by the solar wind; can reach several hundreds of millions of kilometers in length.