A comet is an icy small body that, when close enough to the Sun, displays a visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The discovery by astronomers at the University of California, Berkeley, and Clarion University in Pennsylvania of six likely comets around distant stars suggests that comets – dubbed exocomets – are just as common in other stellar systems with planets.
Leave a Comment