https://phys.org/news/2018-12-christmas-comet-interplanetary-46pwirtanen.html > So what makes 46P/Wirtanen so special, and when can we see this comet hurtling across our skies? > Comets come in a variety of shapes and sizes, with the infamous Hale-Bopp comet roughly 120 kilometres across. Comet 46P/Wirtanen is much smaller: just 1.2km across.