46P/Wirtanen is one of 400 within the Jupiter comet "family," so named because of its relatively short orbit time (46P's is 5.4 years) and proximity to the path of everyone's favorite gas giant. 46P will probably appear in the sky as a fuzzy, greenish ball of light instead of developing the classic tail we associate with comets. The comet glows as its ice melts when it passes near the sun and appears green when ultraviolet light hits gases carried in the rock.