Comet 46P/Wirtanen is arriving on our planetary doorstep and will approach to within about 11.5 million km of Earth on 16 December this month. It’s a small comet (nucleus maybe only around 1km) and will probably only get up to a diffuse magnitude +3 to +4 but would make for at least an interesting small ‘scope, binoculars or camera target in a decent dark sky (possibly noticeable naked eye object in really favourable conditions - angular extent comparable to the full moon). Apparently it is a quite distinctive green: (This image taken within the last 24 hours). Visible in northern skies all this month: More from Sky&Telescope. PS: 46P/Wirtanen was considered as a target option for Rosetta/Philae.