THE BIG THREE

There are three reasonably bright comets and one wild card in this month’s sky. Comets 67P Churyumov-Gerasimenko, 4P/Faye and C/2019 L3 Atlas are all located in the general region centred on Gemini, highest around 00:30 UT on 1 December, 23:30 UT mid-month and 22:30 UT by the month’s end.

67P is the periodic comet visited by the Rosetta spacecraft from 2014 to 2016. It reached perihelion on 2 November when it was brightest at mag. +10.7. During December, 67P fades from mag. +10.9 to +11.7. The comet is relatively