December 3, 2021 – ALPO Comet News for December 2021
Summary
It is now or never for C/2021 A1 (Leonard). Currently magnitude 6.5, Leonard has the potential to become a few magnitudes brighter as it passes 0.23 au from Earth on December 12. Complicating any forecast of how bright or observable it might get are a very low solar elongation (down to 15 degrees), uncertainty in the effect of dust forward scattering to enhance Leonard’s brightness, and signs that the comet is fading or perhaps even breaking up. This is an object well worth watching in the morning sky from the northern hemisphere during the first half of the month and in the evening sky during the second half of December (though at that time it will be much easier to observe from the southern hemisphere).
Other comets brighter than 10th magnitude in December include C/2019 L3 (ATLAS), 19P/Borrelly, and 67P/Churyumov-Gerasimenko.
The monthly ALPO Comet News PDF can be found here. A shorter version of this report is posted on a dedicated Cloudy Nights forum. All are encouraged to join the discussion over at Cloudy Nights.
- Carl Hergenrother
