Portal:Astronomy/Events/December 2021
| 3 December, 00:28 | Moon occults Mars |
| 4 December, 07:33 | New moon and total solar eclipse |
| 4 December, 10:01 | Moon at perigee |
| 4 December, 12:43 | Moon occults Mercury |
| 14 December, 06:44 | Peak of Geminids meteor shower |
| 18 December, 02:16 | Moon at apogee |
| 19 December, 04:36 | Full moon |
| 21 December, 15:59 | Earth southern solstice |
| 22 December, 15:00 | Peak of Ursids meteor shower |
| 31 December, 20:13 | Moon occults Mars |