| Caption: | Totality viewed from Union Glacier Camp, Antarctica |
A total solar eclipse occurred at the Moon’s descending node of orbit on Saturday, December 4, 2021,[1] with a magnitude of 1.0367. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's and the apparent path of the Sun and Moon intersect, blocking all direct sunlight and turning daylight into darkness; the Sun appears to be black with a halo around it. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. Occurring only about 2.5 hours before perigee (on December 4, 2021, at 10:00 UTC), the Moon's apparent diameter was larger.[2]
This eclipse was unusual as the path of the total eclipse moved from east to west across West Antarctica, while most eclipse paths move from west to east. This reversal is only possible in polar regions. Its path across Antarctica crossed near Berkner Island, traversed an arc over the continent and passed over Shepard Island. A partial eclipse was visible for parts of Southern Africa, Antarctica, and Tasmania.
Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.[3]
| First Penumbral External Contact | 2021 December 04 at 05:30:26.5 UTC | |
| First Umbral External Contact | 2021 December 04 at 07:01:16.7 UTC | |
| First Central Line | 2021 December 04 at 07:04:03.2 UTC | |
| First Umbral Internal Contact | 2021 December 04 at 07:07:04.8 UTC | |
| Greatest Eclipse | 2021 December 04 at 07:34:37.9 UTC | |
| Greatest Duration | 2021 December 04 at 07:34:40.1 UTC | |
| Ecliptic Conjunction | 2021 December 04 at 07:44:11.1 UTC | |
| Equatorial Conjunction | 2021 December 04 at 07:57:20.3 UTC | |
| Last Umbral Internal Contact | 2021 December 04 at 08:01:55.8 UTC | |
| Last Central Line | 2021 December 04 at 08:04:57.6 UTC | |
| Last Umbral External Contact | 2021 December 04 at 08:07:44.3 UTC | |
| Last Penumbral External Contact | 2021 December 04 at 09:38:39.3 UTC |
| Eclipse Magnitude | 1.03673 | |
| Eclipse Obscuration | 1.07481 | |
| Gamma | −0.95261 | |
| Sun Right Ascension | 16h43m32.4s | |
| Sun Declination | -22°16'29.4" | |
| Sun Semi-Diameter | 16'13.6" | |
| Sun Equatorial Horizontal Parallax | 08.9" | |
| Moon Right Ascension | 16h42m35.0s | |
| Moon Declination | -23°13'22.3" | |
| Moon Semi-Diameter | 16'44.7" | |
| Moon Equatorial Horizontal Parallax | 1°01'27.3" | |
| ΔT | 70.6 s |
See also: Eclipse cycle. This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.