| Type: | partial |
| Date: | December 31, 2009 |
| Gamma: | 0.9765 |
| Magnitude: | 0.0779 |
| Saros Ser: | 115 |
| Saros No: | 57 of 72 |
| Partiality: | 59 minutes, 58 seconds |
| Penumbral: | 251 minutes, 3 seconds |
| P1: | 17:17:08 |
| U1: | 18:52:43 |
| Greatest: | 19:22:39 |
| U4: | 19:52:41 |
| P4: | 21:28:11 |
| Previous: | August 2009 |
| Next: | June 2010 |
A partial lunar eclipse occurred at the Moon’s descending node of orbit on Thursday, December 31, 2009,[1] with an umbral magnitude of 0.0779. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A partial lunar eclipse occurs when one part of the Moon is in the Earth's umbra, while the other part is in the Earth's penumbra. Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. Occurring only about 20 hours before perigee (on January 1, 2010, at 15:30 UTC), the Moon's apparent diameter was larger.[2]
This eclipse was the last of four lunar eclipses in 2009, with the others occurring on February 9 (penumbral), July 7 (penumbral), and August 6 (penumbral).
This lunar eclipse was also notable, because it occurred during a blue moon (a second full moon in December) and was near perigee (making it a supermoon). The next eclipse on New Year's Eve and blue moon will occur on December 31, 2028.
Only a small portion of the Moon entered the Earth's umbral shadow, but there was a distinct darkening visible over the Moon's southern surface at greatest eclipse.
The eclipse was completely visible over Europe, Asia, and much of Africa, seen rising over eastern North America and setting over Australia and the Pacific Ocean.[3]
Progression from Degania A, Israel
Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.[4]
| Penumbral Magnitude | 1.05719 | |
| Umbral Magnitude | 0.07793 | |
| Gamma | 0.97660 | |
| Sun Right Ascension | 18h44m37.2s | |
| Sun Declination | -23°02'33.1" | |
| Sun Semi-Diameter | 16'15.9" | |
| Sun Equatorial Horizontal Parallax | 08.9" | |
| Moon Right Ascension | 06h45m22.4s | |
| Moon Declination | +24°01'10.3" | |
| Moon Semi-Diameter | 16'36.6" | |
| Moon Equatorial Horizontal Parallax | 1°00'57.6" | |
| ΔT | 66.1 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.
This eclipse is the one of four lunar eclipses in a short-lived series. The lunar year series repeats after 12 lunations or 354 days (Shifting back about 10 days in sequential years). Because of the date shift, the Earth's shadow will be about 11 degrees west in sequential events.
It was part of Saros series 115.
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).[5] This lunar eclipse is related to two partial solar eclipses of Solar Saros 122.