December 2009 lunar eclipse
A partial lunar eclipse occurred at the Moon’s descending node of orbit on Thursday, 31 December 2009, 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, the Moon's apparent diameter was larger.
This eclipse was the last of four lunar eclipses in 2009, with the others occurring on February 9, July 7, and August 6.
This lunar eclipse was also notable, because it occurred during a blue moon and was near perigee. The next eclipse on New Year's Eve and blue moon will occur on 31 December 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.
Visibility
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.Eclipse details
Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.| Parameter | Value |
| 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 |
Eclipse season
This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months 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.| December 31 Descending node | 15 January Ascending node |
| Partial lunar eclipse Lunar Saros 115 | Annular solar eclipse Solar Saros 141 |
Related eclipses
Eclipses in 2009
- An annular solar eclipse on 26 January.
- A penumbral lunar eclipse on 9 February.
- A penumbral lunar eclipse on 7 July.
- A total solar eclipse on 22 July.
- A penumbral lunar eclipse on 6 August.
- '''A partial lunar eclipse on 31 December.'''
Metonic
- Preceded by: Lunar eclipse of 14 March 2006
- Followed by: Lunar eclipse of 18 October 2013
Tzolkinex
- Preceded by: Lunar eclipse of 20 November 2002
- Followed by: Lunar eclipse of 11 February 2017
Half-Saros
- Preceded by: Solar eclipse of 25 December 2000
- Followed by: Solar eclipse of 6 January 2019
Tritos
- Preceded by: Lunar eclipse of 31 January 1999
- Followed by: Lunar eclipse of 30 November 2020
Lunar Saros 115
- Preceded by: Lunar eclipse of 21 December 1991
- Followed by: Lunar eclipse of 12 January 2028
Inex
- Preceded by: Lunar eclipse of 20 January 1981
- Followed by: Lunar eclipse of 11 December 2038
Triad
- Preceded by: Lunar eclipse of 3 March 1923
- Followed by: Lunar eclipse of 31 October 2096
Half-Saros cycle
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days. This lunar eclipse is related to two partial solar eclipses of Solar Saros 122.| 25 December 2000 | 6 January 2019 |