December 2009 lunar eclipse
| Partial eclipse | |||||||||||||
Partiality as viewed from Munster, Ireland, 19:43 UTC | |||||||||||||
| Date | December 31, 2009 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gamma | 0.9765 | ||||||||||||
| Magnitude | 0.0779 | ||||||||||||
| Saros cycle | 115 (57 of 72) | ||||||||||||
| Partiality | 59 minutes, 58 seconds | ||||||||||||
| Penumbral | 251 minutes, 3 seconds | ||||||||||||
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A partial lunar eclipse occurred at the Moon’s descending node of orbit on Thursday, December 31, 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 (on January 1, 2010, at 15:30 UTC), 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 (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.