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December 31st, 2009 Partial Lunar Eclipse

This is the last astronomical major event for 2009 and thus amazingly occurring just on the last day of the year! This lunar eclipse is officially termed a partial lunar eclipse as the observers will note that its geometry better assigns it to a penumbral. Like the diagram for the eclipse is showing, it's just the tip of the southernmost polar regions of the Moon which will skim into the Earth's umbra -the definition for a partial eclipse. The most of the lunar disk will transit inside the penumbra, this lighter part of the Earth's shadow. A partial eclipse occurs when the Moon is partially passing only into the Earth's dark 'umbra', leading to that some part of the Moon is neatly darkened (at the opposite of a penumbral eclipse, when the dimming is more subtile, in a way, to observe). for more about Moon eclipses, theoretically, see our tutorial: Moon Eclipses

Like a partial one, this one eclipse will be more neatly showcasing a darkening of the Moon and, due to the geometry of the eclipse, that will be mostly seen for the southern parts of it. The fact that just the tip of the Moon will be skimmed by the umbra makes this eclipse worth the observation. The whole of the eclipse is observable in an area stretching from Greenland to Indonesia, and from southern Africa (the westermost part excepted) and Algeria to the Russian Far East, and Japan! The Canadian Labrador, the northeasternmost corner of Brazil, a good part of West Africa, and the southwestern parts of southern Africa have the eclipse en cours by moonrise. From the Alaska and the northwesternmost parts of Canada, down to most of Australia, and in the western Pacific Ocean, they will have the eclipse interrupted by moonset. Most of Americas, interestingly, and Hawai do not have any eclipse

The eclipse's main data are the following (data as of beginning of July 2009). for more about how to observe a lunar eclipse, see our tutorial "Observing a Moon Eclipse":
- umbral magnitude (fraction of Moon's diameter immersed in the umbra at greatest): 0.0820
- penumbral magnitude (fraction of Moon's diameter immersed in the penumbra at greatest): 1.0808
- greatest eclipse: 19:22:41.4 UT
- eclipse semi-duration (penumbral): 02:07:25
- eclipse semi-duration (umbral): 00:31:06
- eclipse contacts (in UT): P1 at 17:15:18, U1 at 18:51:38, U4 at 19:53:51, P4 at 21:30:07

see a map of the December 31st, 2009 Partial Lunar Eclipse (path of the Moon within the Earth's umbra and map of the visibility of the eclipse worldwide) (44 ko). map courtesy Fred Espenak - NASA/Goddard Space Flight Center, site NASA Eclipse Web Site

. for more about this eclipse and for more about solar and lunar eclipses generally, see Fred Espenak's NASA Eclipse Web Site

a view of the December 31st, 2009 partial Moon eclipse at the greatest, as observed by the webmaster of the site Amateur Astronomy. site 'Amateur Astronomy'

Observation Reports: The weather was clement to allow the webmaster to watch the eclipse! The observation began only by 18H 50 UT, about when the Moon was catching the umbra (U1). The umbral shadow was seen obvious by Moon's south pole, to the bottom left of the Tycho Crater. The show was seen both naked-eye, or with binoculars. The umbra then is seen transiting South of Tycho. By the eclipse's greatest, the shadow was neat, curved and southeast of Tycho! The shadow was grey-black, with no hint of any copper tint all along the partial eclipse, likely hinting either to clouds in the atmosphere, or to any volcanoe's eruption. It might that, by U4, some dark glow is remaining during some time, albeit the umbra theoretically has left the Moon's disk. It's possible at last that the penumbral be few remarkable only as that was likely due to that the geometry of the eclipse had the northern part of the Moon remaining, for the most, outside the 'penumbra'. That eclipse was not observable in North America. That full Moon however was the second to occur in a same month, and thus called a 'blue moon'