NOTA:  La informacion esta TOTALMENTE EN INGLES, pero MR ECLIPSE (FRED ESPENAK) es la mayor autoridad mundial en materia de eclipses.

La APAA (Asociacion Panameña de Aficionados a la Astronomia) esta pendiente de este acontecimiento, cualquier actividad que se organize para esa noche (martes 21 de dic de 2010  - madrugada del miercoles 22 de dic de 2010), estaremos avisando sobre la misma.

Los horarios que aparecen en el diagrama de las fases del eclipse (que se encuentra mas abajo de este POST), corresponden a la hora del este de los EE.UU, que en esta epoca del año coincide con la hora de Panama.

http://www.mreclipse.com/LEdata/TLE2010Dec21/image/TLE2010Dec21-EST.GIF

Atte,

Jorge Luis Rojas (APAA – Secretario 2010-2011)

http://www.mreclipse.com/LEdata/TLE2010Dec21/image/TLE2010Dec21-EST.GIF

The Total Lunar Eclipse of Oct. 27, 2004 was widely seen from the USA.
The next one is on Dec. 21, 2010.
(click for larger image)

Total Lunar Eclipse of December 21, 2010

by Fred Espenak

http://www.mreclipse.com/LEdata/TLE2010Dec21/TLE2010Dec21.html

Introduction

A total eclipse of the Moon occurs during the early morning hours of December 21, 2010 (for observers in western North America and Hawaii, the eclipse actually begins on the evening of December 20). The entire event is visible from North America, Greenland and Iceland. Western Europe will see the beginning stages of the eclipse before moonset while western Asia will get the later stages after moonrise. During a total lunar eclipse, the Moon’s disk can take on a dramatically colorful appearance from bright orange to blood red to dark brown and (rarely) very dark gray.

An eclipse of the Moon can only take place at Full Moon, and only if the Moon passes through some portion of Earth’s shadow. The shadow is actually composed of two cone-shaped parts, one nested inside the other. The outer shadow or penumbra is a zone where Earth blocks some (but not all) of the Sun’s rays. In contrast, the inner shadow or umbra is a region where Earth blocks all direct sunlight from reaching the Moon.

When only part of the Moon passes through the umbra, a partial eclipse is seen. If the entire Moon passes through the umbral shadow, then a total eclipse of the Moon occurs. It is also possible to have an eclipse where the Moon passes through only the penumbra. Each of these eclipses has a unique and distinct appearance (see Visual Appearance of Lunar Eclipses). For more information on how, what, why, where and when of lunar eclipses, see the special web page Lunar Eclipses for Beginners.

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Path of the Moon through Earth’s umbral and penumbral shadows
during the Total Lunar Eclipse of December 21, 2010.
(click for larger map)

Lunar Eclipse Diagrams

The following diagrams show the Moon’s path through Earth’s shadows during December’s eclipse (higher resolution versions of the above figure). The times of major eclipse stages are given for time zones throughout North America. Please choose the diagram for your own time zone. Each diagram is a GIF file with a size of about 140 kB.

• Eclipse Diagram for GMT (Greenwich Mean Time)
• Eclipse Diagram for AST (Atlantic Standard Time)
• Eclipse Diagram for EST (Eastern Standard Time)
• Eclipse Diagram for CST (Central Standard Time)
• Eclipse Diagram for MST (Mountain Standard Time)
• Eclipse Diagram for PST (Pacific Standard Time)
• Eclipse Diagram for AKST (Alaska Standard Time)
• Eclipse Diagram for HST (Hawaiian Standard Time)

From Europe and the eastern USA and Canada (time zones AST, EST and CST), the entire eclipse occurs during the early morning hours of December 21. From the western USA and Canada (time zones MST and PST), the eclipse acually begins before midnight on the night of December 20, and ends sometime after midnight on the morning of December 21. Finally, for observers in Alaska and Hawaii (time zones AKST and HST), most of the eclipse occurs on the night of December 20, but ends early on December 21.

Some people may be puzzled that the Moon’s motion in these diagrams is from west to east (right to left), instead of its daily east to west (left to right) motion across the sky. However, the Moon actually moves WEST to EAST (right to left in the Northern Hemisphere) with respect to the Earth’s shadow and the stars. At the same time, the Moon, shadow and stars all rise in the east and set in the west.

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2004 Lunar Eclipse Sequence
The total lunar eclipse of Oct. 28, 2004 was widely visible from the USA.
This sequence of images captures the eclipse from start (right) to finish (left).
(click to see larger image)

Times and Phases of the Total Lunar Eclipse of December 21, 2010

From start to finish, December’s lunar eclipse lasts about three hours and twenty-eight minutes (not including the penumbral phases which are very difficult to see). The partial eclipse begins as the Moon’s eastern edge slowly moves into the Earth’s umbral shadow. During the partial phases, it takes just over an hour for the Moon’s orbital motion to carry it entirely within the Earth’s dark umbra. The color and brightness of the totally eclipsed Moon can vary considerably from one eclipse to another. Dark eclipses are caused by volcanic gas and dust which filters and blocks much of the Sun’s light from reaching the Moon. The recent volcanic eruptions of Mount Merapi in Indonesia may possibly result in a darker eclipse that may take on a deep red or brown color during the total phase. After the total phase ends, it is once again followed by a partial eclipse as the Moon gradually leaves the umbral shadow. The Visual Appearance of Lunar Eclipses describes what each of these eclipse phases looks like.

The total phase of a lunar eclipse is called totality. At this time, the Moon is completely immersed within the Earth’s dark umbral shadow. During the December 21 eclipse totality will last just over 72 minutes. This is quite a bit longer than the last total lunar eclipse on February 21, 2008 which lasted 50 minutes.

The major phases of the eclipse occur as follows (all times are GMT or Greenwich Mean Time). The partial eclipse commences with first umbral contact at 06:33 GMT. Totality begins at 07:41 GMT and lasts until 08:53 GMT. The partial phases end at 10:01 GMT. Eclipse times for time zones in the United States and Canada are shown in the following table.

Total Lunar Eclipse of December 21, 2010
	Europe	North America						Pacific
Event	GMT	AST	EST	CST	MST	PST	AKST	HST
Partial Eclipse Begins:	06:33 am	02:33 am	01:33 am	12:33 am	11:33 pm*	10:33 pm*	09:33 pm*	08:33 pm*
Total Eclipse Begins:	07:41 am	03:41 am	02:41 am	01:41 am	12:41 am	11:41 pm*	10:41 pm*	09:41 pm*
Mid-Eclipse:	08:17 am	04:17 am	03:17 am	02:17 am	01:17 am	12:17 am	11:17 pm*	10:17 pm*
Total Eclipse Ends:	08:53 am	04:53 am	03:53 am	02:53 am	01:53 am	12:53 am	11:53 pm*	10:53 pm*
Partial Eclipse Ends:	10:01 am	06:01 am	05:01 am	04:01 am	03:01 am	02:01 am	01:01 am	12:01 am

* Event occurs on evening of December 20, 2010

Key to Time Zones
Zone	Description
GMT	Greenwich Mean Time
AST	Atlantic Standard Time (GMT – 4 hours)
EST	Eastern Standard Time (GMT – 5 hours)
CST	Central Standard Time (GMT – 6 hours)
MST	Mountain Standard Time (GMT – 7 hours)
PST	Pacific Standard Time (GMT – 8 hours)
AKST	Alaska Standard Time (GMT – 9 hours)
HST	Hawaii Standard Time (GMT – 10 hours)

The table above provides times of the major eclipse phases for North American time zones and Greenwich Mean Time (GMT). Eclipse times for other time zones can be calculated by taking the difference between local time and Greenwich and adding it to the tabulated GMT times.

To determine the Moon’s altitude at each stage of the eclipse as seen from your city or location, see Javascript Lunar Eclipse Explorer. This web page allows you to calculate the viewing circumstances of all lunar eclipses visible from your city over a five-thousand year period.

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Visibility of the Total Lunar Eclipse of December 21, 2010

December’s lunar eclipse is perfectly placed for North America, Greenland and Iceland where the entire event will be visible. Observers in western Europe and the eastern half of South America will miss the last stages of the eclipse because they occur after moonset. Similarly, observers in eastern Asia, Japan, Australia and New Zealand will miss the early stages of the elipse since it begins before moonrise. None of the eclipse is visible from eastern Africa, the Middle East or South Asia.

Preceeding and following the eclipse are hour-long penumbral phases but these are faint and quite difficult to see. The more interesting and photogenic partial and total phases always take center stage to the penumbral phases.

Map showing the global visibility of the Total Lunar Eclipse of December 21, 2010.

(Click here to see larger version of this map)

http://www.mreclipse.com/LEdata/TLE2010Dec21/image/TLE2010Dec21-Map2.GIF

Key to Eclipse Visibility Map
U1	Partial eclipse begins
U2	Total eclipse begins
U3	Total eclipse ends
U4	Partial eclipse ends

The map above shows the geographic regions of visibility for each phase of the eclipse. The entire eclipse is visible from start to finish in the white (unshaded) portion of the map, while none of the eclipse can be seen from the dark gray areas.

For anyone located in the gray shaded region labeled Eclipse at Moonset, this means that the Moon will set while some phase of the eclipse is already in progress. The contact curves labeled U1, U2, U3, and U4 represent each phase of the eclipse (see the key above). If you are east (right) of a particular curve, that phase occurs after moonset and you will not see it. However, if you are west (left) of a curve, that phase occurs before moonset and you will see it (weather permitting).

For example, on the above map most of Ireland lies west (left) of the U3 curve (total eclipse ends) and east (right) of the curve U4 (partial eclipse ends). This means that from this region, the Moon sets during the partial phases following totality.

For observers located within the second gray shaded region labeled Eclipse at Moonrise, the situation is reversed. Here the Moon rises while some phase of the eclipse is already in progress. If you are west (left) of a particular curve (U1, U2, U3, or U4), that phase occurs before moonrise and you will not see it. However, if you are east (right) of a contact curve, that phase occurs after moonrise and you will see it (weather permitting).

All total eclipses begin with penumbral and partial phases before totality. After the total phase, the eclipse ends with more partial and penumbral phases. Since the penumbral phases of the eclipse are so difficult to see, we will ignore them.

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The Total Lunar Eclipse of July 16, 2000 was a very long total eclipse (1 hour 47 minutes)
that won’t be exceeded for over a thousand years.
(click for larger image)

Wonderful Totality

At the instant of mid-totality (08:17 GMT), the Moon will lie in the zenith for observers in the Pacific Ocean southwest of Baja Mexico. At this time, the umbral eclipse magnitude peaks at 1.2561. Eclipse magnitude is the fraction of the Moon’s diameter immersed in Earth’s umbral shadow at greatest eclipse. This value is always 1.0 or larger for total eclipses.

From the eclipse diagrams shown earlier, it is clear that the southern (bottom) edge of the Moon will dip much deeper into the Earth’s shadow than will the northern (top) edge. Since Earth’s umbral shadow is darker in the center than at the edge, the Moon’s appearance will likely change dramatically with time as the total phase progresses. A large variation in shadow brightness can be expected and observers are encouraged to estimate the Danjon value at different times during totality (Danjon Brightness Scale). Note that it may also be necessary to assign different Danjon values to different portions of the Moon at different times.

This could be an excellent opportunity for budding astronomers and students to test their observing skills. Try recording your estimates of the Moon’s brightness every ten minutes during totality using the Danjon Scale. Compare your results with your companions and classmates and discover how the Moon’s appearance changes during the total eclipse. The brightness of the totally eclipsed Moon is very sensitive to the presence of volcanic dust in Earth’s atmosphere. As part of a continuing research project, Dr. Richard Keen has been using reports of lunar eclipse brightnesses to calculate a history of optical thicknesses of volcanic dust layers (see: What Will 2004′s Lunar Eclipses Look Like?). If you’d like to help Dr. Keen by making eclipse observations, you can contact him at Richard.Keen@colorado.edu.

The amount of dust and sulfur dioxide in Earth’s atmosphere also has an effect on the diameter of the umbral shadow. Amateur astronomers with telescopes can make careful timings of when some of the Moon’s major craters enter or exit the umbra. Such observations are valuable in determining the enlargement of Earth’s shadow. A table of crater predictions identifies twenty well-defined craters useful for this purpose. For more information, see: Crater Timings During Lunar Eclipses.

An eclipse of the Moon also presents a tempting subject to photograph. Since the Moon appears quite small in the sky, you’ll need a fairly powerful telephoto lens (400 mm or more) or even a small telescope to attach to your camera. A typical ISO 400 speed (either digital or film) is a good choice. For more information on equipment, film, recommended exposures and additional tips, see How to Photograph a Lunar Eclipse.

Unlike solar eclipses, lunar eclipses are completely safe to watch. Protective filters are not necessary and neither is a telescope. A lunar eclipse can be observed with nothing more than the naked eye. However, a pair of binoculars will magnify the view and make the red coloration brighter and easier to see. A standard pair of 7×35 or 7×50 binoculars is sufficient.

During the eclipse, the Moon will be in eastern Taurus near the border with Gemini. The bright red star Aldebaran (“Eye of the Bull”) lies 20 degrees west of the Moon. The winter constellations Gemini, Auriga, Taurus and Orion surround the eclipsed Moon.

Although total eclipses of the Moon are of limited scientific value, they are remarkably beautiful events which do not require expensive equipment. They help to cultivate interest in science and astronomy in children and to provide a unique learning opportunity for families, students and teachers. To the nature lover and naturalist, the lunar eclipse can be appreciated and celebrated as an event which vividly illustrates our place among the planets in the solar system. The three dimensional reality of our universe comes alive in a graceful celestial ballet as the Moon swings through the Earth’s shadow. Hope for clear skies, dress warmly and enjoy the show!

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The Eclipse and the Winter Solstice

The Winter Solstice of 2010 also occurs on Dec. 21 at 11:38 pm GMT. This is just 15.3 hours after the mid-point of the total lunar eclipse (08:17 am GMT). There is no special significance to this coincidence since a lunar eclipse can occur on any calendar date of the year. However, it does mean that this eclipse will take place with the Moon at its maximum northern position in its orbit.

The last time a lunar eclipse occurred on Dec. 21 was in 1991 and the next one is in 2094. Of course, the Winter Solstice does not always fall on Dec. 21 because our calendar is composed of 365 complete days (366 days in leap years), while the actual time it takes Earth to make one orbit around the Sun is 365.24 days (with respect to Earth’s axial tilt). This difference means that the date of the Winter Solstice can be as early as Dec. 20 and as late as Dec. 23 (for the period 1900 to 2100).

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This multiple exposure sequence hows both partial and total phases of the Total Lunar Eclipse of January 21, 2000.

Eclipse Frequency and Future Eclipses

During the five millennium period from 2000 BC through AD 3000, there are 7,718 eclipses[1] of the Moon (including both partial and total eclipses). From 0 to 3 lunar eclipses (partial or total) occur each year. The last time three total lunar eclipses occurred in one calendar year was in 1982. On average, partial eclipses slightly outnumber total eclipses by 7 to 6[2].

The last total lunar eclipse visible from the entire continental United States occurred on February 21, 2008. North Americans will have their next opportunity to see a total lunar eclipse on April 15, 2014.

The table below lists every lunar eclipse from 2010 through 2015. Click on the eclipse Date to see a map and diagram of an eclipse. Although penumbral lunar eclipses are included in this list, they are usually quite difficult to observe because of their subtlety. The penumbra is a partial shadow which still permits some direct sunlight to reach the Moon.

The Umbral Eclipse Magnitude is the fraction on the Moon’s diameter immersed in the umbra at maximum eclipse. For values of 1.0 or greater, the eclipse is total. For negative values, the eclipse is penumbral. The Total Duration is the duration of the total phase (total eclipses only).

[1] Only eclipses where the Moon passes through Earth’s umbral shadow are included in these values. A minor type of eclipse is the penumbral eclipse which occurs when the Moon passes through the Earth’s faint penumbral shadow. Penumbral eclipses are rarely discernible to the naked eye and are of lesser importance than umbral eclipses.

[2] Penumbral eclipses are excluded from these statistics.

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Lunar Eclipses: 2010 – 2015
Date	Eclipse Type	Saros	Umbral Magnitude	Eclipse Duration	Geographic Region of Eclipse Visibility
2010 Jun 26	Partial	120	0.542	02h44m	e Asia, Aus., Pacific, w Americas
2010 Dec 21	Total	125	1.262	03h29m 01h13m	e Asia, Aus., Pacific, Americas, Europe
2011 Jun 15	Total	130	1.705	03h40m 01h41m	S.America, Europe, Africa, Asia, Aus.
2011 Dec 10	Total	135	1.110	03h33m 00h52m	Europe, e Africa, Asia, Aus., Pacific, N.A.
2012 Jun 04	Partial	140	0.376	02h08m	Asia, Aus., Pacific, Americas
2012 Nov 28	Penumbral	145	-0.184	-	Europe, e Africa, Asia, Aus., Pacific, N.A.
2013 Apr 25	Partial	112	0.015	00h27m	Europe, Africa, Asia, Aus.
2013 May 25	Penumbral	150	-0.934	-	Americas, Africa
2013 Oct 18	Penumbral	117	-0.272	-	Americas, Europe, Africa, Asia
2014 Apr 15	Total	122	1.291	03h35m 01h18m	Aus., Pacific, Americas
2014 Oct 08	Total	127	1.166	03h20m 00h59m	Asia, Aus., Pacific, Americas
2015 Apr 04	Total	132	1.001	03h29m 00h05m	Asia, Aus., Pacific, Americas
2015 Sep 28	Total	137	1.276	03h20m 01h12m	e Pacific, Americas, Europe, Africa, w Asia

Geographic abbreviations (used above): n = north, s = south, e = east, w = west, c = central

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The Total Lunar Eclipse of July 16, 2000 as seen from Maui.