February 20th Total Lunar Eclipse

Introduction

A total eclipse of the Moon occurs during the night of Wednesday, February 20/21, 2008. The entire event is visible from South America and most of North America (on Feb. 20) as well as Western Europe, Africa, and western Asia (on Feb. 21). 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.

If only part of the Moon passes through the umbra, a partial eclipse is seen. However, if the entire Moon passes through the umbral shadow, then a total eclipse of the Moon occurs. For more information on how, what, why, where and when of lunar eclipses, see the special web page lunar eclipses for beginners.

Lunar Eclipse Diagrams

The following diagrams show the Moon's path through Earth's shadows (higher resolution versions of the above figure). The times of major stages of the eclipse are given for a number of time zones in North America. Please choose the diagram for your own time zone. Each diagram is a GIF file with a size of about 100k.

• 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 AST (Alaska Standard Time)
• Eclipse Diagram for HST (Hawaiian Standard Time)

• Eclipse Diagram for GMT (Greenwich Mean Time)
• Eclipse Diagram for GMT +1 (Greenwich Mean Time + 1 Hour)
• Eclipse Diagram for GMT +2 (Greenwich Mean Time + 2 Hours)

Some people may be puzzled that the Moon's motion is from west to east (right to left) in these diagrams, instead of its daily east to west (left to right) motion in 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.

Times and Phases of the Total Lunar Eclipse of February 20/21, 2008

From start to finish, February's lunar eclipse lasts about three hours and twenty-six 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. But since no major volcanic eruptions have taken place recently, the Moon will probably take on a vivid red or orange 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 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 February 20 eclipse totality will last just under 50 minutes. This is quite a bit less than the last total lunar eclipse ( August 28, 2007) which lasted 90 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 01:43 GMT. Totality begins at 03:01 GMT and lasts until 03:51 GMT. The partial phases end at 05:09 GMT. Eclipse times for time zones in the United States and Canada are shown in the following table.

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-thosuand year period.

Visibility of the Total Lunar Eclipse of February 20, 2008

February's lunar eclipse is well-placed for North and South America as well as Europe and Africa. Observers along North America's west coast miss the early stages of the partial eclipse because it begins before moon rise. Alaskans in Anchorage and Fairbanks experience moonrise during totality but bright evening twilight will make it difficult for sourdoughs to view the event. Western Europe and northwest Africa also see the entire eclipse. Further to the east (east Africa and central Asia), the Moon sets before the eclipse ends. None of the eclipse is visible from eastern Asia or Australia.

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.

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 blue 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 P1, U1, U2, U3, U4, and P4 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 Turkey lies west (left) of the U3 curve (total eclipse end) 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 blue 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 (P1, U1, U2, U3, U4, or P4), 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 start with a penumbral followed by a partial eclipse, and end with a partial followed by a penumbral eclipse (the total eclipse is sandwiched in the middle). Since the penumbral phases of the eclipse are so difficult to see, we will ignore them.

At the instant of mid-totality (03:37 GMT), the Moon will lie in the zenith for observers in French Guiana. At this time, the umbral eclipse magnitude peaks at 1.1062.

From the diagram above, it is clear that the northern (top) edge of the Moon will dip much deeper into the Earth's shadow than will the southern (bottom) edge. Since the Earth's umbral shadow is darker in the center than at the edge, the Moon's appearance will likely change dramatically with time. 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 lunar eclipse photography.

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 7x35 or 7x50 binoculars is sufficient.

During the eclipse, the Moon will be in Leo. Saturn and bright star Regulus are only 3 degrees east and west, respectively, of the Moon. Geminii, Orion, Taurus and other winter constellations will occupy the south and western sky for North American eclipse watchers. viewers.

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!

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].

[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.

The last total lunar eclipse visible from the entire continental United States occurred on August 28, 2007. North Americans will have their next opportunity to see a total lunar eclipse on 2010 Dec 21.

The table below lists every lunar eclipse from 2007 through 2012. 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).

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

Web Resources

• More on February's eclipse: sunearth.gsfc.nasa.gov/eclipse/OH/OH2008.html
• Lunar Eclipses from 1991 to 2000: sunearth.gsfc.nasa.gov/eclipse/LEcat/LEdecade1991.html
• Lunar Eclipses from 2001 to 2010: sunearth.gsfc.nasa.gov/eclipse/LEcat/LEdecade2001.html
• Lunar Eclipses from 2011 to 2020: sunearth.gsfc.nasa.gov/eclipse/LEcat/LEdecade2011.html
• 5,000 Year Catalog of Lunar Eclipses: sunearth.gsfc.nasa.gov/eclipse/LEcat/LEcatalog.html
• Lunar Eclipses of Historical Interest: sunearth.gsfc.nasa.gov/eclipse/LEhistory/LEhistory.html

• Sky & Telescope - Lunar Eclipse

• How to Photograph a Lunar Eclipse
• Lunar Eclipse Photography

• IOTA Occultations - predictions of occultations of faint stars during the eclipse
• More Lunar Eclipse Photography

References

• Espenak, F., 1989, Fifty Year Canon of Lunar Eclipses: 1986-2035, Sky Publishing Corp., Cambridge, MA.
• Espenak, F., 2006, "Eclipses During 2007", Observer's Handbook - 2007, Royal Astronomical Society of Canada, Toronto, Ontario.

Reproduction of Eclipse Data

All eclipse calculations are by Fred Espenak, and he assumes full responsibility for their accuracy. Permission is freely granted to reproduce this data when accompanied by the following acknowledgment:

"Eclipse Predictions by Fred Espenak, NASA's GSFC"