Eclipses During 2007
Fred Espenak
Published in Observer's Handbook 2007, Royal Astronomical Society of Canada
Two central solar and two lunar eclipses occur in 2007 as follows:
- 2007 Mar 03: Total Lunar Eclipse
- 2007 Mar 19: Partial Solar Eclipse
- 2007 Aug 28: Total Lunar Eclipse
- 2007 Sep 11: Partial Solar Eclipse
Predictions for the eclipses are summarized in Figures 1 through 4. World maps show the regions of visibility for each eclipse. The lunar eclipse diagrams also include the path of the Moon through Earth's shadows. Contact times for each principle phase are tabulated along with the magnitudes and geocentric coordinates of the Sun and Moon at greatest eclipse.
All times and dates used in this publication are in Universal Time or UT. This astronomically derived time system is colloquially referred to as Greenwich Mean Time or GMT. To learn more about UT and how to convert UT to your own local time, see Time Zones and Universal Time.
Total Lunar Eclipse of 2007 Mar 03
Total Lunar Eclipse of March 03
The first of two total lunar eclipses in 2007 is unique in that it is partly visible from every continent around the world. The eclipse occurs at the descending node, 3.2 days before apogee and 1.9 days after the Moon occults Saturn (northern and eastern Europe). During the eclipse, the Moon is in southern Leo, about 13º east of the 1.3-magnitude star Regulus (alpha Leo). The Moon's orbital trajectory takes it through the northern half of Earth's umbral shadow. Although the eclipse is not central, the total phase still lasts 73 minutes. The timings of the major phases of the eclipse are listed below.
Penumbral Eclipse Begins: 20:18:11 UT
Partial Eclipse Begins: 21:30:22 UT
Total Eclipse Begins: 22:44:13 UT
Greatest Eclipse: 23:20:56 UT
Total Eclipse Ends: 23:57:37 UT
Partial Eclipse Ends: 01:11:28 UT
Penumbral Eclipse Ends: 02:23:44 UT
The Moon's path through Earth's shadows as well as a map illustrating worldwide visibility of the event are shown in Figure 1.
At the instant of greatest eclipse (23:21 UT) the Moon will lie in the zenith for observers in Nigeria and Cameroon. At this time, the umbral magnitude peaks at 1.2331 as the Moon's southern limb passes 2.4 arc-minutes north of the shadow's central axis. In contrast, the Moon's northern limb will lie 6.9 arc-minutes from the northern edge of the umbra and 32.2 arc-minutes from the shadow centre. Thus the northern sections of the Moon will appear much brighter than the southern part, which lies deeper in the shadow. Since the Moon samples a large range of umbral depths during totality, its appearance will change dramatically with time. It is not possible to predict the exact brightness distribution in the umbra, so observers are encouraged to estimate the Danjon value at different times during totality (see Danjon Scale of Lunar Eclipse Brightness). Note that it may also be necessary to assign different Danjon values to different portions of the Moon (i.e. north vs. south).
During totality, the spring constellations will be well placed for viewing so a number of bright stars can be used for magnitude comparisons. Spica (mv = +0.98) is 40º southeast of the eclipsed Moon, while Arcturus (mv = -0.05) is 49º to the northeast. Alphard or Alpha Hya (mv = +1.99) is 28º to the southwest and Procyon (mv = -0.05) is 50º to the west. Saturn shines at magnitude +0.8 about 24º northwest of the Moon near the western border of Leo.
The entire event will be visible from Europe, Africa and western Asia. In eastern Asia, moonset occurs during various stages of the eclipse. For example, the Moon sets while in total eclipse from central China and southeast Asia. Western Australia catches part of the initial partial phases but the Moon sets before totality. Observers in eastern North and South America will find the Moon already partially or totality eclipsed at moonrise. From western North America, only the final penumbral phases are visible.
Table 1 lists predicted umbral immersion and emersion times for 20 well-defined lunar craters. The timing of craters is useful in determining the atmospheric enlargement of Earth's shadow (see Crater Timings During Lunar Eclipses).
Partial Solar Eclipse of March 19
The first solar eclipse of 2007 occurs at the Moon's ascending node in Pisces and is visible from eastern Asia and parts of northern Alaska (Figure 2). Greatest eclipse [1] takes place at 02:31:56 UT when the eclipse magnitude [2] will reach 0.8754. The penumbral contact times with Earth are listed below.
Partial Eclipse Begins: 00:38:26 UT
Partial Eclipse Ends: 04:25:00 UT
Local circumstances for a number of cities within the zone of partial eclipse are given in Universal Time in Table 2. The Sun's altitude and azimuth, the eclipse magnitude and obscuration[3] are all given at the instant of local maximum eclipse.
This event is the 20th partial eclipse of Saros series 149. After one more partial eclipse, the series will produce its first total solar eclipse on 2043 Apr 09.
Click for special web page on the Total Lunar Eclipse of 2007 Aug 28
Total Lunar Eclipse of August 28
The second lunar eclipse of the year is another total eclipse. It is a deeper event since it is the first central total eclipse since 2000. The eclipse occurs at the ascending node of Luna's orbit in southern Aquarius. Since the Moon is 2.6 days shy of perigee, it will appear 8% larger (= 1.2 arc-minutes) than it was during March's eclipse. The Moon's trajectory takes it deep into the southern umbral shadow, resulting in a total eclipse that lasts 90 minutes. At mid-totality the Moon's centre passes just 12.8 arc-minutes south of the shadow axis. This places the Moon's northern limb only 3.4 arc-minutes north of the axis while the southern limb is 15.4 arc-minutes from the umbra's southern edge.
Since different parts of the Moon will probe radically different portions of Earth's umbral shadow, a large variation in shadow brightness can be expected. As a consequence of this geometry, the southern half of the totally eclipsed Moon will appear considerably brighter than the northern half. Observers are encouraged to estimate the Danjon value at mid-totality (see Danjon Scale of Lunar Eclipse Brightness).
The penumbral phase of August's eclipse begins at about 07:54 UT, but most observers will not be able to visually detect the shadow until about 08:30 UT. A timetable for the major phases of the eclipse is listed below.
Penumbral Eclipse Begins: 07:53:39 UT
Partial Eclipse Begins: 08:51:16 UT
Total Eclipse Begins: 09:52:22 UT
Greatest Eclipse: 10:37:22 UT
Total Eclipse Ends: 11:22:24 UT
Partial Eclipse Ends: 12:23:30 UT
Penumbral Eclipse Ends: 13:21:01 UT
The Moon's path through Earth's shadows as well as a map illustrating worldwide visibility of the event are shown in Figure 3.
At the instant of mid-totality (10:37 UT) the Moon will stand near the zenith for observers in French Polynesia. At that time, the umbral eclipse magnitude will be 1.4760.
All of North America will witness some portion of the eclipse, but western observers are favored. The early penumbral or umbral phases will be in progress at moonset for observers in Maritime Canada. From the eastern USA, the Great Lakes region and Ontario, the Moon sets in total eclipse. Only observers to the west of the Rockies (including Alaska) will be treated to the entire event. All phases of the eclipse are also visible from islands of the Pacific Ocean, New Zealand and eastern Australia. Various stages of the eclipse are in progress at moonrise for eastern Asia. No eclipse is visible from Europe, Africa and western Asia.
Table 3 lists predicted umbral immersion and emersion times for 20 well-defined lunar craters. The timing of craters is useful in determining the atmospheric enlargement of Earth's shadow (see Crater Timings During Lunar Eclipses).
Partial Solar Eclipse of September 11
The last eclipse of 2007 is a partial solar eclipse at the Moon's descending node in southern Leo. Its visibility is confined to parts of South America, Antarctica and the South Atlantic (Figure 4). Greatest eclipse takes place at 12:31:21 UT when the eclipse magnitude will reach 0.7505. The penumbral contact times with Earth are as follows:
Partial Eclipse Begins: 10:25:46 UT
Partial Eclipse Ends: 14:36:33 UT
Local circumstances for a number of cities within the zone of partial eclipse are given in Table 4. All times are given in Universal Time. The Sun's altitude and azimuth, the eclipse magnitude and obscuration are all given at the instant of maximum eclipse.
This event is the sixth partial eclipse of Saros series 154. After one more partial eclipse (2025 Sep 25) The series will produce the first of many annular eclipses eclipse beginning with 2043 Oct 03.
Solar Eclipse Figures
An orthographic projection map of Earth shows the path of penumbral (partial) eclipse for each event. North is up, and the daylight terminator is plotted for the instant of greatest eclipse. An asterisk (*) indicates the sub-solar point [4] on Earth.
The limits of the Moon's penumbral shadow delineate the region of visibility of the partial eclipse. This irregular or saddle-shaped region often covers nearly half of the daylight hemisphere of Earth and consists of several distinct zones or limits. At the northern and/or southern boundaries lie the limits of the penumbra's path. Partial eclipses have only one of these limits. Great loops at the western and eastern extremes identify the areas where the eclipse begins and ends at sunrise and sunset, respectively. The curves are connected in a distorted figure 8. Bisecting the "eclipse begins/ends" loops is the curve of maximum eclipse at sunrise (western loop) and sunset (eastern loop). The points P1 and P4 mark the coordinates where the penumbral shadow first contacts (partial eclipse begins) and last contacts (partial eclipse ends) Earth's surface.
A curve of maximum eclipse is the locus of all points where the eclipse is at maximum at a given time. The curves are plotted at each half hour Universal Time. Curves of constant eclipse magnitude delineate the locus of all points where the magnitude at maximum eclipse is constant. These curves run exclusively between the curves of maximum eclipse at sunrise and sunset. Furthermore, they run parallel to the northern and southern penumbral limits. In fact, the northern and southern limits of the penumbra can be thought of as curves of constant magnitude of 0.0. The adjacent curves are for magnitudes of 0.2, 0.4, 0.6, and 0.8 (i.e. 20%, 40%, 60%, and 80%).
Greatest eclipse is the instant when the axis of the Moon's shadow passes closest to Earth's centre. For partial eclipses, the shadow axis misses Earth entirely. The point on Earth's surface closest to the axis is marked by an asterisk. This point lies on the day/night terminator, so the Sun appears on the horizon.
Each map includes data pertinent to the eclipse. The instant of conjunction of the Sun and Moon in right ascension and the instant of greatest eclipse are expressed as both Universal Times and Julian Dates. The eclipse magnitude is defined as the fraction of the Sun's diameter obscured by the Moon at greatest eclipse. Gamma is the minimum distance of the Moon's shadow axis from Earth's centre in Earth radii at greatest eclipse. The Saros series of the eclipse is listed, followed by the member position. The first member number identifies the sequence position of the eclipse in the Saros, while the second is the total number of eclipses in the series.
In the upper left and right corners are the geocentric coordinates of the Sun and the Moon, respectively, at the instant of greatest eclipse. They are:
R.A. - Right Ascension
Dec. - Declination
S.D. - Apparent Semi-Diameter
H.P. - Horizontal Parallax
To the lower left in the figures are exterior/interior contact times of the Moon's penumbral shadow with Earth, which are defined as follows:
P1 - Instant of first exterior tangency of Penumbra with Earth's limb. (Partial Eclipse Begins)
P4 - Instant of last exterior tangency of Penumbra with Earth's limb. (Partial Eclipse Ends)
At bottom left is a list of parameters used in the eclipse predictions. The list at bottom right gives the Moon's geocentric libration (optical + physical) at greatest eclipse.
Lunar Eclipse Figures
Each lunar eclipse has two diagrams associated with it along with data pertinent to the eclipse. The top figure shows the path of the Moon through Earth's penumbral and umbral shadows. Above this figure are listed the instant of conjunction in right ascension of the Moon with Earth's shadow axis and the instant of greatest eclipse, expressed as both Universal Times and Julian Dates. The penumbral and umbral magnitudes are defined as the fraction of the Moon's diameter immersed in the two shadows at greatest eclipse. The radii of the penumbral and umbral shadows, "P. Radius" and "U. Radius", are also listed. "Gamma" is the minimum distance in Earth radii of the Moon's centre from Earth's shadow axis at greatest eclipse, and "Axis" is the same parameter expressed in degrees. The Saros series of the eclipse is listed, followed by a pair of numbers. The first number identifies the sequence position of the eclipse in the Saros; the second is the total number of eclipses in the series.
In the upper left and right corners are the geocentric coordinates of the Sun and the Moon, respectively, at the instant of greatest eclipse. They are:
R.A. - Right Ascension
Dec. - Declination
S.D. - Apparent Semi-Diameter
H.P. - Horizontal Parallax
To the lower left are the semi, or half, durations of the penumbral, umbral (partial), and total eclipses. Below them are the Sun/Moon ephemerides used in the predictions, followed by the extrapolated value of ΔT (the difference between Terrestrial Dynamical Time and Universal Time). To the lower right are the contact times of the Moon with Earth's penumbral and umbral shadows, defined as follows:
P1 - Instant of first exterior tangency of Moon with Penumbra. (Penumbral Eclipse Begins)
U1 - Instant of first exterior tangency of Moon with Umbra. (Partial Umbral Eclipse Begins)
U2 - Instant of first interior tangency of Moon with Umbra.
(Total Umbral Eclipse Begins)
U3 - Instant of last interior ta ngency of Moon with Umbra.
(Total Umbral Eclipse Ends)
U4 - Instant of last exterior tangency of Moon with Umbra (Partial Umbral Eclipse Ends)
P4 - Instant of last exterior tangency of Moon with Penumbra. (Penumbral Eclipse Ends)
The bottom figure is an equidistant cylindrical projection map of Earth that shows the regions of visibility for each stage of the eclipse. In particular, the moonrise/moonset terminator is plotted for each contact and is labeled accordingly. The point where the Moon is in the zenith at greatest eclipse is indicated by an asterisk. The region that is completely unshaded will observe the entire eclipse, while the darkly shaded area will witness no eclipse. The remaining lightly shaded areas will experience moonrise or moonset while the eclipse is in progress. The shaded zones east of the asterisk will witness moonset before the eclipse ends, and the shaded zones west will witness moonrise after the eclipse has begun.
Shadow Diameters and Lunar Eclipses
Chauvenet [1891] is credited with the introduction of an empirical enlargement of 1/50 to the diameters of the umbral and penumbral shadows to compensate for Earth's atmosphere when calculating the circumstances of a lunar eclipse. This rule has been employed by long tradition in many of the national institutes in their official eclipse predictions (including the author's work at NASA). However, Danjon [1951] pointed out that the correct procedure is to enlarge Earth's diameter by 1/85 to compensate for the atmosphere. The umbral and penumbral shadow diameters are then calculated based on this modified geometry. The French almanac "Connaissance des Temps" has used the Danjon rule in its eclipse predictions since 1951. The resulting umbral and penumbral eclipse magnitudes are approximately 0.005 and 0.026 magnitudes smaller, respectively, than predictions using the traditional 1/50 rule.
Beginning with Eclipses During 2007, we will use the Danjon rule rather than the traditional (and flawed) 1/50 rule in calculating lunar eclipse circumstances.
Danjon Scale of Lunar Eclipse Brightness
The Moon's appearance during a total lunar eclipse can vary enormously from one eclipse to the next. Obviously, the geometry of the Moon's path through the umbra plays an important role. Not as apparent is the effect that Earth's atmosphere has on total eclipses. Although the physical mass of Earth blocks all direct sunlight from the umbra, the planet's atmosphere refracts some of the Sun's rays into the shadow. Earth's atmosphere contains varying amounts of water (clouds, mist, precipitation) and solid particles (meteoric dust, organic debris, volcanic ash). This material significantly filters and attenuates the sunlight before it is refracted into the umbra. For instance, large or frequent volcanic eruptions dumping huge quantities of ash into the atmosphere are often followed by very dark, red eclipses for several years. Extensive cloud cover along Earth's limb also tends to darken the eclipse by blocking sunlight.
The French astronomer André-Louis Danjon proposed a useful five-point scale for evaluating the visual appearance and brightness of the Moon during total lunar eclipses. L values for various luminosities are defined as follows:
L=0 Very dark eclipse.
(Moon almost invisible, especially at mid-totality)
L=1 Dark eclipse, grey or brownish in coloration.
(details distinguishable only with difficulty)
L=2 Deep red or rust-coloured eclipse.
(very dark central shadow, while outer umbra is relatively bright)
L=3 Brick-red eclipse.
(umbral shadow usually has a bright or yellow rim)
L=4 Very bright copper-red or orange eclipse.
(umbral shadow has a bluish, very bright rim)
The assignment of an L value to lunar eclipses is best done with the naked eye, binoculars, or a small telescope near the time of mid-totality. It's also useful to examine the Moon's appearance just after the beginning and just before the end of totality. The Moon is then near the edge of the shadow, providing an opportunity to assign an L value to the outer umbra. In making any evaluations, the instrumentation used and the time should both be recorded. Also note any variations in colour and brightness in different parts of the umbra, as well as the apparent sharpness of the shadow's edge. Pay attention to the visibility of lunar features within the umbra. Notes and sketches made during the eclipse are often invaluable in recalling important details, events, and impressions.
Crater Timings During Lunar Eclipses
In 1702, Pierre de La Hire made a curious observation about Earth's umbra. In order to accurately predict the duration of a lunar eclipse, he found it necessary to increase the radius of the shadow about 1% more than is warranted by geometric considerations. Although the effect is clearly related to Earth's atmosphere, it is not completely understood, since the shadow enlargement seems to vary from one eclipse to the next. The enlargement can be measured through careful timings of lunar craters as they enter and exit the umbra.
Such observations are best made using a low-power telescope and a clock or watch synchronized with radio time signals. Timings should be made to a precision of 0.1 min. Record the instant when the most abrupt gradient at the umbra's edge crosses the apparent centre of the crater. In the case of large craters like Tycho and Copernicus, record the times when the shadow touches the two opposite edges of the crater. The average of these times is equal to the instant of crater bisection.
As a planning guide, Table 1 and Table 3 list 20 well-defined craters with predicted umbral immersion and emersion times during the two lunar eclipses of 2007. You should be thoroughly familiar with these features before viewing an eclipse in order to prevent confusion and misidentification. The four umbral contacts with the Moon's limb can also be used in determining the shadow's enlargement. However, these events are less distinct and therefore difficult to time accurately. Observers are encouraged to make crater timings and to send their results to Sky & Telescope (Sky Publishing Corporation, 90 Sherman St., Cambridge MA 02140, USA) for analysis.
Note that all predictions presented here use Danjon's rule of shadow enlargement (see: Shadow Diameters and Lunar Eclipses). In particular, the diameter of the umbral shadow has been calculated assuming an enlargement of Earth's radius of 1/85 to account for the opacity of the terrestrial atmosphere. The effects of Earth's oblateness have also been included.
Eclipse Altitudes and Azimuths
The altitude "a" and azimuth "A" of the Sun or Moon during an eclipse depend on the time and the observer's geographic coordinates. They are calculated as follows:
h = 15 (GST + UT - α ) + λ
a = arcsin [sin δ sin φ + cos δ cos h cos φ]
A = arctan [-(cos δ sin h)/(sin δ cos φ - cos δ cos h sin φ)]
where
h = hour angle of Sun or Moon
a = altitude
A = azimuth
GST = Greenwich Sidereal Time at 0:00 UT
UT = Universal Time
α = right ascension of Sun or Moon
δ = declination of Sun or Moon
λ = observer's longitude (east +, west -)
φ = observer's latitude (north +, south -)
During the eclipses of 2007, the values for GST and the geocentric Right Ascension and Declination of the Sun or the Moon (at greatest eclipse) are as follows:
Eclipse Date GST α δ Total Lunar 2007 Mar 03 10.757 10.964 6.934 Partial Solar 2007 Mar 19 11.751 23.884 -0.751 Total Lunar 2007 Aug 28 22.418 22.447 -9.955 Partial Solar 2007 Sep 11 23.343 11.289 4.587
Eclipses During 2008
Next year (2008), there will be two solar and two lunar eclipses:
- 2008 Feb 07: Annular Solar Eclipse
- 2008 Feb 21: Total Lunar Eclipse
- 2008 Aug 01: Total Solar Eclipse
- 2008 Aug 16: Partial Lunar Eclipse
A full report on eclipses during 2008 will be published next year in the Observer's Handbook 2008.
NASA Solar Eclipse Bulletins
Special bulletins containing detailed predictions and meteorological data for future solar eclipses of interest are prepared by F. Espenak and J. Anderson and are published through NASA's Publication series. The bulletins are provided as a public service to both the professional and lay communities, including educators and the media. A list of currently available bulletins and an order form can be found at:
http://eclipse.gsfc.nasa.gov/SEpubs/RPrequest.html
The latest bulletin in the series is Total Solar Eclipse of 2008 August 01 which is visible from northern Canada, Russia, Mongolia and China. Single copies of the eclipse bulletins are available at no cost by sending a 9 x 12-in. self-addressed envelope stamped with postage for 11 oz. (310 g). Please print the eclipse year on the envelope's lower left corner. Use stamps only, since cash and cheques cannot be accepted. Requests from outside the United States and Canada may include 10 international postal coupons. Mail requests to: Fred Espenak, NASA's Goddard Space Flight Center, Code 693, Greenbelt MD 20771, USA.
The NASA eclipse bulletins are also available over the Internet, including out-of-print bulletins. Using a Web browser, they can be read or downloaded through the World Wide Web from the GSFC/SDAC (Solar Data Analysis Center) eclipse page:
Eclipse Web Sites
The NASA Eclipse Web Site is available at:
http://eclipse.gsfc.nasa.gov/eclipse.html
The site features predictions and maps for all solar and lunar eclipses well into the 21st century, with special emphasis on eclipses occurring during the next two years. Detailed maps, tables, graphs, and meteorological data are included. A world atlas of solar eclipses provides maps of all central eclipse paths from 1000 AD to 3000 AD. Additional catalogues list every solar and lunar eclipse over a 5000-year period.
Detailed information on solar and lunar eclipse photography and tips on eclipse observing and eye safety may be found at:
Acknowledgments
All eclipse predictions were generated on an Apple G4 iMac computer using algorithms developed from the Explanatory Supplement (1974) with additional algorithms from Meeus, Grosjean, and Vanderleen (1966). The solar and lunar ephemerides were generated from Newcomb and the Improved Lunar Ephemeris by Eckert, Jones, and Clark (1954). For lunar eclipses, the diameter of the umbral and penumbral shadows were calculated using Danjon's rule of enlarging Earth's radius by 1/85 to compensate for the opacity of the terrestrial atmosphere; corrections for the effects of oblateness have also been included. Text and table composition was done on a Macintosh using Microsoft Word. Additional figure annotation was performed with Claris MacDraw Pro.
All calculations, diagrams, tables, and opinions presented in this paper are those of the author, and he assumes full responsibility for their accuracy.
Special thanks to National Space Club summer intern Jesse Marder for his valuable assistance in preparing the web page (July 2006).
Footnotes
[1] The instant of greatest eclipse occurs when the distance between the Moon's shadow axis and Earth's geocentre reaches a minimum.
[2] Eclipse magnitude is defined as the fraction of the Sun's diameter occulted by the Moon
[3] Eclipse obscuration is defined as the fraction of the Sun's surface area occulted by the Moon.
[4] The sub-solar point is the geographic location where the Sun appears directly overhead (zenith).
References
Eckert, W.J., Jones, R., and Clark, H.K., Improved Lunar Ephemeris 1952-1959, U. S. Naval Observatory, Washington, DC, 1954.
Espenak, F., Fifty Year Canon of Solar Eclipses: 1986-2035, Sky Publishing Corp., Cambridge, MA, 1988.
Espenak, F., Fifty Year Canon of Lunar Eclipses: 1986-2035, Sky Publishing Corp., Cambridge, MA, 1989.
Espenak, F. and J. Anderson, 2004, Total Solar Eclipse of 2006 March 29, NASA TP2004-212762, Washington DC.
Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac, Her Majesty's Nautical Almanac Office, London, 1974.
Littmann, M., Willcox, K., & Espenak, F., Totality-Eclipses of the Sun, Oxford University Press, New York, 1999.
Meeus, J., Grosjean, C.C., & Vanderleen, W., Canon of Solar Eclipses, Pergamon Press, New York, 1966.
Meeus, J. & Mucke, H., Canon of Lunar Eclipses: -2002 to +2526, Astronomisches Buro, Wien, 1979.
Meeus, J., Mathematical Astronomy Morsels, Willmann-Bell, Richmond, 1997.
Newcomb, S., "Tables of the Motion of the Earth on its Axis Around the Sun," Astron. Papers Amer. Eph., Vol. 6, Part I, 1895.
