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Eclipses During 1996

by Fred Espenak

Published in Observer's Handbook 1996, Royal Astronomical Society of Canada

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Two solar and two lunar eclipses occur in 1996. Although the solar eclipses are only partial, both lunar eclipses are total events. The eclipses occur as follows:

1996 April 4: Total Lunar Eclipse

1996 April 17: Partial Solar Eclipse

1996 September 27: Total Lunar Eclipse

1996 October 12: Partial Solar Eclipse

Predictions for three of the eclipses are summarized in figures 1 through 3. 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 principal phase are tabulated along with the magnitudes and geocentric coordinates of the Sun and Moon at greatest eclipse.

Total Lunar Eclipse of April 4

The year's first lunar eclipse occurs in Virgo as the Moon approaches its ascending node (Figure 1). Spica lies about eight degrees to the southeast of the Moon and will shine prominently during totality. This is a relatively deep total eclipse, especially for the Moon's northern limb which passes through the centre of Earth's umbral shadow. Although first penumbral contact occurs at 21:15.5 UT (April 3), most observers will have difficulty detecting the eclipse much before 22:00 UT. The partial eclipse commences with first umbral contact at 22:20.7 UT. The total umbral eclipse begins at 23:26.3 UT and ends at 00:53.0 UT. The partial phase ends at 01:58.8 UT and the Moon leaves the penumbral shadow at 03:03.8 UT. At the instant of mid-eclipse (00:09.8 UT), the Moon will stand at the zenith for observers from Ascension Island. At this time, the umbral magnitude peaks at 1.3845 as the Moon's northern limb passes through the shadow's axis. In comparison, the Moon's southern limb lies 12 arc-minutes from the southern edge of the umbra. It should be particularly interesting to note the difference in appearance between the northern and southern hemispheres of the Moon during this event. Since the Moon samples a large range of umbral depths during totality, its appearance will likely change dramatically with time. However, it's impossible 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). This event will be visible in its entirety from Europe, Africa and western-most Asia. Although the eclipse is already in progress at moonrise for most Western Hemisphere observers, some portion of totality will still be visible from the eastern third of Canada and the U. S.. The partial phases end before moonrise for observers along the Pacific coast of North America. Table 1 lists predicted umbral immersion and emersion times for twenty 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 April 17

The first solar eclipse of the year is partial and is visible only from parts of New Zealand and the coastline of Antarctica (Figure 2). First and last penumbral contacts occur at 20:31 UT and 00:43 UT, respectively. Greatest eclipse takes place at 22:37 UT when the penumbral magnitude will reach 0.880. Local circumstances for two cities in New Zealand are given in Table 2. All times are in Universal Time. Sun's altitude and azimuth, the eclipse magnitude and obscuration are all given at the instant of maximum eclipse. This event is the twentieth partial eclipse of Saros series 148. The series will deliver its first central eclipse in the year 2032 and will subsequently produce some 40 total eclipses in the ensuing seven centuries.

Total Lunar Eclipse of September 27

The second lunar eclipse of 1996 is more favorably placed for the Western Hemisphere (Figure 3). It is another total lunar eclipse which occurs in central Pisces two days after perigee. Of particular note is the close proximity of Saturn about 3 south of the Moon during totality. The penumbral phase begins at 00:12.3 UT, but sharp eyed observers won't notice anything until over half the Moon lies within the tenuous outer shadow. The partial eclipse commences as the Moon enters the dark umbra at 01:12.2 UT. The seventy minute total phase begins at 02:19.2 UT and ends at 03:29.3 UT. After totality ends, the partial phases resume and continue until 04:36.4 UT. The eclipse ends as the Moon finally exits the penumbra at 05:36.5 UT. At mid-eclipse (02:54.4 UT), the umbral magnitude reaches a value of 1.245. The Moon's southern limb then passes just 4 arc-minutes of the umbra's center while the northern limb lies within 8 arc-minutes of the shadow's edge. A large variation in shadow brightness can be expected and 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). This event will be widely visible from the Americas'. Observers in the western third of North America will miss the early partial phases which begin before moonrise. Europe and western Africa will also see the entire event. Moonset occurs before the eclipse ends for observers in eastern Africa and western Asia. At mid-eclipse, the Moon appears in the zenith from the northern coast of Brazil. Table 3 lists predicted umbral immersion and emersion times for twenty 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 October 12

The last event of the year is a partial solar eclipse visible from portions of the northern hemisphere (Figure 4). The eclipse begins at sunrise from northern Hudson Bay at 11:59.5 UT. Northern Manitoba and Ontario will both witness the event in progress as the Sun rises. Most of Quebec and the maritime provinces will also observe a small magnitude partial eclipse shortly after sunrise. Greatest eclipse occurs at 14:02.0 UT with a magnitude of 0.757. All of Europe is well placed for the event. In particular, Scandinavia will witness a low elevation eclipse whose magnitude exceeds 0.6. The southern limit of the penumbra's path passes through northern Africa. Observers in the Middle East witness the event at sunset. The eclipse ends in Libya at 16:04.8 UT as the shadow leaves Earth along the sunset terminator. Eclipse times and local circumstances for a number of cities are found in Table 4. The Sun's altitude and azimuth, the eclipse magnitude and obscuration are given at the instant of maximum eclipse. If the eclipse is in progress at sunrise or sunset, this information is indicated by ' r' or ' s', respectively.

Key to Solar Eclipse Maps

Key to Lunar Eclipse Maps

Danjon Scale of Lunar Eclipse Brightness

Crater Timings During Lunar Eclipses

Eclipse Altitudes and Azimuths

The altitude a and azimuth A of the Sun or Moon during an eclipse depends on the time and the observer's geographic coordinates. They are calculated as follows:
             h  = 15 (GST + UT - ra ) + l
             a  =  ArcSin  [ Sin d Sin f + Cos d Cos h Cos f ]
             A  =  ArcTan  [ - (Cos d Sin h) / (Sin d Cos f -  Cos d Cos h Sin f) ]

     where:
             h  =  Hour Angle of Sun or Moon
             a  =  Altitude
             A  =  Azimuth
           GST  =  Greenwich Sidereal Time at 0:00 UT
            UT  =  Universal Time
            ra  =  Right Ascension of Sun or Moon
             d  =  Declination of Sun or Moon
             l  =  Observer's Longitude (East +, West -)
             f  =  Observer's Latitude (North +, South -)
During the eclipses of 1996, the values for GST and the geocentric Right Ascension and Declination of the Sun or the Moon (at greatest eclipse) are as follows:
                     Date        GST        ra         d

                    Apr  4     12.840     12.886     -5.951
                    Apr 17     14.756      1.746     10.829
                    Sep 27      0.412      0.255      2.027
                    Oct 12      1.429     13.201     -7.638

Eclipses During 1997

Next year, there will be two solar eclipses and two lunar eclipses:

1997 March 9: Total Solar Eclipse

1997 March 24: Partial Lunar Eclipse

1997 September 2: Partial Solar Eclipse

1997 September 16: Total Lunar Eclipse

A full report Eclipses During 1997 will be published next year in the Observer's Handbook 1997. Details for the 1997 March 9 total solar eclipse have been published by NASA (see: NASA Solar Eclipse Bulletins).

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 Reference Publication series. The nominal publication date of each bulletin is 24 to 36 months before each eclipse. The bulletins are provided as a public service to both the professional and lay communities, including educators and the media. For more information and ordering instructions, see: NASA Solar Eclipse Bulletins

Total Solar Eclipse of 1998 February 26

There is already a great deal of interest in the total solar eclipse of 1998. The path of this eclipse passes through the northern Galapagos Islands, northern Colombia, Venezuela and the Caribbean. The centre line duration is between 3 and 4 minutes, depending on the longitude. As a preview of things to come, a map of the path through the Caribbean is included (Figure 5). Caribbean islands in the path include Aruba (Oranjestad - 2m52s), Curacao (Willemstad - 1m55s), Montserrat (Plymouth - 02m56s), Antigua (St. Johns - 2m11s) and Guadeloupe (Basse-Terre - 1m13s; Les Abymes - 02m19s). Preliminary eclipse durations for cities are in parentheses. Detailed predictions for this eclipse are available in NASA RP 1383 - Total Solar Eclipse of 1998 February 26 [Espenak and Anderson, 1995].

Acknowledgments

All eclipse predictions were generated on a Macintosh Quadra 630 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. As in previous years, the author uses a smaller value of k (=0.272281) for total and annular calculations than the one adopted by the 1982 IAU General Assembly. This results in a better approximation of Moon's minimum diameter and a slightly shorter total or longer annular eclipse. The IAU value for k (=0.2725076) is retained for partial phases. For lunar eclipses, the diameter of the umbral shadow was enlarged by 2% to compensate for Earth's atmosphere and the effects of oblateness have been included. Text and table composition were done on a Quadra 630 using Microsoft Word. Additional figure annotation was performed with Claris MacDraw Pro.

The author wishes to thank Goddard's Laboratory for Extraterrestrial Physics for several minutes of computer time. All calculations, diagrams, tables and opinions presented in this paper are those of the author and he assumes full responsibility for their accuracy.

References

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Last revised: 2004 Jul 28 - F. Espenak