The first of two total lunar eclipses in 2004 is best seen from the Eastern Hemisphere. The eclipse occurs 1 1/3 days before perigee so the Moon will appear rather large (33.1 arc-minutes). During this event, the Moon is low on the ecliptic in western Libra just 1.5° south of the 2.8 magnitude star Zuben Elgenubi (Alpha Librae).
The Moon's path takes it through the southern part of Earth's umbral shadow. Although the eclipse is not central, the total phase still lasts 1 hour 16 minutes. The major phases of the eclipse are as follows:
Penumbral Eclipse Begins: 17:50:53 UT Partial Eclipse Begins: 18:48:20 UT Total Eclipse Begins: 19:52:07 UT Greatest Eclipse: 20:30:16 UT Total Eclipse Ends: 21:08:27 UT Partial Eclipse Ends: 22:12:15 UT Penumbral Eclipse Ends: 23:09:36 UT
At the instant of greatest eclipse (20:30 UT), the Moon will lie in the zenith for observers near northern Madagascar. At this time, the umbral magnitude 1 peaks at 1.309 as the Moon's northern limb passes 2.5 arc-minutes south of the shadow's axis. In contrast, the Moon's southern limb will lie 10.2 arc-minutes from the southern edge of the umbra and 35.6 arc-minutes from the shadow centre. Thus, the southern sections of the Moon will appear much brighter than the northern part which will lie deeper in the shadow. 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 section: 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. Antares (mv = +1.06) is 25° to the east of the eclipsed Moon, while Spica (mv = +0.98) is 22° west and Arcturus (mv = -0.05) is 37° to the northwest. The planet Jupiter will appear low in the west in Leo.
The eclipse will be widely visible from the Europe, Africa, Asia and Australia. North America will miss the entire event, but most of South America will witness the last stages of the eclipse which will already be in progress at moonrise. Similarly, the Moon sets in eastern Asia and Australia during various stages of the eclipse.
Table 2 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 section: Crater Timings During Lunar Eclipses).