The night sky will give us quite a show Saturday night as the first of two total lunar eclipses in 2007 occurs. This eclipse will be unique in that does not discriminate and will be at least partly visible from every continent around the world. This eclipse occurs at the descending node, 3.2 days before apogee and 1.9 days after the Moon occults Saturn (northern and eastern Europe).
Keep an eye on Leo, as the Moon will be in southern Leo, about 13º east of the 1.3-magnitude star Regulus (alpha Leo) during the eclipse. 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
Observers in Nigeria and Cameroon will see the Moon at in the zenith the instant of greatest eclipse (23:21 UT). 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.