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Total Lunar Eclipse 20/21 Feb 2008

The only total Lunar Eclipse of 2008 occurs on the evening of 20/21 February (there will be a partial Lunar eclipse on 16th Aug 2008). This will be visible from the Mid West. A Lunar eclipse occurs when our Moon’s path takes it through the Earth’s shadow cone.

The Full Moon will be just under and to the right of the constellation of Leo, with Saturn 4º east (to its left), making a rather nice backdrop during the eclipse. From the Mid-West, the eclipse starts at 23.45 on 20th Feb. as the outer part (penumbra) of Earth’s shadow starts to eat into the disc of the Moon from the lower left. By 00:40 on 21st Feb. the Moon will be completely in the Penumbra. The Moon will then start to enter the central shadow of the Earth, called the Umbra. At 02:00 it will be completely in the Umbra and will be totally eclipsed between 02:00 and 03:00, before exiting the shadow.

How the Moon looks when it is totally eclipsed is what causes great interest and excitement for observers. If our planet’s atmosphere is very dusty or cloudy, the Full Moon that night may disappear completely to the naked eye, but don’t worry, wait an hour and our familiar natural satellite will once again become resident in our night sky. Alternately, it may turn an orange or red colour, an effect caused by sunlight bending around a clear Earth atmosphere before striking the Moon. The event finishes at 05:00 the following morning.

Though a lunar eclipse offers us little science opportunities today, in comparison say to a solar eclipse, it is none the less a lovely phenomenon to observe, especially since it is relatively infrequent. You do not need any optical aid to watch the eclipse, but it can be fun to watch the edge of the shadow race across the lunar surface through a pair of binoculars or a small telescope. Why do we not get an eclipse at every Full Moon? The Moon’s orbit of the Earth is tilted about 5 degrees to that of the Earth’s, so that as it passes behind us in relation to the Sun, this tilt and the narrow shadow cone are sufficient to avoid it passing into darkness on every orbit. It thus depends upon the very precise alignment of the Moon, Earth and Sun in order to obtain a total eclipse. It is rare, so enjoy it. Let’s hope for clear skies.