03-03-2007 Total Lunar Eclipse (Article 75)

Simon Kenny · Post by **Simon Kenny** » Wed Feb 04, 2009 10:44 am

Total Lunar Eclipse (Article 75)

The only Total Lunar Eclipse of 2007 occurs on evening of 3rd March, when our Moon’s path takes it through the Earth’s shadow cone. If our planet’s atmosphere is very dusty or cloudy, the Full Moon that night may disappear completely to the unaided 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 atmosphere before striking the Moon. See image from 2001 eclipse captured by SAC club member Dave Lillis.

The Full Moon rises in southern Leo, with Saturn to its upper right, making a rather nice backdrop during the demise of the lunar light. From the mid-west, the eclipse stars at 21.00 as the outer part (penumbra) of Earth’s shadow starts to eat into the disc of the Moon from the lower left. The total eclipse is between 21.45 and 22.40, when the Moon lies within the umbral part of the shadow before exiting the shadow to left to right. The event finishes at 01.12 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. Our March meeting on 7th reviews the Galileo Mission to Jupiter with Ronan Newman, Galway Astronomy Club.