This diagram shows that the Moon enters the very narrow, complete shadow of the Earth (Umbra) during a Total or Partial Eclipse of the Moon, while the Moon enters the much wider, but only partial shadow of the Earth (Penumbra) during a Penumbral Eclipse of the Moon. (Image Source: Wikipedia.org )
By Glenn A. Walsh
Reporting for SpaceWatchtower
The last Lunar Eclipse or Eclipse of the Moon for 2013 will be a minor Penumbral Eclipse of the Moon on Friday evening (2013 October 18). Unlike a Total or Partial Eclipse of the Moon, a Penumbral Eclipse of the Moon is more difficult to notice, because only a partial shadow of the Earth falls on the Moon. Unlike a Solar Eclipse or Eclipse of the Sun, an Eclipse of the Moon is safe to view with the naked-eye, binoculars, or a telescope.
Friday's Penumbral Eclipse of the Moon will be visible for most viewers on our planet (except Australia, Japan, Pacific Ocean islands, a large portion of Alaska, most of Siberia, and a small portion of northeastern China.). However, in the Americas it will be visible as the Moon is rising, while in most of Asia it will be visible as the Moon is setting.
Although NASA describes Friday's eclipse as "a relatively deep penumbral eclipse with a magnitude of 0.7659," do not expect a darkened Moon, as might be seen in other Total or Partial Lunar Eclipses. It will simply appear a wee bit darker than a normal Full Moon.
As North American viewers will see this eclipse shortly after sunset, and while the Moon is rising, this will make it even more difficult to notice any shading on the Moon. While the Moon is rising, light from the Moon has to travel through a greater amount of Earth's atmosphere to reach a viewer's eyes. And, at this time, the Earth's atmosphere is not completely dark, as the Sun has just recently set.
The event will probably not be visible to most people until about 66 percent of the Moon's disk is immersed in the Earth's penumbra shadow. This is estimated to occur between 7:30 and 8:10 p.m. Eastern Daylight Time (23:30 October 18 to 0:10 October 19 Coordinated Universal Time); the time of greatest eclipse is 7:50:16.9 p.m. Eastern Daylight Time (23:50:16.9 Coordinated Universal Time). Then a dusky shading of the southern half of the Moon could be visible, depending on atmospheric conditions and the ability of a viewer to detect minor shading.
All Lunar Eclipses occur at the time of a Full Moon. This month, the Penumbral Eclipse of the Moon comes on the day of the Hunter's Moon: 7:38 p.m. Eastern Daylight Time (23:38 Coordinated Universal Time). The Hunter's Moon often occurs when many leaves have fallen off of the trees and the harvesting of most crops has been completed. Hence, with a bright Full Moon appearing shortly after sunset, tree leaves no longer blocking the moonlight, and fields cleared of crops, it created the best time to hunt for meat, to store for the long Winter ahead.
More on this Penumbral Eclipse of the Moon from NASA:
Link >>> http://eclipse.gsfc.nasa.gov/OH/OH2013.html#LE2013Oct18N
Information from Wikipedia.org on --
This Penumbral Eclipse of the Moon: Link >>> http://en.wikipedia.org/wiki/October_2013_lunar_eclipse
Lunar Eclipses, in General: Link >>> http://en.wikipedia.org/wiki/Lunar_eclipse
Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
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