| 2024 Sep 17: Challenging Partial Lunar Eclipse (2023-12-17) ⬅︎ |
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Shortly after sunset on September 17, a partial lunar eclipse will be occurring in the Starry Hill region. Part of the Moon will be turning deep red. But several factors will make seeing the 'red' very challenging.
As the Sun sets in the west at 7:15 PM, the Moon will rise in the east just two minutes later. But the eclipse will have already started over an hour earlier... at 5:41 PM. Stargazers much further to the east will have the opportunity to watch the entire eclipse but not those in Washington State.
The eclipse will reach its maximum at 7:45 PM -- less than an half hour after moonrise. This means the Moon will still be quite low in the eastern sky -- just 4° above the horizon. So, to view the maximum, a location with an unobstructed view of the horizon to the east will be essential. This also means that the sky will still be bathed in twilight making the Moon dim and somewhat difficult to see.
An additional challenge is that only a small part of the top of the Moon -- just 3.5% -- will enter the umbra and turn deep red.
Here's some background info on lunar eclipses... first imagine sunlight shining on the earth. The earth, of course, blocks some of the light which
creates a shadow that extends into space beyond the earth. The shadow is a bit complex in that it has two parts --
a central umbra that is red since earth's atmosphere scatters the blue light that grazes its edges. Surrounding the
umbra is a much lighter penumbra which is more neutral in color.
The Moon crosses the region of space with the shadow at Full Moons. Most of the time, the Moon travels either above or below the shadow. But if the geometry is just right, it may enter the penumbra and darken and then enter the umbra partially or totally and appear part or all red.
With the eclipse on September 17, only a small part of the Moon will enter the umbra. Since the Moon will be low and dim at the time of maximum, it will help to have binoculars or a small telescope to capture more light.
With such a challenge, if you are able to spot the reddening Moon, it will be quite an accomplishment.
Good luck!
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