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| Penumbral Eclipse |
Friday evening the Moon will have a close encounter with the Earth's shadow 240,000 miles out in space. As the Moon reaches its full phase just after sunset (from the west coast), it will darken somewhat as it passes through the light outer shadow of the Earth. This shadow is called the 'Penumbra' and is not as dark as the central 'Umbral' shadow so this won't be a blood Moon or anything even close to that. But for the careful observer it will be an interesting sight as the Moon rises in mid-eclipse and displays a darkening on its upper limb as it enters the Earth's penumbral shadow. The Moon rises at 5:45 pm for viewers in San Francisco and will already be well along in the eclipse for viewers in the eastern USA and Europe.
This eclipse marks the start of an '
Eclipse Season' in which we will experience one Lunar Eclipse (in this case a Penumbral Eclipse) and two weeks later a Solar Eclipse (in this case an Annular Eclipse visible only in the southern hemisphere). Eclipses come in waves approximately every six months and this particular Eclipse Season is the last one before the
Total Solar Eclipse of 2017 across the United States.
Sky & Telescope has an
excellent online article detailing the February 10th Penumbral Eclipse in much more detail.
Image courtesy Sky & Telescope.
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