Partial eclipse visible Friday evening

The last of three lunar eclipses of this year occurs Friday as the moon passes through the Earth's shadow. This partial penumbral lunar eclipse is the least impressive of the eclipses, but it is still worth a look between 7 and 9 p.m. Partly cloudy skies are expected to provide enough gaps to see the show.

Every shadow cast by a solid object, (like say, the Earth) has two parts. The umbra ("shadow" in Latin) is the center, darkest part and the penumbra ("nearly in shadow" in Latin) is the lighter area surrounding the umbra. About 75 percent of the moon will pass through that penumbra between 5:50 p.m. EDT and 9:52 p.m. EDT on Friday.

The sun sets and the moon rises around 6:30 p.m., but this won't the best time to view the eclipse. The moon will already be 40 minutes into eclipse, and skies won't be sufficiently dark here in central North Carolina to see much until twilight ends around 7 p.m.

Shortly before 8 p.m., the moon will be at its greatest point of eclipse. Look closely and you'll see that the top, right area of the moon is a bit brighter. Over the next two hours, the remainder will steadily grow in brightness until 9:52 p.m. when it leaves Earth's shadow and the full moon will show brightly again.

Looking forward to 2014, there will be a pair of total lunar eclipses.

Between 2 and 3 a.m. on April 15, 2014, the moon will slide into the Earth's umbra. It will be a rusty orange color for about an hour before exiting totality. Here in Raleigh, the first half of the total lunar eclipse on Oct. 8, 2014, will be visible before sunrise with first sunlight appearing in the sky just as it reaches totality.