It seems that eclipses always happen in far-away places or at inconvenient times. But that’s not the case on Thursday, August 27, when, given clear skies, we’ll see a lunar eclipse during “primetime” from the Western Slope!
On August 27 the Sun sets late, around 7:46 PM MDT, which allows enough time to get home from work or school, eat dinner, and get ready for the lunar show. The eclipse begins at 7:21 PM MDT, before the moon rises locally at around 7:44 PM MDT. That’s when the eastward-moving Moon first touches the partial shade of the penumbra, the “less dark” part of Earth’s shadow. But we won’t miss much during these 23 minutes with no Moon, because the early stages of penumbral eclipses are almost undiscernible from Earth. But an astronaut on the Moon, standing within the penumbra, would see a partial eclipse of the Sun by the Earth. The real action starts at 8:33 PM MDT, when the partial eclipse begins as the Moon first encounters the umbra, the darker part of Earth’s shadow. This happens in fading twilight on the Western Slope with the Moon about 9 degrees above our east-southeastern horizon - that’s about the width of your fist held at arm’s length. Through binoculars, the edge of the umbra will look ragged, rather than sharp. That’s due to clouds and other features of Earth’s atmosphere. A lunar astronaut, standing within the umbra, would see a total eclipse of the Sun by the Earth, a phenomenon that was photographed by a robotic lunar lander during the eclipse of March 14, 2025. Such eclipses will be amazing experiences for future lunar explorers!
At the midpoint at 10:12 PM MDT, this eclipse becomes almost total, when 93% of the Moon’s diameter and 96% of its area are covered by the Earth’s umbral shadow. Although this lunar eclipse is not total, it’s almost as good – it’s a very deep, partial eclipse. Around mid-eclipse at 10:12 PM MDT, we’ll likely see the darkened part of the Moon glowing with an ashen, reddish light. The reddish hue is caused by sunlight that is bent by Earth’s atmosphere into the umbra. We’ll see the effects of countless reddish sunsets and sunrises around the periphery of the Earth as reflected by the Moon. After 10:12 PM MDT, the Moon will start moving out of Earth’s umbra, and the partial eclipse will end at 11:52 PM MDT, still early enough to get some sleep before dawn.
Let’s hope for clear skies on the evening of August 27, so we can enjoy an amazing lunar eclipse experience!
Music written and produced by Kenny Mihelich (ma-HELL-itch). Western Slope Skies is produced by the Colorado Mesa University Astronomy Club, the Western Slope Dark Sky Coalition, and KVNF Community Radio. This feature was written and voiced by Art Trevena.