Late night near miss total lunar eclipse
Another Blood Moon is on the way over Butler! Catch a nap this Thursday afternoon, because later that night we’ll have a lunar eclipse beginning after 10:30 p.m. It’s not officially a total lunar eclipse, but it’s about as close as it can be to one. Total lunar eclipses are also known in our pop culture world as Blood Moons. Despite its menacing moniker, the Blood Moon should be enjoyed, not feared.
Lunar eclipses, or Blood Moons, if you insist, occur when the Earth is nearly in a straight line between the sun and the moon and the moon slips into the Earth’s shadow, as you can see in the diagram. The Earth doesn’t have to be in an exact line between the sun and the moon, because at the distance of the moon, the Earth’s umbra shadow is around 5,500 miles wide. Since the moon is less than 2,200 miles in diameter, getting into the Earth’s shadow isn’t a huge accomplishment. There’s plenty of the Earth’s shadow to go around.
We don’t have a lunar eclipse every full moon because the moon’s 27.3-day orbit around the Earth tilts by five degrees with respect to Earth’s 365-day orbit around the Sun. Because of that, the full moon misses the Earth’s shadow most of the time. This time around however, the full moon is full at one of the two points where the moon’s orbital plane nearly intersects the Earth’s orbital plane — the right place at the right time for a total lunar eclipse.
On Thursday evening around 10 p.m., the full moon will be shining in the low southeastern sky. At 10:33 p.m., you’ll start to see the moon begin to darken on its lower left side. Over the next several hours, the darkening will continue to increase, advancing to the lunar disk's right side. The circular edge of the shadow is visual proof that the Earth is indeed round.
At 12:19 a.m., the moon will be almost totally eclipsed. I say almost because all but the extreme upper edge of the moon will be darkened. The moon could take on an orange or bloody red hue. That’s why this is not officially a lunar eclipse. No one can really predict what shade the eclipsed moon will take on. Only the shadow knows — the Earth’s umbra shadow that is. The umbra shadow is not completely dark because some of the sunlight does manage to get through Earth’s atmospheric shell, as you can see in the diagram. The light that does get through is bent and strained as it comes through our atmosphere. All of the blue and yellow components of the light are scattered away, leaving just the red to bathe the eclipsed moon. The color of red light that reaches the moon is determined by Earth's atmospheric conditions, which affect the sunlight as it passes through on its way to the moon.
No matter what shade of red the moon takes on, it will be beautiful and perfectly safe to view. You don’t have to look through any special glasses or anything else. An occasional gander through a telescope at the eclipsed moon is nice. Still, I think it’s a wonderful experience to watch it with just your natural eyesight or maybe a pair of binoculars. After the mid-eclipse at 11:59 p.m., the moon will begin to gradually retreat from Earth’s shadow. The moon is totally out of Earth’s shadow at 1:52 a.m. Friday morning.
I hope you enjoy the lunar show in the late-night hours this Thursday. Let’s hope for clear skies because the next lunar eclipse isn’t until Jan. 11, 2028, but that’ll just be a very slight partial eclipse. The next total eclipse around here won’t be until June 28, 2029!
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is also the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and at adventurepublications.net. Contact him at mikewlynch@comcast.net.
