Focus on Arts and Ecology

The 6-hour partial lunar eclipse on Nov. 19 won’t have an equal for another 648 years.

ByMichael d'Estries, Published November 17, 2021

In the early morning hours of November 19, the Earth’s shadow will begin a slow creep across the lunar surface, transforming it from a standard pearly white into eerie shades of red. Only 3% of the full Moon’s surface will remain untouched, dropping it into the partial lunar eclipse category by the smallest of margins. 

“This is an exceptionally deep partial eclipse with an umbral eclipse magnitude of 0.9742,” explains EarthSky. “With just a thin sliver of the moon exposed to direct sun at maximum eclipse, the rest of the moon should take on the characteristically ruddy colors of a total lunar eclipse.”

Before you scoff and vow only to sacrifice sleep for a full lunar eclipse, know this: a partial lunar eclipse of this extreme duration hasn’t happened since February 18, 1440—or around the time Machu Picchu was considered brand new and Johannes Gutenberg was hard at work on something called “the printing press.” It won’t be surpassed until February 8, 2669. In that span of 1,200 years featuring 973 partial lunar eclipses, this is the big one. 

Witnessing a once-in-a-millennium event is a pretty decent excuse for one day’s worth of sleep-deprived exhaustion, right? 

Why Is This Partial Lunar Eclipse the Longest in Centuries? 

As a quick primer, a lunar eclipse (both partial or full) occurs when the Moon and Sun are on the exact opposite sides of the Earth. The Moon’s orbit takes it through two different portions of the Earth’s shadow. The first, called the penumbral, is the lighter inner and outer shadow. The second is called the umbral and is the innermost and darkest part of the Earth’s shadow. 

While total and partial lunar eclipses always happen when the Moon is full, the distance at which this unfolds isn’t always the same. This is because the Moon’s orbit around the Earth is elliptical, bringing it as close as 221,500 miles (called perigee) or as far as 252,700 miles (called apogee). The farther away the Moon is, the longer it takes to cross through Earth’s shadow. 

On November 19, the Moon will be very close to apogee. As a result, the time to pass through both the inner and outer shadow of the penumbral will take about 6 hours and 2 minutes. The middle umbral phase alone will last just over 3 hours and 28 minutes. According to EarthSky, this makes November’s partial eclipse longer than most total eclipses.1 

When Should I Look Up and What Should I Expect to See? 

In terms of global viewing, people in North America will have a front-row seat for this partial eclipse, as will those residing in Japan, New Zealand, Eastern Australia, and anywhere in the Pacific Ocean. 

The Moon will enter the outer edges of the Earth’s shadow at approximately 1:02 a.m. EST, reaching maximum eclipse three hours later at 4:02 a.m. EST, and concluding at 7:03 a.m. EST. (You can check your own local timeline for the eclipse here.)

During the deep umbral stage of the eclipse (lasting from about 2:30 a.m. EST to 5:30 a.m. EST), the Moon’s surface will take on a hauntingly beautiful red color. This is because, despite the Earth blocking direct sunlight, refracted light in its atmosphere still manages to cast its glow on the lunar surface. 

"Lunar eclipses ... reflect our world," astronomer and podcaster Pamela Gay tells Space.com. "A blood-colored moon is created [by] ash from fires and volcanoes, ... dust storms and pollution all filtering sunlight as it scatters around our world.”

Right Place, Right Time

So, congrats! Of all the humans that have lived since the 15th century and all those to come leading up to the 27th, you are alive at this special moment to take in a celestial event centuries in the making. Of course, there will be other lunar eclipses to marvel at (there are on average about three each year), but this one demands your attention. So make your mark on history, fist-pump the night sky in the predawn hours, and proudly exclaim to the blood Moon that you were there! 

And then go and get some sleep. You’ve earned it. Wishing you clear skies!

(Sources: Treehugger)