Early risers and night owls across the United States enjoyed a near total lunar eclipse Friday morning, during which 97 percent of the moon’s visible surface was immersed in an eerie rusty-brown hue. The eclipse peaked in magnitude at 4:02 a.m. Eastern time but was visible in partial stages for hours as the Earth’s shadow swept across the otherwise full “beaver” moon.

The Native Americans called the November full moon the beaver moon because the rodents are active in preparation for winter at this time of year, according to NASA.

Once eclipsed, the beaver moon morphed into a “blood moon” because of its reddish or rusty tone.

Friday morning’s partial lunar eclipse was the longest lasting since 1440, some 52 years before Columbus began his voyage across the Atlantic. A whopping 3 hours, 28 minutes and 24 seconds elapsed between the time the umbra, or darkest part of the Earth’s shadow, first nicked the lunar disk and the time it finally withdrew.

For those who missed it, there’s a total lunar eclipse coming up on May 16, 2022. Thursday morning’s lunar eclipse also precedes a total solar eclipse that will cast a thin shadow over a slice of Antarctica on Dec. 4, but only intrepid adventurers who travel by plane or ship will see it. Ordinarily, eclipses come in pairs about two weeks apart.

Lunar eclipses occur when the Earth intercedes between the sun and moon, blocking sunlight from illuminating the lunar surface. Common sense dictates that the moon should be plunged into darkness, its light source occulted and extinguished. That doesn’t happen though. Instead, the moon turns red as sunlight passes lengthwise through the Earth’s atmosphere and is refracted, or bent, toward the moon.

Because the sunlight is passing through the Earth’s atmosphere at a low angle, it has more air to pass through. The gaseous molecules that comprise the atmosphere scatter short wavelengths, allowing only the reddish hues to penetrate. It’s the same premise that explains why sunrises and sunsets appear orange and red.

During a total lunar eclipse, the light that illuminates the moon is that which is simultaneously responsible for every sunrise and sunset on Earth. In a sense, witnessing a near-total or total lunar eclipse is like watching a projection of the world population’s collective starts and ends to their days.

The color of a lunar eclipse can be an indicator of aerosols or tiny particles present in the atmosphere. The total lunar eclipse of June 10, 1816, was exceptionally dark, coming a year after the explosive eruption of Mount Tambora in Indonesia. Tambora’s eruption was the most powerful in recorded human history, the volcano ejecting up to 50 cubic miles of material into the atmosphere. That proved enough to darken the moon.

Astronomer Henrik B. Claussen, who worked at the University of Copenhagen in Denmark, studied ice cores from Greenland using equipment that gauges electrical conductivity, and found an abundance of sulfate particles tied to the volcano in the layer corresponding to 1816.

Scientists use the Danjon Scale to ascribe a 0 through 4 categorical value to the shading of a lunar eclipse. Colors can vary markedly between eclipses. Eclipses that are hardly visible earn a zero, like the Dec. 9, 1992, one that followed the 1991 eruption of Mount Pinatubo in the Philippines.

Thursday night’s near-total lunar eclipse exhibited coppery red tones, likely mapping to a 3 on the scale. While cloudy and inclement weather spoiled the show for many in the western United States, many skywatchers in the central and eastern parts of the country were treated to a memorable celestial spectacle. Things were dicey in the Northeast where a cold front was found, but rapidly clearing skies behind the front made for some stellar photo-ops.

Check out these shots from readers, mostly from the Mid-Atlantic: