COLUMBUS (WCMH) — The longest partial lunar eclipse in a century will become visible, clouds permitting, early Friday at 2:19 A.M Eastern time, when Earth’s darkest shadow will begin to cover the moon.

The peak portion of the near-total lunar eclipse will occur at 4:03 a.m. ET, when 97.4% of the moon will be cloaked by Earth’s shadow. The partial eclipse will end at 5:47 a.m., a period of 3 hours and 28 minutes.

The eclipse actually commences tonight at 1:02 a.m. ET, when the soft outer shadow of Earth (penumbra) begins to cross the full moon, though this will hardly be noticeable until the deeper shadow (umbra) is observed a little more than an hour later. The entire duration of the eclipse, when a portion of the moon is covered by Earth’s shadow, is six hours, ending at 7:04 a.m., the longest lunar eclipse in 580 years.

The reason for the historically long duration is that the full Beaver Moon is at its farthest point in its elliptical orbit, or apogee, as it slides behind Earth tonight, according to Don Stevens, director of Perkins Observatory at Ohio Wesleyan University in Delaware, Ohio.

The partial lunar eclipse will be visible over virtually all of North America, and portions of South America, Europe, Australia and Asia.

Partial lunar eclipse will be visible in North America, and portions of South America, Europe, Australia and Asia Nov. 18-19, 2021. (Credit: NASA)

A lunar eclipse occurs when Earth is nearly precisely aligned with the sun and moon. blocking out the sun’s light that comprises moonlight. A little red light is refracted or bent around Earth’s atmosphere and scattered on the surface of the moon, creating a reddish-brown or rust caste, known as a “blood moon.”

“Our atmosphere acts as a lens bending the light of the Sun around the planet. It bends mostly the red light because our atmosphere scatters most of the blue part of the light coming from the Sun. That’s what makes the sky blue on a clear day and why the sunsets are red,” Stevens explained.

Stevens noted that “If you were standing on the moon during the lunar eclipse, you would see a sunset all the way around Earth. It will almost look like a ring of fire.”

“When the Moon is at the closest point in its orbit, it moves faster. When it is at its farthest point, it moves slower,” Stevens said. 

The full beaver moon reflects the naming of a full moon by Native Americans at a time when beavers were preparing for winter. Dress warmly, since temperatures will be in the low 30s and upper 20s during the partial eclipse. The moon will leave Earth’s umbra at 5:47 a.m.

A lunar eclipse is more widely seen than a solar eclipse when Earth is turned away from the sun. No special viewing glasses are needed for a lunar eclipse since you are only seeing reflected sunlight. (A solar eclipse can only be safely viewed with specially filtered glasses without risking permanent eye damage.)

The next total solar eclipse, when the moon passes between the sun and Earth. visible in the United States occurs on April 8, 2024, which will reach totality over the northwest half of Ohio–a rarity.