If you’re interested in stargazing, especially lunar eclipses, you’re in for a special treat this week. The partial lunar eclipse that will take place in the early morning hours of Thursday, November 19, will be the longest since February 18, 1440 — about the time the Incas were building Machu Picchu in South America.
As an added bonus, the partial lunar eclipse will be visible in all 50 states. It also will be visible in South America and Australia, as well as across much of Europe and Asia.
Why Lunar Eclipses Occur
A lunar eclipse happens when the sun, earth, and full moon are perfectly aligned. However, it is a bit of a freak occurrence because the moon’s orbit around earth lies in a slightly different plane than earth’s orbit around the sun. That difference means the sun, earth, and moon cannot be in perfect alignment during each full moon.
Here’s what happens during a lunar eclipse.
“Earth casts two shadows that fall on the moon during a lunar eclipse: The umbra, a full, dark shadow, and the penumbra, a partial outer shadow,” Space.com explains. “The moon passes through these shadows in stages. The initial and final stages — when the moon is in the penumbral shadow — are not so noticeable, so the best part of an eclipse is during the middle of the event when the moon is in the umbral shadow.”
What Will Happen
The penumbral phase, when the moon begins to be covered by earth’s shadow, will begin at 1:02 a.m. EST on November 19. The overall duration of the eclipse — from the moment the moon enters earth’s penumbra, to the moment it leaves — will be just over 6 hours.
Since the event will be a partial lunar eclipse, earth’s dark, umbral shadow will cover almost 97 percent of the full moon’s surface. That means just a thin sliver of the moon will be exposed to the sun’s rays.
When You Can See The Partial Lunar Eclipse
As was noted, the partial lunar eclipse will begin at 1:02 a.m. on November 19. The event won’t conclude until just after 7:00 a.m.
If you’re thinking 6 hours seems like an unusually long time for a partial lunar eclipse, you’re right. Here’s why the event will take so long.
“The maximum point of the eclipse comes about 41 hours before the moon reaches apogee, its farthest point from earth,” Space.com explains. “The farther away the moon is, the slower it travels along its orbit, which means it takes longer to pass through earth’s shadow.”
You can check to see when the partial lunar eclipse will be visible in your location here.
If the sky will be cloudy in your location or the weather makes being outside unenjoyable, you can watch a live stream of the lunar eclipse here.
One More Thing
A lunar eclipse, of any type, only occurs during a full moon. November’s full moon is known as the Beaver Moon.
“The full moon for November is named after beavers because this is the time they become particularly active building their winter dams in preparation for the cold season,” timeanddate.com explains. “The beaver is mainly nocturnal, so they keep working under the light of the full moon.”
November’s full moon is also sometimes known as the frost moon because many areas across North America begin to experience frost during November.
While you’re thinking about it, be sure to read the rest of our stargazing content, including: