Though it’s technically not a total lunar eclipse, it’s about as close as one can get to totality without actually being there. At peak, 97 percent of the moon will be covered by the umbra, or the darkest part of Earth’s shadow. Only a sliver on the bottom left of the moon will remain faintly illuminated.
A striking element of Thursday night’s eclipse will be its duration — 3 hours, 28 minutes and 24 seconds, according to Space.com, which says that will make it the longest partial eclipse in 580 years.
At the time of the eclipse, the moon will be full. Some refer to the November full moon as the “beaver moon,” a name assigned by Native Americans when beavers were particularly active in preparation for winter and it was time to set traps, according to NASA. The November full moon is also sometimes called the frost, frosty or snow moon for the wintry conditions beginning at this time of year, NASA writes.
A moon, once eclipsed, is also sometimes called a “blood moon” because of its reddish or rusty tone.
The eclipse will begin when many people are asleep along the East Coast, but those residing on the West Coast don’t need to be night dwellers to take in the best parts of the show.
The lunar eclipse will begin at 1:02 a.m. Eastern time Friday, or 10:02 p.m. Pacific time Thursday. That’s when the penumbra, or peripheral darkening associated with the Earth’s shadow, will nick the moon. There won’t be much noticeable difference in how the moon appears. For that, you need to wait until 2:18 a.m. Eastern time, when the umbra begins traversing the moon.
There won’t be any “totality,” but the eclipse will grow deeper and more intense until 4:02 a.m. Eastern time, when more than 97 percent of the moon will be immersed in the umbra. It’s not technically a total eclipse, but for all intents and purposes, it is from a visual standpoint.
Lunar eclipses occur when the Earth intercedes between the sun and the moon. We’re used to seeing the full moon illuminated by light arriving directly from the sun, but when the Earth blocks that light, a shadow sweeps across the lunar surface. During total and near-total lunar eclipses, most of the moon’s face is occupied by that shadow, but some sunlight passing through Earth’s atmosphere can become tinged red and bathe the moon in an eerie amber hue.
Lunar eclipses are much more widely visible than solar eclipses and can be seen anywhere on the night side of Earth. Total solar eclipses are much more difficult to witness and may have a path of totality only a few miles wide. Both usually occur within a couple weeks of one another; a total solar eclipse looms on Dec. 4, but only watchers in the Southern Ocean or Antarctica will get to enjoy totality. For us, the lunar eclipse is a consolation prize.
Unlike with solar eclipses, no special glasses are required for viewing a lunar eclipse. You’re simply looking at sunlight reflected off the moon, rather than staring directly at the sun. The former is okay. The latter is a no-no.
The last total lunar eclipse visible from the United States occurred May 26, and another one is in the cards for May 16, 2022.
As for the next rare and dramatic total solar eclipse, the last one occurred in the United States on Aug. 21, 2017; the next is set for April 8, 2024.
The best weather for viewing the eclipse will focus over the middle of the country, where mostly clear skies are anticipated thanks to high pressure and sinking air.
Conditions will be less than ideal in other areas, where cloud debris slung overhead by a series of autumnal storm systems may spoil the show.
A strong fall cold front in the eastern United States will be pushing east a band of showers; it will probably move along much of the Interstate 95 corridor from New York City to Washington to the Carolinas shortly after sunset, with rapid clearing building in its wake. By 4 a.m. Friday, when the eclipse is near totality, skies will have probably cleared, although it will be rather blustery.
The forecast is especially tricky in New England, where the front will take a bit longer to clear. Despite the yellow and red shading, there will still be pockets of visibility, but the combination of lake-effect clouds and uncertainty in cloud cover trailing the departing front preclude green shading.
Upper-level flow is bringing more moisture to the high altitudes over the western United States, which is setting the stage for clouds ahead of the next larger-scale storm system.
Jason Samenow contributed to this report.