Here’s how to watch this week’s ‘blood moon’ lunar eclipse – The Boston Globe

This particular eclipse isn’t “total,” but in some ways that makes for a more unique viewing experience.

With about 96 percent of the Moon covered by Earth’s shadow, a small sliver will remain illuminated, while the rest of the moon takes on a reddish-copper “blood moon” glow, similar to a penny, at its peak just after midnight. With a solar eclipse, you really need totality for the “wow factor,” but this lunar eclipse still should be pretty cool to see if we get clear skies.

Here’s the timing of the eclipse (all times local for Boston):

• Penumbral eclipse begins: 9:23 p.m.

• Partial eclipse/umbral phase begins: 10:33 p.m.

• Maximum/peak eclipse: 12:12 a.m.

• Partial eclipse/umbral phase ends: 1:51 a.m.

As the eclipse begins, the Moon enters the penumbra, where the change in appearance is subtle. The penumbral shadow starts creeping across the Moon around 9:23 p.m. Thursday, but you won’t notice much until the umbra — Earth’s darker, inner shadow — begins touching the Moon at 10:33 p.m.

Once it enters the umbra, the effect becomes more dramatic, as the shadow takes an increasingly large bite out of the Moon. The shadow will get progressively deeper until maximum eclipse at 12:12 a.m., Friday, when 96 percent of the Moon will sit in shadow, giving off that stunning reddish, “blood moon” hue. This part of the eclipse will be visible in North and South America (except Alaska and northwestern Canada), parts of Western Europe and Western Africa.

The timing of maximum eclipse lines up almost exactly with the official full moon this month, at 12:18 a.m., which is called the Sturgeon Moon. Funny enough, I was watching sturgeon jumping in a cove in Central Maine this weekend — now I know why it’s called that.

The Moon will pull out of the umbra by 1:51 a.m.

Here’s what the forecast cloud cover looks like today:

This eclipse is part of Saros 138 — a series of lunar and solar eclipses that repeat roughly every 6,585 days, or 18 years, 11 days, and eight hours, to be precise. This particular series began in 1521 and won’t wrap up until year 2982. Every eclipse in that series since 1918 has been partial, and this one, at about 96 percent, is the deepest of the bunch.

The next one in the series, in 2044, will finally be total.

For those of you who want to impress your friends, or consider yourself a numbers geek, here are some more fun facts about this eclipse. This is the fourth lunar eclipse over the past 18 months, part of what’s called an “almost tetrad.” It started back in 2025, with the total eclipse on March 14, then another total eclipse on Sept. 8. Earlier this year, on March 3, we got a third total eclipse. Thursday’s eclipse is the fourth and final one in that stretch, but since this one falls just short of total, astronomy enthusiasts are calling it an “almost tetrad” rather than a true tetrad. A true tetrad, four totals in a row, last happened in 2014 and 2015. The next one isn’t until 2032 and 2033.

So let’s hope the weather cooperates and we get a great look at this lunar eclipse. Get outside!