If you happen to be a night owl, you may be able to catch a glimpse of the first total lunar eclipse in three years.
This lunar eclipse is called the “blood worm moon,” partly because of its reddish hue. GBH meteorologist Dave Epstein joined GBH’s All Things Considered guest host Judie Yuill to explain tonight’s show in the sky. What follows is a lightly edited transcript.
Judie Yuill: Now, let’s start with the basics. What occurs during a total lunar eclipse?
Dave Epstein: During a lunar eclipse, the light from the sun — which typically shines on a full moon — is blocked by the Earth. So, the Earth’s shadow is casting across the moon and giving it that reddish glow.
The light’s not completely out; it’s not like a light switch, but we get that wonderful bloodish color from the lineup of the sun, the earth and the moon. It’s called “syzygy,” if you want a technical name for it.
Yuill: Now, why is this called the “blood worm moon?”
Epstein: So, the full moons are given different names by Native Americans, and the March moon is called the worm moon. So regardless of whether we’re having an eclipse or not, that’s the name of the moon.
And then, because we’re going to see this total lunar eclipse, it’ll give the moon a little bit of a reddish or bloodish color. They put together the fact that it’s a blood-looking moon with the fact that it’s a full worm moon, and thus, you get the “blood worm moon.”
Yuill: What causes that red color?
Epstein: The red color is basically the fact that you can’t block out all of the light, so there’s a little bit of light there — it’s like [partially] lit-up, and that gives it that reddish color. Also, the surface of the moon, with some of the colors of the ground, is there as well. That’s why we have that reddish hue to it; it’s not completely blacked out.
Yuill: I know sometimes it seems as though [Native Americans] were naming moons in more agrarian times or at times with more farming. Does the worm refer to spring coming?
Epstein: Yeah. I think it refers to the fact that this time of year is when the worms are coming out. We had some rain a few days ago. I was actually walking around and noticed a few worms popping out of the ground. The ground’s beginning to thaw out; the worms are now getting more active, so it’s sort of what folks noticed.
You have a snow moon, a cold moon, a hunter’s moon … so, all these different things are named because of what’s going on in agrarian — or just in life back then.
Yuill: The last total lunar eclipse happened three years ago. Is that the usual amount of time between these events?
Epstein: It really depends on where we are in the cycles. We have another one coming up in 2026, and there’s going to be a partial one, so we won’t get to see the entire eclipse. And then, in 2029, there’ll actually be two — one of which we’ll see the entire one, and the other we’ll see most of it.
So, it just depends. There [will be] two in one year towards the end of the decade.
Yuill: We’re always told not to look directly at a solar eclipse without those special glasses. It is safe to watch this?
Epstein: Absolutely. I mean, it’s like looking at the moon when it’s full; there’s no problem there. You’re going to have less light than more, so look at it as much as you want and take pictures. Of course, we’ll need to have clear skies.
Yuill: Well, that’s my next question — will the weather conditions be favorable?
Epstein: It’s a great question, and I can say this: We’re sort of on the cusp of whether or not this is going to be visible or not. It’s not 100% sure that it’s going to be visible, nor is it a high percent sure it’s going to be visible. I think that it’s sort of a 50-50 [chance].
It’s definitely worth getting up and looking to see whether or not you get to see it, but I think we’re going to see partially clear skies. It begins at 2:26 in the morning and ends at 3:31, with the maximum at 2:30 in the morning. That’s when the moon will be most covered.
Yuill: Let’s say the skies are clear. Who would be able to see it?
Epstein: Everybody! It doesn’t matter — even if you’re in the city of Boston and the bright lights from the city are there. You know, normally, we talk about … sometimes there’s a star or a constellation that I’ll talk about, and I’m like, “You’ve got to get to dark skies for a comet.”
Not this time. The moon is the moon. It’s bright enough. It shines through all the ambient light that we have. I’d say the one thing about this particular eclipse is that it starts in the wee hours of the morning, so you’re going to either have to stay up really late or get up really early in order to see it.
