Why The Moon Turns Red During An Eclipse & How It Looks From Lunar Orbit?

Space.com

Ernie Wright, a science visualizer at NASA, explains why the moon turns red during a lunar eclipse. Wright also explains how the eclipse would look from the moon in this interview with Space.com's Chelsea Gohd.  Credit: Space.com | Animation: NASA/GSFC / Footage: Griffith Observatory | edited by Steve Spaleta

Transcript

00:00Lunar eclipses, especially total lunar eclipses, are really exciting sky-watching

00:08opportunities for astronomers, families, really all enthusiasts around the world.

00:14What can people looking to see an eclipse expect to see?

00:19Well, during a total lunar eclipse, during totality, the moon turns this copper-red color.

00:26It's weird, and it's beautiful and unusual, and it's caused by light refracting through

00:33the atmosphere of the Earth. So if you're on the moon, you're seeing every sunrise and sunset all

00:40around the Earth, and that light sort of filters into the shadow. It's a way for the Earth to sort

00:46of reach out and touch its nearest neighbor. Definitely. So it might be more colorful than

00:54people are expecting. Yeah, exactly. And the color can vary from one lunar eclipse to another.

00:59It depends on how close the moon is to the center of the shadow. It depends on how much dust and

01:07aerosols and all kinds of things are in the Earth's atmosphere. And it's something that amateur

01:13astronomers can participate in, sort of rating the darkness of the moon and the color of the moon,

01:20because that gives us some insight into what causes the color. We don't fully understand it.

01:27So in that we can't fully understand it, it seems that we also can't fully expect

01:33exactly what's going to happen, but we have a general idea of what we're going to see.

01:37That's right. So it's hard to predict. I mean, we know some of the factors like depth in the shadow,

01:44but we don't know exactly what stuff in the atmosphere, the Earth's atmosphere,

01:49creates some of that color. So the more we observe these and the more we record them and are careful

01:56about, you know, deciding what color it is, the better we'll be able to understand and maybe predict in

02:00the future what color they'll be. Definitely. So how long do lunar eclipses typically last,

02:08and why do they last so much longer than solar eclipses? Well, the Earth's shadow is so much

02:14wider than the moon's shadow. Yeah, the great thing about lunar eclipses is that, you know,

02:20an entire half of the Earth can witness them. It's just the nighttime half gets to see,

02:24gets to see it. You don't have to be in a very specific place the way you do with a solar eclipse.

02:32And, you know, with the shadow being as wide as it is, the eclipses will vary depending on whether

02:40the moon is is just skirting the edge of the shadow or going right through the center of it.

02:46So and maybe the inconvenient part of a lunar eclipse is that it happens at night and sometimes

02:52it's early in the morning and it's three o'clock in the morning and you're like, I don't know if I

02:56want to do this. But I think it's always worth getting up to see. Every time I have an opportunity

03:03to see one, I'm up no matter what time it is. Absolutely. Now, I'm curious, this is a little

03:08bit of a more oddball question, but could you predict what a lunar eclipse might look like from

03:15the surface of the moon? Actually, Apollo 12 witnessed something very much like a lunar eclipse.

03:23The the space capsule passed through the Earth's shadow. And you may know that Alan Bean was became

03:29a painter after he came back to Earth and he painted this several times. Alan's paintings are sometimes

03:36kind of impressionistic. So the colors are more interesting than the reality. But

03:42what he captured was the brilliant ring of bright sunrises and sunsets, how bright that is, how

03:52visually interesting that is. I think it would be great if we had astronauts on the moon to witness

03:58this. Also during Apollo 15, there was a plan to use the camera on the rover to watch a total lunar eclipse.

04:09It was going to happen a couple of weeks after the astronauts left. But one of the one of the gears

04:16that allowed the the camera to point wasn't working after they left. And so we missed that opportunity.

04:22But it's a you know, it's a it would be a cool reason to go back just to be there during a lunar eclipse

04:29and see what the Earth looks like. Definitely. Now, so the rover, you know, the rover's camera,

04:34things didn't go according to plan, but we do still have spacecraft orbiting the moon. There's China's

04:40Changi 4 rover still on the moon. What might these spacecraft see during an eclipse? Like what what

04:47might it look like to them? I well, I work with Lunar Reconnaissance Orbiter and it's a solar powered

04:53mission. So one of the one of the aspects of a lunar eclipse for LRO is that its power gets turned off,

05:00basically. You know, LRO orbits the moon every two hours. It goes through night time every 45 minutes.

05:07So there's a battery on board and that kind of gets it through the night side and and then it charges

05:12back up. But during lunar eclipses, a lot of times it'll come around from the night side and the sun

05:17still isn't there. So it has to run on battery power for, you know, a couple of extra hours. And so LRO has

05:24to make preparations for that. Usually most of the instruments get turned off and the things that

05:32they leave on are like the heater, something important to keep all the stuff from freezing.

05:37But it's a it's a challenging sort of operational thing that LRO does. So it's not it's not having

05:45the same kind of fun that we have on the Earth. It's it's actually having to protect itself.

05:50Yeah. So I don't I don't know of any any missions like LRO that have actually turned to the Earth

05:58during an eclipse and taken a picture of it, because I think that would be really cool.

06:03I'd like to see it. Right. Definitely. So I just have one more question for you,

06:09you know, leaving it off on something fun to you. What's the most amazing part of watching a lunar eclipse?

06:16Yes. Well, I always I mean, I'm a little biased because I work with moon data all the time.

06:22So I'm always going outside and sort of looking up and spending at least a couple of seconds

06:27and contemplating the moon and what it means. But a lunar eclipse is such a spectacular visual event

06:33that you get caught up in it. And, you know, during the partial phases, you see the moon sort of getting

06:38slowly eaten away over the course of maybe an hour, an hour and a half. And then suddenly it's it's

06:46quite a bit darker, but it's also this deep red color. And you're like, it's a it's a chance for

06:53you to sort of think about your place in the in the cosmos, you know, this this alignment of the sun

06:58and the earth and the moon spending just a little bit of time thinking about how amazing that is and

07:06how cool it is. And you are in a very specific place to be able to see it. You know, aside from

07:13just the visual beauty of it, I like thinking about that aspect of it.

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