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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
00:02Lunar eclipses, especially total lunar eclipses, are really exciting sky-watching
00:08opportunities for astronomers, families, really all enthusiasts around the world.
00:13What can people looking to see an eclipse expect to see?
00:18Well, during a total lunar eclipse, during totality, the moon turns this copper-red color.
00:27It'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
01:07and
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 deciding what color it is, the better we'll be able to understand and maybe predict in the future
02:01what color they'll be. Definitely. So how long do lunar eclipses typically last and why do they last
02:09so much longer than solar eclipses? Well, the Earth's shadow is so much wider than the moon's shadow.
02:16Yeah, the great thing about lunar eclipses is that, you know, an entire half of the Earth can witness
02:22them. It's just the nighttime half gets to see it. You don't have to be in a very specific place
02:29the
02:29way you do with a solar eclipse. And, you know, with the shadow being as wide as it is,
02:38the eclipses will vary depending on whether the moon is is just skirting the edge of the shadow or
02:43going right through the center of it. So and maybe the inconvenient part of a lunar eclipse is that it
02:51happens at night and sometimes it's early in the morning and it's three o'clock in the morning and
02:55you're like, I don't know if I want to do this. But I think it's always worth getting up to
03:00see.
03:01Every time I have an opportunity to see one, I'm up no matter what time it is.
03:07Absolutely. Now, I'm curious, this is a little bit of a more oddball question,
03:10but could you predict what a lunar eclipse might look like from the surface of the moon?
03:17Actually, Apollo 12 witnessed something very much like a lunar eclipse. The space capsule passed
03:25through the Earth's shadow. And you may know that Alan Bean was became a painter after he came back
03:31to Earth and he painted this several times. Alan's paintings are sometimes kind of impressionistic.
03:38So the colors are more interesting than the reality. But but what he captured was the the
03:47brilliant ring of, you know, bright sunrises and sunsets, how bright that is, how visually interesting
03:53that is. I think it would be great if we had astronauts on the moon to witness this. Also,
04:00during 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
04:16gears that allowed the the camera to point wasn't working after they left. And so we missed that
04:21opportunity. But it's a you know, it's a it would be a cool reason to go back just to be
04:27there during
04:28a lunar eclipse and see what the Earth looks like. Definitely. Now, so the rover, you know,
04:33the rover's camera, things didn't go according to plan. But we do still have spacecraft orbiting the
04:39moon. There's China's Changi 4 rover still on the moon. What might these spacecraft see during an
04:46eclipse? Like what what might it look like to them? I well, I work with Lunar Reconnaissance Orbiter,
04:51and it's a solar powered mission. So one of the one of the aspects of a lunar eclipse for LRO
04:58is that
04:59its power gets turned off, basically. You know, LRO orbits the moon every two hours. It goes through
05:05nighttime every 45 minutes. So there's a battery on board and that kind of gets it through the night
05:10side and and then it charges back up. But during lunar eclipses, a lot of times it'll come around
05:16from the night side and the sun still isn't there. So it has to run on battery power for, you
05:21know, a
05:21couple of extra hours. And so LRO has to make preparations for that. Usually, most of the
05:27instruments get turned off. And the things that they leave on are like the heater, something important
05:35to keep all the stuff from freezing. But it's a it's a challenging sort of operational thing that LRO
05:42does. So it's not it's not having the same kind of fun that we have on the Earth. It's it's
05:48actually
05:49having to protect itself. Yeah. So I don't I don't know of any any missions like LRO that have actually
05:58turned to the Earth during an eclipse and taken a picture of it, because I think that would be really
06:01cool. I'd like to see it. Right. Definitely. So I just have one more question for you. You know,
06:10leaving it off on something fun to you. What's the most amazing part of watching a lunar eclipse?
06:17Well, 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. 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
06:53to sort of think about your place in the in the cosmos, you know, this this alignment of the sun
06:58and the
06:59earth and the moon spending just a little bit of time thinking about how amazing that is and how cool
07:07it is. And you are in a very specific place to be able to see it. You know, aside from
07:13just the visual
07:14beauty of it, I like thinking about that aspect of it.
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