Suggested Searches

Total Eclipse Over America

Season 1Aug 18, 2017

Dr. Mark Matney, Space Debris Scientist and Astronomer, talks about the science and history of eclipses. He also describes the total solar eclipse that will sweep over the U.S. on August 21, 2017, and how to safely view it. HWHAP Episode 7.

houston podcast episode 7 total solar eclipse america

houston podcast episode 7 total solar eclipse america

“Houston, We Have a Podcast” is the official podcast of the NASA Johnson Space Center, the home of human spaceflight, stationed in Houston, Texas. We bring space right to you! On this podcast, you’ll learn from some of the brightest minds of America’s space agency as they discuss topics in engineering, science, technology and more. You’ll hear firsthand from astronauts what it’s like to launch atop a rocket, live in space and re-enter the Earth’s atmosphere. And you’ll listen in to the more human side of space as our guests tell stories of behind-the-scenes moments never heard before.

Houston, we have a podcast

Episode 7 features Dr. Mark Matney, Space Debris Scientist and Astronomer, who talks about the science and history of eclipses. He also describes the total solar eclipse that will sweep over the U.S. on August 21, 2017, and how to safely view it. This podcast was recorded on July 19, 2017.

Transcript

Gary Jordan (Host):Houston, we have a podcast. Welcome to the official podcast of the NASA Johnson space center, episode 7: total eclipse over America. I’m Gary Jordan and I’ll be your host today. So this is the podcast where we bring in the experts– NASA scientists, engineers, astronauts– all to tell you the coolest stuff about NASA. So today we’re talking about eclipses with Mark Matney. He is a space debris scientist here at the NASA Johnson space center in Houston Texas, and he also has degrees in astronomy and space physics, and is an avid eclipse aficionado. We had a great discussion about what an eclipse is, some of the history of eclipses, and some of the science that we’ve learned and continue to learn from them. This is an exciting conversation, especially because on august 21, 2017, a total solar eclipse will sweep across America. Mark and I talked about where the eclipse will pass through and how you’ll be able to see it. They don’t happen very often– the last time a total solar eclipse happened over the states was back in 1991, and we won’t see another until 2024. Anyway, we’ll get into all that good stuff during this episode. So with no further delay, let’s go light speed and jump right ahead to our talk with dr. Mark Matney. Enjoy.

[ Music ]

>> t minus five seconds and counting. Mark. [ Indistinct radio chatter ]

>> Houston, we have a podcast.

[ Music ]

Host:all right, well, Mark, thank you for coming on the podcast today. Perfect timing, because very soon we’re going to have a total solar eclipse that’s going to pass over the united states. And so I think this is a good chance for us to sit down and talk about eclipses. And you went above and beyond for this one, Mark, because you have a lot of different things. I mean, we’re talking a lot of science, we’re talking a long and detailed history of eclipses. You know, this is not just a, ooh, look at that. Pretty eclipse. No, NASA is going all out for this– is that fair to say?

Mark Matney: Well, I think this is– I mean, eclipses have been part of human history as far back as we can record. People have been fascinated, scared, terrified by eclipses.

Host:Oh, sure.

Mark Matney: And a lot of important scientific discoveries have been driven by eclipses. I think today– we’re doing some science today, but much of the important science was done in the past. But this kind of links us in some sort of way to those early scientists who were trying to puzzle out the mysteries of the universe by using this amazing sight in the sky. So we have some science that’s going on, we have some citizen science that’s going on, and there’s going to be a whole lot of people traveling to see this eclipse. In fact, I was reading that this eclipse is the first cross continent eclipse across the united states since the interstate system was built.

Host:Oh, wow.

Mark Matney: And so we might see one of the largest migrations of Americans in a short period of time that we’ve ever seen. [ Laughter ] because there’s going to be a lot of people, perhaps tens of millions of people, traveling to see this eclipse.

Host:That’s very true, and they’re all going to be, I mean, closer to that nice, thin line– we’re talking about that path of totality, and we’ll get into that really shortly, but you know, let’s go and start at the very beginning, right? So we’re talking about a total solar eclipse– this is great– passing over the united states. But what is that? What is a total solar eclipse?

Mark Matney: So a total eclipse is when the disk of the sun is completely covered by the moon. So the moon s size is maybe slightly larger than the sun, so we can get complete coverage. This particular eclipse is going to be about two and a half minutes of totality. Some eclipses are as high as seven minutes. Some of them are just a few seconds.

Host:And it’s just the way things are aligning?

Mark Matney: Well, it turns out that the moon is actually not on a perfectly circular orbit. It’s in a slightly elliptical orbit. So sometimes it’s a little closer, and sometimes it’s a little farther.

Host:Oh, I see.

Mark Matney: And so [ indistinct ] a little farther, it doesn’t quite cover the surface of the sun. And what you end up with is a narrow ring all around. That’s called an annular eclipse. And if the moon is a little larger– in other words, a little closer, it appears a little larger in the sky, you get a total eclipse. And sometimes we actually have what’s called a hybrid eclipse where you get an annular eclipse, but the mountains on the moon make it’so it’s actually a broken ring in the sky. It’s so close, because actually, the mountains peeking up cover part of that sun ring.

Host:So can you see some of the sun peeking through those alleys, I guess?

Mark Matney: That’s right, yes.

Host:Oh, interesting.

Mark Matney: And then that one, turns out if you could get higher in the altitude, in a balloon or plane, you might see a total eclipse in those kinds. But that’s a special kind of eclipse that’s actually quite rare.

Host:Wow.

Mark Matney: And then we also have a partial eclipse, and that’s what– it turns out this eclipse is interesting– as far as I can tell, anyone in any of the 50 united states– weather permitting– should be able to see a partial eclipse, including Alaska and Hawaii. The partial eclipse is where the disk of the moon covers part of the sun but doesn’t actually get to– it’s off to one side.

Host:Okay.

Mark Matney: And so you– we’re going to get a pretty good partial eclipse here from Houston, but I think everybody, like I said, somewhere in the united states, one of the 50 states, should be able to see a partial eclipse.

Host:That’ll be cool.

Mark Matney: So by the way, it’s august 21st– we didn’t say the date.

Host:Yeah, so august 21st. And this will come out august 18th, so this will be like–

Mark Matney: oh, okay– perfect.

Host:This will be right next to it, yeah, absolutely. So a partial eclipse– is there– how– is there a way that is very apparent to observe that? Like, will the sky get a little bit darker, or–

Mark Matney: it depends on the percentage. When it’s like about 50%, it’s hard to notice. But once you get on to 60, 70, 80, 90%, the sky takes on an unusual color. And in fact, that’s one of the things I’m going to recommend eclipse observers– just kind of note how the sky changes color, because it’s a very interesting phenomenon.

Host:Yeah.

Mark Matney: But unless it’s really– in ancient times, people did not even notice a partial eclipse unless it was like 80, 90% because they started to see the sun dim, and they would look up at the sun and see there was no longer a disk in the sky.

Host:Wow. Okay, so from here in Houston, what are we expecting percentage-wise?

Mark Matney: Well, I tried– it’s about somewhere around 70%. I don’t know the exact area, but there’s several tables. Also, that’s another thing, is where you are, where the maximum eclipse changes on the clock. So there are computer resources where you can look and put in your location or your city and find out when the maximum eclipse is and how much.

Host:Oh, okay. Very cool. That’s a lot of good stuff. All right, so that’s 70%. We’ll be able to see–

Mark Matney: something like 70, yeah.

Host:A somewhat noticeable change in the sky, then, at least here from Houston. That’s really cool. So yeah, you said total versus partial. This is the solar eclipse, though, right?

Mark Matney: Right.

Host:This is when the moon is going in between the earth and the sun.

Mark Matney: Right.

Host:Like you said, they’re relatively the same size in the sky, just based on distance and size, and so it only blocks off this tiny little strip of shadow that’s going to go across the united states. And it goes– you said it happens quite often, but just I guess at different parts of the world.

Mark Matney: Correct.

Host:It just so happens that it’s going to line up this time going from coast to coast.

Mark Matney: And sometimes it’s an annular, and sometimes– but it turns out we get from three to five eclipses, solar eclipses, every year.

Host:Oh, okay.

Mark Matney: Which is actually kind of surprising.

Host:We meaning the earth.

Mark Matney: Someone on the earth, in other words, can see an eclipse. We actually have fewer– there’s another kind of eclipse called a lunar eclipse, and the lunar eclipse is when the earth gets between the moon and the sun.

Host:Right.

Mark Matney: And so as the moon moves into the shadow, it starts to turn dark, and sometimes has an interesting red color.

Host:Yeah.

Mark Matney: It turns out there are actually fewer of those than solar eclipses.

Host:Really?

Mark Matney: But because a whole hemisphere can see it, they’re much– you can see them much more often than solar eclipses.

Host:Oh, that– okay.

Mark Matney: Because you’re looking up in the sky and seeing the moon eclipse, so anybody on that side of the earth can see it– weather permitting, of course.

Host:Wow. Why is it that color, though?

Mark Matney: Well, that’s an interesting phenomenon. As you know, the sky is blue from the scattering of particles in the atmosphere—it scatters the blue light. But the red is transmitted just like we see in a red sunset. Well, the earth s atmosphere actually refracts the red light, and so if you were standing on the moon during a lunar eclipse, the earth, of course, would block the sun, but you would see this red ring around the earth, which is the atmosphere refracting the light of the sun.

Host:So that’s the red ring of the earth refracting off the surface of the moon?

Mark Matney: No, no, it’s– the light is coming through the atmosphere and refracting slightly to your position on the moon.

Host:Oh.

Mark Matney: So you would see this narrow, narrow red glowing ring around the earth.

Host:Oh, wow.

Mark Matney: So it’s– but of course, no one’s ever seen that.

Host:Yeah.

Mark Matney: Maybe someday when we have a base on the moon.

Host:Oh, and so wait– okay, so this is assuming that– yeah, you’re assuming that you are an observer on the moon.

Mark Matney: You’re an astronaut standing on the moon, right.

Host:I see, and there’s a red ring. So what about the lunar eclipse– the perception from the earth? Doesn’t a lunar eclipse– the moon looks a little orange?

Mark Matney: Yeah, it’s orange-ish, sometimes. It actually depends on– it depends on what’s happening in the atmosphere.

Host:Oh, okay.

Mark Matney: For instance, I saw an eclipse in 1982. We were expecting the red moon, but in fact, the moon looked charcoal gray. And that was right after the el chichon volcano in Mexico erupted. And so the dust from the volcano had changed the dust in the atmosphere, so we didn’t get much red.

Host:Oh.

Mark Matney: So it actually– you never know what you’re going to see when you see a lunar eclipse, but they’re often red. And again, that’s the red light that is bent by the earth s atmosphere and shines on the moon.

Host:Yeah, and it’s reflecting– interesting. So it’s all entirely about perception, then, it’s about the– so you’re a person on the earth, and this is what you perceive from the perspective of earth. If you were outside floating millions of miles away just observing it from afar, it would just look like the earth and the moon– the moon wouldn’t look a certain color.

Mark Matney: Well, you could see the color, because it’s lit up with that color. Let me– let’s change it around. Let’s say you were on the moon looking at the earth during a solar eclipse. And we have some photographs from the ISS of previous eclipses, and you actually see a– you can actually see the dark shadow. You can’t see the sharp edge of the shadow, but you see this fuzzy black thing on the surface of the earth. And so you would see– but instead of being the whole earth swallowed up, you just see this black fuzzy spot moving across the earth from space.

Host:Interesting.

Mark Matney: So hopefully– it depends on where the ISS will be at the time of the eclipse, but hopefully they’ll be able to photograph it from– they probably will not be in the eclipse path, but they could look down on the earth and see the shadow, hopefully, of the eclipse.

Host:Yeah, I think– I think they are predicting that the ISS is going to be somewhere over Canada but will have a nice view of the states whenever it’s actually the solar eclipse.

Mark Matney: It would be very, very coincidental if we happened to fly through the shadow, because the shadow is very narrow. It could happen, but I mean–

Host:the odds are against us.

Mark Matney: The odds are against us. So a lunar eclipse happens at the full moon.

Host:Okay.

Mark Matney: When, of course, the sun is on the other side of the earth and the moon is– if you’re standing on the earth, the sun is behind you, because it’s nighttime, and you see the– and a solar eclipse happens at a new moon, when the moon is– you can’t really see it in the sky, because you’re seeing the dark side of the moon.

Host:So you’ll never see a crescent moon in a lunar eclipse?

Mark Matney: No, no, it’s definitely a full moon, so as full as it gets. Another thing is lunar and solar eclipses are often paired, because that tilt of the moon s orbit, the point when it crosses the earth-sun orbit plane, is on both sides. And so usually we get an accompanying lunar eclipse with a solar eclipse. And in fact, the accompanying lunar eclipse for this eclipse is on august 7th, and will be visible from Europe, Africa, Asia, and Australia.

Host:Oh, okay. Well, there you go.

Mark Matney: Or was visible, I guess.

Host:August 7th, yeah. I guess– aw.

Mark Matney: You want me to say that again? [ Laughter ]

Host:if we could go back in time okay, so I mean, that’s kind of from the perspective of earth, right? We’ve got solar eclipses, and when the moon is in between us here on earth and the sun, and then the opposite for the lunar eclipse. In general, if you had to give like a general overview, where else in the universe do eclipses happen?

Mark Matney: Everywhere.

Host:How about that.

Mark Matney: Anywhere where you have bodies moving around, one will often eclipse the view of another. But usually, what you– you won’t get to see the amazing sight on earth, because it’s very rare that the object eclipsing looks in the sky the same size as the sun.

Host:Oh.

Mark Matney: So we know, for instance, there are eclipses caused by Jupiter s moons as it orbits Jupiter, and you can see the shadow on the surface of Jupiter– or the clouds, actually, of Jupiter.

Host:Right.

Mark Matney: And in fact, there was a fellow named ole r mer– if I’m pronouncing correctly– back in the 1600s that first detected the finite speed of light by looking at the timing of those eclipses on Jupiter. So that’s one of those science things that eclipses have allowed us to do.

Host:That’s amazing– just by looking at shadows across the universe, you can get all this crazy science.

Mark Matney: And sometimes– I know we’ve done occultations of stars, where a planet moves between us and the starlight of a star, and by measuring that star, we’ve seen, like– we’ve found the rings of Uranus, as the star would twinkle or would blink out just before Uranus crossed the star.

Host:Oh.

Mark Matney: So you can actually do things like look for difficult to see rings, or also, as the light comes through the atmosphere, sometimes you can see the absorption of different chemicals in the atmosphere of the planet.

Host:And then understand the composition of the planet itself.

Mark Matney: Exactly.

Host:That’s amazing.

Mark Matney: Let me add one thing we hadn’t talked about.

Host:Yeah, sure.

Mark Matney: I found an interesting statistic, and it said that if you picked a random spot on the earth and you just stayed right there, you would see a solar eclipse about once every 375 years, on average.

Host:Okay, so you should move a little bit.

Mark Matney: Yeah, well– you’re not following. [ Laughter ] so during a normal person s long lifetime– say, 70 years– we’re looking at a 20-25% chance that you would sometime in your lifetime see an eclipse, a total eclipse of the sun. So yes, it’s rare, but not totally unknown.

Host:Yeah.

Mark Matney: So I just know that one never comes by my house, so I have to go chase it down. [ Laughter ]

Host:well, that’s the great thing, is we have NASA– we folks at NASA are actually looking at this stuff and making predictions. We know exactly where it’s going to be on august 21st.

Mark Matney:That’s correct, that’s right.

Host:Yeah, so that kind of will help you see it a little bit, too. [ Laughter ] I think one of my favorites, though, when it comes to eclipses across the universe, is Kepler, right? So if you think about– you said occultations as one of them. That’s when something passes in front of a star and changes the light that we’re receiving.

Mark Matney: Right.

Host:That’s how we are detecting planets outside of our solar system, correct?

Mark Matney: That’s correct, yeah. The Kepler mission is looking at a large group of stars and monitoring them constantly. And it has very, very sensitive instruments, so they can look at very small dips in the light as a planet– a previously unknown planet– transits the face of that star. And we’ve been able– and when they see them repeating, they can work out the relative sizes of the planets and their period, and work out where they are in orbit around that star. And we’ve seen– I don’t know what the count is– a thousand?

Host:Yeah, yeah. We keep finding more and more.

Mark Matney: There’s a bunch of them. So this is actually one of the most interesting discoveries, I think, astronomers have made in the last several years, is that our galaxy is full of stars with planets. And it’s pretty exciting– it’s kind of star trek stuff.

Host:It is! Especially just recently, the discovery of the trappist-1 system.

Mark Matney: Yes, indeed.

Host:And those– we’re talking about earth-like planets, and some of which are in what we like to call the goldilocks zone, right?

Mark Matney: That’s right.

Host:And that’s– you know, water doesn’t freeze, it doesn’t–

Mark Matney: that’s right, it’s not too hot, not too cold.

Host:Not too cold, right, and liquid water can exist. And that’s conditions for life, and it’s very exciting.

Mark Matney: It is.

Host:That’s what we’re looking for, right– life outside of the universe.

Mark Matney: And I’ll also mention we also have transits here, just like what we see with Kepler, of the planets mercury and Venus, which are inside the orbit of earth. And we recently had a Venus transit visible from the us.

Host:Yeah, 2012, right??

Mark Matney: That’s right, I think it was 2012. And I’ve also seen mercury transits as well. Those have an interesting history, because scientists in the 18th century were trying– they’d figured out the relative distance to the different planets, but they didn’t know an absolute distance. And they were actually going to use different observers on the earth to measure the transit of Venus to try and get an absolute scale. And so that was the cutting edge science in the 18th century.

Host:Wow. [ Laughter ]

Mark Matney: but so that’s another point where transits and eclipses have been an important part of the history of science.

Host:Amazing. I mean, that’s kind of a big theme here, right, especially for eclipses, is the science that we can get from observing these phenomena.

Mark Matney: That’s right.

Host:So I mean, from here on the ground, what are some of the things that we can learn– and I guess in the instance of a solar eclipse, but you know, eclipses in general– what are some of the things that we can learn from studying these?

Mark Matney: Well, let’s kind of go through some of the discoveries that were made with eclipses.

Host:Sure.

Mark Matney: So from ecl– we all look up at the sun and see a bright disk. That’s called the photosphere. It’s very, very bright, and we’ll talk about that a little bit. That’s the part we’re familiar with. It’s about 10,000 degrees Fahrenheit– it’s nice and hot. But during eclipses, astronomers notice some red layer– a thin red layer around the sun. And that’s known as the chromosphere. And that was discovered by eclipses, and it turns out chromosphere is due to emissions from atomic hydrogen in the sun s atmosphere.

Host:Okay.

Mark Matney: And so if you– the soho spacecraft sometimes show– I mean– the soho spacecraft show– is constantly monitoring the sun. And one of its instruments is a hydrogen alpha filter, and you can see what that chromosphere looks like. It’s a very thin layer of the sun, again, that we discovered by looking at eclipses. The next section– oh, by the way, some scientists– in 1868, there was a new instrument that was developed called the spectroscope. And the spectroscope splits light into its component colors. And they had discovered that there were specific lines, almost like a fingerprint, that defined– that were unique to each chemical, to each chemical element.

Host:Okay.

Mark Matney: And so there were– some scientists were very excited to use the spectroscope to look at the eclipse. And in the chromosphere, they saw some lines from an element that they had never seen before. And they couldn’t figure out what it was. So one of the scientists named it after the Greek word for the sun– Helios. They named it helium.

Host:Oh! [ Laughter ]

Mark Matney: and it was several decades before helium was finally isolated and studied on the earth, but it was first discovered in the sun s atmosphere.

Host:How about that. That’s– is it called spectroscopy?

Mark Matney: Spectroscopy, yeah. They use a spectroscope for spectroscopy.

Host:Yeah, yeah, and studying the– I guess there’s little gaps in the light, and they look like gaps in the–

Mark Matney: sometimes there’s bright lines, sometimes there’s dark lines.

Host:Okay.

Mark Matney: It depends on the situation. But the point is these lines are like a fingerprint. And that’s how we understand the components of stars millions of light-years away. We can–

Host:so you said photosphere, and then you discovered the chromosphere, right?

Mark Matney: Chromosphere.

Host:So what’s the difference between those?

Mark Matney: Well, the chromosphere is actually a very thin layer– it’s actually– starts as cooler than the photosphere, and then it heats up again.

Host:Ooh.

Mark Matney: Solar astronomers are always trying to figure out the exact details, but what gets interesting is when you look up at the eclipse when it’s total eclipse, there’s what looks like a halo, or a garland, or a crown around it, and that’s called the corona. So the chromosphere s a transition between the hot photosphere and the much hotter corona. And the corona is up to– it’s more than 100 times hotter than the photosphere. It’s very, very hot.

Host:Wow.

Mark Matney: And that’s, like I said, this halo that you see around the sun. That is actually very important– to monitor that part of the sun– in predicting solar storms.

Host:Oh.

Mark Matney: And solar storms affect things like satellites and our communication and our power systems. And so there are solar astronomers who are constantly monitoring the sun looking for these types of solar storms. But the corona was discovered by looking at eclipses.

Host:Wow.

Mark Matney: And in fact, it’s so important that we’ve launched satellites that create artificial eclipses. They put a little obstacle in the way so that we can monitor the chromosphere– I’m sorry, the corona– at all times.

Host:So I guess, are they hard to predict, solar storms?

Mark Matney: They’re getting better at it. The big thing is they need to be able to see on the far side of the sun. So we’ve actually launched a couple of spacecraft called stereo, and they’re now on the far side of the sun– not totally– they’re part way around the earth s orbit, but they can see the other parts of the sun, and we can see storms developing as the sun rotates around. The sun actually rotates, also.

Host:Wow. So what happens if– say there’s an instance, if there’s a solar storm, and it does disrupt satellite communications coverage, whatever it is. What can we expect if that were to happen? Are you talking about cell phones? Are you talking about– what would happen here on earth?

Mark Matney: Well, one of the worst things we’re worried about is a really, really big solar storm which could knock out power grids in certain areas.

Host:Wow.

Mark Matney: And so you could actually have power outages.

Host:That’s heavy.

Mark Matney: But usually satellites, they put them in safe mode. But it can damage satellites. And as you know, telecommunications is a multi-million-dollar business.

Host:Right.

Mark Matney: So there’s a lot of interest in solar storms.

Host:But they have a safe mode to–

Mark Matney: yep, that’s right.

Host:That’s amazing, okay. So they just put it in there if they see something bad coming.

Mark Matney: It’s still dangerous, but they can put it in a safer mode. [ Laughter ] one other thing that was observed during eclipses is there’s sometimes these little arcs– they’re not little– they’re bigger than the earth, but these little arcs of plasma jutting off the sun. And you’ve probably seen pictures of them. They look like arches or flames coming off the sun.

Host:Yeah.

Mark Matney: They’re called prominences, and they’re plasma in the strong magnetic field of the sun moving through the atmosphere. And they’re really quite spectacular.

Host:Yeah, I’ve seen some images and videos of them—they really are. It’s amazing.

Mark Matney: Again, those were discovered by eclipses. And I’ll tell you another set of experiments. It turned out that by the mid-1800s, scientists had started working out the mathematics of planets, and had noticed when a planet gets perturbed and sort of gets nudged a little bit, they said, well, that must mean another planet that’s tugging on it with its gravity. And that’s how Neptune was discovered. They saw the perturbation in the motion of Uranus. And they noticed that there was a slight perturbation in the orbit of mercury. So scientists began speculating that that was due to another planet even closer in to the sun, which they nicknamed Vulcan. So what happened was they then sent– in the 1860s and 1870s, scientists deployed around the world for some eclipses to try and look for Vulcan. And they didn’t find anything, which puzzled them. They looked at multiple eclipses, multiple times– no Vulcan. But in 1915, Albert Einstein began publishing– began communicating his work on the general theory of relativity. And Einstein had postulated that gravity is caused by the bending of space-time. And one of his– one of his– one of the predictions of his theory was that you would see this perturbation of the orbit of mercury. So he explained that with his general theory of relativity. But another prediction was that this bending of space-time would actually bend light. So he showed why there wasn’t a Vulcan, but then he said, if you look at an eclipse of the sun, and look at the light of stars very, very close to the disk of the sun, you should be able to see the light bent in a way that it displaces the apparent position of the star. In 1919, Arthur Eddington, the British astronomer, deployed for an eclipse out on an island in the Atlantic Ocean. And they actually measured this slight change in the apparent position of the stars. And it was a huge event, because when Einstein postulated his theory of general relativity, it was crazy. It was overturning newton. And here they actually– his prediction turned true, and that’s sort of what propelled Einstein into his fame, was that discovery. So that was perhaps the most important scientific discovery ever during an eclipse, was showing how the light of stars is bent by the presence of the mass of the sun.

Host:And that– so it was just the mass of the sun.

Mark Matney: That’s right.

Host:And there was no Vulcan.

Mark Matney: No Vulcan. [ Laughter ] although, there are two eclipse stories related, sort of quasi-related to the same thing there.

Host:But everything comes together, right? That’s why we’re– like, going back to the general theme here, a lot of science to learn from eclipses.

Mark Matney: A lot of science. Let me talk about a couple things that are going on with the science this time around.

Host:Okay.

Mark Matney: We have one group that’s going to have a series of telescopic cameras set up along the eclipse path. And they’re going to try and take video of the inner corona, which is very difficult to see except during the eclipse. And the idea is one camera will record a little segment of the inner corona, and the next camera will record the next segment, and they can stitch them together and have a rather extended video of the corona.

Host:Oh.

Mark Matney: So for scientists who study the interaction of the corona. Another one is some other scientists are going to be studying the polarization. Some light is polarized in different directions that tells us information about the magnetic fields and other things. But they’re going to be looking at the spectrum and the polarization of the– again, the inner corona, which is difficult to measure in other ways, because it’s difficult to get so close– to measure such dim phenomena so close to the disk of the sun.

Host:And this is– going back, I’m sorry– you might’ve already addressed this, but these are NASA telescopes, or these are others?

Mark Matney: It’s a variety of– NASA is cooperating on some of these, and some of them are universities, and some of them are amateur. So it’s actually a whole team of different kinds of people.

Host:Wow, okay.

Mark Matney: NASA is helping to coordinate some of these.

Host:Yeah, all working together, okay. Cool.

Mark Matney: We’ve got another group that are actually going to repeat the general theory of relativity experiment with some more modern digital equipment with more sensitive cameras to look for some very dim stars, again, to try and fine tune those measurements to see how close Einstein got to the prediction.

Host:Wow.

Mark Matney: And then, we also have some radio enthusiasts who are– during the daylight, the sun ionizes gas in the upper atmosphere and we have an ionosphere. And it, both enhances and sometimes interferes with radio communications. So these scientists are going to look at how the ionosphere changes as the sun gets eclipsed, and the sunlight starts to drop off, and then go back up again. So, they’re going to observe how the ionosphere changes.

Host:Interesting.

Mark Matney: So lots of interesting experiments. And of course– and many of these are by these amateur citizen scientists, which is kind of a fun thing, too.

Host:Yeah, absolutely. So, we’re measuring the earth s atmosphere, we’re measuring a lot of about the sun.

Mark Matney: Mm-hmm.

Host:I know out of here, the wb-57, those high altitude planes, they’re going to be flying above most of the atmosphere, about 90% of it, and they’re going to take a look at the sun and study the sun s corona.

Mark Matney: Yeah, a bit.

Host:And measure how energy goes through the sun s atmosphere, but then also take a look at mercury.

Mark Matney: Oh, that’s right.

Host:Yeah.

Mark Matney: I wanted to tell you, when you see the eclipse you will see a number of planets visible in the sky.

Host:Oh.

Mark Matney: So, if you get a chance, you’ll see stars. Venus is off to the west; mars is even closer. It’s– Venus is about 35 degrees to the west, mars is about 10 degrees to the west, mercury s about 10 degrees to the east, and Jupiter’s way over on the other side of the sky at 60 degrees to the east. And the star, regulars, which is a bright star, will be about 5 degrees to the east of the sun, so you can see if you can see that.

Host:And this will happen during totality, right?

Mark Matney: During totality, because the stars will come out.

Host:Wow, amazing. So you’ll be able to see all of these, and you’re talking about from the perspective if you’re looking up and– the sun–

Mark Matney: right.

Host:Once it goes to totality– and we can get to safety in a minute, but I do know, once it gets to totality you can take off your glasses for about that two minutes, right?

Mark Matney: That’s right. Yeah.

Host:And then, that’s when you’ll be able to see all those different parts.

Mark Matney: Yes.

Host:That’s really cool.

Mark Matney: Yeah, that’s it. Let’s talk a little about the history, because there’s some interesting history, of course.

Host:Sure, yeah.

Mark Matney: The most famous story, which is probably legendary, but the story about a Chinese astronomer, or possibly two Chinese astronomers, named xi he, who was hired by the king. He was the high astronomer, the head astronomer.

Host:Mm-hmm.

Mark Matney: To make predictions about primarily with astrology to make sure that nothing bad was going to happen to the king. Well, apparently there was a solar eclipse he did not predict.

Host:Oh.

Mark Matney: And apparently, he had had a little too much to drink and he wasn’t on the job when the time came.

Host:Oh.

Mark Matney: And the Chinese actually thought, and a lot of ancient cultures thought, that something bad was happening. The Chinese thought a dragon was swallowing the sun, and they would bang on pots and pans to scare the dragon away. And that’s actually still practiced in many parts of the world, the bang on pots and pans.

Host:Yeah, they don’t know the– like, the science behind this total solar eclipse, so they’re–

Mark Matney: that’s right.

Host:Yeah, right, go ahead.

Mark Matney: I think part of this tradition is passed on.

Host:Yeah, tradition, yeah.

Mark Matney: Well, unfortunately, this poor Chinese astronomer that didn’t do his job, he got executed.

Host:Oh.

Mark Matney: So, fortunately, we don’t hold our scientists to this same level there.

Host:I’m very thankful of that.

Mark Matney: Yes.

Host:I’m sure we are. Yeah.

Mark Matney: But, lots of ancient people were scared of eclipses because they thought they– I mean, it’s a very amazing thing to happen in the sky and they were worried about it. It’s warning of some tragedy.

Host:Mm-hmm.

Mark Matney: So early scientists in multiple cultures– the Mayans, the Babylonians, the Chinese– studied eclipses and tried to understand and predict when they would occur. It turned out there was a Greek by the name of Thales who predicted an eclipse in 585 b.c. And this was recorded and the Greek historian, Herodotus, there was a big battle going on between two countries. There were the meds and the Lydian’s, in what’s now turkey.

Host:Hmm.

Mark Matney: And there was a war going on and they had lined up for battle. And they were about to do battle and suddenly there was a solar eclipse.

Host:Oh.

Mark Matney: So, needless to say, the two generals met in the middle of the field and said, maybe we ought not to fight today. And so they drew up a peace treaty and those two countries never fought again. So just a–

Host:all right. So an example of solar eclipse saving lives.

Mark Matney: That’s right. Indeed, indeed. And so, but what happened was, a lot of these– as people began to learn to write things down– the Babylonians on clay tablets, and the Chinese court records, and the Greek historians– people began to pull together this information to understand how to predict eclipses and understand how the cycles occur. And that helped the—that sort of spawned the whole science of astronomy. How do you– how’d the mathematics occur on these objects.

Host:Hmm.

Mark Matney: And one of the things they discovered was called the saros cycle, and this actually– Edmond Halley named it the saros cycle. They didn’t– they had different names in ancient times. But what they discovered was that an eclipse will recur approximately every 6,585.3 days, which is 18 years, 11 days, and 8 hours. So it turns out that the eclipse we’re about to have is part of a saros cycle that occurred– the last one was in Europe in august 11, 1999, and the next one will be in Asia and the pacific one September 2nd, 2035. And it looks almost exactly the same except shifted by 8 hours around the other, 123 degrees in longitude.

Host:Oh.

Mark Matney: So these repeating cycles were how the ancients were able to predict eclipses.

Host:How about that. Wow.

Mark Matney: And it’s just all the different cycles of the sun and the moon add up to this repeating cycle of eclipses.

Host:Interesting.

Mark Matney: Another thing that science that was done in ancient times was the Greeks looked up at a lunar eclipse– when we’re talking about how the moon moves into the shadow of the earth. And what they discovered is when the moon is near the horizon and eclipsed the shadow of the earth is not a line, if the earth were flat. It’s still round. So the Greeks realized that the earth must be a sphere based on– based on the shadow of the earth on the moon under an eclipse.

Host:Oh, wow.

Mark Matney: So that was the first scientific discovery that the earth was indeed a sphere.

Host:Back in the Mayan– wow, okay.

Mark Matney: Back in the Greek times, that was.

Host:Oh, that was Greek times.

Mark Matney: Yeah, it was.

Host:Okay, okay. Interesting. Wow!

Mark Matney: There’s a lot of interesting history associated with eclipses.

Host:Absolutely. That– so we’ve learned a lot through history. I mean, we’re talking about, yeah, the shape of the earth. We’re talking about—it stopped a battle.

Mark Matney: Nature of the sun, yeah.

Host:The nature of the sun.

Mark Matney: Yup. The earliest eclipse that was– that, as far as we know, was recorded, that Chinese eclipse was probably about 2000 b.c. And there was maybe the one in 2137 b.c. But, the one we’re sure about was there was an eclipse recorded in the town of Ugarit, or Ugarit, on– in what is now, I believe, Syria.

Host:Hmm.

Mark Matney: It was my 3rd, 1375 b.c. It was recorded that the sun grew dark.

Host:Oh.

Mark Matney: So there’s a number of those recorded in ancient texts and tablets.

Host:Okay. So, wait, so the Chinese one was not recorded? It was just–

Mark Matney: well, just know it’s actually probably semi legendary. We’re not sure.

Host:Got it, okay.

Mark Matney: But this is the one we know for sure we can date the eclipse.

Host:Yeah.

Mark Matney: And actually– oh, that was what I was going to tell you, is we have a number of these dated eclipses– eclipse of Thales, we talked about.

Host:Mm-hmm.

Mark Matney: Eclipse in Ugarit. And what happens if you just run– if you just take your computer models and putting gravity and everything and just run the sun and moon backwards in time, it turns out the eclipse is in the wrong place. So, from that, what we’ve learned is that the earth rotation very, very gradually starting to slow down.

Host:Hmm.

Mark Matney: Starting to, it’s been a long time. It’s mainly due to the tidal effects of the moon. It’s actually dragging the earth slightly down. So it’s actually in those several thousand years the earth has slowed down a little bit, a fraction of an– a fraction of a rotation.

Host:Oh.

Mark Matney: But, keep in mind, we’re talking about– we’re talking about 800,000 rotations or something like that since those times. And so, we’ve– the earth s rotation has changed just a little bit in those times. But, that’s another discovery we’ve made that you need that long time scale to see this very gradual slowing down of the earth s rotation.

Host:So, over that long period of time, you said a fraction of a day, is it like an hour? Couple of hours?

Mark Matney: A couple of hours I think, yeah.

Host:Wow.

Mark Matney: But, and recently, some scientists have gone back and looked at Chinese records, and again, been able to fine tune that. So that’s a– that’s using ancient records to fine tune some modern science, so.

Host:All right. Cool. Okay, so let’s go to this eclipse coming up on the 21st.

Mark Matney: All right, do you want to talk about safety or what to expect?

Host:All of it. Let’s do it.

Mark Matney: All right. All right, let’s talk about–

Host:however you want to start.

Mark Matney: Let’s talk about safety a little bit.

Host:Okay, safety.

Mark Matney: Okay, everybody has heard, don’t look at an eclipse, you’ll go blind, right? We’ve all heard that.

Host:Yeah.

Mark Matney: And I remember as a boy, puzzling and puzzling over that. What is it about an eclipse that makes it so dangerous?

Host:Mm-hmm.

Mark Matney: Well, it turns out, you don’t want to stare at the sun ever. It’s bad for your eyes. Your eyes are not designed to be– handle direct sunlight for any length of time.

Host:I feel like it’s a good general rule.

Mark Matney: It’s a good general rule. And when our kids go outside, we say, now, kids, don’t look at the sun, you’ll go blind. It’s true, you don’t want them looking at the sun.

Host:Yeah, yeah.

Mark Matney: The reason why– the eclipse is not any different. It’s just you’re more likely to stare at the sun during an eclipse because you want to see what’s happening.

Host:Oh.

Mark Matney: So, this really– there’s people that think there is some sort of mysterious rays coming off the sun. The only thing is just the sun like we’re normally familiar with, you just don’t want to stare at it. Okay.

Host:Okay.

Mark Matney: All right, so that’s the first thing. So any time the bright disk, that photosphere of the sun, any time the bright disk is visible, even just a little sliver, you’really don’t want to look at the sun with your unaided eye. It’s dangerous. You want to keep your eye for a long — your eyes for a long time, right?

Host:Yeah, I would hope so.

Mark Matney: But we have special– nowadays, we have special eclipse glasses that you can get in museums and different places.

Host:Yeah.

Mark Matney: That are– it’s perfectly safe to put those on and look. By the way, don’t do what I did. I was checking my eclipse glasses the other day. I looked up at the sun, I said, yeah. And I pulled the eclipse glasses off before I stopped looking at the sun, so then I had a bright blob. Just for a second, I had a bright blob in my eyes for a little while. So be careful with them. They’re often made of aluminized Mylar and they look– they’re kind of silvery.

Host:Okay.

Mark Matney: And also, don’t put any pinholes or anything in them. That– you want to– you want to keep them like they are.

Host:Keep them– so what are the special eclipse glasses? They have– they’re just like really intense sunglasses? Is that kind of what I think?

Mark Matney: Yeah, it’s kind of super sunglasses.

Host:Okay.

Mark Matney: Which here’s the thing, you want to avoid any homemade glasses.

Host:Oh.

Mark Matney: Don’t put on multiple sunglasses or something. Don’t use smoked glass, or photographic film, or neutral density filters, or anything like that. You’re not sure there’s enough there to block the light to make it safe.

Host:Okay.

Mark Matney: So stick with the– with the– with the kind that you can get. They’re not very expensive and you can– you can get them online and other places.

Host:Okay.

Mark Matney: One exception is number 14 welder s glass is safe, because that’s designed also for very bright. Like the welders use.

Host:Oh, okay.

Mark Matney: All right, so that’s okay. And the– and even more important part is don’t look at the sun– don’t look at the bright disk of the sun with any instruments, with telescopes or binoculars without proper filters on them, because those things actually magnify the strength of the sun.

Host:Ooh. They’ll your–

Mark Matney: and just like when I was a boy, I used to use the magnifying glass on the ants, you know? That could do that to your eye, so you need to be very, very careful.

Host:Yeah.

Mark Matney: So I would avoid– I would avoid those, unless you have properly designed equipment. Now, don’t like take your binoculars and put your sunglasses at the eyepiece, because it’s so intense it could burn right through your special glasses. So there’s– be very, very careful unless you know what you’re doing with binoculars and telescopes. Don’t even use those.

Host:Right, and that’s, again, that’s only a two-minute eclipse.

Mark Matney: It’s only a two and a half minute at the most.

Host:Yeah.

Mark Matney: So, that’s– that little window of time during totality, after the moon has completely covered the disk of the sun–

Host:mm-hmm.

Mark Matney: –That is the only time you can look safely without glasses.

Host:Okay.

Mark Matney: And it– and the brightness of the– of the eclipsed sun and the corona– it’s like the brightness of a full moon, so there’s no dangerous rays. You just don’t want to be staring at the sun when the sun re-emerges. So, okay. So, just good rules of thumb.

Host:So, when you’re looking at it– say you have the glasses on.

Mark Matney: Mm-hmm.

Host:Is there a specific amount of time that we can say is safe to have the glasses on and be looking at the moon about to cover the sun?

Mark Matney: Well, what’s going to happen–

Host:you don’t want to stare at it for hours.

Mark Matney: No, no. Well, what you’re probably looking for is as the sun– as the very last piece of the sun starts to disappear, you’ll see actually little dots that form, and those are called baily s beads.

Host:Hmm.

Mark Matney: And it’s an interesting phenomena of what– it has to do with the different brightnesses on the edge of the sun, and also the mountains on the moon.

Host:Mm-hmm.

Mark Matney: When those disappear, that’s the time you can take your glasses off and– so you don’t want to be– because that’s actually tiny little pieces of the photosphere of the sun.

Host:Right.

Mark Matney: Oh, there’s the other way– if you don’t have the glasses, there’s some other ways you can look at– and it’s– by the way, if you’re seeing a partial eclipse, you just want to use the glasses. You don’t want to look at the sun directly.

Host:Will you be able to see the moon partially covering the sun with the glasses?

Mark Matney: Yes, it ll look like a cookie with a bite taken out of it.

Host:How about that. That’s cool.

Mark Matney: That’s pretty cool. One method you probably heard of is a pinhole projector, and it’s very easy to make. You need some opaque material, like cardboard, and you make a pinhole, and then you project onto like a white sheet of paper an image of the sun. A pinhole acts like a lens. And I think it’s important, don’t actually look through the pinhole with your eye. It’s not intended to look inside. It’s a projector. It’s a little projector.

Host:You look at the paper.

Mark Matney: You look at the paper and you’ll see a little image of the sun with that. And you can see the progress of the eclipse. Another method I used to do when I was in high school, is if you take a very small mirror or a large mirror with a piece of paper with a circular hole cut out, and you can reflect the image on the sun– of the sun onto a shaded wall, and you can watch the eclipse that way.

Host:Oh.

Mark Matney: And I tell the story, I was in– I was in history class when there was an eclipse of the sun when I was in high school, and I asked the teacher, I said, is it okay if I put this in the window and we can watch the eclipse during class time? The teacher said, okay. So we put it in the window and it put an image of the sun during the eclipse up on the ceiling. We just went along with class and you could watch the progress of the eclipse.

Host:All right.

Mark Matney: So those are– so the mirror, there’s the projector, or your glasses are the three ways to watch the eclipse. And then, the only time, again, to watch the sun– watch the eclipse unaided is during totality, that little short period of time.

Host:Okay, and totality is by far the most narrow section of the u.s.

Mark Matney: That’s right.

Host:So you really have to be in that spot and we– you can go to the website eclipse2017.NASA.gov and find out exactly where that’s going to be passing through.

Mark Matney: That’s right. And it starts– I think I started this, but it comes on the west coast.

Host:Oh, right.

Mark Matney: It arrives in Oregon, it goes across Oregon, Idaho, Wyoming, Nebraska, Missouri, Kentucky, Tennessee, South Carolina. It’s a nice path that goes right through the middle of the united states.

Host:All right.

Mark Matney: And it’s a relatively narrow– relatively narrow path and, of course, it’s actually moving. It’s a round shadow that’s moving across the surface of the earth.

Host:Mm-hmm.

Mark Matney: And if you’re actually anywhere in that band you will see a total eclipse. The closer you are to the center, the longer it will last. Up to a max of two and a half minutes.

Host:All right.

Mark Matney: The other thing though is the weather.

Host:Oh, yeah.

Mark Matney: Yeah. So, it turns out that what eclipse aficionados like to do is they’ll look at the historical weather at that point in the U.S. At that time of year and it turns out some of the areas are more likely to have– to have clouds than others. So it turns out, eastern Oregon is a really good place. They tend to have nice clear weather at that time of year.

Host:Okay.

Mark Matney: Wyoming, Nebraska, Missouri, all the way to Tennessee, tend to be pretty cloud free at that time of year. And then, there’s another– as it goes over the Appalachians, they tend to be cloudier. And then the little section of South Carolina will also have, hopefully, less clouds than other places. But again, you never know. It’s the weather.

Host:Yeah. Oh, yeah.

Mark Matney: All you can do is roll the dice and figure– and hope that you’re lucky, because if– there have been many eclipses that people have gone– scientists have gone specific trips to see and it’s been interfered– the weather interferes.

Host:Yeah, that’s just– yeah, poor luck. But that’s based on data of this day over time at this place.

Mark Matney: That’s right. How often has it been cloudy on this day at this place?

Host:Yeah, and so you’re really rolling the dice, but playing the odds. But those based on statistical data are better off than others.

Mark Matney: Right.

Host:Very cool. Is there any particular spot during the path of totality that may be would be better? Like, for example, is it better to go to like a state park and be away from city lights or anything? Or is being in the city just as fine?

Mark Matney: It’s just as fine.

Host:Okay.

Mark Matney: It doesn’t get totality dark during an eclipse.

Host:Okay.

Mark Matney: It gets dark, but I don’t think that’s– I don’t think that part of it is particularly important.

Host:Okay.

Mark Matney: The main thing, it’s actually much more practical, you want to be somewhere where you’re close to restrooms.

Host:Okay.

Mark Matney: The eclipse itself lasts three hours and there may be a lot of traffic, so the ability to get around maybe limited.

Host:Ooh, yeah.

Mark Matney: So, just very practical things– are you close to food> are you close to supplies? Things like that.

Host:Mm-hmm.

Mark Matney: So let’s talk a little bit about what to expect.

Host:Yeah.

Mark Matney: As I said, there may be a lot of heavy traffic so you want to get to where you want to go early.

Host:Okay.

Mark Matney: And bring things that you’re going to need– your glasses– your eclipse glasses, a camera if you’re going to bring a camera, chairs, sunscreen, water, food, toilet paper, anything that you think you might need while you’re on the road.

Host:Wow, yeah.

Mark Matney: I once had to evacuate here in Houston during hurricane Rita, and it’s maybe a little bit like that and may be stuck on the road with heavy traffic if you’re not careful.

Host:Wow! Are you talking about people stopping on the highway just to–

Mark Matney: no, just talking about large numbers of people moving to see the eclipse.

Host:To see– to be in the path of totality.

Mark Matney: If you’re traveling– for instance, I’m going to be in the Carolinas.

Host:Mm-hmm.

Mark Matney: And every eclipse watched on the Atlantic coast is going to be headed for South Carolina.

Host:Yeah.

Mark Matney: So the interstates are going to be pretty full.

Host:Wow.

Mark Matney: So just allow plenty of time. The total eclipse– I mean, the entire eclipse lasts about three hours, so it’s about an hour and a half leading up to totality and an hour and a half until the moon completely uncovers the sun.

Host:Okay, okay.

Mark Matney: But again, I– and one of the things I thought was interesting was the eclipse veterans gave some very sage advice. They said, if this is your first eclipse, don’t try to photograph it. Don’t try to take telephotos of it. You’ll be so worried about your camera; you’ll miss the spectacular nature of the eclipse. So I think that’s good advice. And so, if you’re a veteran eclipse guy and you want to– and you want to make photographs of things, that’s fine.

Host:Yeah.

Mark Matney: Let the professionals do it. Just enjoy the experience.

Host:Yeah.

Mark Matney: I think that’s a good idea.

Host:I’m sure there’s going to be plenty of imagery coming out from all over the U.S.

Mark Matney: Oh, there will. I bet there’s going to be lots of selfies with people with the moon and the eclipsed sun behind them. But that’s fine.

Host:Do you think selfies will come out, at least during totality? Maybe when it’s dark enough it’ll be okay.

Mark Matney: You may need a flash on yourself.

Host:Oh, okay. A flash on yourself, okay.

Mark Matney: A couple of suggestions to do, so a little citizen science you can do.

Host:Okay.

Mark Matney: One of them is, notice how the sky colors change.

Host:Hmm.

Mark Matney: They’re very unusual colors that you don’t normally see, so that’s an interesting thing. Also, when there’s a tree casting shadows, there are lots of little tiny holes between the leaves that act like pinhole cameras. So sometimes you can see little crescent suns during the partial eclipse on the ground. So you can look for that. It’s kind of fun to take pictures of that.

Host:Oh, that’s really cool.

Mark Matney: Does the temperature change? Does it feel cooler during the eclipse? Does the wind pick up or calm down during the eclipse? Just some kind of scientific things you can observe.

Host:Just is there– are there things that we know of that– what atmospheric changes in the earth? Like–

Mark Matney: it will– it does change the heating of the earth from the sun.

Host:Oh, it does?

Mark Matney: Yeah, and you will feel colder. And people actually have noticed it feels considerably cooler, which will be pleasant probably on august 21st, especially in South Carolina. So just things to notice. Again, the other thing is as totality approaches observers have sometimes noticed what’s called shadow bands, and these are alternating light and dark bands that quickly move across the ground, especially where you have light colored surfaces.

Host:Hmm.

Mark Matney: They occur just before totality and after totality. They’re– actually, we don’t fully understand how they work. They probably have something to do with the atmosphere, the same reason the stars twinkle. But if you can see them– sometimes they’re seen, and sometimes they’re not. Something to look for.

Host:Hmm.

Mark Matney: Another thing to observe is right a s the totality is beginning, there’s just a tiny little sliver of the sun, and it looks very much like a diamond ring in the sky, and it’s called the diamond ring effect. And that’s definitely when the diamond ring occurs at the end of the eclipse. So the baily s beads– that’s the time to put your sunglasses– your special eclipse glasses back on.

Host:Oh, okay.

Mark Matney: But, as the eclipse is about to happen you’ll see the diamond ring effect, and then the diamond will go away, the baily s beads will go away, and then you’ll see the full totality. And again, you can take your eclipse glasses off during totality, but be ready to put them back on.

Host:Yeah.

Mark Matney: And another thing you can look around is take a moment– while you’re enjoying the eclipse, take a moment to observe people around you. See how people react to it.

Host:Yeah.

Mark Matney: The expressions on their face. Another thing, is sometimes animals behave strangely during eclipses. Chickens have been known to roost, birds behave differently. Even wasps and bees sometimes behave strangely.

Host:Wow.

Mark Matney: Cows, insect– dogs, insects, anything you can think of that’s close by, just for fun, observe and see if you notice anything.

Host:It is a strange and rare phenomenon to them.

Mark Matney: It is strange and they’re confused by it.

Host:Yeah, yeah.

Mark Matney: And by the way, after totality, the whole sequence will reverse it. So you have all those sequence of things, the partial eclipse, the diamond ring, the baily s beads.

Host:Mm-hmm.

Mark Matney: And that will reverse as the moon uncovers the sun.

Host:Wow. Amazing.

Mark Matney: So if you miss this eclipse, or the weather doesn’t cooperate, we have another chance in 7 years from now.

Host:All right.

Mark Matney: In 2024, there will be an eclipse that will move through Texas and up through new England, and it will be another total eclipse of the sun. So we have two in a very short period of time, but it’s been a long time since we’ve had an eclipse.

Host:All right, yeah.

Mark Matney: So, we’re due. We’re due. We get two– so, two chances, and my wife said, well, why don’t we just go to the one in 7 years? And I said, well, we don’t know what our lives are going to be like in 7 years.

Host:Yeah.

Mark Matney: So I said, carpe eclipsum. Seize the eclipse. So this is your chance.

Host:Fantastic. Yeah, no, I mean, I’m– if anything, why not both, right?

Mark Matney: Well, why not? We can try both. I may become an eclipse junkie, I guess.

Host:Yeah, yeah. No, I mean, it’s so cool. And the fact that we’re able to predict them, and we can go and– we have a bunch of best practices on how you can observe the eclipse, the best that you can possibly do it.

Mark Matney: Yeah.

Host:I know, going back, just one quick thing. Well, you said early. Arrive to your destination early.

Mark Matney: Yeah, if you can, yes.

Host:How early are you– are you talking about like days, or day, or hours?

Mark Matney: Well, it’s difficult to arrive days early now, because virtually every hotel is booked along the eclipse path.

Host:Oh.

Mark Matney: We’re going to be some distance away from the eclipse, so we’re going to have to start early. The eclipse is maximum in South Carolina about 2:30, so I figure if we get off at 8:00 in the morning that gives us about 6 hours to get there. And that may or may not be enough time. We’ll just have to do the best we can. That was just where we– I’m staying with relatives, so that’s–

Host:okay.

Mark Matney: But, a lot of people I know have their hotel rooms booked in the– at– underneath the eclipse, so they can just step outside and watch it.

Host:Yeah, that’s the– oh, I wish I planned ahead there. That would’ve been nice just get a nice, like, resort or something and just lay by the pool, watch the eclipse go by. That d be pretty cool.

Mark Matney: Actually, what I had originally planned– I’ve been planning for this eclipse since I was in graduate school many, many years ago.

Host:Wow.

Mark Matney: And I noticed that it would actually go through grand teton national park. And I thought, that’s what I’ll do. I’ll go to the grand tetons and see the eclipse. But it turns out, the weather is not so– it’s a higher probability of clouds there, so I backed away from that.

Host:Wow.

Mark Matney: Good luck to those of you that– the Tetons. But that would be a beautiful photograph, actually, to see the eclipse over the grand Tetons.

Host:Oh, absolutely. Let’s keep our fingers crossed for that good weather all across the board.

Mark Matney: Hopefully it’ll be clear all across the united states.

Host:Yeah.

Mark Matney: And everybody will be able to enjoy the eclipse.

Host:That would be fantastic. Well, I think that’s all the time we have, unless you have one more story. But– anything?

Mark Matney: I have other stories, but– there are lots of good stories.

Host:Well, hey, yeah. Actually, we have a website and if you stay tuned until after the music here, we’ll tell you where you can go and check out some more info on the eclipse and learn a little bit more about the history, the science, and all kinds of cool stuff, including the citizen science that Mark was talking about here and how you can– what you can do to observe some phenomena about this eclipse. So stay tuned for after the music there. Mark, thank you so much for coming on the podcast today.

Mark Matney: You’re welcome.

Host:I feel like that was– I’m not going to say everything about the eclipse, because like you said, there’s definitely more. But that’s the– I feel like I have a good understanding about eclipses and the science that goes behind it. So there’s a lot about eclipses and a lot that we can learn just from shadows, and it’s just amazing that there’s so much behind it. So thanks for coming on the podcast and talking all about it. And everyone, I hope you enjoy the eclipse on the august 21st. So thanks again, Mark.

Mark Matney: Thank you.

[ Music ]

>> Houston, go ahead.

>> I’m on the space shuttle.

>> Roger, zero-g and I feel fine.

>> Shuttle has cleared the tower.

>> We came in peace for all mankind.

>> It’s actually a huge honor to break the record like this.

>> Not because they are easy, but because they are hard.

>> Houston, welcome to space.

Host:Hey, thanks for sticking around. So, once again, this Monday, august 21st, a total solar eclipse will sweep across America. If you want to know all the information that we have, if this podcast was not enough for you, go to eclipse2017.NASA.gov. You can find out all the science of eclipses, even more than we talked about with Mark Matney today, where it will be, and then how to safely view it from the ground. Just be sure to make sure that you check the glasses and make sure that they are NASA certified. After talking with Mark Matney after the show, we found out that the shadow itself is going to be 68 miles wide, and then that shadow travels faster than 1,000 miles per hour. So, he went back and he was trying to find the width of the shadow. It’s actually a little bit smaller than you would imagine, but how fast it travels– I mean, we’re talking about some of those planes that are going to be following the shadow and studying it, they’re only going to get only a few extra minutes out of it because the shadow s traveling so fast. But, if you think about it, it’s the moon going around the earth, so it’s probably going to be a little bit faster than you would think. Anyway, you can find out more about the eclipse by following us on social media. Obviously, our NASA accounts will be talking about this, but also here at the NASA Johnson space center you can follow our accounts there. We’ll be talking about it. If you follow international space station you can see some of the imagery. You’ll get from there 250 miles above the earth. And then also, ARES astromaterials research, you’ll find them on multiple accounts and you can talk– they will be talking mostly about the science of eclipses, and they are also based here in the Johnson space center. All of these are on either Facebook, twitter, and Instagram. If you want to join the conversation for– and maybe submit some pictures that you are taking from wherever you’re going to be observing the eclipse, and then also sort of see what everyone else is doing, the official hashtag for this event is #eclipse2017. Just use that on your favorite platform and share your experience and maybe ask a couple questions in case all of the information we told you today and anything you can’t find on the website we can still answer even more questions that you have. So this podcast was recorded on July 19th, 2017. Thanks to Alex Perryman, john Stoll, and Tracy Calhoun. And thanks again to dr. Mark Matney for coming on the show. We’ll be back next week.