Neil deGrasse Tyson on Pictures from Space

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Brian Lehrer: Brian Lehrer on WNYC. Last week, President Biden and NASA officials released the first images from the James Webb Space Telescope and wow. By now, you might have seen some of these pictures and awe-inspiring as they are to us non-scientists there's a lot of promise in those first pictures that this telescope will be bringing us not only beautiful art but also groundbreaking science. We'll talk about that in a second with none other than Neil deGrasse Tyson.

Before we get into it, some perspective, that first image that was released, many of you saw it with the many, many galaxies and stars in one frame. It's like if you take a grain of sand, and hold it up at arm's length to the night sky. That's the area covered by that picture. How many grains of sand would it take to fully cover the night sky? That's the task ahead for the James Webb Space Telescope as well as the task ahead for the people associated with it, to explain the images that may be beautiful and awe-inspiring to the layperson, but also not at all clear in what they show or what they mean.

We can't say that over the next 5 to 10 years, we can expect more stunning images of our universe and more than that, we can expect to understand more about how our universe was created because the telescope isn't just looking at things really far away, it's looking back in time, but instead of letting me stumble through trying to explain how a telescope is also a time machine, we'll leave that to our pro-science communicators.

Please help me welcome Neil deGrasse Tyson, Astrophysicist and Director of the Hayden Planetarium at the American Museum of Natural History, a host of the StarTalk Radio podcast, author of the forthcoming Starry Messenger: Cosmic Perspectives on Civilization and so much more. Hey, Neil, thanks for coming on with us again. Always great to have you. Welcome back to WNYC.

Neil deGrasse Tyson: Yes, Brian, it's been too long. We've been COVID separated but happy to be back with you.

Brian Lehrer: Listeners, we can take your questions about the Webb Space Telescope at 212-433-WNYC, 212-433-9692. Maybe you're wondering about the hardware, maybe you saw something in the images that you want to understand better, or even try to call and put into words the inspiration that you feel, looking at these pictures, if they've inspired you in any way or maybe these images have given you some deeper philosophical existential questions about where we are, what we are, who we are, in the context of our just massive universe.

212-433-WNYC, 212-433-9692 for Neil deGrasse Tyson. Neil, let's start with that first picture that was released before the others. It's like a collage of galaxy shapes and eight-pointed stars. I think it's generally compared with the Hubble's Deep Field imagery from the last generation telescope. Help us look at that image with a scientist eyes. What are we looking at?

Neil deGrasse Tyson: You're referring to the one that got leaked by the White House the day before the press conference held at NASA headquarters?

Brian Lehrer: Yes.

Neil deGrasse Tyson: That image is, without question, the deepest. When we use the word deep, we mean, how far away are you observing things. That's the deepest image yet obtained by any telescope in the history of my field and that's just the first one they're putting out. We all have very high expectations for what this telescope will continue to deliver. Those of you who remember the image because this is radio, so I'll be a little more descriptive here that there is some spiky star objects in it.

Those are stars that are sitting on our nose, right here in our own Milky Way galaxy. There are so many stars. It's very hard to find a clear view outside of our galaxy to the rest of the universe. There's always some stars that are photobombing your attempt to obtain images of the rest of the universe. The hardware of the telescope, this is true for any telescope, there's a primary mirror and a secondary mirror and the light bounces back and forth a couple of times before it lands on the detector.

The structure that holds up the secondary mirror has mounts. It's called a spider mount and light from a bright star diffracts around that structure, creating the spiked view that you see.

Brian Lehrer: Oh, that's why these stars look like they have a point.

Neil deGrasse Tyson: Yes, exactly. It's very Star of Bethlehem-like. That is compositely an artifact of the hardware of the telescope. There's nothing cosmic about it. In fact, the spikes are quite annoying because they spill over into regions of the image where you might have a galaxy sitting beneath it. All the spikes, just ignore them. Now we see everything else. If you take a step back, you will notice that many of the galaxies are curved into these little arclets and centered on the middle of the image.

Well, it turns out all of those arclets are actual entire-- Well, every fuzzy thing on there is an entire galaxy but a subset of them curved into these arcs are the most distant galaxies in the image and their light otherwise would have come to us unimpeded, unaltered had to pass by the gravitational field of a galaxy cluster, sitting between us and those galaxies. We know from Einstein, where you have strong sources of gravity, it creates a distortion in the fabric of space and time.

It's called an Einstein lensing is what it's called. What's happening is, these galaxies might not even otherwise be visible were it not for the fact that they were magnified and distorted on their way to us here on Earth. In that image, are countless galaxies, a whole ensemble of galaxies that are at the edge of the known universe, a galaxy cluster, and gravitational lensing, all in one fell swoop.

Brian Lehrer: Well, one of the key things to understand about that, I think, is and I mentioned this in the intro, is that we're looking at things that are thousands of light years away and that's a time reference, as well as a space reference means we're looking into the past. By the time the light gets to the telescope, those images would be out of date by I guess, thousands of years. How far back in time are we looking and how much of the mission is actually centered on that element of time and understanding the history of the universe?

Neil deGrasse Tyson: Yes, a brilliant question there. A couple of things. Because light is not infinitely fast, it has a speed. In American units, it's 186,282 miles per second. Now, that's really fast and we don't think about that in our everyday lives. If you're sitting across the table from me, and we're having a conversation, let's say you're three feet away I actually don't see you as you are. I see you as you once were three billions of a second ago.

Now you live, 80, 90 100 years so a few billions of a second is not a meaningful fraction of your life expectancy. I think of you in the now, not as you once were. Well, if I put you farther and farther away from me, I will be seeing you farther and farther in your past. If I put you on the moon, you were one and a half light seconds old. If I put you on Mars, depending on where it is in its orbit, it could be 10, 20, 30 minutes away.

As you get farther and farther away, the nearest star to the Sun is four light years you see it as it once was four years ago. Again, small compared with a lifetime of a star. We're not lamenting that all the stars we see at night are no longer there because they're not far enough away for that amount of time to be significant in their life expectancy. When you start looking outside of our galaxy to other galaxies farther and farther away, you were seeing them as they were billions of years ago.

They are very different today than they were at the time we're seeing them. Here's the fun part about the telescope. Galaxies being born have a lot of ultraviolet light in them. Brand new stars give off copious amounts of ultraviolet light. That's 13 billion years ago. Now that light is on route through an expanding universe and that the wavelengths of light are affected by the stretching of the fabric of space and time. What starts out as short wavelength, ultraviolet light, by the time it reaches us, it's infrared. This telescope was tuned for the infrared to see the light of galaxies that had been emitted as ultraviolet arriving to us as in infrared light. It's exquisitely tuned just for that reason.

By the way, now that you ask, if it can see infrared, it can penetrate gas clouds that are otherwise opaque to visible light. What happens inside gas clouds? Stars are born. They're stellar nurseries and where you have stars you also have planets. Curiously, this telescope originally conceived to view the birth of galaxies in the universe, also is exquisitely tuned to see the birth of stars in our own galaxy.

Brian Lehrer: Pedro in Mexico City. You're on WNYC with Neil deGrasse Tyson. Hi, Pedro.

Pedro: Hello, thank you. Neil, a huge fan. Quick question for you. Is there anything in the images that surprised you? In other words, did you learn something or do you feel like you know less now?

Neil deGrasse Tyson: That's a great-- No, no. The reason why that's a really good question is you spec a telescope to make discoveries that you expected to make given your state of knowledge at the time. Then you ask, if you're going to open a whole new window to the universe, then might you be discovering things you didn't even know to ask about? Might there be things showing up that you say, "Wait, who ordered that?"

All I can tell you now is in the pure photo, there are arclet galaxies and spiky stars and other galaxies greatly resembling the Hubble Deep Field image that many of us knew and celebrated, but on further analysis, when you get spectra of galaxies, you might say, "Wait a minute, there's a new class of galaxies here. They look like the others, but they're doing things that we did not expect, we did not anticipate."

I can tell you this because I was at the meetings when we were specking what the Hubble Telescope should discover and the meetings where you're specking what the James Webb Telescope should discover. With the Hubble, if you listed the top 10 things it brought to us, at least six of them no one ordered. No one it saw coming. At this very early stage, I didn't see anything that was out of the ordinary. No alien spaceships flying by [laughs] or anything, but further analysis may ultimately reveal that.

Brian Lehrer: That would've been something seeing an alien spaceship flying somewhere thousands of years ago in a far-flung galaxy.

Neil deGrasse Tyson: Billions of years ago.

Brian Lehrer: Robert in Queens, you're on WNYC with Neil deGrasse Tyson. Hi, Robert.

Robert: Hi. Thank you. Since this light that's being picked up is out of the visible spectrum because of the speed that these galaxies are traveling away from earth, how do they come up with the color that they show in the photo? Is it actually seen by the telescope or is there some algorithm that the scientists use to convert whatever the telescope picks up into colors?

Neil deGrasse Tyson: Yes. Another great question. Brian, you got some good listener, dude. [laughs] Thanks for that question. The way to think about this is as you know in your retina, the cones of your retina have three different color sensors and this is where we get RGB. We have red sensors, we have green sensors and we have blue sensors. In the world of light, not in the world of mixing artist paint, in the world of light, when you combine those three colors in equal amounts, you recover white light.

This is why RGB is so important in computer screens and everything else that creates images. Combinations of that will give you all colors, including the color white. What we do is if we have data from another part of the spectrum, I don't care where, radio waves, infrared, ultraviolet, that is otherwise invisible to you. If I obtain data in three different bands, three different bands of light, I can get an image because I have a detector that's sensitive to these places your eye can't see.

Now it's as though my eyes were shifted. Now watch, I have three different bands and in the computer, I assign RGB to those three different bands and I combine them, you get a full-color image, which is what you would see if your RGB of your eyes were shifted into that part of the spectrum. It's an authentic color picture if we were supervisioned people like there's a character in Star Trek Next-Generation, Geordi, who could see all wavelengths of all light, not just this narrow band that we call visible light. In principle, he'd be able to see colors no matter where he was looking. It's a legit exercise.

Brian Lenher: It's not fake. It's not a colorized old, black and white movie.

Neil deGrasse Tyson: Oh no, well, that's correct. Well, and by the way, I would say for some colorized movies, they have a record of what colors things were. You just go in and put the correct color in. The colorization when it began in film, you knew it felt a little not real but they've gotten much better at it, but this is a different process because that was only one black and white image. Here, you get images in three different bands, a sign in RGB, but a Bing, you have a color image and it's, and it's authentic not to be confused, not that you ask, with false color.

False color is an authentic legitimate scientific tactic where we assign a color to something in the image that has nothing to do with color, like to rainfall amounts or wind speeds, or elevations of a terrain. You can instantly see, oh, the blue is at high terrain or the red is heavy rains and so that would be false color because we're very good at seeing color and picking it up instantly rather than reading a number on a chart. That's false color helping you interpret other kinds of data in a photo.

Brian Lehrer: One more call. Edson in Manhattan, you're on WNYC with Neil deGrasse Tyson on the first images from the Webb Space Telescope. Hi, Edson.

Edson: Hi, Brian. Thanks for taking my call. It's worth mention who is the person behind this huge successful project, Mr. Greg Robinson, graduate from Harvard University and he was invited to take over the project and he declined twice and he finally accepted and we see this huge successful now with those beautiful images. I would like to ask your guest how he sees with this images. Is it going to affect our people beliefs in the God creation of the universe?

Neil deGrasse Tyson: Yes. I know we only have a couple of minutes left. I think deeply religious people who see the universe as the handy work of God and then they'll see these beautiful images, they'll see it all as part of God's creation. If you otherwise are a rationalist, you see it as more of what we've already learned as local to us stars and galaxies and the expanding universe. I don't know that it will change people's religiosity, but I do know that it will stoke people's appreciation for the majesty of the universe. I think we all benefit from that no matter where you are on the religious spectrum.

Brian Lehrer: You want to give us 20, 30 seconds on what you hope to learn, ultimately, from what this telescope can provide.

Neil deGrasse Tyson: Here's what I'm going to do. I'm going to give you a cop-out answer. Here's my cop-out answer in the remaining 15 seconds. What I want the telescope to discover are answers to questions we have yet to pose. Then it is truly leading us into a frontier rather than just fulfilling our expectations of what we designed it to do.

Brian Lehrer: Wow. Neil deGrasse Tyson teasing our imaginations with the prospect of questions we have yet to even know to ask, being revealed to us from the Web Space Telescope, Neil deGrasse Tyson from StarTalk, the Museum of Natural History Planetarium, the forthcoming book, Starry Messenger: Cosmic Perspectives on Civilization. I know we just scratched the surface so I'd love to have you back and continue this, certainly when the book comes out, and maybe more than that. Thank you, Neil, so much.

Neil deGrasse Tyson: Thanks for your continued interest.

 

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