Field Trip: The Known Universe
CARTER EMMART (Director of Astrovisualization): Welcome everyone. It's a pleasure to share with you today a tour of what we call the known universe. I'm Carter Emmart. I'm the Director for Astrovisualization for the Museum of Natural History, and we're going to share with you this visual, this visualization of the universe with this software called OpenSpace. It's open source, and it's freely available. If you're interested, our website's openspaceproject.com. And it visualizes what we pulled together as a data set at the time when we were rebuilding the Hayden Planetarium, this Millennium Project, almost-- or about 20 years ago.
What we're seeing here is the Earth, and the Earth is an image from Monday. NASA publishes these mosaics from NASA Goddard-- Goddard Space Flight Center in what's called the Global Imagery Browse Service, and you can look that up, and you'll see these Earth images, and it's a daily mosaic taken by Earth's satellites. And this is one of those views.
We're actually looking now at North and South America, and we're looking all the way up to sort of the North Pole. The time that we see is representative of now, essentially, but we're just seeing the Earth rendered from Monday, which was the last sort of really good map we had that was available. So if we can look down, we see the clouds represented-- represents the weather and so forth that we naturally see on a daily basis. And we also render the atmosphere so that in this beginning, at Earth, before we move away, I just wanted to show you some things.
As we come in closer, we're going to go from this beautiful image with the clouds of just a few days ago, and we're now seeing, as the clouds dissolve away, we can see the width of North America. We can see the Great Lakes, and we're coming in over the western third, over the Rocky Mountains, and so over the United States. And as we come in, we're going to look-- we look back to where New York is, all the way over near the edge of the Earth, about 2,000 miles away from the Rocky Mountains. North America across the United States is about 3,000 miles wide.
What the astronauts see, of course, when they course over a few hundred miles up in the International Space Station is that they see, basically, the clouds below, and they see how thin the atmosphere is. We're going to be flying today. Actually, my navigator-- you can see I have my hands free. But my navigator is Micah Acinapura. He's our developer for OpenSpace at the Museum, and so he's my very capable navigator. So I may actually call him out a couple times to turn things on and so on.
As we come down over the Rocky Mountains, we're looking out to the horizon, and we haven't even seen-- we can't see New York anymore. But what we do see is how thin the atmosphere is. We went from this global image from NASA of the latest satellite imagery, and now we come down over these mountains in the Rocky Mountains that-- what we're seeing is imagery that's been gathered by other satellites in higher resolution, and that's made available to us from Esri, which is one of the largest geographical information systems companies.
And so we work between these different data sets within OpenSpace. We actually see the constellation of Orion just over the limb of the earth. The atmosphere it almost scary. Thin it's only about 20 miles visibly. It tails off exponentially, but what the astronauts see is that 20 miles above the Earth, 30 kilometers, is that it fades to black. And that's it. We live within this atmosphere. We live within this biosphere. And to bring this to you, especially today, given the world situation, this is a reminder that we're part of nature.
And so what OpenSpace will show us here is, perhaps, the broadest view of nature that we know, what we call this known universe. So as Micah moves us away from the Earth, we're seeing, once again, the continent of North America. We see no borders. The astronauts see no borders. The borders are what we impose on top the Earth. But naturally, we're seeing this global view of us, reminding us that we're all in this one place together, this one sort of-- one fish tank.
I'm going to ask Micah to just sort of pause. We see a line over the top of the Earth. And Micah's going to pull around so that we can see this. This is the orbit of the International Space Station, where we have several astronauts right now orbiting the Earth. They orbit just a few hundred miles off the Earth. And this is just high enough to be above the atmosphere and so that going around, that they encounter the least atmospheric drag, but they're close to Earth. Most of our satellites orbit within this range. And so they're just a few hundred miles off the Earth, and they take about an hour and a half to go around.
Farther out, about three Earth diameters away from the Earth here, we have the geosynchronous orbit. So these are the satellites that go around the Earth, and I mentioned that the Space Station goes around about 90 minutes, an hour and a half. But out farther away, the farther away you go, the slower you orbit. And so at this distance of about three Earth diameters, you go around the Earth. Your orbit is 24 hours. And so if you place satellites over the equator, you can use them as sort of stationary beacons that you can see in the sky, geosynchronous satellites.
Ten times that distance is the orbit of the moon, the farthest that humans have ever been. And so we're using this trail. The orbit would be nearly a circle. That's really-- all orbits are ellipses, but we're placing the Earth now-- you can see this line coming out. Just like the moon, we didn't see-- we pulled away. We're not-- the moon's up ahead of that trail, so these trails basically draw out the orbits that are happening.
And so we can see now that the Earth's trail goes around the sun. And so if Micah just dips down a little bit, we'll see the sun. And we'll also see some other trails. And closest to us is the trail of Venus, and then farther in, the closest planet to the solar system, Mercury. So the planets traced out here-- Mercury, Venus, Earth next-- next up orbit out, just coming in now is Mars. Farther out, we have planets of the outer solar system. But between Mars and Jupiter, we have-- that's roughly in that band are the asteroids. And there are different types of asteroids and so on. We're not showing them just now, because this is our quick tour.
Beyond Jupiter, we have the orbit of Saturn, and then beyond that, Uranus. And then, finally, in blue, we see Neptune. And this is the full complement of eight planets. Beyond Neptune, this is the Kuiper belt, where the dwarf planet, Pluto, is a member of. So what I'd like Micah to do is just-- we're going to tip the solar system over a little bit to remind us that it's a disc. Micah, just tip it over a little bit.
And one thing I need to point out-- and also, Micah, if we actually pan a little bit to the left, that might help us. So in this way, what I'm asking Micah to do is he's actually the pilot. Oh, OK, keep going, Micah. And this way, we're passing some of the winter constellations, the star Aldebaran just passing behind our sun. Micah, keep going around, all the way around. Let's do a 180 around our view here.
Well, we see the bright star, Sirius, and the constellation, Orion. And we're now seeing the band of the Milky Way, which Galileo first looked at basically with his telescope and said it was uncountable stars. We now know that that glow is made up of these stars of our Milky Way galaxy. But before I show you that, I want to show you how our solar system is sort of tipped over to the Milky Way. And so here, we can see how the various inclinations of the planet, of the various planets are very flat. So this basically speaks to the fact that when we form-- the solar system formed out of a disc around the star we call the sun.
So we'll pull back a little bit, and what we've done is we've sort of artificially dimmed the sun. Obviously, it would be the brightest thing on screen, too bright to look at. So as we pull away, we're now going to show you the true brightness of the sun. Solar system sort of is in the glare of it. But we're now going to see, especially that star over on the right, is Alpha Centauri, the nearest star. So we're now depicting the sun. We're visualizing its brightness relative in brightness to the other stars.
Alpha Centauri is a triple system, just over four light years away, 6 trillion miles in one light year, so about 24 trillion miles. So we'll talk about light years. That's the distance that light would travel in one year. So now we see the nearby stars around us, and if we just seize here a little bit, Micah, and let's just not move out any farther, and just orbit around, because I want to consider the stars that we're seeing.
Now familiar constellations begin to lose their shape, because we're out in 3D space. We're so far away from the sun now and Alpha Centauri. They're fairly dim, and we can't-- it's very difficult to even see them. The dimness of our star we can thank for its longevity. It's been around about 5 billion years, probably has another 5 billion or so years to go of fuel, and that we've evolved on the Earth, the Earth being about 4 and 1/2 billion years old. We know that from the oldest moon rocks and our understanding of the planets.
So out here in the stars, you might wonder, well, what else is out here? Are there other solar systems? Well, we've actually detected them. Starting in 1995, we are able to look directly at stars and see that they have slight wobble. So if we turn on the exoplanets, Micah's going to turn on a data set where we're actually-- that these circles are actually identifying the locations of stars. In certain cases, you'll see stars bright enough. You'll see them in the middle. In a lot of cases, some of these are dimmer stars.
And so what we're showing here is within the field of stars, we're seeing those as an overlay, essentially, in 3D space of stars that have planets, just like our own solar system. And Micah, if we actually swing around the other way, just kind of keep going. Micah will parade around this. And so we'll keep going in this direction and look at the Milky Way behind us. The Milky Way gets really bright. It's just sort of moving, and the Sagittarius and Scorpius region lines up with the Sagittarius and Scorpius constellation. It's where the Milky Way is brightest.
But over on the left coming in, we see yellow dots, and these are discoveries of the Kepler telescope, which is in orbit around the sun but looking at just sort of one part of sky. And if Micah lines up this sort of wedge that we see, we're going to actually see the field of view of the instrument. And so it was basically sort of a waffle pattern of detectors, and look at how it's filled with exoplanet discoveries, essentially.
And so there's two different ways in the science of how we detect other solar systems, but also, just look at that wedge. We know that that wedge is representative of the entire sky. This is just the part that they were really looking at. So I'd like to actually move away from this now, and Micah, if we actually align us-- oh, actually, one more thing I want to show.
You might wonder sort of the scale of this. I'd like to turn on what we call a radiosphere. Now we might move in just a little bit, Micah. I think we have enough time to do that. So we're going to turn that on. What this is is a sphere. It's actually aligned-- sort of the North Pole a bit that's over to the left is lined up, and we call it the celestial sphere. That big pole of this is lined up with this thin axis of Earth.
But the radius of this is illustrative. We're illustrating how far radio signals in about 80 years of travel away from us, so this is a-- the radius of the sphere is 80 light years, basically since around the time of World War II. At that time, the Earth became radio bright, and so our signals are expanding out. They get sort of dimmer and dimmer with distance, but this shows how far our reach as humanity in a few-- just in a few short generations has reached on out into space at the speed of light.
This will help locate us within the galaxy. If we pull away, Micah, just from here, just from this point of view, with, basically, that bright section of the Milky Way still in view. This will be actually quite nice. I want to bring up a detection that happened really back in the 1920s. So back here, Micah, so here we see exoplanet discoveries. Let's pause here and turn on the globular start clusters.
We're so far away, we're actually going to turn on another data set that indicated that what we were in, the system of the Milky Way band of light that you see across the sky, it's actually this large system of stars that we now know a number of about 200 to 300 billion. These little yellow dots that we're seeing that are augmenting the big cluster around the center of the galaxy indicated to us the size and nature of the galaxy, which we now see portrayed.
Every one of those dots is a star cluster, like a little beehive of stars. They're 100,000 to a million strong. As we move out, notice how this wedge-- Micah, let's actually go below the plane. What I want to do is, before we move out, we're going to tip over so that we're going down below the plane of the Milky Way. And the exoplanet discoveries, which are still on, which is data, representative data points of exoplanets, actually acts as a little arrow to where we are in the galaxy.
So-- and then, Micah, just about here, I want to look at the sun's orbit around the galaxy. So Micah's going to turn that on. Just as the moon goes around the Earth and the Earth goes around the sun, the sun, in turn, goes around the galaxy. And so we can speak in terms of sort of a galaxy here, and so now we see that. So this is the sun's orbit. All the stars are really going around, creating the sort of spiral arms of the galaxy.
The bluishness of the galaxy is where stars are regenerated. This is where stars are born, but it takes us, for one orbit, 250 million years, a quarter of a billion years. We've been around 16 to 18 times around this galaxy. One quarter turn back is when the dinosaurs died off, about 60 million years ago. And so what we can see in just-- in this one loop around the galaxy is it's basically one loop back is when life was crawling out of the oceans and early dinosaurs. So the dinosaurs didn't even last for one orbit, and we've been around for a very, very short time.
So this Milky Way galaxy here and the complement of star clusters is our home. This is us. You might think, well, that's quite vast to think of as us, but as we move out now, we're going to see other galaxies. On the immediate right, we see these dots coming in. This is a data map of galaxies closest to us. Those are the large and small Magellanic clouds. We're now sort of getting really close and congealing just with our location.
Micah, can we turn to labels on just to sort of demonstrate for us what we're seeing-- the labels and illustrates that this is really data. Every one of these points is information. Notice behind the Milky Way is sort of a cluster of galaxies. That's called the Virgo cluster, and right now, in our skies, it's sort of coursing right above us around midnight. Notice how our label for our Milky Way galaxy we call home, because it is home. And around us are other just data points that are mentioned or the locations of these very specific galaxies.
So Micah, we can now move away. The Virgo cluster galaxy is 60 million some odd light years away from us. So the light that we see from there comes in just around the time at the end of the dinosaurs. Andromeda was close to home there. That's one of the nearest galaxies to us. And as we pull out, we're now looking at a grouping of galaxies that's about 30,000. And this was pulled together by our colleague, Brent Tully, the University of Hawaii.
And so this grouping of galaxies really maps out a few hundred million light years around us, tremendous distance. When I say light years, that means that the farthest galaxies here represent a few hundred million years old light. So we're seeing galaxies from 100 million years ago. We pull out farther. What we're looking at now is the Sloan Digital Sky Survey. This is a survey that's been looking across the entire sky. It's been color coded so that the denser regions are yellow, and then the less dense areas are cooler colors.
Notice how this almost web-like nature of this large scale structure of the universe comes into play. We can see this, because, basically, we can get the distances through the galaxies. Notice, also, the areas in black. This is where we get to map. This is-- basically, that's the plane of our Milky Way. Our Milky Way galaxy, the disc that we're looking at, sort of blocks our view. And so it's easier to account for galaxies above it and below it.
Toward the top of the screen aligns with that of the sort of northern-- North American view in the Sloan Digital Sky Survey's view, and to the lower portion of the screen, its view of the southern skies. So it's biased toward, basically, a view from its location point of that survey telescope at Apache Point in Mexico.
As we go out farther, we're getting now out to galaxies that are about a billion light years away. And we begin to transition to some other objects. They're galaxies, but they're really active galaxy nuclei. The galaxy's an informative process. We now seem to understand that most galaxies, if not all galaxies, have a supermassive black hole in the center. When there was still enough gas around to sort of fall in all those black holes, they create a super bright phenomenon. And we can see them, what we call quasars.
They're the most distant objects that we can see-- are now reaching back billions of years into the past. We're seeing a younger and younger universe surrounding us. If we look far enough out, we come to the cosmic microwave background radiation, imaged here by the Planck satellite in 2013. And the slight temperature variations that are exaggerated to give warm and cool colors. Where it's blue, it's slightly denser. Where it's red, slightly less dense. Led back over time, percolate, and that comes together into what we see as a large scale structure, the universe that we saw in the Sloan survey closer to home.
It's about time, I think, that we start running home and maybe take some questions. But I hope that this perspective on the universe is something that reminds us that we are all part of this thing. We really are in nature, part of it. We are part of this nature that has sort of figured this out and mapped it. But consider all of these galaxies, perhaps each with a trillion worlds. Is life unique? Has it evolved before? Have other civilizations also created maps of the universe?
Maybe so, but what's really unique is our life, especially this life of us, humanity, that we've figured this out. As we come home, we consider, what is home? Home is our planet. Home is our galaxy. Home is our universe.
So here we are coming back, Milky Way galaxy surrounded by the large and small Magellanic clouds with the Andromeda Galaxy out there. Here are the globular star clusters on and, once again, pointing our way back to the Kepler survey of exophones. Getting in close, we can see the radiosphere and also some of the strands of the Kepler mission once it lost its angling. It lost a little bit of a spacecraft. So it's doing surveys sort of out in-- we also see other sort of wedges.
And if we turn off these data set, now we were just with the stars. I think Micah's struggling to do that, but he's putting it together. He's doing a fantastic job flying. Thank you, Micah. And as we come in, these are the stars that surround us. I remind us of how dim our sun is, our home sun, our home star, our home planet, just the right distance away from the sun to evolve over billions of years, to us here today to view it.
The glare of our sun, the planets of our solar system, and, finally, huddled close, most of the camp fire in the center, our star, the sun. In our nice little orbit, fairly stable orbit, our moon, the farthest we've been. We last left in December, 1972. And finally, our home, the Earth.
Once again, what we've been driving through is what we call the digital universe 3D Atlas. We have put this together at the museum starting in the late '90s to build a data set to actually fly us through or the productions that we make at the museum. And then we began with the software to really be able to visualize it.
I want to give a big shout out to our partners at OpenSpace. OpenSpace is a project that started because I met a professor from Sweden, Anders Ynnerman, in 2001. And we began collaborating. That collaboration led, eventually, to OpenSpace. And we got NASA funding from NASA's Science Mission Directorate to make this and bring it to you and make it freely available. We're one of a number of different partners funded by the Science Mission Directorate. And so our partners, our museum-- our other partners out there range in a number of educational activities. But those that are developing OpenSpace, Professor Ynnerman comes from Linkoping University in Sweden. And also, we're collaborating with the University of Utah's Scientific Computing and Imaging institute. And then also, New York University's Tandon School of Engineering.
So together, we're developing this OpenSpace, and we continue to add different data sets and missions, visualizations of the science that NASA puts together. It's been a great pleasure to bring it to you. So I'm going to just now look-- I understand that some questions may be coming in. Great.
Let's see. From Sierra Science Center, is this what the real Milky Way galaxy looks like? That's a really good question. And so what you're seeing is actually a constrained simulation of the Milky Way, which means that we take observations of gas clouds and fit that to a model. That was done by colleagues of ours at the National Observatory in Japan. So this is truly an international effort of science.
From Brett Ragan, why do the galaxies appear in a bow tie pattern? Once again, I attempted to mention it-- thanks for asking that again-- because it's where we've looked. It's what we call an observational bias. Notice how in the background, the Milky Way that we see now complicates the matter of looking for really dim galaxies. A few questions about dark matter-- does that explain why the dark areas or holes we saw between stars and galaxies, is dark matter? Dark matter is an interesting aspect. We see that we see, basically, that galaxies spin too fast. They would fly apart. Vera Rubin made this observation back in the 1970s. And before that, Fritz Zwicky had seen back in the 1930s that the motions within galaxy clusters, the speeds, were too great to actually hold galaxies and galaxy clusters together. There must be mass that we don't see, and that's dark matter.
In the last question, Lauren Shulman wanted to know if OpenSpace is software she and her students can use. Absolutely. OpenSpace is designed for everyone to use, and we are proud to make it freely available for everyone. So once again, its website is openspaceproject, one word, openspaceproject.com. And when you go there, we have a download for Mac, a download for Windows. You'll need a good graphics card, essentially, to run it. But-- because it's really-- it's very graphics intensive.
But this visualization is pulling in these different parts of the universe to visualize into one consolidated whole. And that's really what OpenSpace is about. So again, I just want to thank you all for this very enjoyable flight, certainly for me. I want to thank Micah Acinapura again as my pilot-- very capable. And together as a team we present the universe, bring it to you, but it's your universe. Please download that, and check out the Digital Universe 3D Atlas in OpenSpace. It's been a pleasure. Thank you. Thank you very much.
Travel through the Milky Way galaxy and beyond! The Museum’s director of astrovisualization Carter Emmart provided a live guided flight through the universe. Emmart used the new interactive data visualization software OpenSpace to take you to the outer reaches of the Known Universe and take viewer questions.