Although it sounds dramatic, perhaps catastrophic when galaxies collide, the results for us, hypothetically, would not be significant. The Earth and the solar system would continue in its orbits if the galaxy merged with another galaxy and in fact, we know this is going to happen. Although most of the galaxies we see in the sky are moving away from us with the recession velocity, an exception is our nearby neighbor Andromeda M31. M31 is approaching us at a speed of 100 kilometers per second. That's pretty fast but the distance is two and a quarter million light years. So it'll take several billion years before we meet Andromeda. The results, should life still exist on Earth at that time, will be very interesting. Creatures still on the planet will have a ringside view on an amazing architectural rearrangement of two large spiral galaxies as they meet and coalesce. But again, the consequences for denizens of that planet, our planet or any planet in either of the galaxies, need not be catastrophic. This is a large-scale gravitational effect that just moves things around in their orbits and doesn't actually cause collisions. Hi. Good, well we are ready to begin. Do you want me to sit here? That's perfect. Are we prerolling? Great. Okay, so why don't you just introduce yourself. I'm Felicia Day. You hired me. Of course, is this your first time doing an internet video Miss Day? No. Great. Then you know how this works. Nasa Spitzer Space Telescope has been studying galaxies colliding and they've hired us to make an educational film to promote it. Sounds good. I haven't read the script yet. They just gave it to me a few moments ago. Roll cam. Let's try and get this in one take, people. Flunky, put up the image and action Hi, I'm Felicia Day. As you know, colliding galaxies sure are scary. They're scary? The script is down there not up here. But now, the Spitzer Space Telescope has made discoveries that shed new light on the supernatural phenomenon. Okay, supernatural is a bit much. Hue the graphic. Was that an explosion? That Miss Day was the sound of millions of voices crying out in terror and suddenly silenced. In other words, galaxies colliding. Do you even know what it means for galaxies to collide? I'm sure it's something like when cars collide, only hundreds of times bigger and we are on a timetable here, so. Okay. First of all, galactic mergers are pretty common in the Universe. Most large galaxies are formed out of smaller galaxies merging together. Fascinating, again. The point is that you seem to think that it's destructive. Like millions of stars smashing into each other. But in reality, their is so much space between stars that it's extremely unlikely that any two of them would ever collide. So while gravity may toss them around into new orbits, they'll all pretty much survive intact. Okay. Fine. Flunky, lose the explosion. Yes, much more dynamic. I actually think it looks pretty cool. I'm hearing a lot of talking and not a lot of script reading. Okay, sorry, let's see. Galaxies are scary, supernatural phenomenon. Okay, here we go. But I'll bet you want to know what Spitzer has discovered. Right, Sean Astin? I like stars, insert tape number two. What in the name of Josh Whedon was that? We couldn't afford to hire both you and Sean. So we edited together one of his audio books. Cue Sean Astin again. I like stars, insert tape number two. Boy, I like stars too, Sean. But did you know that the Andromeda Galaxy is actually on a collision course with our own galaxy, the Milky Way? Wow, what would happen then? All my friends would [inaudible]. I'm glad you asked, Sean. When our galaxies collide, all life on the planet Earth will be wiped out and well, that's just completely wrong. Cut. Ms. Day, how many North Pasadena Film Festival awards have you won. Well, I haven't really. Okay, that's very impressive. So why don't we leave the film directing to the professionals, all right? I just don't think you quite have a grasp on the science. Here, let me help. Flunky, can you put up the Spitzer IRAC picture of the Andromeda Galaxy, please. Andromeda is about 2.5 million light years away. So it's not going to collide with the Milky Way for a very long time. How long? Opinions vary, but an estimate puts it around 3 billion years. That's a lot of billions. Yes, three. The point is that we don't have to worry about it anytime soon and when it does finally happen, the worst thing we have to worry about is our constellations getting mixed up a little bit. But I like our constellations. Stars are always moving. So it's not like our constellations stay the same for very long anyway. You're really messing with my chi. You know what's great about this picture is that we can see a hole in the bottom right of the galaxy. Astronomers think that's where another smaller galaxy already collided and punched through Andromeda. Again, the stars weren't destroyed, gravity just moved them away. Okay, I got it. We're not all going to die. Once again, Felicia Day sucks all the excitement out of our film. I didn't mean to do that. We'll pick up on page three. Let's go people. We are losing daylight. You know we're indoors, right? Action. But what happens to the central cores of galaxies when they collide? Do they blow up? Felicia, hi I am Sean Astin. No, they don't blow up, Sean, but some people believe that the two super massive black holes in the centers of these galaxies, will try to consume each other creating a time paradox. Okay, is their really anybody who believes that? Please, Felicia Day. Correct us once again. That'll be so fun. Their might be super massive black holes in the centers of some galaxies, but they're not going to create time paradoxes. Like anyone's going to journey to the center of the galaxy and prove us wrong. Okay, let me show you something. Flunky, can you put up an image from Dr. Henrik Spoons research. This is an artist concept of something that Spitzer discovered a little while back. Spitzer detected the formation of tiny crystals in the centers of some galaxies. Crystals, like diamonds? More like crushed glass. It was the first time that silicate crystals had been discovered in a galaxy outside our own. When the galaxies merged, the crystals were kicked up into a virtual sandstorm of dusty glass enveloping the nucleus of each galaxy. Sandstorms of glass, in the center of the galaxies. That is intriguing. That just goes to show you that you don't have to make up explosions or doomsday scenarios to make science interesting. Astronomy is pretty interesting on its own. I think even Sean Astin would agree with me. The Earth is blue and has clouds. You and Sean are right. I guess, I've just been so focused that I lost sight of what this film is really all about. The science. I've learned a really important lesson here today. So do you want to rework the script and maybe finish this off later. I don't think that's necessary. I think you've given us so much great astronomical science already that we can put together a pretty darn good educational film. I think you'll put together a great educational film. Do you validate? Good evening and welcome to the world premiere of our film produced for NASA's Spitzer Space Telescope. Now for those of you who read the original script, this final product may not be exactly what you're expecting, but I think you're going to enjoy it just the same. After all, who doesn't like Felicia Day and Sean Astin? He's in it too, kind of. We are, as you may have heard, having some issues with the Spitzer Space Telescope, people not wanting to use our film. They say it's too sensational or something. I'm sure we'll come to some arrangements soon. In the meantime, Flunky, if you wouldn't mind just going ahead and rolling the projector. When galaxies collide, astronomers say that they can combine into a single much larger galaxy. But just how safe are we? Felicia Day- -knows a lot about colliding galaxies. Felicia Day- -warned us it's happened before and Felicia Day- -says it will happen again. Galactic mergers are pretty common. In fact, the Andromeda Galaxy has already collided with at least one other galaxy and we're next. But how long will it take until Andromeda collides with us? Around 3 billion years. Sounds like plenty of time, right? In the history of the universe, it's the blink of an eye. But when our galaxies collide, could anything dangerous gets stirred up? Crushed glass. Crushed glass? Ouch. The crystals were kicked up into a virtual sandstorm of dusty glass. Sounds pretty painful, Felicia. At night we would sit under the stars. I'm glad you like stars, Sean, because when our galaxies collide there may be a lot more of them. The worst thing we have to worry about is our constellations getting mixed up a little bit. Well, who cares if our constellations change, right? Wait, don't sailors look to the stars for direction? The ancient Greeks used stars for navigation. Someone better warn the argonauts. You know what's great about this? Not a whole lot, Felicia. NASA's Spitzer Space Telescope, we're up in the sky watching. Always watching. I am Sean Astin, thanks for listening to my audio book. The exact nature of the Milky Way Andromeda collision is not known. Simulators, using large computers, have projected what will happen when the Milky Way merges with Andromeda in a couple of billion years and animation shows this. It's a spectacular rearrangement of the stars. Not just the stars that form a new tighter grouping, composed of the sum of the stars in the two individual galaxies, but also large loops and swirls of stars that are flung off into intergalactic space. Two things will happen during this merger. The central stellar regions will combine to form a region even denser in stars, while the peripheries of the galaxies are rearranged with large loops of stars swirling out into distant space, perhaps a million light years from the original galaxies. The central black holes in each of the galaxies, we know the Milky Way has one and we have strong evidence that Andromeda has one too, will eventually combine releasing a torrent of gravity waves. Hopefully, some future civilization will be able to detect this. Meanwhile, there is an exception to the rule that galaxies don't change from one type to another. Simulations indicate that when spiral galaxies combine, the eventual result bears strong resemblance to an elliptical galaxy. So we think that some elliptical galaxies formed by the combination of many small pieces over cosmic time, but some of them actually form from the combination of two large spiral galaxies that subsequently settled into an old stellar population. In a few billion years, we'll get to witness our own example of galaxies colliding. When the Milky Way and its Andromeda neighbor, moving together at a 100 kilometers per second collide. This will not be a collision like two cars colliding because the space between stars is so great that the stars will not hit each other. But the galaxies themselves will be enormously rearranged. The Milky Way will be distorted and the Earth, and the Sun have about a 50 percent chance of being tossed out of the galaxy or sent to the heart of the new combined galaxy.
