Transcription
Welcome folks. So, what we're looking at here? Well, oh, what is this? Let's take a look. Think about what this could be. Just take a moment. Maybe pause the video, write down, just kind of brainstorm half a dozen or so things that this could represent.
All right, so now that you're back, let's think about this. A variety of things. People say is having your like blackboard that somebody's written on with white chalk and tried to erase. That could be it. Or maybe, you know, it's like sponge painting where people take a sponge, dip it in white paint on the black wall or black paint on a white wall. Could be something like the surface of you of an orange, or like surfaces of some concrete or rock. Could be an image of a tree or a bush. Could just be static, which is really cosmic microwave background radiation, constant static that can look like this. One screams could be that probability cloud where the electron is around an atom. Could be the night sky with lots of stars. Could be fog. Be fog. Could be lots of things, right?
So, one of the issues with figuring out what we're looking at here is that it lacks context. Now, we do have some context. You're taking an astronomy course, so you know it's not unreasonable to default to that context. Well, it's probably something to do with this rather than something else. But, you know, the other piece of context it's missing is, well, we don't know if we're looking at something in a really small scale or in a really large scale. And so, not knowing the scale really kind of hinders us from understanding what we're seeing. Or so, it's important to know the scale. So, let me add some scale to this so we can think about what we're looking at.
So, from one edge of the image to the other is not quite ten billion light years. So, one point seven times ten to the nine. So, ten to the nine is a billion with a B. Ten to the six would be a million with an M. And this kind of is a good spot to step back for a moment and think about what those mean, because the reality is, they're very hard concepts to be able to imagine in your mind. A million objects. They go, you know, if you think of like marbles or pennies or something, right? If I've got three pennies, you can immediately imagine what three pennies looks like, right? Or even five things. When you get to ten pennies, you get an image of like, kind of a group of pennies, but not necessarily something you would just look at and go, "Oh yeah, there's ten." Right? And that's not just you. That's something that we've learned is true for all people. Everybody is pretty good at small numbers, being able to imagine them. And then once you start getting up towards ten, people have a very difficult time imagining what that is. And feels done experiments, and you can do this yourself if you have small kids around. You can try playing with them with pennies. Give a little pile of pennies. And I'm talking like a two-year-old, one and a half to three-year-old kid. You go, "Hey, here, hand me one penny." And they're really good at me only. "Angela, one penny." Like you said, "Here, out of the pile there, give me two pennies." Again, most pretty good. Pretty good, depending on how old they are. They could probably go up to five or six pennies or something like that. They may need to kind of count them out or something, but they can pretty much figure that out. But think about that. There's some point they don't just look at the pile and go, "Well, here, six." And just grab six. They probably have to count them out. And it turns out that if you reverse that and show them one penny or two pennies or three pennies, they're good at looking at it. So, "Oh yeah, that's three or two or whatever." But if you had ten pennies in your hand, you know how many pennies they have? A lot, or bazillion. Or they're just gonna kind of guess, right?
So, this is the state of the human mind. It doesn't matter how old you are. There's a point of numeracy, understandable numbers that you just kind of have as an abstract concept. And so, this kind of explains, I think, for a lot of us why we struggle so much with math. I know I struggled with math a lot. And if with a lot of extra time into it to be able to finish all the math that I had to do to get my physics degree and the rest of it. It wasn't easy. And sometimes people think, "Well, you must just be good to a number." "Answer this person must be just really good with numbers." It takes a lot of time and practice. But nobody is just good with numbers out the gate. So, you know, it's not construed, um, or something if you struggle with this stuff. It really is a lack of maybe good instruction or familiarity, footing enough time into working on it, being able to spend the time working on it. It starts to come together. But where I'm going with this is when we, if we can't understand and look at a pile of pennies and say just by looking at it that there's 10 or 15 or 20 or 17 there, how are we going to figure out a million or a billion? Well, we're kind of not.
One of the things I ran into that I found really helpful for myself is to think about it in terms of time. Now, you know how long a second is. You know how long a few seconds are. And so, if you think about that, you can even do a little exercise where hold your breath. And so, we'll do that. Let's count when I say go. Just hold your breath for a moment. So, one, two, three, go. Okay, stop. Now, that was about ten seconds. I just kind of counted it off easily, but that's about ten seconds, right? So, now think about the number a million. And think about how many seconds is a million seconds. So, it turns out a million seconds is pretty close to about ten days. Okay? Ten days is about a million seconds. So, if you think you're ten days from now, you'll have lived a million seconds. Think about that. If you, somebody had a room full of dollar bills and they said, "Here, count these out. I'm gonna give you, you know, this lunchtime or whatever, count them out as long as you count and don't stop, you can take whatever you count out." And you're thinking, "Wow, great opportunity. Let me add it." So, you get to count about one at a time, but just keep counting it. So, you can't get any more in as far as you get, you get to keep that. It's actually a fairly safe bet, even if you know the room had virtually unlimited supply of dollar bills in it. If you think about it, you would have to count off one, two, three, four, day and night for 10 days to get to a million bucks. I think most of us would be highly motivated to try to do that. But think about that. If you were counting out dollar bills, it takes you 10 days working non-stop, if you count one per second, to get to a million. So, now put that in context with somebody says, "Oh, this has three parts per million of whatever." It's three seconds out of ten days. And that kind of gives it some scale.
But here's the other problem. We treat million and billion like they're very, very similar. And the thing is, in astronomy, we're gonna deal with some of these large numbers and talking about things that are millions of light-years away or billions of light-years away. And they sound pretty similar, but there's a huge difference between millions and billions. So, we've just gone through this whole thing of describing how much a million is. But we're looking at a screen here that has something it's on, like I said, it's almost two billion light years across. So, billion with a B. How much time is that? Well, it's shocking, but a billion seconds is about thirty-two years. Think of that. A billion seconds with a B is thirty-two years worth of seconds. We're a million seconds is about ten days worth of seconds. Huge difference. Huge difference. So, again, you'll easily get two million seconds here in ten days, but you won't have lived a billion seconds till you hit about your 32nd birthday. So, pretty crazy. So, that means that we're looking at an image here that if we could move that distance of one light year, remember a light year, it's the distance that light travels in a year's worth of time. If you could travel that distance faster than satellite, if you could go a light year in one second, it would still take you about close to sixty-four years to cover that distance we're observing it. So, we're looking at something that's really, really huge.
So, yeah, that's not a probability cloud of electrons around a nucleus. It's not a tree or fog or the night sky. Strictly speaking, because when we're talking about the night sky, we might be, well, depending where you are, might be thinking fog. But hopefully, you're thinking of stars. That means that every little pixel there is representing a galaxy. So, we're looking at a vast cloud of galaxies there. Each one of those galaxies has millions to billions of stars. So, understanding the scale of what we're dealing with is really important as we move forward through the rest of the term.
So, what we're kind of working with right now is we're beginning to talk about the solar system. And so, looking at the solar system, we can measure things, get into billions, talk about billions of miles. So, for instance, by the time we get out to the Kuiper Belt, which is where Pluto is, that is several billion miles away. We're talking about millions of miles, almost a hundred million miles to the Sun from us. So, there's what we're doing. Millions. So, we do use these terms even within our own solar system.
So, here's an example of something we have a bad concept of scale. If this is the true size of Africa here, remember Africa is a continent. I know some people get confused and think it's a country, but it has many countries within it. But it's a huge landmass. It's the largest continent on the Earth. And notice there, you can put all of China in there, and India, the continental US, most of Europe, and everything in there, Japan, and still not have the same landmass as Africa. So, if you think about how people don't have a good concept of the size of that continent on the Earth, well, we don't have a good grasp of the scale and size of our solar system as well.
So, what is that? Well, here's a couple of folks out here in the park, and they've got a basketball and a tennis ball. We're going to use those as a model for part of our solar system. We're going to start out looking at the basketball being the Earth, and the tennis ball being, stayed in for the moon. And it turns out that's a pretty good representation at that scale. Basketball, so about 12 inches across. The tennis ball is about three inches across. So, it's a four to one ratio for diameters. That's the distance across. So, the distance across the tennis ball compared the distance across the basketball for tennis balls would fit across the basketball. So, that's about correct. It's about four moon diameters across the Earth's diameter. So, that's fine.
So, now we're going to make our model. We want to put the tennis ball the correct distance away from the basketball. The thing is, is it turns out that the distance between the Earth and the Moon is about 30 Earth diameters. So, we've chosen wisely by picking the basketball to represent the Earth because it's 12 inches or a foot across. So, that means the tennis ball is gonna go thirty of those away from the basketball. So, in other words, 30 feet away to set the tennis ball. And that's a proper distance. Now, that's pretty far. It's actually much further than most people would suspect. So, I've loaded a sketch of this to give you some context up on Canvas, so you can see a little sketch of the basketball to the tennis ball. And then if we did that, we probably want to add the Sun in. So, our basketball Earth and tennis ball moon separated by about 30 feet. We're gonna throw in the Sun. Turns out you need about a 10-story building, maybe 11-story building for the size of the Sun. And the Sun is huge. And we'd have to set the Sun about two miles away from the basketball. So, this means we'd have a about a 10-story building two miles away from our basketball. The building would be the Sun, the basketball the Earth, and then 30 feet away from that would be the tennis ball moon. And then we'd have the scale model of that portion of the solar system. Pretty shocking if you really think about it.
So, as large as the Earth is, we kind of put into context here. Here's our terrestrial planets there. Now, this image also includes Pluto, which is just really a big icy mass on the Kuiper Belt. It's a cometary nucleus like many of the tens of thousands of objects out there. There's lots of Pluto-like objects out in the Kuiper Belt as we know now, hence it's not a proper planet. But looking at Mercury, Mars, Earth, and Venus there, you've got a scale representation of those inner terrestrial planets. So, the four inner planets, ones close to the Sun, are we called terrestrial because they're rocky planets. In order, they go Mercury, Venus, Earth, and Mars. As we move out from the Sun, you don't want to know the order of the planets. Ask you as an exam question, and questions about that. And I'll give you a mnemonic here towards the end so you can remember this. But again, Mercury, Venus, Earth, and then Mars. See the relative scale there?
So, let's add the other four proper planets into this. Now, these four are the gaseous planets. Right there, two of them, the closer ones, are liquid gases. And the two outer ones are frozen icy gases that make them up. They're quite a bit larger. So, let's throw them in there. Kind of shocking again. So, you can see the Earth there on the left compared to Uranus and Neptune, the two outer ice giants. And then we have Saturn and Jupiter. And you can see how huge Jupiter is compared to any of the rest of these guys. So, Jupiter is the largest object in our solar system after the Sun. And we tend to call these big gas giants Jovian planets after Jupiter. So, you'll hear them alternately referred to as the Jovians, as the outer planets, as the gas giants. Those are all kind of common terms for them. But well, we we don't have the largest gas-based object. Really, that gas is under such temperature and pressure that it's a plasma, as we talked about plasmas before.
So, let's throw the Sun in there as well. Oh, wow, look at that. So, there's the Sun. So, the ratio of the diameter of the Sun to the Earth. They said we had a basketball and a 10-story building. So, it's about a hundred and ten Earths fit across the diameter of the Sun. So, if you're gonna kind of think of the Earth being like little beads or something, and you want to make like a little belt to go across the Sun, and these beads, it would take a hundred and ten of them roughly to fit across the diameter. This is really, really big difference.
So, what if we used our basketball now to represent the Sun? What object can we use to represent the Earth? Well, you're looking at a grain of sand compared to a basketball Sun, right? If you look at Uranus and Neptune down here, they're probably about the size of a pea. Like a green pea, right? A little sweet pea that you might have some vegetables on your plate. They're probably about that size. Me, a quarter-inch, your little finger, compared to the Sun if it were a basketball. And then, like I said, the Earth's like a grain of sand. So, huge, huge differences here. But again, that scale is important.
So, now let's think about this for a minute. You know, the Sun is a star, right? And so, it's the one star in our solar system. It's the only thing producing light. We've kind of learned that everything else is reflecting light back to us. And it's roughly 93 million miles away from us. So, you know, for easy numbers, we say it's about a hundred million miles, right? And remember, that's one astronomical unit. So, within our solar system, we'll be measuring things. Sometimes we'll talk about miles or kilometers. Typically, we use astronomical units because that's the average distance between the Sun and the Earth. If you recall, talked about a little bit during Kepler's laws, but just to remember that. And then we talked about how many astronomical units out each of the planets are. So, you'll want to be conversant in that, that type of measurement.
So, what would the Sun look like as we move out through the planets? Here's kind of an example for you. So, the Sun, even though it's really huge, it's also really far away from us. So, you know, from the Earth, it's nice and bright up there. It appears large. If you go outside and you take a look at it, if you're measuring it with your fingers, how far apart between your thumb and your first finger or something like it, it's kind of shocking. It turns out it's actually about a quarter inch across in the sky. Now, if you were at Venus or Mercury, which are closer, then it's going to look larger. Mercury is about half an astronomical unit away from the Sun. And Venus is about 70% of an astronomical unit away from the Sun. And so, you know, Mercury being twice as close to you, you notice it's quite a bit larger while it appears in the sky. As we move out, especially get out to the Jovians, those gas giants there, it starts getting smaller and smaller. In fact, you look at Saturn there, you can see that when the Saturn's rings is almost on top of the Sun in this image, and we'd be blocking it. So, that looks almost like a strand of spaghetti hanging there. If you put a strand of spaghetti up in front of your face and run Saturn, you could block out the Sun with it. So, not very large at that point. So, you can imagine by the time you get to Uranus and Neptune, it's just another little dot out there in the sky. It's not looking very impressive as far as how bright it is and the size it appears in the sky. So, it looks very different.
So, I told you I'd give you a mnemonic here to work with so you can remember the order of the planets. And so, again, we have Mercury, Venus, Earth, and Mars are our terrestrial planets. And then the last four, the outer planets, Jupiter, Saturn, Uranus, and Neptune. Those are the Jovians or gas giants. And so, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Mnemonic you can use: My Very Educated Mother Just Served Us Noodles. So, I'll say it again: My Very Educated Mother Just Served Us Noodles. So, there's a little way to remember what you're looking at here and the order of them, the planets. So, you know, use that mnemonic or use something else. But I do know the order and which one's a terrestrial, which ones are Jovian, again, our good gas giants versus our ice giants out here, Uranus and Neptune. All right, folks.