1 00:00:00,000 --> 00:00:05,000 Today we're in Baltimore, Maryland, and this is the Maryland Science Center. 2 00:00:05,000 --> 00:00:10,000 It's home to the Hubble Space Telescope's National Visitor Center, and it's a lot of fun. 3 00:00:10,000 --> 00:00:15,000 It has three floors of hands-on experiments to get students like you interested in astronomy. 4 00:00:15,000 --> 00:00:18,000 Let's go on in and check it out. 5 00:00:18,000 --> 00:00:20,000 Excuse me, sir. 6 00:00:20,000 --> 00:00:34,000 Today's show is called Algebra, Mirror, Mirror on the Universe, and this mirror right here. 7 00:00:34,000 --> 00:00:41,000 It's the same size as the primary mirror on the Hubble Space Telescope, but more on the Hubble later. 8 00:00:41,000 --> 00:00:44,000 First, let's learn about algebra. 9 00:00:44,000 --> 00:00:48,000 Algebra? What's algebra? Sounds scary. 10 00:00:48,000 --> 00:00:52,000 It's really not. Let me show you. Can you read this graph? 11 00:00:52,000 --> 00:00:57,000 I bet you didn't know that when you're reading graphs, you're doing algebra. 12 00:00:57,000 --> 00:01:01,000 Algebra is used to describe a relationship between two or more things. 13 00:01:01,000 --> 00:01:09,000 For example, in this graph, we can say that the number of pizzas is related to the number of people served. 14 00:01:09,000 --> 00:01:13,000 The more pizzas you have, the more people you can serve. That's a relationship. 15 00:01:13,000 --> 00:01:17,000 In fact, this graph shows a linear relationship. 16 00:01:17,000 --> 00:01:22,000 A linear relationship means that the points on the graph appear to form a straight line. 17 00:01:22,000 --> 00:01:30,000 Of course, there are lots of relationships in math, but since these examples don't form a straight line, they aren't linear. Got it? 18 00:01:30,000 --> 00:01:35,000 So, looking at this graph, how many people would one pizza serve? 19 00:01:35,000 --> 00:01:40,000 Let's set up a table to show the relationship we see in the graph. 20 00:01:40,000 --> 00:01:42,000 Let's label our table like this. 21 00:01:42,000 --> 00:01:49,000 n equals the number of pizzas, and p equals the number of people served. 22 00:01:49,000 --> 00:01:57,000 According to our graph, one pizza serves two people. That means there are two servings in one pizza. 23 00:01:57,000 --> 00:02:03,000 For our purposes, this number of servings, two, doesn't change. It's called a constant. 24 00:02:03,000 --> 00:02:07,000 How many people would be served if you have two pizzas? 25 00:02:07,000 --> 00:02:10,000 What about three pizzas? 26 00:02:10,000 --> 00:02:13,000 You should begin to see a pattern developing. 27 00:02:13,000 --> 00:02:21,000 Now, what if you were planning a sleepover, and your mom got carried away and ordered 215 pizzas? 28 00:02:21,000 --> 00:02:25,000 How many people would you have to invite to your slumber party? 29 00:02:25,000 --> 00:02:28,000 Remember the pattern we saw in the graph and table? 30 00:02:28,000 --> 00:02:33,000 Let's use the pattern we saw in the table to set up the relationship. 31 00:02:33,000 --> 00:02:38,000 In algebra, letters called variables help us solve algebraic equations. 32 00:02:38,000 --> 00:02:46,000 Remember how we used the letters n and p in the table to represent the number of pizzas and the number of people being served? 33 00:02:46,000 --> 00:02:49,000 Using those variables, we can set up an equation like this. 34 00:02:49,000 --> 00:02:59,000 n, which is the number of pizzas, times the number of servings in one pizza, equals p, which is the number of people served. 35 00:02:59,000 --> 00:03:01,000 Okay, what do we know? 36 00:03:01,000 --> 00:03:12,000 Well, remembering that there are two servings in one pizza, and that your mom ordered 215 pizzas, we can substitute those numbers like this. 37 00:03:12,000 --> 00:03:16,000 215 times 2 equals p. 38 00:03:16,000 --> 00:03:23,000 According to our graph, you will have to invite 430 people over for your slumber party. 39 00:03:23,000 --> 00:03:26,000 Better tell your mom to cool it. 40 00:03:26,000 --> 00:03:29,000 So you see guys, algebra isn't scary at all. 41 00:03:29,000 --> 00:03:34,000 In fact, algebra is used to solve problems much tougher than the one we just did. 42 00:03:34,000 --> 00:03:37,000 And remember, there are lots of ways to do problems algebraically. 43 00:03:37,000 --> 00:03:44,000 Absolutely. Now that we've gotten a taste of algebra, let's learn more about telescopes. 44 00:03:44,000 --> 00:03:47,000 1608 was a happening year. 45 00:03:47,000 --> 00:03:56,000 In that year, the Italian scientist Galileo became one of the first humans to view celestial objects with the newly invented telescope. 46 00:03:56,000 --> 00:04:02,000 Galileo improved on the design to see objects ten times more clearly than ever before possible. 47 00:04:02,000 --> 00:04:11,000 With his primitive telescope, Galileo saw many thousands of previously invisible stars that make up part of our galaxy. 48 00:04:11,000 --> 00:04:23,000 The ancient Greeks named our galaxy the Milky Way, because most of its visible stars appear overhead on a clear, dark night as a milky band of light extending across the sky. 49 00:04:23,000 --> 00:04:27,000 Hmm. How many galaxies do you think are in the universe? 50 00:04:27,000 --> 00:04:29,000 Maybe a couple trillion? 51 00:04:29,000 --> 00:04:32,000 Well, I know there's at least one. 52 00:04:32,000 --> 00:04:34,000 340 billion. 53 00:04:34,000 --> 00:04:39,000 Those are all good guesses. To get the real answer, stay tuned, because later on in the show, 54 00:04:39,000 --> 00:04:44,000 you'll have the opportunity to estimate the number of galaxies in the universe with our web activity. 55 00:04:44,000 --> 00:04:52,000 During the centuries following Galileo's discoveries, scientists created telescopes of increasing size and complexity. 56 00:04:52,000 --> 00:05:00,000 For more information on telescopes and something called optics, let's visit Marshall Space Flight Center in Huntsville, Alabama.