 You are clear for launch, and with that, shut down your visors, O2 on, and prepare for ignition to O2. You can copy that and, um... Hey there, Mr. Ruschoff. Alright, so in our last lesson I introduced to you what geography is, and I explained the five themes of geography. In this lesson I'm going to go over what is probably the most important tool that geographers use is maps. Now a map is a two dimensional graphical representation of the Earth, and the first map stayed all the way back 25,000 years ago when someone took a mammoth tusk and started to carve in their surroundings on it. Since that time mankind has not only continued to expand their knowledge of the world around them, but how they are able to portray that round world onto a flat map. After all, a globe is round like the Earth. This means it can depict a true proportional representation of the world without any distortion. However, it's not so easy to carry a globe around to navigate or be able to use it to be able to portray information. This is where maps come in, as maps are much easier to use for practical applications. However, if you ever tried to wrap a soccer ball before, you can understand the difficulty of being able to take a round ball and being able to lay it out on a flat surface. The only way this really can be done is through what is called projection, and there's many different types of projection. However, one thing they all have in common is they all make a sacrifice in either the accuracy of the size of landforms or that of distances and direction. Now, some of these projections will take an Earth's surface and cut holes into it. Now, this allows the Earth's round surface to be laid flat, but while the Earth's landforms are displayed accurately, now there's large holes where the ocean is supposed to be. Or, they can be laid out so that it's really not clear which way is north, south, east, or west. This really doesn't help you much if you're a sailor trying to sail across an ocean. The cartographers, these are people who make maps, have worked to be able to stretch the landforms so they can be able to maintain the accurate distances and directions of the oceans. Now, usually projections such as Mercator will make the landforms near the poles appear much larger than they really are. Take Greenland, for example. It seems like it's huge, however, if we took Greenland and actually brought it down to the same latitude as the United States, we'd find it's only about a third of the size of the continental United States. So when you're looking at a map, you always need to keep in mind it's distorted in some way. Now, there are some other things you want to look for in any map you're using. Now while the order of what to look for really doesn't matter, I would always recommend to look at the title first. It's going to give you an idea of what the map's about. Now also on the map, you should always look for a compass rose and maybe look for grid lines or latitude and latitude. These will be able to tell you which direction on the map is supposed to be north. And if you don't have a compass rose, you could pretty much assume that the top of the map is north on most modern maps. Now lines of latitude and longitude will also give you that orientation of the map. Remember lines of longitude always run north and south, but lines of latitude and longitude will also give you an idea of where on the earth the map is supposed to be showing. Then there's something called scale. And the scale of the map tells you the relationship between the distance on a map and the distance on the earth. And it's usually discussed in terms of being a ratio of one to some large number. A one to 50,000 scale map means that for every inch on the map is worth 50,000 inches on the earth. That's about three quarters of a mile. We can compare that to a one to 250,000 scale map, which means that the same inch on the map is now worth five times as long on the earth, which is just less than four miles. But what this really means is that a one to 50,000 map is able to show you much more details. It's almost like it's been zoomed in like a magnifying glass. For this reason, a one to 5,000 scale map, which is often used for a city maps, is considered a larger scale than say a one to 500,000 scale map that is usually used to like portray a state. Think of a larger scale map as being zoomed in. Now, once we understand scale and orientation of our maps, now we start looking at the colors and the symbols of our map. To make sense of these, look for a legend or a key that will tell you what these colors and symbols mean. And we're going to talk about how maps use colors and symbols in a few moments here. The next thing to look for is probably you can be a label. So it's going to be names of countries and states and mountains, rivers and oceans and many, many, many other things. Now, maps can be used for many different purposes. I'll go over four, which are your navigational charts, topographic maps, general reference maps and thematic maps. Now, if you're an airline pilot or a ship captain, you'll be undoubtedly using what is called navigation charts. These are specially designed maps that provides things such as depths of channels, location and navigational, beacons, where there is restricted airspace, all those things that a pilot or a sailor needs to be able to move safely from point A to point B. Topographic maps are something that hikers use a lot. Now, when you look at a topographic map, you're going to find what is called contour lines. And these contour lines represent an elevation interval. This means that for each line might represent, say, a change of 10 feet of elevation. So if you see on a topographic map, we have lots of contour lines very closely together, then it means that the hill is going to be much steeper. However, if those contour lines are spread apart, you know that the terrain's going to be much flatter. You can understand why hikers would use a topographic map as they're trying to be able to determine what route they're going to have on their hike. But geographers really don't use navigational maps or even topographic maps much. What they really use is something called general reference maps and thematic maps. General reference maps are used to give an overview of an area. We can break these into two types, political and physical maps. Political maps are going to show political boundaries such as for countries and states. Physical maps, however, are going to give you an idea of the physical characteristics of the land such as elevation of vegetation. But the maps that are perhaps most used by geographers are thematic maps. Thematic maps are the result of what is known as geographic information systems or GIS. Now, these are computer programs that are layered different categories of information upon a map so people would be able to analyze and make sense of the trends they see on the map. Now, beyond computer technology, remote sensing platforms such as a whole host, especially designed satellites, provide lots of information that is further layered upon and map and analyze. Now, thematic maps are the result of GIS and these are used to display the information about a political topic or a theme which is why we call these thematic maps. Now, using a variety of colors and symbols, there really isn't anything that can't be shown spatially using a thematic map. Now, there are several different types of thematic maps. The first one we'll talk about is dot density maps like this one. A dot density map uses dots to be able to represent an event situation or phenomenon. Simple maps, but they're very effective in quickly showing the distribution of these different characteristics on the earth. Take this map, for example, of the deaths of people being struck by lightning. While the dots do not actually provide the exact location of each death, they easily represent in general terms the frequency where people are more likely to be struck and killed by lightning in the United States. Now, sometimes the symbols in a map will be different sizes. Take, for example, this map that shows the important choke points of the transport and trade of oil. Now, if I ask which straight has the most amount of oil pass through it, it's easy to tell it's a straight of Hormuz because it's represented by the biggest circle. And you can also tell that the second most important straight is the straight of Malacca because it has the second largest circle. This is called a proportional symbol map. Now, proportional symbol maps will use the size of the symbols to be relative to the value of the characteristic they're trying to show. Now, this map is also combined with what is known as a flow map, which shows the movement of people, goods, and ideas through the use of arrows. But even the arrows in the flow map portion is using a proportional symbols to show the amount of oil that goes from one point to another by the thickness of these arrows' lines. Now, beyond dots and lines, there is the use of color-inphematic maps to be able to provide information. Let's look at the dots-in-city map again, and we can see that it uses colors to be able to show the number of men and women that die by lightning. But in addition to changing the color of the symbols, we could add color to the areas themselves. For example, this map shows the languages that are spoken in Europe. And very quickly, you can see where people in Europe speak English, German, French, and the other European languages. This type of map is known as a chorochromatic map. Choral means location, and chromatic comes from the Greek word chroma, which means color. A chorochromatic map uses color to show categories or descriptors of a region. So in this case, each color represents the language that is most spoken in the region. Now, chorochromatic maps can show a whole host of different categories such as religions, languages, government types, and much, much more. But we can use colors to not only represent categories, but we can use them to represent numerical values in what is known as choropleth and isopleth maps. This is a choropleth map that shows the population density of the United States. The different shades of blue makes it easy to see which states have the highest and the lowest population densities. Now, the word choropleth, once again comes with the Greek word choral, which means location, but the word pleth actually means multitude. So a choropleth displays the multitude or the value of a characteristic in an already defined former region by color. So this map shows the population density of the entire state, but a choropleth map using a larger political boundary such as states may not give the level of detail that a geographer really needs. For example, this map here shows that all of Texas has the same population density, which we know is not the true. So a geographer might use a map that uses smaller areas such as this map that shows the population densities by county. This gives you a much, much more detail on what you're trying to look at, but then there are the isopleths. Now, the idea of a isopleth map is really the same as a choropleth map. It's going to use color to be able to represent the numerical value of a particular characteristic spatially. But unlike a choropleth map, it does not use preexisting formal regions to be able to display its results. Rather, it connects areas that have similar values through colors. The word iso actually means line. So it starts with the drawing of lines that all have the same value. Remember our topographic map that uses contour lines to show elevation? This is similar to an isopleth map as it connects the same elevation by a line. But isopleth maps will use color in between these lines to show a value such as the percentage of where you're going to find severe storms in the United States. Now, we generally tend to see isopleth maps used to show physical characteristics such as elevation, temperature, precipitation, and vegetation. However, isopleth maps are also used to provide insights on human characteristics as well. For example, this is a map of Houston, Texas that shows you where you have the most amount of crime. These are also known as heat maps. So let's review our thematic maps real quick. First, there is dot density maps that use dots to be able to represent the frequency of characteristics in the area. Proportional symbol maps uses the different sizes of the symbols to be able to relate the relative value of our particular characteristic in a region. A flow map shows the movement of people, objects, and ideas through arrows. And these arrows also can be proportional symbols as we saw earlier. Then there are our three maps using color. These are our chorochromatic maps that show a particular characteristic depicted by color. If a value such as a percentage or a number scale is displayed, you can use a choropleth map which displays the value using color in a already existing formal region, such as country, states, and so on. And isopleth does the same thing as a choropleth map, but it does not use pre-existing formal regions. Instead, an isopleth map connects areas with similar values as the same color. So if you thought that maps were just what you used to be able to find us where somewhere is, hopefully I'd be able to show you many of the other different ways that maps can be used. By using geographic information systems or GIS, geographers, and other analysts can display pretty much everything there is about the world. All right, until next lesson, keep on learning.