The Earth is covered in features and relationships that we can measure and study in a variety of ways to better understand our environments. For example, if I were to zoom in to yourcommunity, I might measure the space by counting the buildings to get a sense of how big itis. But this is your community, so you know wherethe place to catch up with a neighbor is, like an eclectic coffee shop or walking thesculpture park. I only see the physical buildings, while youunderstand the importance of each building. We’re looking at the space in two differentways. But there are more ways to discuss space,and they each add a new layer of understanding -- from measuring it, to defining it, to understandingthe relationship between places. Just as all historians study events in time,based on what's going on or what's normal for a time period, all geographers study eventsin space. No matter the topic, we end up contextualizingplaces or human-environment interactions based on the space they exist in. I’m Alizé Carrère and this is Crash CourseGeography. Intro In geography, we ask questions to understandwhat is where, why it’s there, and how it’s changing. So when we’re trying to interpret why glaciersmelt or disease outbreaks happen in certain places, we want to both measure space and try to understand the significance spacehas to what’s happening. As geographers, we can think about space infour broad categories that emphasize different aspects and use a suite of tools and techniquesto help us with measuring and understanding our world. In its simplest form, we can think of spaceas a container, like a box or an extra-large Tupperware container for delicious bananabread. We want to know where stuff is basically,what’s inside or outside the container.

Studying space as a container helps us answerthe question “what is where?”, by measuring and locating physical features or bordersor boundaries. To do this, geographers and other people whowork with distances and points, like surveyors, use a coordinate reference system. Like overlaying a square grid on the globe. Even our phones can be used to tell us whatis where. When we open Google Maps on our phones, thephone connects to a Global Positioning System or GPS, which pinpoints the location of anobject on the ground using radio from satellites. When a receiver on Earth -- like our phones-- receives a radio wave from three or more satellites, the phone can translate thosesignals into a precise location, and know where we are. These days all the satellites launched bythe US, China, Russia, the EU, India, and Japan are called the Global Navigation SatelliteSystem. While it's great to know where things are,as geographers we want to go beyond that. Even our phones tell us more than just wherethe sculpture park is. Once we know where things are in space, wecan understand how they’re related, or their spatial relationships. In fact, humans are hardwired to think aboutspatial relationships and how we’re related to the space container around us. To describe those spatial relationships, weneed to recognize topological space, which measures and analyzes how the features inspace are arranged and connect to each other. This term comes from the word topology, whichrefers to how the pieces of something are related or arranged. We also see topological space in action everytime we ask our phones to route us somewhere. We’re really asking Google Maps to lookat how our beginning and ending locations are related and find the most efficient connectionbased on what’s physically in the area. Spatial analysis is a blend of geography andmath that identifies and analyzes those patterns and relationships in space using a range oftechniques including imaging technology, statistics, and geometry. To see those spatial patterns, and understandhow space changes over time, sometimes it helps to zoom out and stand back. Remote sensing, or studying something withoutphysically contacting it, is an entire subfield of geography that lets us do just that. Photogrammetrists and other remote sensing professionals compile and analyze images from satellites, airplanes,or drones that have sensors that record energy reflected from the Earth’s surface. The reflected energy is sensed by a devicethat records the wavelength as a number and turns that number into a pixel in an image. Remote sensing has been particularly helpfulin Antarctica, which is incredibly hard to study in person. Covered in ice and snow, this frigid continenthas been one of the least mapped areas on Earth. And for good reason. Antarctica is considered the coldest placeon Earth and the windiest. Conditions are so extreme that hiking aroundand recording the terrain in a ground-based mapping effort is nearly impossible. So in 1997, researchers collaborated withNASA and the Canadian Space Agency to use remote sensing satellites with radar capabilitiesknown as Radarsat to scan the surface of Antarctica. They generated accurate images of the surfaceice and snow on Antarctica by measuring the echo of radio waves sent from a RADAR satellite. With this data, we can start by defining theboundaries of features in Antarctica, like the location of large cracks in the ice calledcrevasses. We’re defining the space, or container,that is this polar continent. But definitions of any kind are really justthe initial building blocks. In Antarctica, we can use that informationto analyze our relationship to those features. Crevasse zones are dangerous to cross anddifficult to see from the ground, so knowing where they’re located can help create safetravel routes. This can save time and lives when trying tonavigate this dangerous terrain. But our spatial relationships are more thanjust routes. The radar dataset is also used to measurehow quickly glaciers are moving, which gives us insight into the physics of glaciers andlets us better predict how glaciers change. We can build a more complex understandingof a space when we ask not just where is the crevasse but how is it changing? or whereis that ice moving? Now containers and topology are informative,but they don’t let us talk about the more subjective things we know about a space. In geography we can also talk about sociallyconstructed spaces, or those spaces we create and give meaning to as communities. Like that coffee shop or sculpture park. In fact, the socially constructed space doesn’teven have to be physical. 

The way we develop and define virtual spaces-- like the fan communities we form and participate in online -- is a whole sub-field of geography. But let's stay in the physical realm, in - forexample - Harbin, China. Each January, blocks of ice from the SonghuaRiver that flows through the city are carved into sparkling sculptures as part of the annualHarbin International Ice and Snow Sculpture Festival. Originally, ice lanterns were mostly usedat night on the river by fishermen. They gradually became an artform and, eventually,a major social and cultural event. Now the wonder of the Ice and Snow Festivalis synonymous with Harbin. By studying socially constructed spaces, welearn how space is carved out and a place, or location with meaning, is created and canbecome sites for social, political, or economic activity. Individuals, not just communities, can alsocreate meaning in space. We study individually perceived space to incorporatethe idea of place and see how the perception of a space can change person to person orculture to culture. Like a teenage girl living in Harbin mighthold a mental map of her neighborhood that includes points of interest to her, like thecurb she almost twisted her ankle on while jogging. That’s her perception of that space, justlike we all have our own perceptions of our individual spaces. And we can see how the perception of individualsor groups has changed over time. Today, Harbin is the 8th largest city in China. But its name was originally a Manchu wordmeaning “a place for drying fishing nets” which hints at how past inhabitants perceivedand used this space. Any space can be studied through any of thesefour lenses: as a container, topologically, socially, or how we individually perceiveit. Let’s go to the Thought Bubble. In January 2010, a magnitude 7.0 earthquakeshook the nations of Haiti and the Dominican Republic creating massive damage and killinghundreds of thousands of people. But things could still get worse. Relief efforts in Haiti were delayed becauseaid workers didn’t know where to go or how to get there. Clear maps of neighborhoods and remote regionsof the island before the quake just didn’t exist, so international aid workers had nosense of space and no fast way of learning. But the locals did know the area -- what wasthere, how it was organized, and what it meant for their communities. So that collective knowledge -- or perceivedspace -- was put to work. In two weeks, Haiti went from no map to acomplete map in the first crowdsourced mapping effort for humanitarian purposes. A team of mappers organized people aroundthe world to help digitize photos, which means tracing images to create 2D shapes and attachingcoordinates that can be plotted on a map. These humanitarians input aerial and satelliteimages into a mapping platform called OpenStreetMap. With OpenStreetMap, volunteers can look atspace as a container and use those images to trace buildings, parks, roads and moreto create a basic digital map. That map can then be used by anyone in theworld with access to OpenStreetMap. In Haiti, those maps meant relief workerscould see where buildings should be and could use that to help identify where people mightbe trapped. Now they could find efficient routes to pointsthey needed to get to and engage with the topology, or organization, of the space. 

The global effort to map Haiti was such asuccess because it brought together those who had technology to digitize the buildingboundaries and roads, and those who knew the significance of those boundaries and roads. With crowdsourcing, the sense of space couldbe complete. Since 2010, communities around the world haveworked within OpenStreetMap digitizing their buildings, roads, and other features. Local citizens imbue the map with meaning,like which of these buildings are houses, or where there are important community gatheringplaces, hospitals, and businesses. Local groups and humanitarians can then createthe maps they need to achieve their goals -- from identifying areas at risk for diseasespread, to identifying safe areas for persecuted groups, to helping locate people quickly aftera natural disaster. Because anyone can update the map as spatialfeatures change, the data is always fresh and ready to be used. Basically, anyone can be a geographer andcreate the maps their community needs. Space in all its forms is an integral partof our lives. We navigate space every day, rely on freshgeographic data to get from place to place or give meaning to familiar and unfamiliarspaces without much thought. As geographers, we formalize that process. We take in spatial data from satellites, photos,radar, and personal observation and create digital data that allow us to locate buildings,route around traffic or physical features efficiently, and communicate the meaning communitiesgive their spaces. We focus on space explicitly to better understandand explain the world around us. Many maps and borders represent modern geopoliticaldivisions that have often been decided without the consultation, permission, or recognitionof the land's original inhabitants. Many geographical place names also don't reflectthe Indigenous or Aboriginal peoples languages.