Understanding the Earth
What tools can we use to study our planet?
People have been studying and describing the world around them for thousands of years. This focus on understanding the Earth is known as geography. Scientists who study geography are called geographers. Geographers use a variety of tools to help them learn about people and the environments they live in. Can you think of any tools that might help a geographer learn about the Earth?
Maps and Globes
Some of the most important tools a geographer uses are maps. A map is a visual representation of a part of the Earth. Maps can show the locations of places, like cities or states, or can show us information about those places. What are some types of information you think could be displayed on a map?
Maps are usually flat representations of the Earth that are printed on paper or displayed on a screen. We can use other tools, called globes, to represent the Earth as a sphere. Globes can show the same information as maps, but they aren't as easy to carry around!
This is a virtual version of a globe made in 1790 by Italian geographer Giovanni Cassini. It shows the world as it was known at the time, but if you look closely you can see that some places don't look like they do on modern maps.
Absolute Location
We can use relative location to help us find where a place is relative to another place. Sometimes we need to be more precise in describing the location of a certain place. We can use a coordinate system based on latitude and longitude to help us do this. Latitude tells us how far north or south a place is from the Equator. Longitude tells us how far east or west a place is from the Prime Meridian. Using latitude and longitude together give us a specific, fixed spot on the Earth's surface. This is called absolute location.
The thick blue line on the globe above is the Prime Meridian. The prime meridian is the starting point for lines of longitude. The thick red line is the Equator. The Equator is the starting point for lines of latitude. We use units called degrees to measure latitude and longitude. You can click the lines above to see the degrees and directions associated with them. What latitude and longitude lines are closest to some cities you know of in different countries?
What can we do if we don't have a globe or a map to help us find absolute location? Luckily, we have a special technology called GPS that helps us find absolute locations. GPS uses satellites to send signals to special devices, called receivers. These days, GPS receivers can be found in cars, tablets, and cell phones, so it can be used by everyone, not just geographers!
GPS receivers instantly calculate the distance and direction from GPS satellites, and translate those distances and directions into latitude and longitude coordinates.
Satellite Images
Satellites are a very important resources for geographers. Some satellites are used for GPS, but others can be equipped with special cameras that geographers and other scientists use to monitor the Earth. Using satellite images captured from space is known as remote sensing. Satellites are launched into orbit by rockets, similar to space shuttles!
This video shows a rocket carrying a sensor that can capture satellite images of the whole earth, known as Landsat 8.
Once satellites are in orbit, they can begin to take pictures. The satellite images that they gather can be used to help answer many questions. What kinds of things do you think satellite images can help us understand?
Urban Heat Islands in Detroit
Water Quality in Lake Erie
Wetlands in the St. Clair River Delta
Wolves on Isle Royale
Wildfire in the Northwest Territories
Agriculture in the Great Plains
Hurricanes in the Gulf Coast
Urban Heat Islands in Detroit
Detroit is a large city with lots of people. We can use special sensors that measure temperature to help us understand how hot Detroit gets over the course of the year. When we find areas that are too hot, we can try to plant trees to provide more shady, cool places to avoid the heat.
Water Quality in Lake Erie
The Great Lakes provide drinking water for millions of people. We can use satellite images to monitor water quality to make sure that the water is clean to drink.
Wetlands in the St. Clair River Delta
Wetlands provide habitat for fish, ducks, and mammals. We can use special satellite images made with radar to help understand how wetland habitats are changing.
Wolves on Isle Royale
Wolves rely on Lake Superior freezing in the winter to get to Isle Royale. We can use satellite imagery to see when the lake freezes so we can monitor wolves crossing to Isle Royale from the mainland.
Wildfire in the Northwest Territories
Wildfires are a natural occurrence in some parts of the world, but we need to monitor them to understand how they are changing the landscape and to protect people that are nearby. We can use satellite imagery to help with that.
Agriculture in the Great Plains
Crops grown in the Great Plains help to feed people across the country. We can use satellite images to see how healthy the crops are, and to help plan when to water and harvest.
Hurricanes in the Gulf Coast
Satellite images can help us see natural disasters, such as hurricanes. We can watch the path of hurricanes and alert people so they can make sure to take cover.
Now that you have learned all about tools that geographers use, you can start to use them yourself to learn more about the planet! Try visiting the Google Earth app to explore different places all around the world.
