Properly referencing your spatial data while working with maps is very important to obtain accurate and precise results. In ArcMap, the function of project-on-the-fly temporarily changes the projection of a newly added layer to align with the existing layers. Another method to fix or define the projection of a layer is by using the Projection and Transformation tool in ArcMap. This function allow to change the projection of a layer permanently.
Remotely sensed Landsat data records the energy reflected and remitted from earth’s surface in forms of wavelength. With this data, we are able to analysis information which is difficult to assess and obtain on ground. For example, Landsat data can provide data on energy being absorbed by the rain forest in South America, which allow the researcher to map the change in energy used. Landsat data has records since 1970s, and the long history of archive allow analyst to assess and compare the geographical changes over time. All the Landsat data are available in digital form, which makes them are accessible and easy to work with for geographical analysis.