Decades of consistent data from Landsat help scientists monitor the growth of urban areas in a world where more than half of the population lives in cities. For example, Las Vegas, Nevada, one of the fastest growing metropolitan areas in the United States, has seen its population expand from 273,000 in 1972 to 2,204,079 in 2017. That’s an increase of over 700 percent since the launch of the first Landsat satellite.

Urban development appears as green and purple in this series of Landsat images. On land covered by asphalt, concrete, rooftops, and other man-made constructs, rain water does not soak into the ground. Instead, it runs off. Landsat-based mapping of land cover and land use is valuable to urban growth studies and modeling to show how increased water runoff affects groundwater quality, as well as the pressure on resources caused by rapidly increasing populations.

Also visible in the 2018 Landsat 8 image southeast of Las Vegas is the Nevada Solar One solar farm. The project, which covers 400 acres, generates 64 megawatts of power for 14,000 homes.