NASA's Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument recorded this image of ground surface temperatures in Houston and its environs on June 20, 2022, at 6:29 a.m. Central Daylight Time.

Even just after sunrise, manmade urban surfaces near the city center and transportation networks – streets, roads, and highways shown in red and orange – were significantly warmer than the outskirts by up to 18 degrees Fahrenheit (10 degrees Celsius). Clouds, which are cool compared with the ground, are shown in blue and labeled in the image.

Cities are usually warmer than open land because of human activities and the materials used in building and construction. Streets are often the hottest part of the built environment due to asphalt paving. Dark-colored surfaces absorb more heat from the Sun than lighter-colored ones; asphalt absorbs up to 95% of solar radiation and retains the heat for hours into the nighttime.

ECOSTRESS measures the temperature of the ground, which is hotter than the air temperature during the daytime. The instrument launched to the space station in 2018. Its primary mission is to identify plants' thresholds for water use and water stress, giving insight into their ability to adapt to a warming climate. However, ECOSTRESS is also useful for documenting other heat-related phenomena, like patterns of heat absorption and retention. Its high-resolution images, with a pixel size of about 225 feet (70 meters) by 125 feet (38 meters), are a powerful tool for understanding our environment.

NASA's Jet Propulsion Laboratory in Southern California built and manages the ECOSTRESS mission for the Earth Science Division in the Science Mission Directorate at NASA Headquarters in Washington. ECOSTRESS is an Earth Venture Instrument mission; the program is managed by NASA's Earth System Science Pathfinder program at NASA's Langley Research Center in Hampton, Virginia.

More information about ECOSTRESS is available here: https://ecostress.jpl.nasa.gov/.