What is the primary purpose of infrared scanners on satellites?

The primary purpose of infrared scanners on satellites is to measure heat. Infrared sensors detect thermal radiation emitted by objects on the Earth's surface, which is directly related to their temperature. By capturing this infrared radiation, satellites can create images that indicate variations in surface temperatures. This capability is particularly useful for applications such as monitoring environmental changes, assessing vegetation health, and studying urban heat islands.

Understanding heat measurements through infrared sensors allows scientists to analyze factors such as land use, climate patterns, and energy balance in the atmosphere. For example, thermal infrared data can help identify hot spots of urban development or areas affected by natural disasters, providing critical information for emergency response and urban planning.

The other options, while they may involve satellite technology in different capacities, do not align with the primary function of infrared scanners. Atmospheric pressure is generally measured using barometric sensors rather than infrared technology. Assessing soil nutrients typically requires ground-based sampling or other remote sensing techniques that are not focused on thermal imagery. Tracking moving objects is more suited to radar or optical systems that monitor changes in position over time rather than infrared-based heat measurements.