The Earth is constantly under observation from dozens of satellites orbiting the planet and collecting data. Weather reports are one familiar application of this information-gathering technique. The satellite images, as well as the actual predictions, are obtained through remote sensing of the Earth.
Airplanes also provide platforms for remote sensing, and some sensors operate from land.
Many types of sensors collect electromagnetic information. Microwave radiometers, laser meters, magnetic sensors and cameras all gather different types of data that can be interpreted to derive accurate, large-scale information about the Earth's surface and atmosphere. Because these data and images are digital, they can easily be quantified and manipulated using computers. This makes remote sensing a uniquely versatile tool, since the same data can be analyzed in different ways for different applications. Some of the fields that use remote sensing are agriculture, geology, archaeology, oceanography, and even architecture.