In remote sensing, the size of the smallest object that can be detected or recognized by a satellite sensor is referred to as its spatial resolution.
Spatial resolution determines how detailed the image or data from a satellite sensor will be. It is usually expressed in terms of the size of the area on the ground that each pixel represents. For example:
A satellite with a 1-meter spatial resolution can detect objects as small as 1 meter in size on the ground.
A higher spatial resolution means better detail and clarity, while a lower resolution means less detailed imagery.
For instance, satellites like GeoEye-1 or WorldView-3 have high spatial resolutions (up to 30 cm), allowing them to detect very small objects, while others, like MODIS, have coarser resolutions (250 meters to 1 km).