At present, there are several remote sensing satellites providing imagery for research and operational applications.
Satellite imagery has a generally lower resolution compared to aerial photography.
However, ground resolution of 1 m or less will be commercially available in the near future with the launch of commercial very high resolution remote sensing satellites. A satellite follows a generally elliptical orbit around the earth. The time taken to complete one revolution of the orbit is called the orbital period . The satellite traces out a path on the earth surface, called its ground track , as it moves across the sky. As the earth below is rotating, the satellite traces out a different path on the ground in each subsequent cycle.