Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object and thus in contrast to on site observation. Remote sensing is a sub-field of geography. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth. Aerospace is the human effort in science, engineering and business to fly in the atmosphere of Earth (aeronautics) and surrounding space (astronautics). Aerospace organisations research, design, manufacture, operates, or maintains aircraft and/or spacecraft. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace is not the same as airspace, which is the physical air space directly above a location on the ground. The beginning of space and the ending of the air is considered as 100 km above the ground according to the physical explanation that the air pressure is too low and recognized by authorities. These are the fields in the Remote sensing are GIS (Geographical information system), Electronic surveying, Digital image processing, Cartography, Digital Photogrammetry, Probability and Statistical methods, Fluid Mechanics, Space Dynamics, Flight Mechanics, Aerodynamics, Propulsion.