To measure the characteristics of an object from a distance, the technique of remote sensing is used. By this technique we can collect all information about an object without making any physical contact with that object. Each object reflects some part of the light that falls on that object. This reflected light is collected, judged and then recorded. So, it is cleared that in the technique of remote sensing, the light emitted from the object is measured. From this light physical properties of object are measured. Some of the common physical properties which are measured are color, size, temperature, nature, etc. Electromagnetic techniques are used in remote sensing.
In the electromagnetic technique the object whose physical properties are to be measured is illuminated with the help of an electromagnetic object. This object is known as active remote sensing instrument.
If we don’t make use of any electromagnetic object and the object is analyzed with the help of sunlight, then this technique is known as passive remote sensing technique.
With the new inventions now remote sensing is also used in space. For this we need a remote sensing satellite. It should follow a fixed orbit and should cross a particular location at a same time. The orbit of remote sensing satellite is known as sun-synchronous satellite. The major task of the remote sensing satellite is to take photographs of the earth’s surface. This process is repeated again and again. This satellite moves over the earth a no of time and each time it take lot of photographs.
Basically, the weather predictions are announced on the basis of reports collected from the satellite.
List of Indian remote sensing satellites is shown below:
1. IRS-1B
2. IRS-1C
3. IRS-1A
Some other common uses of the remote sensing satellites are shown below:
1. Maps of unused lands are prepared with the technique of remote sensing.
2. For completing the surveys of ground water present on the surface.
3. To see the area covered by the forests on the earth’s surface.
4. To determine the pollution present in atmosphere.
5. It is also used to find those places where nuclear explosions have took place.
6. By using remote sensing we can also point out the enemy positions.
