How Can Getting Farther Away from Earth Help Us See It More Clearly?
ESU101  Passive Imaging
Satellites carry instruments that gather a wide variety of data. These instruments can collect data using two different approaches, either passive or active.
NASA, Goddard Space Flight Center
The Moderate-resolution Imaging Spectroradiometer (MODIS) on the Terra satellite uses passive imaging.

Instruments that gather and record naturally emitted or reflected energy from Earth’s surface use a passive approach to imaging. These instruments simply record the amount of energy that strikes them.

Digital cameras are one example of passive imaging instruments. When the camera shutter opens, the array of sensors inside records the intensity of light that strikes them. The sensor passively collects light measurements, and the data are processed into images.

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