The intensity of a colour. A highly saturated colour is vivid and brilliant. To dull a colour and decrease its saturation, add small amounts of its complement, making it closer to grey.


Each Landsat image collected is a scene. Each Landsat scene is 115x106 miles long. The globe is divided into 57,784 scenes, and each Landsat scene has about 3 billion bytes of data. 


A satellite fleet, or constellation, which is part of the Copernicus Programme. 

Sentinel consists of the following satellites: Sentinel 1, Sentinel 2, Sentinel 3, Sentinel 4, Sentinel 5, Sentinel 5P and Sentinel 6. 

Each satellite has a different purpose or capability, and together, they address six thematic areas: land, marine, atmosphere, climate change, emergency management and security. 

For more information, see Copernicus: Discover our satellites, Glossary: Copernicus Programme.

Solar irradiance

The solar irradiance is the output of light energy from the entire disk of the Sun, measured at the Earth.

Spatial resolution

The area on the ground that an imaging system, such as a satellite sensor, can distinguish.

Spectral response

The ratio of the relative amplitude of the response of a detector and the frequency of incident electromagnetic radiation.


An optical instrument that splits the light received from an object into its component wavelengths by means of a diffraction grating, and then measures the amplitudes of the individual wavelengths.

Sun-synchronous orbit

An orbit in which a satellite is always in the same position with respect to the rotating Earth at the same time of day.

Surface reflectance

Surface reflectance is defined as the fraction of incoming solar radiation that is reflected from Earth's surface for specific incident or viewing cases (directional, conical, and hemispherical cases).