One of the first photos taken by Envisat, ESA's Earth observation satellite in April 2002.
This image is a colour composite generated from ASAR data acquired on 8 April 2002 in Alternating Polarisation (AP) mode. The red channel contains the VV polarised image; the green channel contains the HH polarised image; the blue channel contains the magnitude of the difference between the amplitudes in VV and HH.
It shows an area, 100 km wide, around the city of Arzamas in Russia (bottom right), 300 km east of Moscow. The city appears bright yellow because backscatter is equally high in VV and HH polarisation. To the north and south are agricultural regions, where individual fields are visible in shades of magenta and purple because of the strong VV backscatter. The green/yellow colour that dominates the centre of the image results from the forests in this region (medium backscatter in VV and HH). The Tesha River skirts the northern edge of the lower region. In the centre of the image the banks of a large river system, which is probably still frozen, are highlighted in cyan (HH backscatter dominates).