The image on the left is an Envisat ASAR mosaic of Arctic ice acquired on 24 August 2005. The right image is an EOS Aqua AMSR-E ice concentration acquired on the same day. The uniform grey area in the ASAR image and the pink colour in the AMSR-E image are both consistent all the way around the pole (black hole), indicating pack ice with 100% ice concentration. Credit: Polar View, Leif Toudal Pedersen