Each December Antarctica enjoys round-the-clock sunlight. The light arrives at a low angle, however, as the Sun makes a daily circuit around the horizon, and icebergs cast long shadows over the surrounding sea ice.

Surrounding the icebergs are two kinds of ice: sea ice and fast ice. Along the left edge of the image, the sea ice is thinner, with gaps that reveal the dark ocean below. Clinging to the shore, fast ice is thicker,