21.   Satellites can take high-resolution pictures of the ground, intercept radio and mobile telephone communications and take radar images.

22.   Radar images and data are put side-by-side to provide a composite picture of sea and air traffic.

23.   Radar images showed the enormous storm hovering directly over Puerto Rico late Monday night, its center close to the southern coast.

24.   That allows radar images to be relayed to the ground without landing for a film drop-off.

25.   The continuing radar images after that could indicate an in-flight breakup, with smaller pieces drifting down more slowly.

26.   The spill cast dark oblong spots in sepia-toned radar images.