Sea Ice Cracks Up

In less than a day, a chunk of ice bigger than Rhode Island broke away from Antarctica and shattered into many pieces this week.

NASA's Aqua and Terra satellites captured the event, at the Ronne-Filchner Ice Shelf, in a series of photo-like images on Jan. 12-13.

The long, narrow tongue of ice is a bridge of sea ice linking the A-23A iceberg to the Ronne-Filchner Ice Shelf in West Antarctica. The ice bridge is fast ice, or sea ice that does not move because it is anchored to the shore. Compared to an ice shelf, the sea ice is a thin shell of ice over the ocean.

The difference in thickness is visible in the images. The taller, thicker Ronne-Filchner Ice Shelf casts a visible shadow on the ice bridge made of sea ice. This particular ice bridge breaks up and reforms regularly. Even though the images show a routine event, they provide a spectacular view of the sometimes dramatic arrival of summer in the Polar South.

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