Around July 10–12, 2017, in the middle of the long, dark Antarctic winter, a rift in the Larsen C Ice Shelf broke through the last few miles of ice to the Weddell Sea and formed a new iceberg. The NOAA National Ice Center has given the Delaware-sized iceberg the designation A-68. Even in the darkness, Earth-observing satellites are monitoring this new iceberg with infrared imaging.

In a July 12 image, the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA’s Aqua satellite shows relatively warm open water completely around the new iceberg. The crack between the iceberg and the ice shelf is really a soup of floating, broken pieces of ice on top of the water.

On the same date, the Thermal Infrared Sensor (TIRS) on Landsat 8 recorded its own image showing the relative temperature of the ice and the rift. The bright line, located at the edge of the Landsat scene, is sea water at the freezing point rather than frozen solid. Normally, Landsat acquisitions for Antarctica are suspended when the Sun gets close to the horizon around early April. A special acquisition request was made to get nighttime imagery of the Larsen C area to help track the growth of the rift as it got closer to breaking free.

Landsat and MODIS will continue to monitor the movement of the iceberg as it separates from the ice shelf and likely drifts northward along the Antarctic Peninsula. Many factors will affect the iceberg’s future motion, including wind, tide, and current, and the fact that ice on the sea next to the iceberg will inhibit it from drifting as far as it would if there were no ice. All of these factors will be visible thanks to the satellites’ thermal infrared imaging.