World's largest iceberg stuck spinning in ocean near Antarctica
A23a formed in 1986 when it calved from the Filchner-Ronne Ice Shelf on the northwestern side of Antarctica.
World's largest iceberg stuck spinning in ocean near Antarctica
Satellite imagery shows the Rhode Island-sized iceberg known as A23a spinning in place near Antarctica throughout the month of October. (Courtesy: CSU/CIRA & NOAA)
Satellite imagery shows the Rhode Island-sized iceberg known as A23a spinning in place near Antarctica throughout the month of October.
Currently located north of the South Orkney Islands of Antarctica, A23a can be seen spinning counterclockwise about 15 degrees a day.
The spinning iceberg. (CSU/CIRA & NOAA / FOX Weather)
This movement is being caused by a column of whirling water called a "Taylor Column," which trapped the iceberg back in April, according to NASA. Objects caught in a Taylor Column can remain trapped for as little as a few days to as much as a few years.
A23a became trapped in the water column back in April, as it was riding the ocean currents from the Weddell Sea to the Southern Ocean toward South America, NASA said.
Known as "Iceberg Alley," this path would have brought the iceberg to warmer waters, where it would eventually melt.
True color image of A23a from Oct. 20, 2024. (NASA / NASA)
NASA scientists are unsure about when A23a will reach those warmer waters or when A23a will stop spinning inside the Taylor Column off of Iceberg Alley.
"How long this will continue is anyone’s guess," they stated.
A23a formed in 1986 when it calved from the Filchner-Ronne Ice Shelf on the northwestern side of Antarctica. Unlike other icebergs that float off, A23a became stuck as it hit the seafloor of the Weddell Sea almost immediately after calving.
The iceberg only became free about 34 years later in 2020, according to NASA. Since then, it has ridden the currents off the Antarctic coast.
Path of A23a, from Aug. 2011 (dark blue spot) until Nov. 2023 (white iceberg shape). The southern tip of South America can be seen near the top left corner of the image. (NASA Earth Observatory / NASA)
The iceberg was named "A23a" due to the naming system of the U.S. National Ice Center (USNIC), in which "A" denotes the Bellingshausen/Weddell Sea quadrant the iceberg was from, "23" meaning it was the 23rd iceberg in that quadrant to be tracked by the USNIC, and "a" means it was the main or parent iceberg that calved.