An unusual, rectangular iceberg floating in a sea off Antarctica was captured by one of NASA’s research planes.
The aircraft flyover was part Operation IceBridge, NASA’s longest-running aerial survey of polar ice. It flew over the Weddell Sea in the northern Antarctic Peninsula on Oct. 16, 2018.
Jeremy Harbeck, a scientist with the U.S. space agency, spotted the unusually angular iceberg.
“I often see icebergs with relatively straight edges, but I’ve not really seen one before with two corners at such right angles like this one had,” Harbeck said in a statement.
The U.S. space agency said the object’s sharp angles and flat surface suggested it had recently broken away from an ice shelf. The sharpness of the edges indicates the iceberg had not yet been worn down by ocean waves.
“The iceberg’s sharp angles and flat surface indicate that it probably recently calved from the ice shelf,” NASA tweeted, referring to the Larsen C ice shelf.
From yesterday's #IceBridge flight: A tabular iceberg can be seen on the right, floating among sea ice just off of the Larsen C ice shelf. The iceberg's sharp angles and flat surface indicate that it probably recently calved from the ice shelf. pic.twitter.com/XhgTrf642Z
— NASA ICE (@NASA_ICE) October 17, 2018
Harbeck’s camera also captured a similarly regular, though slightly less rectangular, iceberg. The second iceberg is called A68.
“I was actually more interested in capturing the A68 iceberg that we were about to fly over, but I thought this rectangular iceberg was visually interesting and fairly photogenic, so on a lark, I just took a couple photos,” Harbeck said.
One of Harbeck’s photos includes both a fragment of the rectangular iceberg, as well as A68 in the distance.
Scientists said icebergs with regular features are common enough to be known by a special term—tabular icebergs.
Geophysicist Kristin Poinar from the University at Buffalo told National Geographic that icebergs are full of cracks, along which they may fracture.
“[Icebergs] look like these beautiful pristine white things from a distance, but if you look a little closer, they’re really mangled and full of cracks,” she said.
“The Larsen C is a large ice shelf. The ice has time to spread out and become perfectly flat,” Poinar added, explaining that as the ice shears off, or calves, it may be highly regular in shape.
Sea ice specialist Alek Petty, a research scientist with Operation IceBridge, told NPR that the process could be compared to a glass plate shattering, where the edges are often straight. “You can just get these fracture lines that can form these interesting geometric structures,” he said.
A case in point would be a triangle-shaped iceberg spotted by NASA scientists recently and tweeted on Oct. 19.
From yesterday's #IceBridge flight:Triangular iceberg surrounded by many different types of sea ice, off the Larsen ice shelf in the Weddell Sea. In the open water, grease ice is forming. pic.twitter.com/L4WB36bV5H
— NASA ICE (@NASA_ICE) October 19, 2018
While it is difficult to estimate the size of the iceberg from the photograph, experts said it was likely over a mile (1.6 kilometers) in length.
Senior research scientist Ted Scambos with the University of Colorado at Boulder told National Geographic that in his estimation, the iceberg is about 130 feet (40 meters) tall and anywhere from a mile or two long.
“If you total the tons of ice [it contains], it would fill every swimming pool in California several times over,” he said.
NASA said the flight that captured the rectangular iceberg originated in Punta Arenas, Chile, and is part of a five-weeklong IceBridge deployment that started on Oct. 10.
The aim of the survey is to assess changes in the ice height of several glaciers draining into the Larsen A, B, and C embayments.