A massive hole opened in the middle of the frozen Weddell Sea of Antarctica last month. Persistent areas of open water in places where you’d expect sea ice, such as in the Arctic and Antarctic, are known as polynyas, according to the National Snow and Ice Data Center. This Weddell polynya, however, is somewhat remarkable. No one knows why it formed, and the hole is located quite far from the sea ice coastline, where such openings more frequently appear. And despite being exposed to freezing wintry

winds over the past month, the polynya has persisted — so whatever force caused it to form is strong enough to keep it from refreezing. But it’s not the first time this particular hole has appeared. Scientists observed a similar polynya in the same area of Antarctica in 1974, according to NASA Earth Observatory. It reappeared during the austral winters of 1975 and 1976, then disappeared and it didn’t re-emerge for decades. It re-appeared again in August 2016,  READ MORE