The Siljan Ring in south-central Sweden Today’s Image of the Day from NASA Earth Observatory features Dalarna County in south-central Sweden, which contains the Siljan Ring.

During the Late Devonian period about 380 million years ago, this region was the site of a major asteroid impact. 

The Siljan impact structure, also known as the “Siljan Ring,” is still visible after hundreds of millions of years of erosion. The structure, which measures about 30 miles across, is the largest of its kind in Europe. Sweden , officially the Kingdom of Sweden (Swedish: Konungariket Sverige [ˈkôːnɵŋaˌriːkɛt ˈsvæ̌rjɛ] (listen)), is a Nordic country in Northern Europe. It borders Norway to the west and north, Finland to the east, and is connected to Denmark in the southwest by a bridge-tunnel across the Öresund Strait. At 450,295 square kilometres (173,860 sq mi), Sweden is the largest country in Northern Europe, the third-largest country in the European Union, and the fifth largest country in Europe. The capital city is Stockholm. Sweden has a total population of 10.4 million; and a low population density of 25 inhabitants per square kilometre (65/sq mi). 87% of Swedes live in urban areas, which cover 1.5% of the entire land area. The highest concentration is in the central and southern half of the country.

According to NASA, people have lived for millennia near the crater without knowing its cosmic origin. A recent study in 2019 found that deep, fractured rocks in the crater were suitable for ancient life.  The National Aeronautics and Space Administration is an independent agency of the U.S. federal government responsible for the civilian space program, as well as aeronautics and space research.

The image of the Siljan Ring was captured on June 24, 2020 by the Operational Land Imager (OLI) on Landsat 8. 

Image Credit: NASA Earth Observatory 

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By Chrissy Sexton, Earth.com Staff Writer