The largest and brightest cluster of urban lights is South Korea’s capital city, Seoul (population 9.67 million), located on the coast of the Yellow Sea. Only two small clusters of lights are easily visible in North Korea: the capital Pyongyang (population 3.16 million) and Yangdŏk in the country’s center.

Just north of Seoul, a thin line of lights crosses the peninsula from the Yellow Sea to the Sea of Japan, marking the demilitarized zone (DMZ) between North and South Korea. The DMZ border, established in 1953 by the United Nations, is about 4 kilometers (2.5 miles) wide and 250 kilometers (155 miles) long.

Differences in the brightness and expanse of city lights illustrates the distinction between the population sizes—South Korea with about 52 million people and North Korea with about 26 million—and between the extent of urban development in the two countries. Images of nighttime lights have also been used for studying economies and gross domestic product (GDP). Because of its dynamic industrial growth since the 1960s, South Korea has been termed one of Asia’s four “economic tigers” along with Singapore, Taiwan, and Hong Kong.

Astronaut photograph ISS070-E-80670 was acquired on January 24, 2024, with a Nikon D5 digital camera using a focal length of 24 millimeters. It is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 70 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by Justin Wilkinson, Texas State University, JETS II Contract at NASA-JSC.