Beyond City Lights—Java Sea

The visible lights produced by modern civilization are often obscured by the more intense light of the Sun during the day. However, as this photograph—taken over the Java Sea by a member of the Expedition 42 crew onboard the International Space Station—reveals, at night these “nighttime lights” become visible. To the discerning eye, these lights reveal intricate details of both natural phenomena and the unmistakable footprints of human civilization. The photo, taken on October 20, 2014, captured light from roads and cities, fishing boats, lightning, airglow, and even a few gas flares. North of the city of Surabaya, the capital of East Java province, large numbers of boat lights dot the darkened Java Sea. Many of these vessels are likely fishing boats using bright lights to attract squid and other sea life. According to one estimate based on satellite observations, there were over 500 fishing boats in the area on a single night in September 2014. The same study pointed out that two of the brighter points of light in the area are gas flares emanating from offshore oil infrastructure. In addition to the human activity, the photograph also showcases a few natural splashes of light and color. The blue-white patch on the far left is a flash of lightning, a common sight for astronauts. The glowing line along Earth’s limb—or edge of the atmosphere—is airglow, a type of light that is produced by chemical reactions in the upper atmosphere. While airglow can also be green or blue, red airglow like this comes from excited oxygen atoms at heights of about 90 to 190 miles (150 to 300 kilometers).

See NASA Earth Observatory