This oblique nighttime image, taken by an astronaut aboard the International Space Station, reveals Indonesia's main island chain. With coasts illuminated by city lights, the islands stand out against the darkness of the Indian Ocean. The island of Java is the geographic and economic center of Indonesia. With a population of more than 141 million people, it is the world's most populous island.

Java is part of the Greater Sunda Islands, a chain of active volcanoes that form an island arc. The volcanoes constrain the growth of populated areas and can be distinguished at night as a line of dark circles surrounded by city lights. These densely populated islands are at risk of volcanic eruptions, earthquakes, and tsunamis due to tectonic activity from the Sunda Subduction Zone that formed the islands.

The brightest urban area is Java's port city of Surabaya, Indonesia's second largest city and the capital of the province of East Java. The Port of Tanjung Perak, located at Surabaya, is Indonesia's second busiest sea port. Ships arriving and departing transport over 33 million tons of cargo and 9 million people annually. Individual and clustered lights seen around Java are ships and fishing boats. The fishing boats emit bright lights of different colors to attract fish, squid, and plankton.