An astronaut aboard the International Space Station (ISS) focused a camera on the Bosphorus, also called the Istanbul Strait, which famously divides Europe (lower half of the image) from Asia (upper). Turkey’s largest city, Istanbul, flanks both shorelines.

Forested parks (lower left) contrast with the red roof tiles of the cityscape, one of the most striking features of Istanbul when viewed from space. Three bridges connect the opposite shores, two of which appear in the image—the Bosphorus Bridge and the Fatih Sultan Mehmet Bridge, which is named for Mehmed the Conqueror.

Highways lace the city, connecting clusters of high-rise buildings that stand out from the tiled roofs and cast more shadow than shorter buildings. Taksim Square is the center of modern Istanbul. It appears as an open space near the Dolmabahce Palace, the administrative heart of the Ottoman Empire in pre-republic centuries.

The Bosphorus enables significant amounts of international shipping to move between the Mediterranean Sea and the Black Sea. It is especially important as an outlet for Russian oil products.

In this photograph, a few ships are visible in the waterway. At several points they need to make dangerously sharp turns, with coastlines obstructing visibility. This is especially true at Yeniköy and Kandilli Point. Navigation is made more hazardous because currents can reach 7 to 8 knots (3.6 to 4.1 meters per second). The risks of navigating the Bosphorus are multiplied by the heavy ferry traffic linking the European and Asian shores.

To reduce the number of ships and to improve safety in this narrow waterway—just 1050 meters (1140 yards) at the Bosphorus Bridge—officials have proposed to dig a new waterway. The Kanal Istanbul would connect the Mediterranean and Black Sea at a point 70 kilometers (45 miles) to the west of Istanbul.

Astronaut photograph ISS051-E-12977 was acquired on April 13, 2017, with a Nikon D4 digital camera using an 1150 millimeter lens, and 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 51 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 Contract at NASA-JSC.