![]() In space, it allows astronauts to compensate for the movement of the Space Station relative to the Earth below. On the ground, the device allows photographers to compensate for the rotation of the Earth relative to the stars. The camera is mounted on a hinged platform that can be moved very slowly and precisely (by turning a knob). A barn-door tracker is a camera mount commonly used by astronomers and photographers on the ground to capture images of stars and planets in the night sky. In late 2002 and early 2003, astronaut Don Pettit, part of International Space Station Expedition 6, spent some time accumulating spare parts from around the space station, and constructed a device called a barn-door tracker. Image ISS016-E-27162 was taken on February 4, 2008, using the 400 mm lens, providing superior resolution. Orange sodium vapor lights illuminate the port facilities of Long Beach, California, supporting the round-the-clock operations of one of the world’s busiest commercial cargo ports. The longer the exposure, the more motion blurring there will be. As the Space Station (or Space Shuttle) flies over Earth, however, the city the astronaut is trying to photograph will move across the camera’s field of view while the shutter is open-a recipe for blurry images. With the Earth’s surface in darkness, night images of cities require much longer exposure times. With daylight illumination, an onboard camera can be set to take an image with an exposure time of just 1/500 of a second. ISS007-E-16525 (bottom) was taken on October 7, 2003, with a 50 mm lens.īut taking pictures in the dark is difficult at best, made even more difficult by the fact that the International Space Station moves more than 7 kilometers per second (15,659 miles per hour) relative to Earth’s surface. By night (lower), the region’s ten million people cannot be missed. By day (top), the cement-colored urban center of the city blends almost imperceptibly into the gray-green colors of suburbs and then farmland. ![]() Onboard cameras and a bit of experimentation allow astronauts to take highly detailed images of our cities at night and share them with the rest of us.Ĭhicago, Illinois, is home to roughly three million people, but the wider metropolitan area includes nearly 10 million. That “Night Lights” map, widely distributed on the Internet, helped many people visualize the world’s distribution of people and cities.Īstronauts circling the Earth have the wonderful vantage point of observing the nighttime Earth from 350-400 kilometers above the surface, taking in whole regions at once. Image ISS016-E-27034 was taken on February 1, 2008, using a 28 mm lens.Īt night however, city lights present the space observer spectacular evidence of our existence, our distribution, and our ability to change our environment.Ī few years ago, NASA and NOAA joined forces to present the first world map of the nighttime Earth using 9 months of data collected by the DMSP (Defense Meteorological Satellite Program) satellite from an altitude of 830 kilometers (1 kilometer is 0.62 miles) above Earth. Looking east from a location southwest of Ireland, an astronaut took this nighttime panorama of population centers in Ireland and the United Kingdom. But what about humanity’s signature footprint-cities? By day, cities viewed from space can blend into the countryside, or appear as gray smudges, depending on the style of development and size of the urban area. They include the regular patterns of irrigated cropland, straight lines of roads and railways running across continents, reservoirs on river systems, and the cement rectangles of ports and seawalls along coastlines. To an observer in space, humanity’s footprints on the surface of the Earth are large and varied. At the time of publication, it represented the best available science. This page contains archived content and is no longer being updated.
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