The Earth at night: Stunning images of the cities that light up the globe



It may look like an intriguing star constellation far away in space, but these lights are actually far closer to home. This image shows London at night as viewed by the International Space Station.

Taken by astronaut Donald Pettit on his last mission on the ISS, it shows England's capital shortly after 7.22pm on a cloudy February 4, 2003. He is due to return to space for the second time on the shuttle Endeavour later this week and no doubt looks forward to capturing yet more stunning images.





The orbital motion photo shows London at night (top). Cloud obscures some of the smaller cities

London's orbital motorway, the M25, is most clearly running south of the city. The darkened Thames river estuary fans out to the east, while dark pockets slightly west of the densely packed lights in the centre reveal Hyde Park and Regent's Park.

Mr Pettit captured his images after he constructed a device called a camera mount called a barn-door tracker on board the station.

Donald Pettit looks out at the Canary Islands from the space station

It is commonly used by astronomers on the ground to capture images of the stars, which compensates for the rotation of the Earth relative to the stars. However, Mr Pettit used it to compensate for the movement of the space station relative to the Earth below.

The careful coordination kept the target city in the same position during a long exposure, producing detailed photos. The astronauts have now captured hundreds of images of cities from around the world with this technique with a level of detail of about 60 metres.

Border cities like Ciudad Juaréz, Mexico and El Paso, Texas, show cultural differences influencing city planning.

On the U.S. side of the Rio Grande, El Paso is marked by the brightly-lit Interstate Highway that cuts through the city. The American-style grids of the city differs markedly from Ciudad Juaréz, which has a European inspired pattern of curved streets.

This image shows El Paso in America to the North and the far more densely populated Ciudad Juar in Mexico below

Tokyo Bay: Lights in Japan glow a cooler blue-green colour

Cities from different regions of the Earth can also be identified by the different colours that the lights throw off. Japanese cities such as Tokyo glow a cooler blue-green than other regions of the world and patches of orange along the shore of Tokyo Bay reveal more advanced orange sodium vapour lamps, compared to the light green mercury vapour lamps inland.

As populations expand and urban areas grow, individual cities will merge into ever larger bright blobs. More roads will connect those cities to form an illuminated, lace-like web across the continents. And the snappers on the ISS no doubt hope there will be someone up in space to chart the changes.



More images taken by astronauts in space can be viewed at http://eol.jsc.nasa.gov/

