Far out: How the Earth looks at night

Images of the Earth taken from space may soon be available online only hours after they're snapped.

NASA, which has just released the first global look of the world as seen from space at night in five years, says earthgazers won't have to wait so long in future.

"Produced every decade or so, such maps have spawned hundreds of pop culture uses and dozens of economic, social science and environmental research projects," the space agency wrote on its website on Thursday.

"But what would happen if night lights imagery could be updated yearly, monthly or even daily?"

The NASA-NOAA Suomi National Polar-orbiting Partnership (NPP) satellite, launched in 2011, sees almost every spot on the planet twice a day. Improvements have been made in analysing data from its VIIRS instrument, taking into account the different lighting conditions the moon and weather cause.

India as seen from space, 2016 (NASA)
India as seen from space, 2016 (NASA)

As a result, its imagery has six times the resolutionand 250 times better lighting range than previous cameras pointed at Earth.

"And because Suomi NPP is a civilian science satellite, the data are freely available to scientists within minutes to hours of acquisition," NASA says.

Artist illustration of the Suomi NPP satellite (file)
Artist illustration of the Suomi NPP satellite (file)

Getting the images online quickly could help with short-term weather forecasting and disaster response.

"Thanks to VIIRS, we can now monitor short-term changes caused by disturbances in power delivery, such as conflict, storms, earthquakes and brownouts," says scientist Miguel Román of NASA's Goddard Space Flight Center.

"We can monitor cyclical changes driven by reoccurring human activities such as holiday lighting and seasonal migrations. We can also monitor gradual changes driven by urbanisation, out-migration, economic changes, and electrification.

"The fact that we can track all these different aspects at the heart of what defines a city is simply mind-boggling."

NASA's website has example shots from 2012 and 2016, showing how cities have grown and populations have spread in the past few years.

It calls the nighttime map 'Black Marble', a reference to the 1972 photograph of the Earth taken by the Apollo 17 crew, known as 'Blue Marble'.

NASA also used the 'Blue Marble' name for its daytime Earth maps.