Help NASA create atlas of night-time photos of our planet!

A host of images of Earth at night taken by astronauts on the International Space Station (ISS) could help save energy and improve our understanding of atmospheric chemistry - but NASA needs your help to make that happen.
The images are available to the public through 'The Gateway to Astronaut Photography of Earth'. The database has photographs beginning with those taken during Mercury missions in the early 1960s up to recent images from the station.
As of August 2014, the collection included a total of nearly 1.8 million images, more than 1.3 million of them from the space station. Approximately 30 per cent of those were taken at night.

The photographs taken by astronauts on the station are the highest-resolution night imagery available from orbit, according to William Stefanov, PhD, associate programme scientist for Earth observations for the space station.
While the pictures are clear, their location may not be, which limits their usefulness. This is where citizen science comes in.
The Complutense University of Madrid (UCM) is leading a project called Cities at Night to catalog the images. It includes three citizen science components: Dark Skies of ISS, Night Cities, and Lost at Night.

Dark Skies asks people to sort images into those of cities, stars and other objects. The simplest of the three projects, it requires no specific expertise.

"Anyone can help. In fact, without the help of citizens, it is almost impossible to use these images scientifically. Algorithms cannot distinguish between stars, cities, and other objects, such as the moon. Humans are much more efficient for complex image analysis," said Alejandro Sanchez, a PhD student at UCM.
For Night Cities, citizen scientists use their knowledge of local geography to identify points in night images and match them to positions on maps.
As Sanchez explained, a resident of a city can likely identify its features more easily than someone who does not live there.
Lost at Night requires the most skill, seeking to identify cities in images encompassing a circle 498 km around.

"We don't know which direction the astronaut pointed the camera, only where the station was at the time the image was taken," said Sanchez.
So far, hundreds of volunteers have classified nearly 20,000 images, but to ensure accuracy, each one should be classified by multiple individuals.
The primary goal of the project is producing an open atlas of night time images available any time for use by the media, public, and scientists.
Scientists can, for example, use colours in images to estimate the types of light sources and, thus, the energy efficiency of a particular city.
Other potential applications include evaluating lighting for road and public safety and correlating light pollution with effects on human health and biodiversity.