Careful observers of the new "Black Marble" images of Earth at night released this week by NASA and the National Oceanic and Atmospheric Administration have noticed bright areas in the western part of Australia that are largely uninhabited. Why is this area so lit up, many have asked?

Away from the cities, much of the night light observed by the NASA-NOAA Suomi NPP satellite in these images comes from wildfires.

In the bright areas of western Australia, there are no nearby cities or industrial sites but, scientists have confirmed, there were fires in the area when Suomi NPP made passes over the region. This has been confirmed by other data collected by the satellite.

The extent of the night lights in this area is also a function of composite imaging. These new images were assembled from data acquired over nine days in April 2012 and 13 days in October 2012.

This means fires and other lighting (such as ships) could have been detected on any one day and integrated into the composite picture, despite being temporary phenomena.

Because different areas burned at different times when the satellite passed over, the cumulative result in the composite view gives the appearance of a massive blaze. These fires are temporary features, in contrast to cities which are always there.

Other features appearing in uninhabited areas in these images could include fishing boats, gas flaring, lightning, oil drilling, or mining operations, which can show up as points of light. One example is natural gas drilling in the Bakken Formation in North Dakota.