A night-time image of Australia by the new space-borne VIIRS
instrument shows what looks like large cities in the most remote
outback. What gives?
It turns out VIIRS (which stands for Visible Infrared Imaging Radiometer Suite) is so sensitive it can make out
fires, and even discriminate between bright flames and electric lights, and a whole lot more.
NASA has been recently pelted with questions about Australia's remote lights because it and NOAA recently released skads of new VIIRS images and a "black marble" visualization od the Earth at night.
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.
