There are five spots on this map that should be illuminated at night. They are, from left to right, Perth (bottom left corner), Adelaide, Melbourne, Sydney, and Brisbane. Everywhere else should be largely dark because Australia's interior is one of the least populated regions on Earth. NASA describes why there's so much light:
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.