Maps

What Produces More Light Pollution in Australia: Cities or Wildfires?

Parts of the outback are lit up with so much flame they look like huge metropolises at night.

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When we published NASA's phenomenal surveillance photos of sleeping Earth, some people wondered why powerful lights were blazing in areas with no significant population centers. Wrote one observer: "There's something wrong with that image – way too much light showing up in the Australian outback."

It seems other folks were bugging NASA about these phantom cities, too. On Thursday, the space agency released a picture of one of the biggest generators of mystery glows, Western Australia, explaining that what people were seeing in that remote terrain are humongous wildfires burning the bush away. (Super-large version here.)

These backwoods conflagrations appear so colossal that they outshine the city lights of Sydney, Melbourne, Perth and other Australian metropolises. But that's partly due to an optical illusion created by the way this image was generated. The blackened Australia above is actually a composite of Suomi NPP satellite photos taken over 22 days in April and October. Explains NASA:

Fires and other lights that were detected on one day were integrated into the composite, multi-day picture despite being temporary phenomena. Because different lands burned at different times that the satellite passed over, the cumulative result is the appearance of a massive blaze. But while the cities are fixed, the fires were temporary, moveable features. The night lights data set is a scientific work in progress, and the maps will be refined and improved over time.

So if you live in Australia, you can stop worrying about immense wildfires sucking all the oxygen from the air. Don't be led into thinking that these outlands eruptions are small affairs, though. Here's what they looked like to an astronaut aboard the International Space Station one night last September:

(NASA)

Anybody who ventures out of the city and into the Outback will find a smoky territory pocked with the scars of old burns. In just 13 days in October, fires consumed a chunk of real estate much huger than the sprawl of five major Australian cities, represented here in black:

(NASA/MODIS)

So that's one braintwister solved. As to that other question of why North Dakota is lit up like a military base on full alert, NASA's got your answer right here – it's drilling equipment and gas flares in the oil-rich Bakken shale.

Top image courtesy of the NASA Earth Observatory.

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