The discovery of the Parshall Oil Field in 2006 set off a multi-billion dollar energy boom in North Dakota's Bakken Oil Patch.

Daytime imagery from Earth-observing satellites has documented explosive urban growth in places like Williston and Watford City. But proof of the oil industry's rapid expansion is clearest when the sun goes down. In 1995, North Dakota cities are small but distinct yellow spots. After the boom, bursts of light explode across that landscape to create a brightness footprint for the Bakken less luminous but larger than the one created by the Twin Cities of Minneapolis and St. Paul.

The wide scale images represent the artificial lights of cities and well-lit oil pads. But finer resolution nighttime imagery from Landsat reveals another aspect of the oil boom: gas flares.

Natural gas is a byproduct of oil drilling. Much of it is captured, refined and sold, but about 20% of North Dakota's gas is burned off at the drill site. Landsat's thermal, shortwave infrared, and near infrared bands render the gas flares as blue-green flecks corresponding with oil pads visible in daytime imagery.