Internet forums exploded after an astonishing time-lapse video of the Earth taken from the International Space Station revealed more that was first thought - a mystery city that 'shouldn't have existed'.
The dramatic video displays the Earth illuminated by the green glow of the Aurora Borealis, and cities represented as bright spots of electric lights.
Taken by the crew of the ISS between August and October 2011, the clip was an immediate online hit.
But one of the thousands of people who saw the video noticed what appeared to be a mystery city, located near Edmonton in Canada, that did not appear on any map.
The strange collection of lights in North Dakota, USA, appeared to be equivalent in size to cities as large as Calgary and Minneapolis, but seemed impossible to identify.
The mystery was solved when a local news editor, Ken Paulman, used surrounding locations to work out that the 'city' was in fact... an oil field.
A really big oil field.
The giant Dakken oil field, to be precise, which along with the buildings housing machinery and its workers also experiences a fair few natural gas flares - hence the bright lights.
The precise size and output of the enormous facility is the subject of huge debate, but as the video shows whatever its precise dimensions it's definitely large enough. Things that are visible from space tend to be, after all...
Take a look for yourself at around 0:34 in the video, below.