A disc of dark matter might have just been found hanging over the Equator of the Earth. But don't panic.
The startling claim has been made by a scientist examining why the Earth appears to be slightly heavier than previously thought.
Dark matter is the almost-theoretical substance which helps explain why there is nowhere near enough visible matter in the universe to account for the way it's developed since the Big Bang.
But while most models of the universe suggest dark matter is abundant, experiments have tried (and so far mostly failed) to find direct evidence of it.
Now one scientist says it might have been hanging above our heads the entire time.
Ben Harris, from the University of Texas, said at the American Geophysical Union that GPS data implies the Earth is heavier than it 'should' be.
The difference between the number he's calculated, and that taken as read by the International Astronomical Union, could be caused by the presence of nearby Dark Matter, he thinks.
In his study, Harris used data from the European Galileo, U.S., GPS, GLONASS and Russian satellite groups, and measured the weight of the Earth. His result is 0.005-0.008 percent bigger than current estimates. A disc of dark matter over the equator could account for the difference, he said - being picked up by satellites overhead while being missed by regular methods used to weigh our planet.
This disc would be 191 kilometres thick and 70,000 km wide, he suggests.
However, we have to add a hefty load of caveats here. First, there are potential flaws with the methodology. New Scientist points out that the study doesn't account for subtle changes in the orbit of satellites caused by relativity and the gravity of the sun and moon. It's also pretty much conjecture, even if the data is accurate - there is no direct evidence of dark matter above our Earth, and much more study would be needed to get it.
On the other hand, if 80% of our universe really is dark matter, it wouldn't be crazy to think there would be some nearby. If only it wasn't so - well - dark, we might just be able to see it in plain sight very close to home indeed.