Earth may have a dark matter disc

Our planet Earth may have a disc of dark matter around the equator, according to a new study that analysed data from GPS satellites.
Ben Harris at the University of Texas at Arlington conducted an analysis of Global Positioning System (GPS) satellite orbits and found that Earth is heavier than thought, perhaps due to a halo of dark matter.
Dark matter is estimated to constitute more than 80 per cent of the total matter in the universe, but little else is known about it, including its distribution in the solar system.
Harris collected nine months of data from several GPS satellites that are in orbit around our planet and calculated Earth's mass as "felt" by each one, 'New Scientist' reported.

Harris found an average figure that was between 0.005 and 0.008 per cent greater than the value for Earth's mass established by the International Astronomical Union.
A disc of dark matter around the equator 191 kilometres thick and 70,000 km across can explain this, he said.
However, Harris's theory does not take into account changes in orbits of satellites that occur because of relativity, or the impact of gravity from the Sun and Moon.
The study was presented at a meeting of the American Geophysical Union in San Francisco in December.