What does this mean? Well, it could indicate some unforeseen error in data collection or analysis (in the GPS or IAU measurements), but there is another more intriguing possibility.
ANALYSIS: How Low Can a Dark Matter Halo Go?
This mass discrepancy could be the influence of a halo, or ring, of dark matter surrounding Earth. By Harris' reckoning, to explain his measurements, the invisible planetary dark matter halo would need to straddle the equator and be 191 kilometers (119 miles) thick by 70,000 kilometers (43,500 miles) wide.
As noted by New Scientist's Anil Ananthaswamy, Harris has yet to factor in the effects of relativity and gravitational interactions with the sun and moon.
This research highlights the gaps in our knowledge dark matter. Non-baryonic matter is believed to account for 85 percent of all matter in the universe, but we have yet to directly observe this elusive form of matter, let alone create it in immense particle accelerators like the Large Hadron Collider. We know it's out there, however, bulking-out galactic clusters and warping spacetime. Through indirect means, such as gravitational lensing and orbital motions, we can detect the stuff and this most recent GPS measurements provide another tantalizing means of understanding the subtle mass effects on a potential Earth-dark matter coupling.